Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
#include "cache.h"
|
|
|
|
|
#include "tree-walk.h"
|
|
|
|
|
#include "xdiff-interface.h"
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
#include "blob.h"
|
|
|
|
|
#include "exec_cmd.h"
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
|
|
|
|
|
static const char merge_tree_usage[] = "git merge-tree <base-tree> <branch1> <branch2>";
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
static int resolve_directories = 1;
|
|
|
|
|
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
struct merge_list {
|
|
|
|
|
struct merge_list *next;
|
|
|
|
|
struct merge_list *link; /* other stages for this object */
|
|
|
|
|
|
|
|
|
|
unsigned int stage : 2,
|
|
|
|
|
flags : 30;
|
|
|
|
|
unsigned int mode;
|
|
|
|
|
const char *path;
|
|
|
|
|
struct blob *blob;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
static struct merge_list *merge_result, **merge_result_end = &merge_result;
|
|
|
|
|
|
|
|
|
|
static void add_merge_entry(struct merge_list *entry)
|
|
|
|
|
{
|
|
|
|
|
*merge_result_end = entry;
|
|
|
|
|
merge_result_end = &entry->next;
|
|
|
|
|
}
|
|
|
|
|
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
static void merge_trees(struct tree_desc t[3], const char *base);
|
|
|
|
|
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
static const char *explanation(struct merge_list *entry)
|
|
|
|
|
{
|
|
|
|
|
switch (entry->stage) {
|
|
|
|
|
case 0:
|
|
|
|
|
return "merged";
|
|
|
|
|
case 3:
|
|
|
|
|
return "added in remote";
|
|
|
|
|
case 2:
|
|
|
|
|
if (entry->link)
|
|
|
|
|
return "added in both";
|
|
|
|
|
return "added in local";
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/* Existed in base */
|
|
|
|
|
entry = entry->link;
|
|
|
|
|
if (!entry)
|
|
|
|
|
return "removed in both";
|
|
|
|
|
|
|
|
|
|
if (entry->link)
|
|
|
|
|
return "changed in both";
|
|
|
|
|
|
|
|
|
|
if (entry->stage == 3)
|
|
|
|
|
return "removed in local";
|
|
|
|
|
return "removed in remote";
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
extern void *merge_file(const char *, struct blob *, struct blob *, struct blob *, unsigned long *);
|
|
|
|
|
|
|
|
|
|
static void *result(struct merge_list *entry, unsigned long *size)
|
|
|
|
|
{
|
|
|
|
|
enum object_type type;
|
|
|
|
|
struct blob *base, *our, *their;
|
|
|
|
|
|
|
|
|
|
if (!entry->stage)
|
|
|
|
|
return read_sha1_file(entry->blob->object.sha1, &type, size);
|
|
|
|
|
base = NULL;
|
|
|
|
|
if (entry->stage == 1) {
|
|
|
|
|
base = entry->blob;
|
|
|
|
|
entry = entry->link;
|
|
|
|
|
}
|
|
|
|
|
our = NULL;
|
|
|
|
|
if (entry && entry->stage == 2) {
|
|
|
|
|
our = entry->blob;
|
|
|
|
|
entry = entry->link;
|
|
|
|
|
}
|
|
|
|
|
their = NULL;
|
|
|
|
|
if (entry)
|
|
|
|
|
their = entry->blob;
|
|
|
|
|
return merge_file(entry->path, base, our, their, size);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void *origin(struct merge_list *entry, unsigned long *size)
|
|
|
|
|
{
|
|
|
|
|
enum object_type type;
|
|
|
|
|
while (entry) {
|
|
|
|
|
if (entry->stage == 2)
|
|
|
|
|
return read_sha1_file(entry->blob->object.sha1, &type, size);
|
|
|
|
|
