[PATCH 1/4] tag: speed up --contains calculation
- From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
- Date
- Jun 11, 2011, 19:04 UTC
- Message-ID
- <1307819051-25748-2-git-send-email-avarab@gmail.com>
- In-Reply-To
- <1307819051-25748-1-git-send-email-avarab@gmail.com>
From: Jeff King <peff@peff.net>
When we want to know if commit A contains commit B (or any one of a set of commits, B through Z), we generally calculate the merge bases and see if B is a merge base of A (or for a set, if any of the commits B through Z have that property).
When we are going to check a series of commits A1 through An to see whether each contains B (e.g., because we are deciding which tags to show with "git tag --contains"), we do a series of merge base calculations. This can be very expensive, as we repeat a lot of traversal work.
Instead, let's leverage the fact that we are going to use the same --contains list for each tag, and mark areas of the commit graph is definitely containing those commits, or definitely not containing those commits. Later tags can then stop traversing as soon as they see a previously calculated answer.
This sped up "git tag --contains HEAD~200" in the linux-2.6 repository from:
real 0m15.417s user 0m15.197s sys 0m0.220s
to:
real 0m5.329s user 0m5.144s sys 0m0.184s
Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> --- builtin/tag.c | 46 +++++++++++++++++++++++++++++++++++++++++++++- 1 files changed, 45 insertions(+), 1 deletions(-)
diff --git a/builtin/tag.c b/builtin/tag.c index ec926fc..575a03c 100644 --- a/builtin/tag.c +++ b/builtin/tag.c @@ -12,6 +12,8 @@ #include "tag.h" #include "run-command.h" #include "parse-options.h" +#include "diff.h" +#include "revision.h" static const char * const git_tag_usage[] = { "git tag [-a|-s|-u <key-id>] [-f] [-m <msg>|-F <file>] <tagname> [<head>]", @@ -29,6 +31,48 @@ struct tag_filter { struct commit_list *with_commit; }; +static int in_commit_list(const struct commit_list *want, struct commit *c) +{ + for (; want; want = want->next) + if (!hashcmp(want->item->object.sha1, c->object.sha1)) + return 1; + return 0; +} + +static int contains_recurse(struct commit *candidate, + const struct commit_list *want) +{ + struct commit_list *p; + + /* was it previously marked as containing a want commit? */ + if (candidate->object.flags & TMP_MARK) + return 1; + /* or marked as not possibly containing a want commit? */ + if (candidate->object.flags & UNINTERESTING) + return 0; + /* or are we it? */ + if (in_commit_list(want, candidate)) + return 1; + + if (parse_commit(candidate) < 0) + return 0; + + /* Otherwise recurse and mark ourselves for future traversals. */ + for (p = candidate->parents; p; p = p->next) { + if (contains_recurse(p->item, want)) { + candidate->object.flags |= TMP_MARK; + return 1; + } + } + candidate->object.flags |= UNINTERESTING; + return 0; +} + +int contains(struct commit *candidate, const struct commit_list *want) +{ + return contains_recurse(candidate, want); +} + static int show_reference(const char *refname, const unsigned char *sha1, int flag, void *cb_data) { @@ -47,7 +91,7 @@ static int show_reference(const char *refname, const unsigned char *sha1, commit = lookup_commit_reference_gently(sha1, 1); if (!commit) return 0; - if (!is_descendant_of(commit, filter->with_commit)) + if (!contains(commit, filter->with_commit)) return 0; }
-- 1.7.5.3