kernel/git - git - PowerEL Git System

Commit Graph

Author	SHA1	Message	Date
Vicent Marti	2db1a43f41	add `ignore_missing_links` mode to revwalk When pack-objects is computing the reachability bitmap to serve a fetch request, it can erroneously die() if some of the UNINTERESTING objects are not present. Upload-pack throws away HAVE lines from the client for objects we do not have, but we may have a tip object without all of its ancestors (e.g., if the tip is no longer reachable and was new enough to survive a `git prune`, but some of its reachable objects did get pruned). In the non-bitmap case, we do a revision walk with the HAVE objects marked as UNINTERESTING. The revision walker explicitly ignores errors in accessing UNINTERESTING commits to handle this case (and we do not bother looking at UNINTERESTING trees or blobs at all). When we have bitmaps, however, the process is quite different. The bitmap index for a pack-objects run is calculated in two separate steps: First, we perform an extensive walk from all the HAVEs to find the full set of objects reachable from them. This walk is usually optimized away because we are expected to hit an object with a bitmap during the traversal, which allows us to terminate early. Secondly, we perform an extensive walk from all the WANTs, which usually also terminates early because we hit a commit with an existing bitmap. Once we have the resulting bitmaps from the two walks, we AND-NOT them together to obtain the resulting set of objects we need to pack. When we are walking the HAVE objects, the revision walker does not know that we are walking it only to mark the results as uninteresting. We strip out the UNINTERESTING flag, because those objects _are_ interesting to us during the first walk. We want to keep going to get a complete set of reachable objects if we can. We need some way to tell the revision walker that it's OK to silently truncate the HAVE walk, just like it does for the UNINTERESTING case. This patch introduces a new `ignore_missing_links` flag to the `rev_info` struct, which we set only for the HAVE walk. It also adds tests to cover UNINTERESTING objects missing from several positions: a missing blob, a missing tree, and a missing parent commit. The missing blob already worked (as we do not care about its contents at all), but the other two cases caused us to die(). Note that there are a few cases we do not need to test: 1. We do not need to test a missing tree, with the blob still present. Without the tree that refers to it, we would not know that the blob is relevant to our walk. 2. We do not need to test a tip commit that is missing. Upload-pack omits these for us (and in fact, we complain even in the non-bitmap case if it fails to do so). Reported-by: Siddharth Agarwal <sid0@fb.com> Signed-off-by: Vicent Marti <tanoku@gmail.com> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago
Jeff King	200abe7458	list-objects: only look at cmdline trees with edge_hint When rev-list is given a command-line like: git rev-list --objects $commit --not --all the most accurate answer is the difference between the set of objects reachable from $commit and the set reachable from all of the existing refs. However, we have not historically provided that answer, because it is very expensive to calculate. We would have to open every tree of every commit in the entire history. Instead, we find the accurate set difference of the reachable commits, and then mark the trees at the boundaries as uninteresting. This misses objects which appear in the trees of both the interesting commits and deep within the uninteresting history. Commit `fbd4a70` (list-objects: mark more commits as edges in mark_edges_uninteresting, 2013-08-16) noticed that we miss those objects during pack-objects, and added code to examine the trees of all of the "--not" refs given on the command-line. Note that this is still not the complete set difference, because we look only at the tips of the command-line arguments, not all of their reachable commits. But it increases the set of boundary objects we consider, which is especially important for shallow fetches. So we are trading extra CPU time for a larger set of boundary objects, which can improve the resulting pack size for a --thin pack. This tradeoff probably makes sense in the context of pack-objects, where we have set revs->edge_hint to have the traversal feed us the set of boundary objects. For a regular rev-list, though, it is probably not a good tradeoff. It is true that it makes our list slightly closer to a true set difference, but it is a rare case where this is important. And because we do not have revs->edge_hint set, we do nothing useful with the larger set of boundary objects. This patch therefore ties the extra tree examination to the revs->edge_hint flag; it is the presence of that flag that makes the tradeoff worthwhile. Here is output from the p0001-rev-list showing the improvement in performance: Test HEAD^ HEAD ----------------------------------------------------------------------------------------- 0001.1: rev-list --all 0.69(0.65+0.02) 0.69(0.66+0.02) +0.0% 0001.2: rev-list --all --objects 3.22(3.19+0.03) 3.23(3.20+0.03) +0.3% 0001.4: rev-list $commit --not --all 0.04(0.04+0.00) 0.04(0.04+0.00) +0.0% 0001.5: rev-list --objects $commit --not --all 0.27(0.26+0.01) 0.04(0.04+0.00) -85.2% Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago
