void assoc_delete(const char *key, const size_t nkey, const uint32_t hv) {
//得到前驱结点的h_next成员地址
item **before = _hashitem_before(key, nkey, hv);
if (*before) {//查找成功
item *nxt;
hash_items--;
/* The DTrace probe cannot be triggered as the last instruction
* due to possible tail-optimization by the compiler
*/
MEMCACHED_ASSOC_DELETE(key, nkey, hash_items);
//因为before是一个二级指针，其值为所查找item的前驱item的h_next成员地址
//所以*before指向的是所查找的item。因为before是一个二级指针，所以*before
//作为左值时，可以给h_next成员变量赋值。所以下面三行代码是
//使得删除中间的item后，前后的item还能连接起来。
nxt = (*before)->h_next;
(*before)->h_next = 0; /* probably pointless, but whatever. */
*before = nxt;
return;
}
/* Note: we never actually get here. the callers don't delete things
they can't find. */
assert(*before != 0);
}
item *assoc_rcu_replace(const char *key, const size_t nkey, const uint32_t hv, item *it)
{
item **before = _hashitem_before(key, nkey, hv);
if (*before) {
item *nxt, *old;
old = *before;
nxt = (*before)->h_next;
it->h_next = nxt;
*before = it;
return old;
}
return NULL;
}
void assoc_delete(struct persistent_engine *engine, uint32_t hash, const char *key, const size_t nkey) {
hash_item **before = _hashitem_before(engine, hash, key, nkey);
if (*before) {
hash_item *nxt;
engine->assoc.hash_items--;
/* The DTrace probe cannot be triggered as the last instruction
* due to possible tail-optimization by the compiler
*/
nxt = (*before)->h_next;
(*before)->h_next = 0; /* probably pointless, but whatever. */
*before = nxt;
return;
}
/* Note: we never actually get here. the callers don't delete things
they can't find. */
assert(*before != 0);
}
void assoc_delete(const char *key, const size_t nkey, const uint32_t hv) {
item **before = _hashitem_before(key, nkey, hv);
if (*before) {
item *nxt;
// hash_items--;
/* The DTrace probe cannot be triggered as the last instruction
* due to possible tail-optimization by the compiler
*/
// MEMCACHED_ASSOC_DELETE(key, nkey, hash_items);
nxt = (*before)->h_next;
/* (*before)->h_next = 0; /\* probably pointless, but whatever. *\/ */
*before = nxt;
return;
}
/* Note: we never actually get here. the callers don't delete things
they can't find. */
assert(*before != 0);
}