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/*

* Copyright (C) the libgit2 contributors. All rights reserved.

*

* This file is part of libgit2, distributed under the GNU GPL v2 with

* a Linking Exception. For full terms see the included COPYING file.

*/

#include "common.h"

#include "repository.h"

#include "commit.h"

#include "thread-utils.h"

#include "util.h"

#include "cache.h"

#include "odb.h"

#include "object.h"

#include "git2/oid.h"

GIT__USE_OIDMAP

bool git_cache__enabled = true;

ssize_t git_cache__max_storage = (256 * 1024 * 1024);

git_atomic_ssize git_cache__current_storage = {0};

static size_t git_cache__max_object_size[8] = {

0, /* GIT_OBJ__EXT1 */

4096, /* GIT_OBJ_COMMIT */

4096, /* GIT_OBJ_TREE */

0, /* GIT_OBJ_BLOB */

4096, /* GIT_OBJ_TAG */

0, /* GIT_OBJ__EXT2 */

0, /* GIT_OBJ_OFS_DELTA */

0 /* GIT_OBJ_REF_DELTA */

};

int git_cache_set_max_object_size(git_otype type, size_t size)

{

if (type < 0 || (size_t)type >= ARRAY_SIZE(git_cache__max_object_size)) {

giterr_set(GITERR_INVALID, "type out of range");

return -1;

}

git_cache__max_object_size[type] = size;

return 0;

}

void git_cache_dump_stats(git_cache *cache)

{

git_cached_obj *object;

if (kh_size(cache->map) == 0)

return;

printf("Cache %p: %d items cached, %d bytes\n",

cache, kh_size(cache->map), (int)cache->used_memory);

kh_foreach_value(cache->map, object, {

char oid_str[9];

printf(" %s%c %s (%d)\n",

git_object_type2string(object->type),

object->flags == GIT_CACHE_STORE_PARSED ? '*' : ' ',

git_oid_tostr(oid_str, sizeof(oid_str), &object->oid),

(int)object->size

);

});

}

int git_cache_init(git_cache *cache)

{

memset(cache, 0, sizeof(*cache));

cache->map = git_oidmap_alloc();

if (git_rwlock_init(&cache->lock)) {

giterr_set(GITERR_OS, "Failed to initialize cache rwlock");

return -1;

}

return 0;

}

/* called with lock */

static void clear_cache(git_cache *cache)

{

git_cached_obj *evict = NULL;

if (kh_size(cache->map) == 0)

return;

kh_foreach_value(cache->map, evict, {

git_cached_obj_decref(evict);

});

kh_clear(oid, cache->map);

git_atomic_ssize_add(&git_cache__current_storage, -cache->used_memory);

cache->used_memory = 0;

}

void git_cache_clear(git_cache *cache)

{

if (git_rwlock_wrlock(&cache->lock) < 0)

return;

clear_cache(cache);

git_rwlock_wrunlock(&cache->lock);

}

void git_cache_free(git_cache *cache)

{

git_cache_clear(cache);

git_oidmap_free(cache->map);

git_rwlock_free(&cache->lock);

git__memzero(cache, sizeof(*cache));

}

/* Called with lock */

static void cache_evict_entries(git_cache *cache)

{

uint32_t seed = rand();

size_t evict_count = 8;

ssize_t evicted_memory = 0;

/* do not infinite loop if there's not enough entries to evict */

if (evict_count > kh_size(cache->map)) {

clear_cache(cache);

return;

}

while (evict_count > 0) {

khiter_t pos = seed++ % kh_end(cache->map);

if (kh_exist(cache->map, pos)) {

git_cached_obj *evict = kh_val(cache->map, pos);

evict_count--;

evicted_memory += evict->size;

git_cached_obj_decref(evict);

kh_del(oid, cache->map, pos);

}

}

cache->used_memory -= evicted_memory;

git_atomic_ssize_add(&git_cache__current_storage, -evicted_memory);