Nguyễn Thái Ngọc Duy	fbd4a7036d	list-objects: mark more commits as edges in mark_edges_uninteresting The purpose of edge commits is to let pack-objects know what objects it can use as base, but does not need to include in the thin pack because the other side is supposed to already have them. So far we mark uninteresting parents of interesting commits as edges. But even an unrelated uninteresting commit (that the other side has) may become a good base for pack-objects and help produce more efficient packs. This is especially true for shallow clone, when the client issues a fetch with a depth smaller or equal to the number of commits the server is ahead of the client. For example, in this commit history the client has up to "A" and the server has up to "B": -------A---B have--^ ^ / want--+ If depth 1 is requested, the commit list to send to the client includes only B. The way m_e_u is working, it checks if parent commits of B are uninteresting, if so mark them as edges. Due to shallow effect, commit B is grafted to have no parents and the revision walker never sees A as the parent of B. In fact it marks no edges at all in this simple case and sends everything B has to the client even if it could have excluded what A and also the client already have. In a slightly different case where A is not a direct parent of B (iow there are commits in between A and B), marking A as an edge can still save some because B may still have stuff from the far ancestor A. There is another case from the earlier patch, when we deepen a ref from C->E to A->E: ---A---B C---D---E want--^ ^ ^ shallow-+ / have-------+ In this case we need to send A and B to the client, and C (i.e. the current shallow point that the client informs the server) is a very good base because it's closet to A and B. Normal m_e_u won't recognize C as an edge because it only looks back to parents (i.e. A<-B) not the opposite way B->C even if C is already marked as uninteresting commit by the previous patch. This patch includes all uninteresting commits from command line as edges and lets pack-objects decide what's best to do. The upside is we have better chance of producing better packs in certain cases. The downside is we may need to process some extra objects on the server side. For the shallow case on git.git, when the client is 5 commits behind and does "fetch --depth=3", the result pack is 99.26 KiB instead of 4.92 MiB. Reported-and-analyzed-by: Matthijs Kooijman <matthijs@stdin.nl> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	12 years ago
Nguyễn Thái Ngọc Duy	e76a5fb459	list-objects: reduce one argument in mark_edges_uninteresting mark_edges_uninteresting() is always called with this form mark_edges_uninteresting(revs->commits, revs, ...); Remove the first argument and let mark_edges_uninteresting figure that out by itself. It helps answer the question "are this commit list and revs related in any way?" when looking at mark_edges_uninteresting implementation. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	12 years ago
Jeff King	6e454b9a31	clear parsed flag when we free tree buffers Many code paths will free a tree object's buffer and set it to NULL after finishing with it in order to keep memory usage down during a traversal. However, out of 8 sites that do this, only one actually unsets the "parsed" flag back. Those sites that don't are setting a trap for later users of the tree object; even after calling parse_tree, the buffer will remain NULL, causing potential segfaults. It is not known whether this is triggerable in the current code. Most commands do not do an in-memory traversal followed by actually using the objects again. However, it does not hurt to be safe for future callers. In most cases, we can abstract this out to a "free_tree_buffer" helper. However, there are two exceptions: 1. The fsck code relies on the parsed flag to know that we were able to parse the object at one point. We can switch this to using a flag in the "flags" field. 2. The index-pack code sets the buffer to NULL but does not free it (it is freed by a caller). We should still unset the parsed flag here, but we cannot use our helper, as we do not want to free the buffer. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	12 years ago
Nguyễn Thái Ngọc Duy	d688cf07b1	tree_entry_interesting(): give meaningful names to return values It is a basic code hygiene to avoid magic constants that are unnamed. Besides, this helps extending the value later on for "interesting, but cannot decide if the entry truely matches yet" (ie. prefix matches) Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	14 years ago
Junio C Hamano	4947367267	list-objects: pass callback data to show_objects() The traverse_commit_list() API takes two callback functions, one to show commit objects, and the other to show other kinds of objects. Even though the former has a callback data parameter, so that the callback does not have to rely on global state, the latter does not. Give the show_objects() callback the same callback data parameter. Signed-off-by: Junio C Hamano <gitster@pobox.com>	14 years ago