entry = entry->link;
|
|
|
|
|
}
|
|
|
|
|
return NULL;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static int show_outf(void *priv_, mmbuffer_t *mb, int nbuf)
|
|
|
|
|
{
|
|
|
|
|
int i;
|
|
|
|
|
for (i = 0; i < nbuf; i++)
|
|
|
|
|
printf("%.*s", (int) mb[i].size, mb[i].ptr);
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void show_diff(struct merge_list *entry)
|
|
|
|
|
{
|
|
|
|
|
unsigned long size;
|
|
|
|
|
mmfile_t src, dst;
|
|
|
|
|
xpparam_t xpp;
|
|
|
|
|
xdemitconf_t xecfg;
|
|
|
|
|
xdemitcb_t ecb;
|
|
|
|
|
|
|
|
|
|
xpp.flags = XDF_NEED_MINIMAL;
|
|
|
|
|
memset(&xecfg, 0, sizeof(xecfg));
|
|
|
|
|
xecfg.ctxlen = 3;
|
|
|
|
|
ecb.outf = show_outf;
|
|
|
|
|
ecb.priv = NULL;
|
|
|
|
|
|
|
|
|
|
src.ptr = origin(entry, &size);
|
|
|
|
|
if (!src.ptr)
|
|
|
|
|
size = 0;
|
|
|
|
|
src.size = size;
|
|
|
|
|
dst.ptr = result(entry, &size);
|
|
|
|
|
if (!dst.ptr)
|
|
|
|
|
size = 0;
|
|
|
|
|
dst.size = size;
|
|
|
|
|
xdi_diff(&src, &dst, &xpp, &xecfg, &ecb);
|
|
|
|
|
free(src.ptr);
|
|
|
|
|
free(dst.ptr);
|
|
|
|
|
}
|
|
|
|
|
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
static void show_result_list(struct merge_list *entry)
|
|
|
|
|
{
|
|
|
|
|
printf("%s\n", explanation(entry));
|
|
|
|
|
do {
|
|
|
|
|
struct merge_list *link = entry->link;
|
|
|
|
|
static const char *desc[4] = { "result", "base", "our", "their" };
|
|
|
|
|
printf(" %-6s %o %s %s\n", desc[entry->stage], entry->mode, sha1_to_hex(entry->blob->object.sha1), entry->path);
|
|
|
|
|
entry = link;
|
|
|
|
|
} while (entry);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void show_result(void)
|
|
|
|
|
{
|
|
|
|
|
struct merge_list *walk;
|
|
|
|
|
|
|
|
|
|
walk = merge_result;
|
|
|
|
|
while (walk) {
|
|
|
|
|
show_result_list(walk);
|
|
|
|
|
show_diff(walk);
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
walk = walk->next;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
/* An empty entry never compares same, not even to another empty entry */
|
|
|
|
|
static int same_entry(struct name_entry *a, struct name_entry *b)
|
|
|
|
|
{
|
|
|
|
|
return a->sha1 &&
|
|
|
|
|
b->sha1 &&
|
|
|
|
|
!hashcmp(a->sha1, b->sha1) &&
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
a->mode == b->mode;
|
|
|
|
|
}
|
|
|
|
|
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
static struct merge_list *create_entry(unsigned stage, unsigned mode, const unsigned char *sha1, const char *path)
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
{
|
|
|
|
|
struct merge_list *res = xcalloc(1, sizeof(*res));
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
|
|
|
|
|
res->stage = stage;
|
|
|
|
|
res->path = path;
|
|
|
|
|
res->mode = mode;
|
|
|
|
|
res->blob = lookup_blob(sha1);
|
|
|
|
|
return res;
|
Handling large files with GIT
On Tue, 14 Feb 2006, Linus Torvalds wrote:
>
> Here, btw, is the trivial diff to turn my previous "tree-resolve" into a
> "resolve tree relative to the current branch".
Gaah. It was trivial, and it happened to work fine for my test-case, but
when I started looking at not doing that extremely aggressive subdirectory
merging, that showed a few other issues...