}

static bool cache_should_store(git_otype object_type, size_t object_size)

{

size_t max_size = git_cache__max_object_size[object_type];

return git_cache__enabled && object_size < max_size;

}

static void *cache_get(git_cache *cache, const git_oid *oid, unsigned int flags)

{

khiter_t pos;

git_cached_obj *entry = NULL;

if (!git_cache__enabled || git_rwlock_rdlock(&cache->lock) < 0)

return NULL;

pos = kh_get(oid, cache->map, oid);

if (pos != kh_end(cache->map)) {

entry = kh_val(cache->map, pos);

if (flags && entry->flags != flags) {

entry = NULL;

} else {

git_cached_obj_incref(entry);

}

}

git_rwlock_rdunlock(&cache->lock);

return entry;

}

static void *cache_store(git_cache *cache, git_cached_obj *entry)

{

khiter_t pos;

git_cached_obj_incref(entry);

if (!git_cache__enabled && cache->used_memory > 0) {

git_cache_clear(cache);

return entry;

}

if (!cache_should_store(entry->type, entry->size))

return entry;

if (git_rwlock_wrlock(&cache->lock) < 0)

return entry;

/* soften the load on the cache */

if (git_cache__current_storage.val > git_cache__max_storage)

cache_evict_entries(cache);

pos = kh_get(oid, cache->map, &entry->oid);

/* not found */

if (pos == kh_end(cache->map)) {

int rval;

pos = kh_put(oid, cache->map, &entry->oid, &rval);

if (rval >= 0) {

kh_key(cache->map, pos) = &entry->oid;

kh_val(cache->map, pos) = entry;

git_cached_obj_incref(entry);

cache->used_memory += entry->size;

git_atomic_ssize_add(&git_cache__current_storage, (ssize_t)entry->size);

}

}

/* found */

else {

git_cached_obj *stored_entry = kh_val(cache->map, pos);

if (stored_entry->flags == entry->flags) {

git_cached_obj_decref(entry);

git_cached_obj_incref(stored_entry);

entry = stored_entry;

} else if (stored_entry->flags == GIT_CACHE_STORE_RAW &&

entry->flags == GIT_CACHE_STORE_PARSED) {

git_cached_obj_decref(stored_entry);

git_cached_obj_incref(entry);

kh_key(cache->map, pos) = &entry->oid;

kh_val(cache->map, pos) = entry;

} else {

/* NO OP */

}

}

git_rwlock_wrunlock(&cache->lock);

return entry;

}

void *git_cache_store_raw(git_cache *cache, git_odb_object *entry)

{

entry->cached.flags = GIT_CACHE_STORE_RAW;

return cache_store(cache, (git_cached_obj *)entry);

}

void *git_cache_store_parsed(git_cache *cache, git_object *entry)

{

entry->cached.flags = GIT_CACHE_STORE_PARSED;

return cache_store(cache, (git_cached_obj *)entry);

}

git_odb_object *git_cache_get_raw(git_cache *cache, const git_oid *oid)

{

return cache_get(cache, oid, GIT_CACHE_STORE_RAW);

}

git_object *git_cache_get_parsed(git_cache *cache, const git_oid *oid)

{

return cache_get(cache, oid, GIT_CACHE_STORE_PARSED);

}

void *git_cache_get_any(git_cache *cache, const git_oid *oid)

{

return cache_get(cache, oid, GIT_CACHE_STORE_ANY);

}

void git_cached_obj_decref(void *_obj)

{

git_cached_obj *obj = _obj;

if (git_atomic_dec(&obj->refcount) == 0) {

switch (obj->flags) {

case GIT_CACHE_STORE_RAW:

git_odb_object__free(_obj);

break;

case GIT_CACHE_STORE_PARSED:

git_object__free(_obj);

break;

default:

git__free(_obj);

break;

}

}

}