Nguyễn Thái Ngọc Duy	97d0b74a49	Improve tree_entry_interesting() handling code t_e_i() can return -1 or 2 to early shortcut a search. Current code may use up to two variables to handle it. One for saving return value from t_e_i temporarily, one for saving return code 2. The second variable is not needed. If we make sure the first variable does not change until the next t_e_i() call, then we can do something like this: int ret = 0; while (...) { if (ret != 2) { ret = t_e_i(); if (ret < 0) /* no longer interesting / break; if (ret == 0) / skip this round / continue; } / ret > 0, interesting */ } Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	14 years ago
Junio C Hamano	6e7d0efa90	list-objects.c: don't add an unparsed NULL as a pending tree "git rev-list --first-parent --boundary $commit^..$commit" segfaults on a merge commit since `8d2dfc4` (process_{tree,blob}: show objects without buffering, 2009-04-10), as it tried to dereference a commit that was discarded as UNINTERESTING without being parsed (hence lacking "tree"). Signed-off-by: Junio C Hamano <gitster@pobox.com>	14 years ago
Elijah Newren	cc5fa2fdaf	Make rev-list --objects work together with pathspecs When traversing commits, the selection of commits would heed the list of pathspecs passed, but subsequent walking of the trees of those commits would not. This resulted in 'rev-list --objects HEAD -- <paths>' displaying objects at unwanted paths. Have process_tree() call tree_entry_interesting() to determine which paths are interesting and should be walked. Naturally, this change can provide a large speedup when paths are specified together with --objects, since many tree entries are now correctly ignored. Interestingly, though, this change also gives me a small (~1%) but repeatable speedup even when no paths are specified with --objects. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	14 years ago
Linus Torvalds	8d2dfc49b1	process_{tree,blob}: show objects without buffering Here's a less trivial thing, and slightly more dubious one. I was looking at that "struct object_array objects", and wondering why we do that. I have honestly totally forgotten. Why not just call the "show()" function as we encounter the objects? Rather than add the objects to the object_array, and then at the very end going through the array and doing a 'show' on all, just do things more incrementally. Now, there are possible downsides to this: - the "buffer using object_array" _can_ in theory result in at least better I-cache usage (two tight loops rather than one more spread out one). I don't think this is a real issue, but in theory.. - this _does_ change the order of the objects printed. Instead of doing a "process_tree(revs, commit->tree, &objects, NULL, "");" in the loop over the commits (which puts all the root trees _first_ in the object list, this patch just adds them to the list of pending objects, and then we'll traverse them in that order (and thus show each root tree object together with the objects we discover under it) I _think_ the new ordering actually makes more sense, but the object ordering is actually a subtle thing when it comes to packing efficiency, so any change in order is going to have implications for packing. Good or bad, I dunno. - There may be some reason why we did it that odd way with the object array, that I have simply forgotten. Anyway, now that we don't buffer up the objects before showing them that may actually result in lower memory usage during that whole traverse_commit_list() phase. This is seriously not very deeply tested. It makes sense to me, it seems to pass all the tests, it looks ok, but... Does anybody remember why we did that "object_array" thing? It used to be an "object_list" a long long time ago, but got changed into the array due to better memory usage patterns (those linked lists of obejcts are horrible from a memory allocation standpoint). But I wonder why we didn't do this back then. Maybe there's a reason for it. Or maybe there _used_ to be a reason, and no longer is. Signed-off-by: Junio C Hamano <gitster@pobox.com>	16 years ago
Linus Torvalds	cf2ab916af	show_object(): push path_name() call further down In particular, pushing the "path_name()" call _into_ the show() function would seem to allow - more clarity into who "owns" the name (ie now when we free the name in the show_object callback, it's because we generated it ourselves by calling path_name()) - not calling path_name() at all, either because we don't care about the name in the first place, or because we are actually happy walking the linked list of "struct name_path *" and the last component. Now, I didn't do that latter optimization, because it would require some more coding, but especially looking at "builtin-pack-objects.c", we really don't even want the whole pathname, we really would be better off with the list of path components. Why? We use that name for two things: - add_preferred_base_object(), which actually _wants_ to traverse the path, and now does it by looking for '/' characters! - for 'name_hash()', which only cares about the last 16 characters of a name, so again, generating the full name seems to be just unnecessary work. Anyway, so I didn't look any closer at those things, but it did convince me that the "show_object()" calling convention was crazy, and we're actually better off doing _less_ in list-objects.c, and giving people access to the internal data structures so that they can decide whether they want to generate a path-name or not. This patch does that, and then for people who did use the name (even if they might do something more clever in the future), it just does the straightforward "name = path_name(path, component); .. free(name);" thing. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	16 years ago