So in case people want to try, here's a third patch. Oh, and it's against
my _original_ path, not incremental to the middle one (ie both patches two
and three are against patch #1, it's not a nice series).
Now I'm really done, and won't be sending out any more patches today.
Sorry for the noise.
Linus
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static char *traverse_path(const struct traverse_info *info, const struct name_entry *n)
|
|
|
|
|
{
|
|
|
|
|
char *path = xmalloc(traverse_path_len(info, n) + 1);
|
|
|
|
|
return make_traverse_path(path, info, n);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void resolve(const struct traverse_info *info, struct name_entry *branch1, struct name_entry *result)
|
Handling large files with GIT
On Tue, 14 Feb 2006, Linus Torvalds wrote:
>
> Here, btw, is the trivial diff to turn my previous "tree-resolve" into a
> "resolve tree relative to the current branch".
Gaah. It was trivial, and it happened to work fine for my test-case, but
when I started looking at not doing that extremely aggressive subdirectory
merging, that showed a few other issues...
So in case people want to try, here's a third patch. Oh, and it's against
my _original_ path, not incremental to the middle one (ie both patches two
and three are against patch #1, it's not a nice series).
Now I'm really done, and won't be sending out any more patches today.
Sorry for the noise.
Linus
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
{
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
struct merge_list *orig, *final;
|
|
|
|
|
const char *path;
|
|
|
|
|
|
Handling large files with GIT
On Tue, 14 Feb 2006, Linus Torvalds wrote:
>
> Here, btw, is the trivial diff to turn my previous "tree-resolve" into a
> "resolve tree relative to the current branch".
Gaah. It was trivial, and it happened to work fine for my test-case, but
when I started looking at not doing that extremely aggressive subdirectory
merging, that showed a few other issues...
So in case people want to try, here's a third patch. Oh, and it's against
my _original_ path, not incremental to the middle one (ie both patches two
and three are against patch #1, it's not a nice series).
Now I'm really done, and won't be sending out any more patches today.
Sorry for the noise.
Linus
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
/* If it's already branch1, don't bother showing it */
|
|
|
|
|
if (!branch1)
|
|
|
|
|
return;
|
|
|
|
|
|
|
|
|
|
path = traverse_path(info, result);
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
orig = create_entry(2, branch1->mode, branch1->sha1, path);
|
|
|
|
|
final = create_entry(0, result->mode, result->sha1, path);
|
|
|
|
|
|
|
|
|
|
final->link = orig;
|
|
|
|
|
|
|
|
|
|
add_merge_entry(final);
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static int unresolved_directory(const struct traverse_info *info, struct name_entry n[3])
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
{
|
|
|
|
|
char *newbase;
|
|
|
|
|
struct name_entry *p;
|
|
|
|
|
struct tree_desc t[3];
|
|
|
|
|
void *buf0, *buf1, *buf2;
|
|
|
|
|
|
|
|
|
|
if (!resolve_directories)
|
|
|
|
|
return 0;
|
|
|
|
|
p = n;
|
|
|
|
|
if (!p->mode) {
|
|
|
|
|
p++;
|
|
|
|
|
if (!p->mode)
|
|
|
|
|
p++;
|
|
|
|
|
}
|
|
|
|
|
if (!S_ISDIR(p->mode))
|
|
|
|
|
return 0;
|
|
|
|
|
newbase = traverse_path(info, p);
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
buf0 = fill_tree_descriptor(t+0, n[0].sha1);
|
|
|
|
|
buf1 = fill_tree_descriptor(t+1, n[1].sha1);
|
|
|
|
|
buf2 = fill_tree_descriptor(t+2, n[2].sha1);
|
|
|
|
|
merge_trees(t, newbase);
|
|
|
|
|
|
|
|
|
|
free(buf0);
|
|
|
|
|
free(buf1);
|
|
|
|
|
free(buf2);
|
|
|
|
|
free(newbase);
|
|
|
|
|
return 1;
|
|
|
|
|
}
|
|
|
|
|
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
|
|
|
|
|
static struct merge_list *link_entry(unsigned stage, const struct traverse_info *info, struct name_entry *n, struct merge_list *entry)
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
{
|
|
|
|
|
const char *path;
|
|
|
|
|
struct merge_list *link;
|
|
|
|
|
|
|
|
|
|
if (!n->mode)
|
|
|
|
|
return entry;
|
|
|
|
|
if (entry)
|
|
|
|
|
path = entry->path;
|
|
|
|
|
else
|
|
|
|
|
path = traverse_path(info, n);
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
link = create_entry(stage, n->mode, n->sha1, path);
|
|
|
|
|
link->link = entry;
|
|
|
|
|
return link;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void unresolved(const struct traverse_info *info, struct name_entry n[3])
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
{
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
struct merge_list *entry = NULL;
|
|
|
|
|
|
|
|
|
|
if (unresolved_directory(info, n))
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
return;
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Do them in reverse order so that the resulting link
|
|
|
|
|
* list has the stages in order - link_entry adds new
|
|
|
|
|
* links at the front.
