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pack: refcount entries and add a mutex around cache access

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This commit is contained in:
Carlos Martín Nieto 2012-12-20 07:55:51 +01:00
parent c0f4a0118d
commit 525d961c24
2 changed files with 35 additions and 10 deletions
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42
src/pack.c
View File

@ -47,13 +47,13 @@ static int packfile_error(const char *message)
}
static git_pack_cache_entry *new_cache_object(git_off_t off, git_rawobj *source)
static git_pack_cache_entry *new_cache_object(git_rawobj *source)
{
git_pack_cache_entry *e = git__malloc(sizeof(git_pack_cache_entry));
if (!e)
return NULL;
e->off = off;
e->refcount.val = 0;
memcpy(&e->raw, source, sizeof(git_rawobj));
return e;
@ -63,6 +63,7 @@ static void free_cache_object(void *o)
{
git_pack_cache_entry *e = (git_pack_cache_entry *)o;
assert(e->refcount.val == 0);
if (e != NULL) {
git__free(e->raw.data);
git__free(e);
@ -361,7 +362,7 @@ static int packfile_unpack_delta(
{
git_off_t base_offset, base_key;
git_rawobj base, delta;
git_pack_cache_entry *cached;
git_pack_cache_entry *cached = NULL;
int error, found_base = 0;
khiter_t k;
@ -375,15 +376,21 @@ static int packfile_unpack_delta(
if (!p->bases) {
p->bases = git_offmap_alloc();
GITERR_CHECK_ALLOC(p->bases);
git_mutex_init(&p->bases_lock);
}
base_key = base_offset; /* git_packfile_unpack modifies base_offset */
git_mutex_lock(&p->bases_lock);
k = kh_get(off, p->bases, base_offset);
if (k != kh_end(p->bases)) { /* found it */
cached = kh_value(p->bases, k);
git_atomic_inc(&cached->refcount);
found_base = 1;
memcpy(&base, &cached->raw, sizeof(git_rawobj));
} else { /* have to inflate it */
}
git_mutex_unlock(&p->bases_lock);
if (!cached) { /* have to inflate it */
error = git_packfile_unpack(&base, p, &base_offset);
/*
@ -410,12 +417,27 @@ static int packfile_unpack_delta(
if (error < 0)
goto on_error;
if (!found_base) {
cached = new_cache_object(base_key, &base);
if (found_base) {
git_atomic_dec(&cached->refcount);
} else {
cached = new_cache_object(&base);
if (cached) {
k = kh_put(off, p->bases, base_key, &error);
assert(error != 0);
kh_value(p->bases, k) = cached;
int exists;
git_mutex_lock(&p->bases_lock);
/* Add it to the cache if nobody else has */
exists = kh_exist(p->bases, kh_get(off, p->bases, base_key));
if (!exists) {
k = kh_put(off, p->bases, base_key, &error);
assert(error != 0);
kh_value(p->bases, k) = cached;
}
git_mutex_unlock(&p->bases_lock);
/* Somebody beat us to adding it into the cache */
if (exists) {
free_cache_object(cached);
git__free(base.data);
}
}
}
@ -738,6 +760,8 @@ static int packfile_open(struct git_pack_file *p)
p->bases = git_offmap_alloc();
GITERR_CHECK_ALLOC(p->bases);
git_mutex_init(&p->bases_lock);
/* TODO: open with noatime */
p->mwf.fd = git_futils_open_ro(p->pack_name);

3
src/pack.h
View File

@ -54,7 +54,7 @@ struct git_pack_idx_header {
};
typedef struct git_pack_cache_entry {
git_off_t off;
git_atomic refcount;
git_rawobj raw;
} git_pack_cache_entry;
@ -77,6 +77,7 @@ struct git_pack_file {
git_vector cache;
git_oid **oids;
git_mutex bases_lock;
git_offmap *bases; /* delta base cache */
/* something like ".git/objects/pack/xxxxx.pack" */