show-branch: Fix another performance problem.

When naming commits, stop walking the parent chain as soon as we find
a commit that already has a name. The parent chain of that commit will
be walked later on in any case (or may even have been walked already).
This avoids O(n^2) behavior; on a tree where show-branch displays 6800
commits, the total run time drops from 77 seconds to 5 seconds.

Signed-off-by: Alexandre Julliard <julliard@winehq.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/builtin-show-branch.c b/builtin-show-branch.c
index 3d240ca435e3079530dd3515ce78bd20858e3a6f..82f75b72dea1a5e6c620003d5c0c4c414dfe42e3 100644 (file)
--- a/builtin-show-branch.c
+++ b/builtin-show-branch.c
@@ -89,6 +89,8 @@ static int name_first_parent_chain(struct commit *c)
                        name_parent(c, p);
                        i++;
                }
+               else
+                       break;
                c = p;
        }
        return i;