|
|
|
|
|
*/
|
|
|
|
|
entry = link_entry(3, info, n + 2, entry);
|
|
|
|
|
entry = link_entry(2, info, n + 1, entry);
|
|
|
|
|
entry = link_entry(1, info, n + 0, entry);
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
|
|
|
|
|
add_merge_entry(entry);
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Merge two trees together (t[1] and t[2]), using a common base (t[0])
|
|
|
|
|
* as the origin.
|
|
|
|
|
*
|
|
|
|
|
* This walks the (sorted) trees in lock-step, checking every possible
|
|
|
|
|
* name. Note that directories automatically sort differently from other
|
|
|
|
|
* files (see "base_name_compare"), so you'll never see file/directory
|
|
|
|
|
* conflicts, because they won't ever compare the same.
|
|
|
|
|
*
|
|
|
|
|
* IOW, if a directory changes to a filename, it will automatically be
|
|
|
|
|
* seen as the directory going away, and the filename being created.
|
|
|
|
|
*
|
|
|
|
|
* Think of this as a three-way diff.
|
|
|
|
|
*
|
|
|
|
|
* The output will be either:
|
|
|
|
|
* - successful merge
|
|
|
|
|
* "0 mode sha1 filename"
|
|
|
|
|
* NOTE NOTE NOTE! FIXME! We really really need to walk the index
|
|
|
|
|
* in parallel with this too!
|
|
|
|
|
*
|
|
|
|
|
* - conflict:
|
|
|
|
|
* "1 mode sha1 filename"
|
|
|
|
|
* "2 mode sha1 filename"
|
|
|
|
|
* "3 mode sha1 filename"
|
|
|
|
|
* where not all of the 1/2/3 lines may exist, of course.
|
|
|
|
|
*
|
|
|
|
|
* The successful merge rules are the same as for the three-way merge
|
|
|
|
|
* in git-read-tree.
