revision: avoid work after --max-count is reached

diff --git a/revision.c b/revision.c
index 5b81a92e3ac65ab0295f25198511fc83b4bbf1c9..7e3965557ac2e2d2d432e47b8b745c4dc0e184b6 100644 (file)
--- a/revision.c
+++ b/revision.c
@@ -2361,29 +2361,28 @@ static struct commit *get_revision_internal(struct rev_info *revs)
        }
 
        /*
-        * Now pick up what they want to give us
+        * If our max_count counter has reached zero, then we are done. We
+        * don't simply return NULL because we still might need to show
+        * boundary commits. But we want to avoid calling get_revision_1, which
+        * might do a considerable amount of work finding the next commit only
+        * for us to throw it away.
+        *
+        * If it is non-zero, then either we don't have a max_count at all
+        * (-1), or it is still counting, in which case we decrement.
         */
-       c = get_revision_1(revs);
-       if (c) {
-               while (0 < revs->skip_count) {
-                       revs->skip_count--;
-                       c = get_revision_1(revs);
-                       if (!c)
-                               break;
+       if (revs->max_count) {
+               c = get_revision_1(revs);
+               if (c) {
+                       while (0 < revs->skip_count) {
+                               revs->skip_count--;
+                               c = get_revision_1(revs);
+                               if (!c)
+                                       break;
+                       }
                }
-       }
 
-       /*
-        * Check the max_count.
-        */
-       switch (revs->max_count) {
-       case -1:
-               break;
-       case 0:
-               c = NULL;
-               break;
-       default:
-               revs->max_count--;
+               if (revs->max_count > 0)
+                       revs->max_count--;
        }
 
        if (c)