Björn Steinbrink	de551d472e	process_{tree,blob}: Remove useless xstrdup calls The name of the processed object was duplicated for passing it to add_object(), but that already calls path_name, which allocates a new string anyway. So the memory allocated by the xstrdup calls just went nowhere, leaking memory. This reduces the RSS usage for a "rev-list --all --objects" by about 10% on the gentoo repo (fully packed) as well as linux-2.6.git: gentoo: \| old \| new ----------------\|------------------------------- RSS \| 1537284 \| 1388408 VSZ \| 1816852 \| 1667952 time elapsed \| 1:49.62 \| 1:48.99 min. page faults\| 417178 \| 379919 linux-2.6.git: \| old \| new ----------------\|------------------------------- RSS \| 324452 \| 292996 VSZ \| 491792 \| 460376 time elapsed \| 0:14.53 \| 0:14.28 min. page faults\| 89360 \| 81613 Signed-off-by: Björn Steinbrink <B.Steinbrink@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	16 years ago
Christian Couder	11c211fa06	list-objects: add "void *data" parameter to show functions The goal of this patch is to get rid of the "static struct rev_info revs" static variable in "builtin-rev-list.c". To do that, we need to pass the revs to the "show_commit" function in "builtin-rev-list.c" and this in turn means that the "traverse_commit_list" function in "list-objects.c" must be passed functions pointers to functions with 2 parameters instead of one. So we have to change all the callers and all the functions passed to "traverse_commit_list". Anyway this makes the code more clean and more generic, so it should be a good thing in the long run. Signed-off-by: Christian Couder <chriscool@tuxfamily.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	16 years ago
Martin Koegler	a301b0c8f2	list-objects.c::process_tree/blob: check for NULL As these functions are directly called with the result from lookup_tree/blob, they must handle NULL. Signed-off-by: Martin Koegler <mkoegler@auto.tuwien.ac.at> Signed-off-by: Junio C Hamano <gitster@pobox.com>	17 years ago
Shawn O. Pearce	295dd2ad20	Fix memory leak in traverse_commit_list If we were listing objects too then the objects were buffered in an array only reachable from a stack allocated structure. When this function returns that array would be leaked as nobody would have a reference to it anymore. Historically this hasn't been a problem as the primary user of traverse_commit_list() (the noble git-rev-list) would terminate as soon as the function was finished, thus allowing the operating system to cleanup memory. However we have been leaking this data in git-pack-objects ever since that program learned how to run the revision listing internally, rather than relying on reading object names from git-rev-list. To better facilitate reuse of traverse_commit_list during other builtin tools (such as git-fetch) we shouldn't leak temporary memory like this and instead we need to clean up properly after ourselves. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	18 years ago
Martin Waitz	302b9282c9	rename dirlink to gitlink. Unify naming of plumbing dirlink/gitlink concept: git ls-files -z '*.[ch]' \| xargs -0 perl -pi -e 's/dirlink/gitlink/g;' -e 's/DIRLNK/GITLINK/g;' Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Linus Torvalds	6e2f441bd4	Teach git list-objects logic to not follow gitlinks This allows us to pack superprojects and thus clone them (but not yet check them out on the receiving side.. That's the next patch) Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Linus Torvalds	ea376fa7f2	Teach git list-objects logic not to follow gitlinks This allows us to pack superprojects and thus clone them (but not yet check them out on the receiving side - that's the next patch) Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 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
Junio C Hamano	8d1d8f83b5	pack-objects: further work on internal rev-list logic. This teaches the internal rev-list logic to understand options that are needed for pack handling: --all, --unpacked, and --thin. It also moves two functions from builtin-rev-list to list-objects so that the two programs can share more code. Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago
Junio C Hamano	c64ed70d25	Separate object listing routines out of rev-list Create a separate file, list-objects.c, and move object listing routines from rev-list to it. The next round will use it in pack-objects directly. Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago

28 Commits (46a0613f00f2cf6a61d04fa49131fcbe3afaad07)