|
|
|
|
|
*/
|
|
|
|
|
static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *info)
|
|
|
|
|
{
|
|
|
|
|
/* Same in both? */
|
|
|
|
|
if (same_entry(entry+1, entry+2)) {
|
|
|
|
|
if (entry[0].sha1) {
|
|
|
|
|
resolve(info, NULL, entry+1);
|
|
|
|
|
return mask;
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
}
|
|
|
|
|
}
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
|
|
|
|
|
if (same_entry(entry+0, entry+1)) {
|
|
|
|
|
if (entry[2].sha1 && !S_ISDIR(entry[2].mode)) {
|
|
|
|
|
resolve(info, entry+1, entry+2);
|
|
|
|
|
return mask;
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
}
|
|
|
|
|
}
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
|
|
|
|
|
if (same_entry(entry+0, entry+2)) {
|
|
|
|
|
if (entry[1].sha1 && !S_ISDIR(entry[1].mode)) {
|
|
|
|
|
resolve(info, NULL, entry+1);
|
|
|
|
|
return mask;
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
unresolved(info, entry);
|
|
|
|
|
return mask;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void merge_trees(struct tree_desc t[3], const char *base)
|
|
|
|
|
{
|
|
|
|
|
struct traverse_info info;
|
|
|
|
|
|
|
|
|
|
setup_traverse_info(&info, base);
|
|
|
|
|
info.fn = threeway_callback;
|
|
|
|
|
traverse_trees(3, t, &info);
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void *get_tree_descriptor(struct tree_desc *desc, const char *rev)
|
|
|
|
|
{
|
|
|
|
|
unsigned char sha1[20];
|
|
|
|
|
void *buf;
|
|
|
|
|
|
|
|
|
|
if (get_sha1(rev, sha1))
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
die("unknown rev %s", rev);
|
|
|
|
|
buf = fill_tree_descriptor(desc, sha1);
|
|
|
|
|
if (!buf)
|
|
|
|
|
die("%s is not a tree", rev);
|
|
|
|
|
return buf;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
int cmd_merge_tree(int argc, const char **argv, const char *prefix)
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
{
|
|
|
|
|
struct tree_desc t[3];
|
|
|
|
|
void *buf1, *buf2, *buf3;
|
|
|
|
|
|
|
|
|
|
if (argc != 4)
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
usage(merge_tree_usage);
|
|
|
|
|
|
|
|
|
|
buf1 = get_tree_descriptor(t+0, argv[1]);
|
|
|
|
|
buf2 = get_tree_descriptor(t+1, argv[2]);
|
|
|
|
|
buf3 = get_tree_descriptor(t+2, argv[3]);
|
|
|
|
|
merge_trees(t, "");
|
|
|
|
|
free(buf1);
|
|
|
|
|
free(buf2);
|
|
|
|
|
free(buf3);
|
Prepare "git-merge-tree" for future work
This changes how "git-merge-tree" works in two ways:
- instead of printing things out as we walk the trees, we save the
results in memory.
- when we've walked the tree fully, we print out the results in a more
explicit way, describing the data.
This is basically preparatory work for extending the git-merge-tree
functionality in interesting directions.
In particular, git-merge-tree is also how you would create a diff between
two trees _without_ necessarily creating the merge commit itself. In other
words, if you were to just wonder what another branch adds, you should be
able to (eventually) just do
git merge-tree -p $base HEAD $otherbranch
to generate a diff of what the merge would look like. The current merge
tree already basically has all the smarts for this, and the explanation of
the results just means that hopefully somebody else than me could do the
boring work.
(You'd basically be able to do the above diff by just changing the
printout format for the explanation, and making the "changed in both"
first do a three-way merge before it diffs the result).
The other thing that the in-memory format allows is rename detection
(which the current code does not do). That's the basic reason why we don't
want to just explain the differences as we go along - because we want to
be able to look at the _other_ differences to see whether the reason an
entry got deleted in either branch was perhaps because it got added in
another place..
Rename detection should be a fairly trivial pass in between the tree
diffing and the explanation.
In the meantime, this doesn't actually do anything new, it just outputs
the information in a more verbose manner.
For an example merge, commit 5ab2c0a47574c92f92ea3709b23ca35d96319edd in
the git tree works well and shows renames, along with true removals and
additions and files that got changed in both branches. To see that as a
tree merge, do:
git-merge-tree 64e86c57 c5c23745 928e47e3
where the two last ones are the tips that got merged, and the first one is
the merge base.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
|
|
|
|
|
show_result();
|
Handling large files with GIT
On Tue, 14 Feb 2006, Junio C Hamano wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > If somebody is interested in making the "lots of filename changes" case go
> > fast, I'd be more than happy to walk them through what they'd need to
> > change. I'm just not horribly motivated to do it myself. Hint, hint.
>
> In case anybody is wondering, I share the same feeling. I
> cannot say I'd be "more than happy to" clean up potential
> breakages during the development of such changes, but if the
> change eventually would help certain use cases, I can be
> persuaded to help debugging such a mess ;-).
