From 75c42d8cc3b42e4b82946848b8ba902b4bbcc38d Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 25 Jun 2005 19:30:20 -0700 Subject: Add a "max_size" parameter to diff_delta() Anything that generates a delta to see if two objects are close usually isn't interested in the delta ends up being bigger than some specified size, and this allows us to stop delta generation early when that happens. --- pack-objects.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) (limited to 'pack-objects.c') diff --git a/pack-objects.c b/pack-objects.c index dfa9d44a15..d9328a98d8 100644 --- a/pack-objects.c +++ b/pack-objects.c @@ -83,8 +83,8 @@ static void *delta_against(void *buf, unsigned long size, struct object_entry *e if (!otherbuf) die("unable to read %s", sha1_to_hex(entry->delta->sha1)); - delta_buf = diff_delta(buf, size, otherbuf, othersize, &delta_size); - if (delta_size != entry->delta_size) + delta_buf = diff_delta(buf, size, otherbuf, othersize, &delta_size, ~0UL); + if (!delta_buf || delta_size != entry->delta_size) die("delta size changed"); free(buf); free(otherbuf); @@ -292,6 +292,7 @@ static int try_delta(struct unpacked *cur, struct unpacked *old) struct object_entry *cur_entry = cur->entry; struct object_entry *old_entry = old->entry; unsigned long size, oldsize, delta_size; + long max_size; void *delta_buf; /* Don't bother doing diffs between different types */ @@ -300,6 +301,8 @@ static int try_delta(struct unpacked *cur, struct unpacked *old) /* Size is guaranteed to be larger than or equal to oldsize */ size = cur_entry->size; + if (size < 50) + return -1; oldsize = old_entry->size; if (size - oldsize > oldsize / 4) return -1; @@ -311,15 +314,14 @@ static int try_delta(struct unpacked *cur, struct unpacked *old) * more space-efficient (deletes don't have to say _what_ they * delete). */ - delta_buf = diff_delta(cur->data, size, old->data, oldsize, &delta_size); + max_size = size / 2 - 20; + if (cur_entry->delta) + max_size = cur_entry->delta_size-1; + delta_buf = diff_delta(cur->data, size, old->data, oldsize, &delta_size, max_size); if (!delta_buf) - die("unable to create delta"); - if (delta_size + 20 < size / 2) { - if (!cur_entry->delta || cur_entry->delta_size > delta_size) { - cur_entry->delta = old_entry; - cur_entry->delta_size = delta_size; - } - } + return 0; + cur_entry->delta = old_entry; + cur_entry->delta_size = delta_size; free(delta_buf); return 0; } -- cgit v1.3