From 20e95d0a8475ce467903e1aaad5c2fd47777fcc8 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Nguy=E1=BB=85n=20Th=C3=A1i=20Ng=E1=BB=8Dc=20Duy?= Date: Sat, 14 Jan 2012 19:19:55 +0700 Subject: [PATCH] index-pack: eliminate unlimited recursion in get_base_data() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Revese the order of delta applying so that by the time a delta is applied, its base is either non-delta or already inflated. get_base_data() is still recursive, but because base's data is always ready, the inner get_base_data() call never has any chance to call itself again. Signed-off-by: Nguyễn Thái Ngọc Duy Signed-off-by: Junio C Hamano --- builtin/index-pack.c | 53 ++++++++++++++++++++++++++++++++++++-------- 1 file changed, 44 insertions(+), 9 deletions(-) diff --git a/builtin/index-pack.c b/builtin/index-pack.c index 38ff03a5c..dd1c5c961 100644 --- a/builtin/index-pack.c +++ b/builtin/index-pack.c @@ -515,14 +515,52 @@ static int is_delta_type(enum object_type type) return (type == OBJ_REF_DELTA || type == OBJ_OFS_DELTA); } +/* + * This function is part of find_unresolved_deltas(). There are two + * walkers going in the opposite ways. + * + * The first one in find_unresolved_deltas() traverses down from + * parent node to children, deflating nodes along the way. However, + * memory for deflated nodes is limited by delta_base_cache_limit, so + * at some point parent node's deflated content may be freed. + * + * The second walker is this function, which goes from current node up + * to top parent if necessary to deflate the node. In normal + * situation, its parent node would be already deflated, so it just + * needs to apply delta. + * + * In the worst case scenario, parent node is no longer deflated because + * we're running out of delta_base_cache_limit; we need to re-deflate + * parents, possibly up to the top base. + * + * All deflated objects here are subject to be freed if we exceed + * delta_base_cache_limit, just like in find_unresolved_deltas(), we + * just need to make sure the last node is not freed. + */ static void *get_base_data(struct base_data *c) { if (!c->data) { struct object_entry *obj = c->obj; + struct base_data **delta = NULL; + int delta_nr = 0, delta_alloc = 0; - if (is_delta_type(obj->type)) { - void *base = get_base_data(c->base); - void *raw = get_data_from_pack(obj); + while (is_delta_type(c->obj->type) && !c->data) { + ALLOC_GROW(delta, delta_nr + 1, delta_alloc); + delta[delta_nr++] = c; + c = c->base; + } + if (!delta_nr) { + c->data = get_data_from_pack(obj); + c->size = obj->size; + base_cache_used += c->size; + prune_base_data(c); + } + for (; delta_nr > 0; delta_nr--) { + void *base, *raw; + c = delta[delta_nr - 1]; + obj = c->obj; + base = get_base_data(c->base); + raw = get_data_from_pack(obj); c->data = patch_delta( base, c->base->size, raw, obj->size, @@ -530,13 +568,10 @@ static void *get_base_data(struct base_data *c) free(raw); if (!c->data) bad_object(obj->idx.offset, "failed to apply delta"); - } else { - c->data = get_data_from_pack(obj); - c->size = obj->size; + base_cache_used += c->size; + prune_base_data(c); } - - base_cache_used += c->size; - prune_base_data(c); + free(delta); } return c->data; } -- 2.30.2