kernel/git - git - PowerEL Git System

Commit Graph

Author	SHA1	Message	Date
Linus Torvalds	6dd4b66fde	Fix diffcore-break total breakage Ok, so on the kernel list, some people noticed that "git log --follow" doesn't work too well with some files in the x86 merge, because a lot of files got renamed in very special ways. In particular, there was a pattern of doing single commits with renames that looked basically like - rename "filename.h" -> "filename_64.h" - create new "filename.c" that includes "filename_32.h" or "filename_64.h" depending on whether we're 32-bit or 64-bit. which was preparatory for smushing the two trees together. Now, there's two issues here: - "filename.c" remained. Yes, it was a rename, but there was a new file created with the old name in the same commit. This was important, because we wanted each commit to compile properly, so that it was bisectable, so splitting the rename into one commit and the "create helper file" into another was not an option. So we need to break associations where the contents change too much. Fine. We have the -B flag for that. When we break things up, then the rename detection will be able to figure out whether there are better alternatives. - "git log --follow" didn't with with -B. Now, the second case was really simple: we use a different "diffopt" structure for the rename detection than the basic one (which we use for showing the diffs). So that second case is trivially fixed by a trivial one-liner that just copies the break_opt values from the "real" diffopts to the one used for rename following. So now "git log -B --follow" works fine: diff --git a/tree-diff.c b/tree-diff.c index 26bdbdd..7c261fd 100644 --- a/tree-diff.c +++ b/tree-diff.c @@ -319,6 +319,7 @@ static void try_to_follow_renames(struct tree_desc t1, struct tree_desc t2, co diff_opts.detect_rename = DIFF_DETECT_RENAME; diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT; diff_opts.single_follow = opt->paths[0]; + diff_opts.break_opt = opt->break_opt; paths[0] = NULL; diff_tree_setup_paths(paths, &diff_opts); if (diff_setup_done(&diff_opts) < 0) however, the end result does not work. Because our diffcore-break.c logic is totally bogus! In particular: - it used to do if (base_size < MINIMUM_BREAK_SIZE) return 0; /* we do not break too small filepair / which basically says "don't bother to break small files". But that "base_size" is the smaller* of the two sizes, which means that if some large file was rewritten into one that just includes another file, we would look at the (small) result, and decide that it's smaller than the break size, so it cannot be worth it to break it up! Even if the other side was ten times bigger and looked nothing like the samell file! That's clearly bogus. I replaced "base_size" with "max_size", so that we compare the bigger of the filepair with the break size. - It calculated a "merge_score", which was the score needed to merge it back together if nothing else wanted it. But even if it was so different that we would never want to merge it back, we wouldn't consider it a break! That makes no sense. So I added if (merge_score_p > break_score) return 1; to make it clear that if we wouldn't want to merge it at the end, it was definitely* a break. - It compared the whole "extent of damage", counting all inserts and deletes, but it based this score on the "base_size", and generated the damage score with delta_size = src_removed + literal_added; damage_score = delta_size * MAX_SCORE / base_size; but that makes no sense either, since quite often, this will result in a number that is bigger than MAX_SCORE! Why? Because base_size is (again) the smaller of the two files we compare, and when you start out from a small file and add a lot (or start out from a large file and remove a lot), the base_size is going to be much smaller than the damage! Again, the fix was to replace "base_size" with "max_size", at which point the damage actually becomes a sane percentage of the whole. With these changes in place, not only does "git log -B --follow" work for the case that triggered this in the first place, ie now git log -B --follow arch/x86/kernel/vmlinux_64.lds.S actually gives reasonable results. But I also wanted to verify it in general, by doing a full-history git log --stat -B -C on my kernel tree with the old code and the new code. There's some tweaking to be done, but generally, the new code generates much better results wrt breaking up files (and then finding better rename candidates). Here's a few examples of the "--stat" output: - This: include/asm-x86/Kbuild \| 2 - include/asm-x86/debugreg.h \| 79 +++++++++++++++++++++++++++++++++++------ include/asm-x86/debugreg_32.h \| 64 --------------------------------- include/asm-x86/debugreg_64.h \| 65 --------------------------------- 4 files changed, 68 insertions(+), 142 deletions(-) Becomes: include/asm-x86/Kbuild \| 2 - include/asm-x86/{debugreg_64.h => debugreg.h} \| 9 +++- include/asm-x86/debugreg_32.h \| 64 ------------------------- 3 files changed, 7 insertions(+), 68 deletions(-) - This: include/asm-x86/bug.h \| 41 +++++++++++++++++++++++++++++++++++++++-- include/asm-x86/bug_32.h \| 37 ------------------------------------- include/asm-x86/bug_64.h \| 34 ---------------------------------- 3 files changed, 39 insertions(+), 73 deletions(-) Becomes include/asm-x86/{bug_64.h => bug.h} \| 20 +++++++++++++----- include/asm-x86/bug_32.h \| 37 ----------------------------------- 2 files changed, 14 insertions(+), 43 deletions(-) Now, in some other cases, it does actually turn a rename into a real "delete+create" pair, and then the diff is usually bigger, so truth in advertizing: it doesn't always generate a nicer diff. But for what -B was meant for, I think this is a big improvement, and I suspect those cases where it generates a bigger diff are tweakable. So I think this diff fixes a real bug, but we might still want to tweak the default values and perhaps the exact rules for when a break happens. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>	17 years ago
Linus Torvalds	9f38e1ef7e	Fix up "git log --follow" a bit.. This fixes "git log --follow" to hopefully not leak memory any more, and also cleans it up a bit to look more like some of the other functions that use "diff_queued_diff" (by not using it directly as a global in the code, but by instead just taking a pointer to the diff queue and using that). As to "diff_queued_diff", I think it would be better off not as a global at all, but as being just an entry in the "struct diff_options" structure, but that's a separate issue, and there may be some subtle reason for why it's currently a global. Anyway, no real changes. Instead of having a magical first entry in the diff-queue, we now end up just keeping the diff-queue clean, and keeping our "preferred" file pairing in an internal "choice" variable. That makes it easy to switch the choice around when we find a better one. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	18 years ago
Linus Torvalds	750f7b668f	Finally implement "git log --follow" Ok, I've really held off doing this too damn long, because I'm lazy, and I was always hoping that somebody else would do it. But no, people keep asking for it, but nobody actually did anything, so I decided I might as well bite the bullet, and instead of telling people they could add a "--follow" flag to "git log" to do what they want to do, I decided that it looks like I just have to do it for them.. The code wasn't actually that complicated, in that the diffstat for this patch literally says "70 insertions(+), 1 deletions(-)", but I will have to admit that in order to get to this fairly simple patch, you did have to know and understand the internal git diff generation machinery pretty well, and had to really be able to follow how commit generation interacts with generating patches and generating the log. So I suspect that while I was right that it wasn't that hard, I might have been expecting too much of random people - this patch does seem to be firmly in the core "Linus or Junio" territory. To make a long story short: I'm sorry for it taking so long until I just did it. I'm not going to guarantee that this works for everybody, but you really can just look at the patch, and after the appropriate appreciative noises ("Ooh, aah") over how clever I am, you can then just notice that the code itself isn't really that complicated. All the real new code is in the new "try_to_follow_renames()" function. It really isn't rocket science: we notice that the pathname we were looking at went away, so we start a full tree diff and try to see if we can instead make that pathname be a rename or a copy from some other previous pathname. And if we can, we just continue, except we show that particular diff, and ever after we use the _previous_ pathname. One thing to look out for: the "rename detection" is considered to be a singular event in the _linear_ "git log" output! That's what people want to do, but I just wanted to point out that this patch is not carrying around a "commit,pathname" kind of pair and it's not going to be able to notice the file coming from multiple different files in earlier history. IOW, if you use "git log --follow", then you get the stupid CVS/SVN kind of "files have single identities" kind of semantics, and git log will just pick the identity based on the normal move/copy heuristics _as_if_ the history could be linearized. Put another way: I think the model is broken, but given the broken model, I think this patch does just about as well as you can do. If you have merges with the same "file" having different filenames over the two branches, git will just end up picking _one_ of the pathnames at the point where the newer one goes away. It never looks at multiple pathnames in parallel. And if you understood all that, you probably didn't need it explained, and if you didn't understand the above blathering, it doesn't really mtter to you. What matters to you is that you can now do git log -p --follow builtin-rev-list.c and it will find the point where the old "rev-list.c" got renamed to "builtin-rev-list.c" and show it as such. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	18 years ago
