git/cache.h, branch v2.4.2

Merge branch 'jc/hash-object' into maint

2015-05-26T20:49:25Z

"hash-object --literally" introduced in v2.2 was not prepared to take a really long object type name. * jc/hash-object: write_sha1_file(): do not use a separate sha1[] array t1007: add hash-object --literally tests hash-object --literally: fix buffer overrun with extra-long object type git-hash-object.txt: document --literally option

Merge branch 'jk/prune-mtime' into maint

2015-05-13T21:05:50Z

Access to objects in repositories that borrow from another one on a slow NFS server unnecessarily got more expensive due to recent code becoming more cautious in a naive way not to lose objects to pruning. * jk/prune-mtime: sha1_file: only freshen packs once per run sha1_file: freshen pack objects before loose reachable: only mark local objects as recent

hash-object --literally: fix buffer overrun with extra-long object type

2015-05-05T17:14:18Z

"hash-object" learned in 5ba9a93 (hash-object: add --literally option, 2014-09-11) to allow crafting a corrupt/broken object of unknown type. When the user-provided type is particularly long, however, it can overflow the relatively small stack-based character array handed to write_sha1_file_prepare() by hash_sha1_file() and write_sha1_file(), leading to stack corruption (and crash). Introduce a custom helper to allow arbitrarily long typenames just for "hash-object --literally". [jc: Eric's original used a strbuf in the more common codepaths, and I rewrote it to avoid penalizing the non-literally code. Bugs are mine] Signed-off-by: Eric Sunshine Signed-off-by: Junio C Hamano

sha1_file: only freshen packs once per run

2015-04-20T20:09:40Z

Since 33d4221 (write_sha1_file: freshen existing objects, 2014-10-15), we update the mtime of existing objects that we would have written out (had they not existed). For the common case in which many objects are packed, we may update the mtime on a single packfile repeatedly. This can result in a noticeable performance problem if calling utime() is expensive (e.g., because your storage is on NFS). We can fix this by keeping a per-pack flag that lets us freshen only once per program invocation. An alternative would be to keep the packed_git.mtime flag up to date as we freshen, and freshen only once every N seconds. In practice, it's not worth the complexity. We are racing against prune expiration times here, which inherently must be set to accomodate reasonable program running times (because they really care about the time between an object being written and it becoming referenced, and the latter is typically the last step a program takes). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

reachable: only mark local objects as recent

2015-04-20T20:09:27Z

When pruning and repacking a repository that has an alternate object store configured, we may traverse a large number of objects in the alternate. This serves no purpose, and may be expensive to do. A longer explanation is below. Commits d3038d2 and abcb865 taught prune and pack-objects (respectively) to treat "recent" objects as tips for reachability, so that we keep whole chunks of history. They built on the object traversal in 660c889 (sha1_file: add for_each iterators for loose and packed objects, 2014-10-15), which covers both local and alternate objects. In both cases, covering alternate objects is unnecessary, as both commands can only drop objects from the local repository. In the case of prune, we traverse only the local object directory. And in the case of repacking, while we may or may not include local objects in our pack, we will never reach into the alternate with "repack -d". The "-l" option is only a question of whether we are migrating objects from the alternate into our repository, or leaving them untouched. It is possible that we may drop an object that is depended upon by another object in the alternate. For example, imagine two repositories, A and B, with A pointing to B as an alternate. Now imagine a commit that is in B which references a tree that is only in A. Traversing from recent objects in B might prevent A from dropping that tree. But this case isn't worth covering. Repo B should take responsibility for its own objects. It would never have had the commit in the first place if it did not also have the tree, and assuming it is using the same "keep recent chunks of history" scheme, then it would itself keep the tree, as well. So checking the alternate objects is not worth doing, and come with a significant performance impact. In both cases, we skip any recent objects that have already been marked SEEN (i.e., that we know are already reachable for prune, or included in the pack for a repack). So there is a slight waste of time in opening the alternate packs at all, only to notice that we have already considered each object. But much worse, the alternate repository may have a large number of objects that are not reachable from the local repository at all, and we end up adding them to the traversal. We can fix this by considering only local unseen objects. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

Merge branch 'jc/report-path-error-to-dir'

2015-03-26T18:57:13Z

Code clean-up. * jc/report-path-error-to-dir: report_path_error(): move to dir.c

Merge branch 'jk/prune-with-corrupt-refs'

2015-03-25T19:54:26Z

"git prune" used to largely ignore broken refs when deciding which objects are still being used, which could spread an existing small damage and make it a larger one. * jk/prune-with-corrupt-refs: refs.c: drop curate_packed_refs repack: turn on "ref paranoia" when doing a destructive repack prune: turn on ref_paranoia flag refs: introduce a "ref paranoia" flag t5312: test object deletion code paths in a corrupted repository

report_path_error(): move to dir.c

2015-03-24T21:12:10Z

The expected call sequence is for the caller to use match_pathspec() repeatedly on a set of pathspecs, accumulating the "hits" in a separate array, and then call this function to diagnose a pathspec that never matched anything, as that can indicate a typo from the command line, e.g. "git commit Maekfile". Many builtin commands use this function from builtin/ls-files.c, which is not a very healthy arrangement. ls-files might have been the first command to feel the need for such a helper, but the need is shared by everybody who uses the "match and then report" pattern. Move it to dir.c where match_pathspec() is defined. Signed-off-by: Junio C Hamano

refs: introduce a "ref paranoia" flag

2015-03-20T19:40:49Z

Most operations that iterate over refs are happy to ignore broken cruft. However, some operations should be performed with knowledge of these broken refs, because it is better for the operation to choke on a missing object than it is to silently pretend that the ref did not exist (e.g., if we are computing the set of reachable tips in order to prune objects). These processes could just call for_each_rawref, except that ref iteration is often hidden behind other interfaces. For instance, for a destructive "repack -ad", we would have to inform "pack-objects" that we are destructive, and then it would in turn have to tell the revision code that our "--all" should include broken refs. It's much simpler to just set a global for "dangerous" operations that includes broken refs in all iterations. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

Merge branch 'jk/prune-mtime' into maint

2015-03-05T21:13:08Z

In v2.2.0, we broke "git prune" that runs in a repository that borrows from an alternate object store. * jk/prune-mtime: sha1_file: fix iterating loose alternate objects for_each_loose_file_in_objdir: take an optional strbuf path