"git rev-list --objects v1.8.4" time is reduced from 29s to 10s with
this patch. But it is still a long way to catch up with v2: 4s.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
The problem I see with decode_entries() is that given n copy
sequences, it re-reads the same base n times. 30+ copy sequences are
not unusual at all with git.git.
I'm thinking of adding a cache to deal with one-base trees, which is
all we have now. If we know in advance what base a tree needs without
parsing the tree, we could unpack from base up like we do with
ref-deltas. Because in this case we know the base is always flat, we
could have a more efficient decode_entries that only goes through the
base once. I want to get the timing down to as close as possible to
v2 before adding v4-aware interface.
Pack cache is an idea being cooked for a while by Jeff. Maybe we
could merge his work to pack v4 or require it when pack v4 is finally
merged to 'next'.
packv4-parse.c | 17 +++++++++++++++--
packv4-parse.h | 2 ++
sha1_file.c | 14 ++++++++++++++
3 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/packv4-parse.c b/packv4-parse.c
index 5002f42..b8855b0 100644
--- a/packv4-parse.c
+++ b/packv4-parse.c
@@ -415,8 +415,20 @@ static int decode_entries(struct packed_git *p, struct pack_window **w_curs,
unsigned int nb_entries;
const unsigned char *src, *scp;
off_t copy_objoffset = 0;
+ const void *cached = NULL;
+ unsigned long cached_size, cached_v4_size;
+
+ if (hdr) /* we need offset point at obj header */
+ cached = get_cached_v4_tree(p, offset,
+ &cached_size, &cached_v4_size);
+
+ if (cached) {
+ src = cached;
+ avail = cached_v4_size;
+ hdr = 0;
+ } else
+ src = use_pack(p, w_curs, offset, &avail);
- src = use_pack(p, w_curs, offset, &avail);
scp = src;
if (hdr) {
@@ -452,7 +464,8 @@ static int decode_entries(struct packed_git *p, struct pack_window **w_curs,
while (count) {
unsigned int what;
- if (avail < 20) {
+ /* fixme: need to put bach the out-of-bound check when cached == 1 */
+ if (!cached && avail < 20) {
src = use_pack(p, w_curs, offset, &avail);
if (avail < 20)
return -1;
diff --git a/packv4-parse.h b/packv4-parse.h
index 647b73c..f584c31 100644
--- a/packv4-parse.h
+++ b/packv4-parse.h
@@ -16,6 +16,8 @@ unsigned long pv4_unpack_object_header_buffer(const unsigned char *base,
unsigned long *sizep);
const unsigned char *get_sha1ref(struct packed_git *p,
const unsigned char **bufp);
+const void *get_cached_v4_tree(struct packed_git *p, off_t base_offset,
+ unsigned long *size, unsigned long *v4_size);
void *pv4_get_commit(struct packed_git *p, struct pack_window **w_curs,
off_t offset, unsigned long size);
diff --git a/sha1_file.c b/sha1_file.c
index b176316..82570be 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1967,6 +1967,20 @@ static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
return eq_delta_base_cache_entry(ent, p, base_offset);
}
+const void *get_cached_v4_tree(struct packed_git *p, off_t base_offset,
+ unsigned long *size, unsigned long *v4_size)
+{
+ struct delta_base_cache_entry *ent;
+ ent = get_delta_base_cache_entry(p, base_offset);
+
+ if (!eq_delta_base_cache_entry(ent, p, base_offset) ||
+ ent->type != OBJ_PV4_TREE)
+ return NULL;
+ *size = ent->size;
+ *v4_size = ent->v4_size;
+ return ent->data;
+}
+
static void clear_delta_base_cache_entry(struct delta_base_cache_entry *ent)
{
ent->data = NULL;
--
1.8.2.83.gc99314b
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