[PATCH] Avoid loading commits twice in log with diffs
- From
Thomas Rast <trast@student.ethz.ch>
- Date
- Mar 2, 2013, 10:05 UTC
- Message-ID
- <3193c96cf5b036a91bc78b508b8b30ac87ca0f21.1362218700.git.trast@student.ethz.ch>
If you run a log with diffs (such as -p, --raw, --stat etc.) the current code ends up loading many objects twice. For example, for 'log -3000 -p' my instrumentation said the objects loaded more than once are distributed as follows:
2008 blob 2103 commit 2678 tree
Fixing blobs and trees will be harder, because those are really used within the diff engine and need some form of caching.
However, fixing the commits is easy at least at the band-aid level. They are triggered by log_tree_diff() invoking diff_tree_sha1() on commits, which duly loads the specified object to dereference it to a tree. Since log_tree_diff() knows that it works with commits and they must have trees, we can simply pass through the trees.
This has a quite dramatic effect on log --raw, though only a negligible impact on log -p:
Test with patch before -------------------------------------------------------------------- 4000.2: log --raw -3000 0.50(0.43+0.06) 0.54(0.46+0.06) +7.0%*** 4000.3: log -p -3000 2.34(2.20+0.13) 2.37(2.22+0.13) +1.2% -------------------------------------------------------------------- Significance hints: '.' 0.1 '*' 0.05 '**' 0.01 '***' 0.001
Signed-off-by: Thomas Rast <trast@student.ethz.ch> --- log-tree.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/log-tree.c b/log-tree.c index eb1a1b4..277a38f 100644 --- a/log-tree.c +++ b/log-tree.c @@ -715,7 +715,7 @@ static int log_tree_diff(struct rev_info *opt, struct commit *commit, struct log { int showed_log; struct commit_list *parents; - unsigned const char *sha1 = commit->object.sha1; + unsigned const char *sha1 = commit->tree->object.sha1; if (!opt->diff && !DIFF_OPT_TST(&opt->diffopt, EXIT_WITH_STATUS)) return 0; @@ -742,7 +742,8 @@ static int log_tree_diff(struct rev_info *opt, struct commit *commit, struct log * parent, showing summary diff of the others * we merged _in_. */ - diff_tree_sha1(parents->item->object.sha1, sha1, "", &opt->diffopt); + parse_commit(parents->item); + diff_tree_sha1(parents->item->tree->object.sha1, sha1, "", &opt->diffopt); log_tree_diff_flush(opt); return !opt->loginfo; } @@ -755,7 +756,8 @@ static int log_tree_diff(struct rev_info *opt, struct commit *commit, struct log for (;;) { struct commit *parent = parents->item; - diff_tree_sha1(parent->object.sha1, sha1, "", &opt->diffopt); + parse_commit(parent); + diff_tree_sha1(parent->tree->object.sha1, sha1, "", &opt->diffopt); log_tree_diff_flush(opt); showed_log |= !opt->loginfo;
-- 1.8.2.rc1.393.ga167915