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basic threaded delta search 

this is still rough, hence it is disabled by default.  You need to compile
with "make THREADED_DELTA_SEARCH=1 ..." at the moment.

Threading is done on different portions of the object list to be
deltified. This is currently done by spliting the list into n parts and
then a thread is spawned for each of them.  A better method would consist
of spliting the list into more smaller parts and have the n threads
pick the next part available.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
maint
Nicolas Pitre 2007-09-06 02:13:11 -04:00 committed by Junio C Hamano
parent e334977dfa
commit 8ecce684a3
2 changed files with 90 additions and 1 deletions
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8
Makefile
View File

@ -122,6 +122,9 @@ all::
# If not set it defaults to the bare 'wish'. If it is set to the empty
# string then NO_TCLTK will be forced (this is used by configure script).
#
# Define THREADED_DELTA_SEARCH if you have pthreads and wish to exploit
# parallel delta searching when packing objects.
#

GIT-VERSION-FILE: .FORCE-GIT-VERSION-FILE
@$(SHELL_PATH) ./GIT-VERSION-GEN
@ -662,6 +665,11 @@ ifdef NO_HSTRERROR
COMPAT_OBJS += compat/hstrerror.o
endif

ifdef THREADED_DELTA_SEARCH
BASIC_CFLAGS += -DTHREADED_DELTA_SEARCH
EXTLIBS += -lpthread
endif

ifeq ($(TCLTK_PATH),)
NO_TCLTK=NoThanks
endif

83
builtin-pack-objects.c
View File

@ -15,6 +15,10 @@
#include "list-objects.h"
#include "progress.h"

#ifdef THREADED_DELTA_SEARCH
#include <pthread.h>
#endif

static const char pack_usage[] = "\
git-pack-objects [{ -q | --progress | --all-progress }] \n\
[--max-pack-size=N] [--local] [--incremental] \n\
@ -1290,6 +1294,25 @@ static int delta_cacheable(unsigned long src_size, unsigned long trg_size,
return 0;
}

#ifdef THREADED_DELTA_SEARCH

static pthread_mutex_t read_mutex = PTHREAD_MUTEX_INITIALIZER;
#define read_lock() pthread_mutex_lock(&read_mutex)
#define read_unlock() pthread_mutex_unlock(&read_mutex)

static pthread_mutex_t progress_mutex = PTHREAD_MUTEX_INITIALIZER;
#define progress_lock() pthread_mutex_lock(&progress_mutex)
#define progress_unlock() pthread_mutex_unlock(&progress_mutex)

#else

#define read_lock() 0
#define read_unlock() 0
#define progress_lock() 0
#define progress_unlock() 0

#endif

/*
* We search for deltas _backwards_ in a list sorted by type and
* by size, so that we see progressively smaller and smaller files.
@ -1348,7 +1371,9 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,

/* Load data if not already done */
if (!trg->data) {
read_lock();
trg->data = read_sha1_file(trg_entry->idx.sha1, &type, &sz);
read_unlock();
if (!trg->data)
die("object %s cannot be read",
sha1_to_hex(trg_entry->idx.sha1));
@ -1358,7 +1383,9 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
*mem_usage += sz;
}
if (!src->data) {
read_lock();
src->data = read_sha1_file(src_entry->idx.sha1, &type, &sz);
read_unlock();
if (!src->data)
die("object %s cannot be read",
sha1_to_hex(src_entry->idx.sha1));
@ -1470,9 +1497,11 @@ static void find_deltas(struct object_entry **list, unsigned list_size,
if (entry->preferred_base)
goto next;

progress_lock();
(*processed)++;
if (progress)
display_progress(&progress_state, *processed);
progress_unlock();

/*
* If the current object is at pack edge, take the depth the
@ -1542,6 +1571,58 @@ static void find_deltas(struct object_entry **list, unsigned list_size,
free(array);
}

#ifdef THREADED_DELTA_SEARCH

struct thread_params {
pthread_t thread;
struct object_entry **list;
unsigned list_size;
int window;
int depth;
unsigned *processed;
};

static void *threaded_find_deltas(void *arg)
{
struct thread_params *p = arg;
if (p->list_size)
find_deltas(p->list, p->list_size,
p->window, p->depth, p->processed);
return NULL;
}

#define NR_THREADS 8

static void ll_find_deltas(struct object_entry **list, unsigned list_size,
int window, int depth, unsigned *processed)
{
struct thread_params p[NR_THREADS];
int i, ret;

for (i = 0; i < NR_THREADS; i++) {
unsigned sublist_size = list_size / (NR_THREADS - i);
p[i].list = list;
p[i].list_size = sublist_size;
p[i].window = window;
p[i].depth = depth;
p[i].processed = processed;
ret = pthread_create(&p[i].thread, NULL,
threaded_find_deltas, &p[i]);
if (ret)
die("unable to create thread: %s", strerror(ret));
list += sublist_size;
list_size -= sublist_size;
}

for (i = 0; i < NR_THREADS; i++) {
pthread_join(p[i].thread, NULL);
}
}

#else
#define ll_find_deltas find_deltas
#endif

static void prepare_pack(int window, int depth)
{
struct object_entry **delta_list;
@ -1583,7 +1664,7 @@ static void prepare_pack(int window, int depth)
"Deltifying %u objects...", "",
nr_deltas);
qsort(delta_list, n, sizeof(*delta_list), type_size_sort);
find_deltas(delta_list, n, window+1, depth, &nr_done);
ll_find_deltas(delta_list, n, window+1, depth, &nr_done);
if (progress)
stop_progress(&progress_state);
if (nr_done != nr_deltas)