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Merge branch 'nd/pack-deltify-regression-fix'

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In a recent update in 2.18 era, "git pack-objects" started
producing a larger than necessary packfiles by missing
opportunities to use large deltas.

* nd/pack-deltify-regression-fix:
  pack-objects: fix performance issues on packing large deltas
This commit is contained in:
Junio C Hamano
2018-08-22 11:17:05 -07:00
parent 7e8bfb0412 9ac3f0e5b3
commit 29d9e3e2c4
5 changed files with 58 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

59
pack-objects.h
View File

@ -2,6 +2,7 @@
#define PACK_OBJECTS_H
#include "object-store.h"
#include "thread-utils.h"
#include "pack.h"
#define DEFAULT_DELTA_CACHE_SIZE (256 * 1024 * 1024)
@ -15,7 +16,7 @@
* above this limit. Don't lower it too much.
*/
#define OE_SIZE_BITS 31
#define OE_DELTA_SIZE_BITS 20
#define OE_DELTA_SIZE_BITS 23
/*
* State flags for depth-first search used for analyzing delta cycles.
@ -95,11 +96,12 @@ struct object_entry {
*/
unsigned delta_size_:OE_DELTA_SIZE_BITS; /* delta data size (uncompressed) */
unsigned delta_size_valid:1;
unsigned char in_pack_header_size;
unsigned in_pack_idx:OE_IN_PACK_BITS; /* already in pack */
unsigned z_delta_size:OE_Z_DELTA_BITS;
unsigned type_valid:1;
unsigned type_:TYPE_BITS;
unsigned no_try_delta:1;
unsigned type_:TYPE_BITS;
unsigned in_pack_type:TYPE_BITS; /* could be delta */
unsigned preferred_base:1; /*
* we do not pack this, but is available
@ -109,17 +111,16 @@ struct object_entry {
unsigned tagged:1; /* near the very tip of refs */
unsigned filled:1; /* assigned write-order */
unsigned dfs_state:OE_DFS_STATE_BITS;
unsigned char in_pack_header_size;
unsigned depth:OE_DEPTH_BITS;
/*
* pahole results on 64-bit linux (gcc and clang)
*
* size: 80, bit_padding: 20 bits, holes: 8 bits
* size: 80, bit_padding: 9 bits
*
* and on 32-bit (gcc)
*
* size: 76, bit_padding: 20 bits, holes: 8 bits
* size: 76, bit_padding: 9 bits
*/
};
@ -131,6 +132,7 @@ struct packing_data {
uint32_t index_size;
unsigned int *in_pack_pos;
unsigned long *delta_size;
/*
* Only one of these can be non-NULL and they have different
@ -141,10 +143,29 @@ struct packing_data {
struct packed_git **in_pack_by_idx;
struct packed_git **in_pack;
#ifndef NO_PTHREADS
pthread_mutex_t lock;
#endif
uintmax_t oe_size_limit;
uintmax_t oe_delta_size_limit;
};
void prepare_packing_data(struct packing_data *pdata);
static inline void packing_data_lock(struct packing_data *pdata)
{
#ifndef NO_PTHREADS
pthread_mutex_lock(&pdata->lock);
#endif
}
static inline void packing_data_unlock(struct packing_data *pdata)
{
#ifndef NO_PTHREADS
pthread_mutex_unlock(&pdata->lock);
#endif
}
struct object_entry *packlist_alloc(struct packing_data *pdata,
const unsigned char *sha1,
uint32_t index_pos);
@ -333,18 +354,34 @@ static inline unsigned long oe_delta_size(struct packing_data *pack,
{
if (e->delta_size_valid)
return e->delta_size_;
return oe_size(pack, e);
/*
* pack->detla_size[] can't be NULL because oe_set_delta_size()
* must have been called when a new delta is saved with
* oe_set_delta().
* If oe_delta() returns NULL (i.e. default state, which means
* delta_size_valid is also false), then the caller must never
* call oe_delta_size().
*/
return pack->delta_size[e - pack->objects];
}
static inline void oe_set_delta_size(struct packing_data *pack,
struct object_entry *e,
unsigned long size)
{
e->delta_size_ = size;
e->delta_size_valid = e->delta_size_ == size;
if (!e->delta_size_valid && size != oe_size(pack, e))
BUG("this can only happen in check_object() "
"where delta size is the same as entry size");
if (size < pack->oe_delta_size_limit) {
e->delta_size_ = size;
e->delta_size_valid = 1;
} else {
packing_data_lock(pack);
if (!pack->delta_size)
ALLOC_ARRAY(pack->delta_size, pack->nr_alloc);
packing_data_unlock(pack);
pack->delta_size[e - pack->objects] = size;
e->delta_size_valid = 0;
}
}
#endif