git-pickaxe: cache one already found path per commit.

Depending on how bushy the commit DAG is, this saves calls to
the internal diff-tree for fork-point commits.  For example,
annotating Makefile in the kernel repository saves about a third
of such diff-tree calls.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/builtin-pickaxe.c b/builtin-pickaxe.c
index 32dc3932edfa6c007d75b5369917e1fd744ca317..c9405e918bc5e6da94c61f7fe2cdd00b5da44508 100644 (file)
--- a/builtin-pickaxe.c
+++ b/builtin-pickaxe.c
@@ -141,6 +141,8 @@ static int cmp_suspect(struct origin *a, struct origin *b)
        return strcmp(a->path, b->path);
 }
 
+#define cmp_suspect(a, b) ( ((a)==(b)) ? 0 : cmp_suspect(a,b) )
+
 static void sanity_check_refcnt(struct scoreboard *);
 
 static void coalesce(struct scoreboard *sb)
@@ -213,6 +215,12 @@ static struct origin *find_origin(struct scoreboard *sb,
        struct diff_options diff_opts;
        const char *paths[2];
 
+       if (parent->util) {
+               struct origin *cached = parent->util;
+               if (!strcmp(cached->path, origin->path))
+                       return origin_incref(cached);
+       }
+
        /* See if the origin->path is different between parent
         * and origin first.  Most of the time they are the
         * same and diff-tree is fairly efficient about this.
@@ -259,6 +267,12 @@ static struct origin *find_origin(struct scoreboard *sb,
                }
        }
        diff_flush(&diff_opts);
+       if (porigin) {
+               origin_incref(porigin);
+               if (parent->util)
+                       origin_decref(parent->util);
+               parent->util = porigin;
+       }
        return porigin;
 }
 
@@ -905,7 +919,7 @@ static void pass_blame(struct scoreboard *sb, struct origin *origin, int opt)
                                continue;
                        if (parse_commit(p))
                                continue;
-                       porigin = find(sb, parent->item, origin);
+                       porigin = find(sb, p, origin);
                        if (!porigin)
                                continue;
                        if (!hashcmp(porigin->blob_sha1, origin->blob_sha1)) {
@@ -1371,8 +1385,10 @@ static void sanity_check_refcnt(struct scoreboard *sb)
                        ent->suspect->refcnt = -ent->suspect->refcnt;
        }
        for (ent = sb->ent; ent; ent = ent->next) {
-               /* then pick each and see if they have the the
-                * correct refcnt
+               /* then pick each and see if they have the the correct
+                * refcnt; note that ->util caching means origin's refcnt
+                * may well be greater than the number of blame entries
+                * that use it.
                 */
                int found;
                struct blame_entry *e;
@@ -1386,7 +1402,7 @@ static void sanity_check_refcnt(struct scoreboard *sb)
                                continue;
                        found++;
                }
-               if (suspect->refcnt != found)
+               if (suspect->refcnt < found)
                        baa = 1;
        }
        if (baa) {