/* 删除字典中指定的哈希表
*
* Destroy an entire dictionary
*
* Args:
* d 被删除的哈希表所属的字典
* ht 被删除的哈希表
*
* Returns:
* DICT_OK 删除成功(这个函数不可能失败)
*/
int _dictClear(dict *d, dictht *ht)
{
unsigned long i;
// 遍历整个哈希表，删除所有节点链
/* Free all the elements */
for (i = 0; i < ht->size && ht->used > 0; i++) {
dictEntry *he, *nextHe;
// 碰到空节点链，跳到下一个节点链去
if ((he = ht->table[i]) == NULL) continue;
// 如果节点链非空，就遍历删除所有节点
while(he) {
nextHe = he->next;
dictFreeKey(d, he); // 释放 key 空间
dictFreeVal(d, he); // 释放 value 空间
zfree(he); // 释放节点
ht->used--; // 减少计数器
he = nextHe;
}
}
// 释放哈希表节点指针数组的空间
/* Free the table and the allocated cache structure */
zfree(ht->table);
// 并重置(清空)哈希表各项属性
/* Re-initialize the table */
_dictReset(ht);
return DICT_OK; /* never fails */
}
/* Destroy an entire dictionary */
int _dictClear(dict *d, dictht *ht)
{
#ifdef _WIN32
size_t i;
#else
unsigned long i;
#endif
/* Free all the elements */
for (i = 0; i < ht->size && ht->used > 0; i++) {
dictEntry *he, *nextHe;
if ((he = ht->table[i]) == NULL) continue;
while(he) {
nextHe = he->next;
dictFreeKey(d, he);
dictFreeVal(d, he);
zfree(he);
ht->used--;
he = nextHe;
}
}
/* Free the table and the allocated cache structure */
zfree(ht->table);
/* Re-initialize the table */
_dictReset(ht);
return DICT_OK; /* never fails */
}
/* 删除指定元素的底层实现代码
*
* Args:
* d
* key
* nofree 指示是否释放被删除元素的键和值
*
* Returns:
* DICT_ERR 字典为空，删除失败
* DICT_OK 删除成功
*/
static int dictGenericDelete(dict *d, const void *key, int nofree)
{
unsigned int h, idx;
dictEntry *he, *prevHe;
int table;
// 字典为空，删除失败
if (d->ht[0].size == 0)
return DICT_ERR;
// 平摊 rehash
if (dictIsRehashing(d))
_dictRehashStep(d);
// 哈希值
h = dictHashKey(d, key);
// 遍历
for (table = 0; table <= 1; table++) {
idx = h & d->ht[table].sizemask; // 地址索引
he = d->ht[table].table[idx]; // 表头节点
prevHe = NULL;
while(he) {
if (dictCompareKeys(d, key, he->key)) {
/* Unlink the element from the list */
if (prevHe)
prevHe->next = he->next;
else
d->ht[table].table[idx] = he->next;
if (!nofree) {
dictFreeKey(d, he);
dictFreeVal(d, he);
}
zfree(he);
d->ht[table].used--;
return DICT_OK;
}
// 推进指针
prevHe = he;
he = he->next;
}
if (!dictIsRehashing(d)) break;
}
return DICT_ERR; /* not found */
}