pack-objects: thin pack micro-optimization.

Since we sort objects by type, hash, preferredness and then
size, after we have a delta against preferred base, there is no
point trying a delta with non-preferred base.  This seems to
save expensive calls to diff-delta and it also seems to save the
output space as well.

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

diff --git a/pack-objects.c b/pack-objects.c
index ceb107f..af3bdf5 100644 (file)
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -447,7 +447,7 @@ static int add_object_entry(const unsigned char *sha1, const char *name, int exc
        struct packed_git *p;
        unsigned int found_offset = 0;
        struct packed_git *found_pack = NULL;
-       int ix;
+       int ix, status = 0;
 
        if (!exclude) {
                for (p = packed_git; p; p = p->next) {
@@ -493,6 +493,7 @@ static int add_object_entry(const unsigned char *sha1, const char *name, int exc
                        die("internal error in object hashing.");
                object_ix[-1 - ix] = idx + 1;
        }
+       status = 1;
 
  already_added:
        if (exclude)
@@ -503,7 +504,7 @@ static int add_object_entry(const unsigned char *sha1, const char *name, int exc
                        entry->in_pack_offset = found_offset;
                }
        }
-       return 1;
+       return status;
 }
 
 static void add_pbase_tree(struct tree_desc *tree)
@@ -521,7 +522,10 @@ static void add_pbase_tree(struct tree_desc *tree)
                        continue;
                if (sha1_object_info(sha1, type, &size))
                        continue;
-               add_object_entry(sha1, name, 1);
+
+               if (!add_object_entry(sha1, name, 1))
+                       continue;
+
                if (!strcmp(type, "tree")) {
                        struct tree_desc sub;
                        void *elem;
@@ -543,8 +547,8 @@ static void add_preferred_base(unsigned char *sha1)
        tree.buf = elem;
        if (!tree.buf)
                return;
-       add_object_entry(sha1, "", 1);
-       add_pbase_tree(&tree);
+       if (add_object_entry(sha1, "", 1))
+               add_pbase_tree(&tree);
        free(elem);
 }
 
@@ -774,7 +778,7 @@ static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_de
                                 * already have a delta based on preferred
                                 * one is pointless.
                                 */
-                               return 0;
+                               return -1;
                }
                else if (!old_preferred)
                        max_size = cur_entry->delta_size-1;