From 333e9b661f6a64a9b552230c0dc987d9e69bceae Mon Sep 17 00:00:00 2001 From: Jeff King Date: Fri, 30 May 2014 14:34:41 -0400 Subject: reuse commit->buffer when parsing signatures When we call show_signature or show_mergetag, we read the commit object fresh via read_sha1_file and reparse its headers. However, in most cases we already have the object data available as commit->buffer. This is partially laziness in dealing with the memory allocation issues, but partially defensive programming, in that we would always want to verify a clean version of the buffer (not one that might have been munged by other users of the commit). However, we do not currently ever munge commit->buffer, and not using the already-available buffer carries a fairly big performance penalty when we are looking at a large number of commits. Here are timings on linux.git: [baseline, no signatures] $ time git log >/dev/null real 0m4.902s user 0m4.784s sys 0m0.120s [before] $ time git log --show-signature >/dev/null real 0m14.735s user 0m9.964s sys 0m0.944s [after] $ time git log --show-signature >/dev/null real 0m9.981s user 0m5.260s sys 0m0.936s Note that our user CPU time drops almost in half, close to the non-signature case, but we do still spend more wall-clock and system time, presumably from dealing with gpg. An alternative to this is to note that most commits do not have signatures (less than 1% in this repo), yet we pay the re-parsing cost for every commit just to find out if it has a mergetag or signature. If we checked that when parsing the commit initially, we could avoid re-examining most commits later on. Even if we did pursue that direction, however, this would still speed up the cases where we _do_ have signatures. So it's probably worth doing either way. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- commit.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'commit.h') diff --git a/commit.h b/commit.h index bd841f4d0c..8cde84e4fa 100644 --- a/commit.h +++ b/commit.h @@ -257,7 +257,7 @@ struct merge_remote_desc { */ struct commit *get_merge_parent(const char *name); -extern int parse_signed_commit(const unsigned char *sha1, +extern int parse_signed_commit(const struct commit *commit, struct strbuf *message, struct strbuf *signature); extern void print_commit_list(struct commit_list *list, const char *format_cur, -- cgit v1.2.1