//将item插入到哈希表和LRU队列中，hv为哈希值
int do_item_link(item *it, const uint32_t hv) {
MEMCACHED_ITEM_LINK(ITEM_key(it), it->nkey, it->nbytes);
//确保这个item已经从slab分配出去并且还没插入到LRU队列中
assert((it->it_flags & (ITEM_LINKED|ITEM_SLABBED)) == 0);
mutex_lock(&cache_lock);
//加入link标记
it->it_flags |= ITEM_LINKED;
it->time = current_time;
STATS_LOCK();
stats.curr_bytes += ITEM_ntotal(it);
stats.curr_items += 1;
stats.total_items += 1;
STATS_UNLOCK();
/* Allocate a new CAS ID on link. */
ITEM_set_cas(it, (settings.use_cas) ? get_cas_id() : 0);
//插入到hash表中
assoc_insert(it, hv);
//item插入到链表中
item_link_q(it);
//引用计数加1
refcount_incr(&it->refcount);
mutex_unlock(&cache_lock);
return 1;
}
static ENGINE_ERROR_CODE do_item_link(struct demo_engine *engine, hash_item *it)
{
const char *key = dm_item_get_key(it);
size_t stotal = ITEM_stotal(engine, it);
assert((it->iflag & ITEM_LINKED) == 0);
assert(it->nbytes < (1024 * 1024)); /* 1MB max size */
MEMCACHED_ITEM_LINK(key, it->nkey, it->nbytes);
/* Allocate a new CAS ID on link. */
dm_item_set_cas(it, get_cas_id());
/* link the item to the hash table */
it->iflag |= ITEM_LINKED;
it->time = engine->server.core->get_current_time();
it->hval = engine->server.core->hash(key, it->nkey, 0);
dm_assoc_insert(engine, it->hval, it);
/* update item statistics */
pthread_mutex_lock(&engine->stats.lock);
engine->stats.curr_bytes += stotal;
engine->stats.curr_items += 1;
engine->stats.total_items += 1;
pthread_mutex_unlock(&engine->stats.lock);
return ENGINE_SUCCESS;
}
int do_item_link(item *it) {
MEMCACHED_ITEM_LINK(ITEM_key(it), it->nbytes);
assert((it->it_flags & (ITEM_LINKED|ITEM_SLABBED)) == 0);
assert(it->nbytes < (1024 * 1024)); /* 1MB max size */
it->it_flags |= ITEM_LINKED;
it->time = current_time;
assoc_insert(it);
STATS_LOCK();
stats.curr_bytes += ITEM_ntotal(it);
stats.curr_items += 1;
stats.total_items += 1;
STATS_UNLOCK();
#ifdef USE_REPLICATION
/* Allocate a new CAS ID on link. */
if(!(it->it_flags & ITEM_REPDATA))
it->cas_id = get_cas_id();
#else
/* Allocate a new CAS ID on link. */
it->cas_id = get_cas_id();
#endif /* USE_REPLICATION */
item_link_q(it);
return 1;
}
/* 形成了一个完成的 item 后, 就要把它放入两个数据结构中, 一是 memcached 的哈希表,
memcached 运行过程中只有一个哈希表, 二是 item 所在的 slabclass 的 LRU 队列. */
int do_item_link(item *it, const uint32_t hv) {
MEMCACHED_ITEM_LINK(ITEM_key(it), it->nkey, it->nbytes);
assert((it->it_flags & (ITEM_LINKED|ITEM_SLABBED)) == 0);
mutex_lock(&cache_lock);
it->it_flags |= ITEM_LINKED;
it->time = current_time;
STATS_LOCK();
stats.curr_bytes += ITEM_ntotal(it);
stats.curr_items += 1;
stats.total_items += 1;
STATS_UNLOCK();
/* Allocate a new CAS ID on link. */
ITEM_set_cas(it, (settings.use_cas) ? get_cas_id() : 0);
/* 把 item 放入哈希表 */
assoc_insert(it, hv);
/* 把 item 放入 LRU 队列*/
item_link_q(it);
refcount_incr(&it->refcount);
mutex_unlock(&cache_lock);