Junio C Hamano	1d848f643c	tree_entry_interesting(): allow it to say "everything is interesting" In addition to optimizing pathspecs that would never match, which was done earlier, this optimizes pathspecs that would always match (e.g. "arch/" while the traversal is already in "arch/i386/" hierarchy). This patch makes the worst case slightly more palatable, while improving average case. Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Junio C Hamano	ccc744abbb	tree-diff: avoid strncmp() If we already know that some of the pathspecs can match later entries in the tree we are looking at, we do not have to do more expensive strncmp() upfront before comparing the length of the match pattern and the path, as a path longer than the match pattern will not match it, and a path shorter than the match pattern will match only if the path is a directory-component wise prefix of the match pattern. Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Junio C Hamano	7d2f667b12	Teach tree_entry_interesting() that the tree entries are sorted. When we are looking at a tree entry with pathspecs, if all the pathspecs sort strictly earlier than the entry we are currently looking at, there is no way later entries in the same tree would match our pathspecs, because the entries are sorted. Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Linus Torvalds	6fda5e5180	Initialize tree descriptors with a helper function rather than by hand. This removes slightly more lines than it adds, but the real reason for doing this is that future optimizations will require more setup of the tree descriptor, and so we want to do it in one place. Also renamed the "desc.buf" field to "desc.buffer" just to trigger compiler errors for old-style manual initializations, making sure I didn't miss anything. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Linus Torvalds	5d86501742	Set up for better tree diff optimizations This is mainly just a cleanup patch, and sets up for later changes where the tree-diff.c "interesting()" function can return more than just a yes/no value. In particular, it should be quite possible to say "no subsequent entries in this tree can possibly be interesting any more", and thus allow the callers to short-circuit the tree entirely. In fact, changing the callers to do so is trivial, and is really all this patch really does, because changing "interesting()" itself to say that nothing further is going to be interesting is definitely more complicated, considering that we may have arbitrary pathspecs. But in cleaning up the callers, this actually fixes a potential small performance issue in diff_tree(): if the second tree has a lot of uninterestign crud in it, we would keep on doing the "is it interesting?" check on the first tree for each uninteresting entry in the second one. The answer is obviously not going to change, so that was just not helping. The new code is clearer and simpler and avoids this issue entirely. I also renamed "interesting()" to "tree_entry_interesting()", because I got frustrated by the fact that - we actually had another function called "interesting()" in another file, and I couldn't tell from the profiles which one was the one that mattered more. - when rewriting it to return a ternary value, you can't just do if (interesting(...)) ... any more, but want to assign the return value to a local variable. The name of choice for that variable would normally be "interesting", so I just wanted to make the function name be more specific, and avoid that whole issue (even though I then didn't choose that name for either of the users, just to avoid confusion in the patch itself ;) In other words, this doesn't really change anything, but I think it's a good thing to do, and if somebody comes along and writes the logic for "yeah, none of the pathspecs you have are interesting", we now support that trivially. It could easily be a meaningful optimization for things like "blame", where there's just one pathspec, and stopping when you've seen it would allow you to avoid about 50% of the tree traversals on average. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Linus Torvalds	304de2d2d6	Avoid unnecessary strlen() calls This is a micro-optimization that grew out of the mailing list discussion about "strlen()" showing up in profiles. We used to pass regular C strings around to the low-level tree walking routines, and while this worked fine, it meant that we needed to call strlen() on strings that the caller always actually knew the size of anyway. So pass the length of the string down wih the string, and avoid unnecessary calls to strlen(). Also, when extracting a pathname from a tree entry, use "tree_entry_len()" instead of strlen(), since the length of the pathname is directly calculable from the decoded tree entry itself without having to actually do another strlen(). This shaves off another ~5-10% from some loads that are very tree intensive (notably doing commit filtering by a pathspec). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>" Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Junio C Hamano	822cac0155	Teach --quiet to diff backends. This teaches git-diff-files, git-diff-index and git-diff-tree backends to exit early under --quiet option. Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Nicolas Pitre	21666f1aae	convert object type handling from a string to a number We currently have two parallel notation for dealing with object types in the code: a string and a numerical value. One of them is obviously redundent, and the most used one requires more stack space and a bunch of strcmp() all over the place. This is an initial step for the removal of the version using a char array found in object reading code paths. The patch is unfortunately large but there is no sane way to split it in smaller parts without breaking the system. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Rene Scharfe	2b60356da5	Make git-cherry handle root trees This patch on top of 'next' makes built-in git-cherry handle root commits. It moves the static function log-tree.c::diff_root_tree() to tree-diff.c and makes it more similar to diff_tree_sha1() by shuffling around arguments and factoring out the call to log_tree_diff_flush(). Consequently the name is changed to diff_root_tree_sha1(). It is a version of diff_tree_sha1() that compares the empty tree (= root tree) against a single 'real' tree. This function is then used in get_patch_id() to compute patch IDs for initial commits instead of SEGFAULTing, as the current code does if confronted with parentless commits. Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
David Rientjes	a89fccd281	Do not use memcmp(sha1_1, sha1_2, 20) with hardcoded length. Introduces global inline: hashcmp(const unsigned char sha1, const unsigned char sha2) Uses memcmp for comparison and returns the result based on the length of the hash name (a future runtime decision). Acked-by: Alex Riesen <raa.lkml@gmail.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
David Rientjes	cf995ede2c	Make show_entry void Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Junio C Hamano	a8baa7b9f5	tree-diff: do not assume we use only one pathspec The way tree-diff was set up assumed we would use only one set of pathspec during the entire life of the program. Move the pathspec related static variables out to diff_options structure so that we can filter commits with one set of paths while show the actual diffs using different set of paths. I suspect this breaks blame.c, and makes "git log paths..." to default to the --full-diff, the latter of which is dealt with the next commit. Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago
Peter Eriksen	8e44025925	Use blob_, commit_, tag_, and tree_type throughout. This replaces occurences of "blob", "commit", "tag", and "tree", where they're really used as type specifiers, which we already have defined global constants for. Signed-off-by: Peter Eriksen <s022018@student.dtu.dk> Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago
Junio C Hamano	1b0c7174a1	tree/diff header cleanup. Introduce tree-walk.[ch] and move "struct tree_desc" and associated functions from various places. Rename DIFF_FILE_CANON_MODE(mode) macro to canon_mode(mode) and move it to cache.h. This macro returns the canonicalized st_mode value in the host byte order for files, symlinks and directories -- to be compared with a tree_desc entry. create_ce_mode(mode) in cache.h is similar but is intended to be used for index entries (so it does not work for directories) and returns the value in the network byte order. Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago
Linus Torvalds	50f9a858ad	Make the "struct tree_desc" operations available to others We have operations to "extract" and "update" a "struct tree_desc", but we only used them in tree-diff.c and they were static to that file. But other tree traversal functions can use them to their advantage Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago
Junio C Hamano	7e4a2a8483	avoid asking ?alloc() for zero bytes. Avoid asking for zero bytes when that change simplifies overall logic. Later we would change the wrapper to ask for 1 byte on platforms that return NULL for zero byte request. Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago
Linus Torvalds	ac1b3d1248	Split up tree diff functions into tree-diff.c library This makes the tree diff functionality independent of the "git-diff-tree" program, by splitting the core functionality up into a library file. This will be needed for when we teach git-rev-list to only follow a specified set of pathnames, rather than the global revision history. Most of it is a fairly straightforward code move, but it also involves some calling convention cleanup, and moving some of the static variables from diff-tree.c into the options structure. The actual tree change callback routines also become paramterized by the diff_options structure, allowing the library functionality to do something else than just show the diff on stdout. Right now the only user of this functionality remains git-diff-tree itself. Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago

21 Commits (ae3e76c2991ddd5fd72cff22cd39d5d297e63504)