Actually, I got interested in seeing how hard this is, and wrote a simple
first cut at doing a tree-optimized merger.
Let me shout a bit first:
THIS IS WORKING CODE, BUT BE CAREFUL: IT'S A TECHNOLOGY DEMONSTRATION
RATHER THAN THE FINAL PRODUCT!
With that out of the way, let me descibe what this does (and then describe
the missing parts).
This is basically a three-way merge that works entirely on the "tree"
level, rather than on the index. A lot of the _concepts_ are the same,
though, and if you're familiar with the results of an index merge, some of
the output will make more sense.
You give it three trees: the base tree (tree 0), and the two branches to
be merged (tree 1 and tree 2 respectively). It will then walk these three
trees, and resolve them as it goes along.
The interesting part is:
- it can resolve whole sub-directories in one go, without actually even
looking recursively at them. A whole subdirectory will resolve the same
way as any individual files will (although that may need some
modification, see later).
- if it has a "content conflict", for subdirectories that means "try to
do a recursive tree merge", while for non-subdirectories it's just a
content conflict and we'll output the stage 1/2/3 information.
- a successful merge will output a single stage 0 ("merged") entry,
potentially for a whole subdirectory.
- it outputs all the resolve information on stdout, so something like the
recursive resolver can pretty easily parse it all.
Now, the caveats:
- we probably need to be more careful about subdirectory resolves. The
trivial case (both branches have the exact same subdirectory) is a
trivial resolve, but the other cases ("branch1 matches base, branch2 is
different" probably can't be silently just resolved to the "branch2"
subdirectory state, since it might involve renames into - or out of -
that subdirectory)
- we do not track the current index file at all, so this does not do the
"check that index matches branch1" logic that the three-way merge in
git-read-tree does. The theory is that we'd do a full three-way merge
(ignoring the index and working directory), and then to update the
working tree, we'd do a two-way "git-read-tree branch1->result"
- I didn't actually make it do all the trivial resolve cases that
git-read-tree does. It's a technology demonstration.
Finally (a more serious caveat):
- doing things through stdout may end up being so expensive that we'd
need to do something else. In particular, it's likely that I should
not actually output the "merge results", but instead output a "merge
results as they _differ_ from branch1"
However, I think this patch is already interesting enough that people who
are interested in merging trees might want to look at it. Please keep in
mind that tech _demo_ part, and in particular, keep in mind the final
"serious caveat" part.
In many ways, the really _interesting_ part of a merge is not the result,
but how it _changes_ the branch we're merging into. That's particularly
important as it should hopefully also mean that the output size for any
reasonable case is minimal (and tracks what we actually need to do to the
current state to create the final result).
The code very much is organized so that doing the result as a "diff
against branch1" should be quite easy/possible. I was actually going to do
it, but I decided that it probably makes the output harder to read. I
dunno.
Anyway, let's think about this kind of approach.. Note how the code itself
is actually quite small and short, although it's prbably pretty "dense".
As an interesting test-case, I'd suggest this merge in the kernel:
git-merge-tree $(git-merge-base 4cbf876 7d2babc) 4cbf876 7d2babc
which resolves beautifully (there are no actual file-level conflicts), and
you can look at the output of that command to start thinking about what
it does.
The interesting part (perhaps) is that timing that command for me shows
that it takes all of 0.004 seconds.. (the git-merge-base thing takes
considerably more ;)
The point is, we _can_ do the actual merge part really really quickly.
Linus
PS. Final note: when I say that it is "WORKING CODE", that is obviously by
my standards. IOW, I tested it once and it gave reasonable results - so it
must be perfect.
Whether it works for anybody else, or indeed for any other test-case, is
not my problem ;)
Signed-off-by: Junio C Hamano <junkio@cox.net>
19 years ago
|
|
|
return 0;
|
|
|
|
|
}
|
