[PATCH] Speed up commands that use rev-list when max-count is specified.

[Benjamin C Meyer <bmeyer@rim.com>]

Many command have code similar to the following:

while ((commit = get_revision(rev)) != NULL) { ... }

This results in and extra call to get_revision that first finds the next
revision and then notices max-count is 0 and returns NULL.  Adding
a max-count check before any expensive work reduces the runtime of all
of the commands the have this pattern.

Depending on the use case this can have a big impact on the running time.

Signed-off-by: Benjamin C Meyer <bmeyer@rim.com>
---
 revision.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/revision.c b/revision.c
index 490b484..4673d70 100644
--- a/revision.c
+++ b/revision.c
@@ -2058,6 +2058,9 @@ static struct commit *get_revision_internal(struct rev_info *revs)
 
 struct commit *get_revision(struct rev_info *revs)
 {
+	if (revs->max_count == 0)
+		return NULL;
+
 	struct commit *c;
 	struct commit_list *reversed;
 
-- 
1.7.0.2