return 1;
}
int do_item_link(item *it) {
MEMCACHED_ITEM_LINK(ITEM_key(it), it->nkey, it->nbytes);
assert((it->it_flags & (ITEM_LINKED|ITEM_SLABBED)) == 0);
assert(it->nbytes < (1024 * 1024)); /* 1MB max size */
it->it_flags |= ITEM_LINKED;
it->time = current_time;
assoc_insert(it);
#ifdef MOXI_ITEM_MALLOC
it->refcount++;
#endif
STATS_LOCK();
stats.curr_bytes += ITEM_ntotal(it);
stats.curr_items += 1;
stats.total_items += 1;
STATS_UNLOCK();
/* Allocate a new CAS ID on link. */
ITEM_set_cas(it, (settings.use_cas) ? get_cas_id() : 0);
item_link_q(it);
return 1;
}
int do_item_link(struct default_engine *engine, hash_item *it) {
MEMCACHED_ITEM_LINK(item_get_key(it), it->nkey, it->nbytes);
assert((it->iflag & (ITEM_LINKED|ITEM_SLABBED)) == 0);
assert(it->nbytes < (1024 * 1024)); /* 1MB max size */
it->iflag |= ITEM_LINKED;
it->time = engine->server.core->get_current_time();
assoc_insert(engine, engine->server.core->hash(item_get_key(it),
it->nkey, 0),
it);
pthread_mutex_lock(&engine->stats.lock);
engine->stats.curr_bytes += ITEM_ntotal(engine, it);
engine->stats.curr_items += 1;
engine->stats.total_items += 1;
pthread_mutex_unlock(&engine->stats.lock);
/* Allocate a new CAS ID on link. */
item_set_cas(NULL, NULL, it, get_cas_id());
item_link_q(engine, it);
return 1;
}
//将item加入到hashtable和LRU链中
int do_item_link(item *it, const uint32_t hv) {
syslog(LOG_INFO, "[%s:%s:%d]", __FILE__, __func__, __LINE__);
MEMCACHED_ITEM_LINK(ITEM_key(it), it->nkey, it->nbytes);
assert((it->it_flags & (ITEM_LINKED|ITEM_SLABBED)) == 0); //判断状态，即没有在hash表LRU链中或被释放
mutex_lock(&cache_lock);
it->it_flags |= ITEM_LINKED; //设置linked状态
it->time = current_time;//设置最近访问的时间
STATS_LOCK();
stats.curr_bytes += ITEM_ntotal(it); //增加每个item所需要的字节大小，包括item结构体和item内容大小
stats.curr_items += 1;
stats.total_items += 1;
STATS_UNLOCK();
/* Allocate a new CAS ID on link. */
ITEM_set_cas(it, (settings.use_cas) ? get_cas_id() : 0); //设置新CAS，CAS是memcache用来处理并发请求的一种机制
assoc_insert(it, hv);//插入hashtable
item_link_q(it); //加入LRU链
refcount_incr(&it->refcount);
mutex_unlock(&cache_lock);
return 1;
}
int do_item_link(struct default_engine *engine, hash_item *it) {
const hash_key* key = item_get_key(it);
MEMCACHED_ITEM_LINK(hash_key_get_client_key(key), hash_key_get_client_key_len(key), it->nbytes);
cb_assert((it->iflag & (ITEM_LINKED|ITEM_SLABBED)) == 0);
it->iflag |= ITEM_LINKED;
it->time = engine->server.core->get_current_time();
assoc_insert(engine, crc32c(hash_key_get_key(key),
hash_key_get_key_len(key), 0),
it);
cb_mutex_enter(&engine->stats.lock);
engine->stats.curr_bytes += ITEM_ntotal(engine, it);
engine->stats.curr_items += 1;
engine->stats.total_items += 1;
cb_mutex_exit(&engine->stats.lock);
/* Allocate a new CAS ID on link. */
item_set_cas(NULL, NULL, it, get_cas_id());
item_link_q(engine, it);
return 1;
}