/* Note: this isn't an assoc_update. The key must not already exist to call this */
int assoc_insert(item *it, const uint32_t hv) {
unsigned int oldbucket;
// assert(assoc_find(ITEM_key(it), it->nkey) == 0); /* shouldn't have duplicately named things defined */
if (expanding &&
(oldbucket = (hv & hashmask(hashpower - 1))) >= expand_bucket)
{
it->h_next = old_hashtable[oldbucket];
old_hashtable[oldbucket] = it;
} else {
it->h_next = primary_hashtable[hv & hashmask(hashpower)];
primary_hashtable[hv & hashmask(hashpower)] = it;
}
pthread_mutex_lock(&hash_items_counter_lock);
hash_items++;
if (! expanding && hash_items > (hashsize(hashpower) * 3) / 2) {
assoc_start_expand();
}
pthread_mutex_unlock(&hash_items_counter_lock);
MEMCACHED_ASSOC_INSERT(ITEM_key(it), it->nkey, hash_items);
return 1;
}
//hash,插入元素,hv是这个item键值的哈希值
int assoc_insert(item *it, const uint32_t hv) {
unsigned int oldbucket;
// assert(assoc_find(ITEM_key(it), it->nkey) == 0); /* shouldn't have duplicately named things defined */
// 头插法
if (expanding &&
(oldbucket = (hv & hashmask(hashpower - 1))) >= expand_bucket)
{
//目前处于扩容状态，但这个桶的数据还没有迁移，因此插入到旧表old_hashtable
it->h_next = old_hashtable[oldbucket];
old_hashtable[oldbucket] = it;
} else {
//插入到新表，primary_hashtable
it->h_next = primary_hashtable[hv & hashmask(hashpower)];
primary_hashtable[hv & hashmask(hashpower)] = it;
}
//元素数目+1
hash_items++;
// 适时扩张，当元素个数超过hash容量的1.5倍时
if (! expanding && hash_items > (hashsize(hashpower) * 3) / 2) {
//调用assoc_start_expand函数来唤醒扩容线程
assoc_start_expand();
}
MEMCACHED_ASSOC_INSERT(ITEM_key(it), it->nkey, hash_items);
return 1;
}
//hv是这个item键值的哈希值，用于快速查找该key对应的item，见assoc_find item插入hash表函数assoc_insert
int assoc_insert(item *it, const uint32_t hv) {
unsigned int oldbucket; // 插入hash表函数为assoc_insert 插入lru队列的函数为item_link_q
// assert(assoc_find(ITEM_key(it), it->nkey) == 0); /* shouldn't have duplicately named things defined */
//使用头插法，插入一个item
//第一次看本函数，直接看else部分
if (expanding &&
(oldbucket = (hv & hashmask(hashpower - 1))) >= expand_bucket)
{
it->h_next = old_hashtable[oldbucket];
old_hashtable[oldbucket] = it;
} else {
//使用头插法插入哈希表中
it->h_next = primary_hashtable[hv & hashmask(hashpower)];
primary_hashtable[hv & hashmask(hashpower)] = it;
}
hash_items++;//哈希表的item数量加一
if (! expanding && hash_items > (hashsize(hashpower) * 3) / 2) {
assoc_start_expand();
}
MEMCACHED_ASSOC_INSERT(ITEM_key(it), it->nkey, hash_items);
return 1;
}
//hv是这个item键值的哈希值
int assoc_insert(item *it, const uint32_t hv) {
unsigned int oldbucket;
// assert(assoc_find(ITEM_key(it), it->nkey) == 0); /* shouldn't have duplicately named things defined */
//使用头插法 插入一个item
///第一次看本函数，直接看else部分
if (expanding &&//目前处于扩展hash表状态
(oldbucket = (hv & hashmask(hashpower - 1))) >= expand_bucket)//数据迁移时还没迁移到这个桶
{
//插入到旧表
it->h_next = old_hashtable[oldbucket];
old_hashtable[oldbucket] = it;
} else {
//使用头插法插入哈希表中
//插入到新表
it->h_next = primary_hashtable[hv & hashmask(hashpower)];
primary_hashtable[hv & hashmask(hashpower)] = it;
}
hash_items++;//哈希表的item数量加一
//当hash表的item数量到达了hash表容量的1.5倍时，就会进行扩展
//当然如果现在正处于扩展状态，是不会再扩展的
if (! expanding && hash_items > (hashsize(hashpower) * 3) / 2) {
assoc_start_expand();//唤醒迁移线程，扩展哈希表
}
MEMCACHED_ASSOC_INSERT(ITEM_key(it), it->nkey, hash_items);
return 1;
}
/* Note: this isn't an assoc_update. The key must not already exist to call this */
int assoc_insert(item *it, const uint32_t hv) {
unsigned int oldbucket;
// assert(assoc_find(ITEM_key(it), it->nkey) == 0); /* shouldn't have duplicately named things defined */
if (expanding &&
(oldbucket = (hv & hashmask(hashpower - 1))) >= expand_bucket)
{// 如果正在扩容，并且此时当前这个槽位在正在迁移的槽位后面，那么这个节点应该加到老地方去，因为待会就回扫到他了。
it->h_next = old_hashtable[oldbucket];
old_hashtable[oldbucket] = it;
} else {
it->h_next = primary_hashtable[hv & hashmask(hashpower)];
primary_hashtable[hv & hashmask(hashpower)] = it;
}
hash_items++;
if (! expanding && hash_items > (hashsize(hashpower) * 3) / 2) {
assoc_start_expand();//槽位容量整体大于1.5个时，扩容。那么，缩小呢？
}
MEMCACHED_ASSOC_INSERT(ITEM_key(it), it->nkey, hash_items);
return 1;
}
