[PATCH 4/6] shortlog: optimize "--summary" mode

From: Jeff King <peff@peff.net>
Date: Jan 15, 2016, 17:09 UTC
Message-ID: <20160115170933.GD21102@sigill.intra.peff.net>
In-Reply-To: <20160115170627.GA20983@sigill.intra.peff.net>

If the user asked us only to show counts for each author, rather than the individual summary lines, then there is no point in us generating the summaries only to throw them away. With this patch, I measured the following speedup for "git shortlog -ns HEAD" on linux.git (best-of-five):

  [before]
  real    0m5.644s
  user    0m5.472s
  sys     0m0.176s

  [after]
  real    0m5.257s
  user    0m5.104s
  sys     0m0.156s

That's only ~7%, but it's so easy to do, there's no good reason not to. We don't have to touch any downstream code, since we already fill in the magic string "<none>" to handle commits without a message.

Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/shortlog.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/builtin/shortlog.c b/builtin/shortlog.c
index 256b868..3e1e0d6 100644
--- a/builtin/shortlog.c
+++ b/builtin/shortlog.c
@@ -152,10 +152,12 @@ void shortlog_add_commit(struct shortlog *log, struct commit *commit)
 		goto out;
 	}
 
-	if (log->user_format)
-		pretty_print_commit(&ctx, commit, &oneline);
-	else
-		format_commit_message(commit, "%s", &oneline, &ctx);
+	if (!log->summary) {
+		if (log->user_format)
+			pretty_print_commit(&ctx, commit, &oneline);
+		else
+			format_commit_message(commit, "%s", &oneline, &ctx);
+	}
 
 	insert_one_record(log, author.buf, oneline.len ? oneline.buf : "<none>");

-- 
2.7.0.244.g0701a9d