Skip to content

G
git2
Commit a3ffbf23 by Carlos Martín Nieto
Options

pack: expose a cached delta base directly 

Instead of going through a special entry in the chain, let's pass it as
an output parameter.
parent 9dbd150f
Showing with 92 additions and 97 deletions
src/pack.c
......@@ -40,14 +40,6 @@ static int pack_entry_find_offset(
const git_oid *short_oid,
size_t len);
/**
* Generate the chain of dependencies which we need to get to the
* object at `off`. `chain` is used a stack, popping gives the right
* order to apply deltas on. If an object is found in the pack's base
* cache, we stop calculating there.
*/
static int pack_dependency_chain(git_dependency_chain *chain, struct git_pack_file *p, git_off_t off);
static int packfile_error(const char *message)
{
giterr_set(GITERR_ODB, "Invalid pack file - %s", message);
......@@ -522,6 +514,87 @@ int git_packfile_resolve_header(
return error;
}
/**
* Generate the chain of dependencies which we need to get to the
* object at `off`. `chain` is used a stack, popping gives the right
* order to apply deltas on. If an object is found in the pack's base
* cache, we stop calculating there.
*/
static int pack_dependency_chain(git_dependency_chain *chain_out, git_pack_cache_entry **cached_out,
git_off_t *cached_off, struct git_pack_file *p, git_off_t obj_offset)
{
git_dependency_chain chain = GIT_ARRAY_INIT;
git_mwindow *w_curs = NULL;
git_off_t curpos = obj_offset, base_offset;
int error = 0;
size_t size;
git_otype type;
if (!p->bases.entries && (cache_init(&p->bases) < 0))
return -1;
git_array_init_to_size(chain, 64);
while (true) {
struct pack_chain_elem *elem;
git_pack_cache_entry *cached = NULL;
/* if we have a base cached, we can stop here instead */
if ((cached = cache_get(&p->bases, obj_offset)) != NULL) {
*cached_out = cached;
*cached_off = obj_offset;
break;
}
curpos = obj_offset;
elem = git_array_alloc(chain);
if (!elem) {
error = -1;
goto on_error;
}
elem->base_key = obj_offset;
error = git_packfile_unpack_header(&size, &type, &p->mwf, &w_curs, &curpos);
git_mwindow_close(&w_curs);
if (error < 0)
goto on_error;
elem->offset = curpos;
elem->size = size;
elem->type = type;
elem->base_key = obj_offset;
if (type != GIT_OBJ_OFS_DELTA && type != GIT_OBJ_REF_DELTA)
break;
base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
git_mwindow_close(&w_curs);
if (base_offset == 0) {
error = packfile_error("delta offset is zero");
goto on_error;
}
if (base_offset < 0) { /* must actually be an error code */
error = (int)base_offset;
goto on_error;
}
/* we need to pass the pos *after* the delta-base bit */
elem->offset = curpos;
/* go through the loop again, but with the new object */
obj_offset = base_offset;
}
*chain_out = chain;
return error;
on_error:
git_array_clear(chain);
return error;
}
int git_packfile_unpack(
git_rawobj *obj,
struct git_pack_file *p,
......@@ -531,7 +604,7 @@ int git_packfile_unpack(
git_off_t curpos = *obj_offset;
int error, free_base = 0;
git_dependency_chain chain = GIT_ARRAY_INIT;
struct pack_chain_elem *elem;
struct pack_chain_elem *elem = NULL;
git_pack_cache_entry *cached = NULL;
git_otype base_type;
......@@ -539,7 +612,7 @@ int git_packfile_unpack(
* TODO: optionally check the CRC on the packfile
*/
error = pack_dependency_chain(&chain, p, *obj_offset);
error = pack_dependency_chain(&chain, &cached, obj_offset, p, *obj_offset);
if (error < 0)
return error;
......@@ -547,12 +620,12 @@ int git_packfile_unpack(
obj->len = 0;
obj->type = GIT_OBJ_BAD;
/* the first one is the base, so we expand that one */
elem = git_array_pop(chain);
base_type = elem->type;
if (elem->cached) {
cached = elem->cached_entry;
if (cached) {
memcpy(obj, &cached->raw, sizeof(git_rawobj));
base_type = obj->type;
} else {
elem = git_array_pop(chain);
base_type = elem->type;
}
if (error < 0)
......@@ -563,10 +636,11 @@ int git_packfile_unpack(
case GIT_OBJ_TREE:
case GIT_OBJ_BLOB:
case GIT_OBJ_TAG:
if (!elem->cached) {
if (!cached) {
curpos = elem->offset;
error = packfile_unpack_compressed(obj, p, &w_curs, &curpos, elem->size, elem->type);
git_mwindow_close(&w_curs);
base_type = elem->type;
free_base = 1;
}
if (error < 0)
......@@ -646,7 +720,8 @@ cleanup:
if (error < 0)
git__free(obj->data);
*obj_offset = elem->offset;
if (elem)
*obj_offset = elem->offset;
git_array_clear(chain);
return error;
......@@ -1240,79 +1315,3 @@ int git_pack_entry_find(
git_oid_cpy(&e->sha1, &found_oid);
return 0;
}
static int pack_dependency_chain(git_dependency_chain *chain_out, struct git_pack_file *p, git_off_t obj_offset)
{
git_dependency_chain chain = GIT_ARRAY_INIT;
git_mwindow *w_curs = NULL;
git_off_t curpos = obj_offset, base_offset;
int error = 0;
size_t size;
git_otype type;
if (!p->bases.entries && (cache_init(&p->bases) < 0))
return -1;
git_array_init_to_size(chain, 64);
while (true) {
struct pack_chain_elem *elem;
git_pack_cache_entry *cached = NULL;
curpos = obj_offset;
elem = git_array_alloc(chain);
if (!elem) {
error = -1;
goto on_error;
}
elem->base_key = obj_offset;
/* if we have a base cached, we can stop here instead */
if ((cached = cache_get(&p->bases, obj_offset)) != NULL) {
elem->cached_entry = cached;
elem->cached = 1;
elem->type = cached->raw.type;
break;
}
error = git_packfile_unpack_header(&size, &type, &p->mwf, &w_curs, &curpos);
git_mwindow_close(&w_curs);
if (error < 0)
goto on_error;
elem->cached = 0;
elem->offset = curpos;
elem->size = size;
elem->type = type;
elem->base_key = obj_offset;
if (type != GIT_OBJ_OFS_DELTA && type != GIT_OBJ_REF_DELTA)
break;
base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
git_mwindow_close(&w_curs);
if (base_offset == 0) {
error = packfile_error("delta offset is zero");
goto on_error;
}
if (base_offset < 0) { /* must actually be an error code */
error = (int)base_offset;
goto on_error;
}
/* we need to pass the pos *after* the delta-base bit */
elem->offset = curpos;
/* go through the loop again, but with the new object */
obj_offset = base_offset;
}
*chain_out = chain;
return error;
on_error:
git_array_clear(chain);
return error;
}
src/pack.h
......@@ -62,14 +62,10 @@ typedef struct git_pack_cache_entry {
} git_pack_cache_entry;
struct pack_chain_elem {
int cached;
git_off_t base_key;
/* if we don't have it cached we have this */
git_off_t offset;
size_t size;
git_otype type;
/* if cached, we have this instead */
git_pack_cache_entry *cached_entry;
};
typedef git_array_t(struct pack_chain_elem) git_dependency_chain;
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment