//这个函数也可以作为向外部提供的API使用，外部用户可以添加一个键值不为void*类型的值
//它向字典中添加一个key值并且返回新创建的 entry对象，这个对象交给调用者操作
dictEntry *dictAddRaw(dict *d, void *key)
{
int index;
dictEntry *entry;
dictht *ht;
if (dictIsRehashing(d)) _dictRehashStep(d);
/* Get the index of the new element, or -1 if
* the element already exists. */
//获取对应key的bucket索引
if ((index = _dictKeyIndex(d, key)) == -1)
return NULL;
/* Allocate the memory and store the new entry */
//如果当前在执行rehash，说明需要将ht[0]上的entry转移到ht[1]上，并且尚未执行结束
//这时候就需要加入到ht[1]中，否则加入到ht[0]中
ht = dictIsRehashing(d) ? &d->ht[1] : &d->ht[0];
entry = zmalloc(sizeof(*entry));
//加入到链表的表头
entry->next = ht->table[index];
ht->table[index] = entry;
ht->used++;
/* Set the hash entry fields. */
//最后设置该项的key
dictSetKey(d, entry, key);
return entry;
}
/* Low level add. This function adds the entry but instead of setting
* a value returns the dictEntry structure to the user, that will make
* sure to fill the value field as he wishes.
*
* This function is also directly exposed to the user API to be called
* mainly in order to store non-pointers inside the hash value, example:
*
* entry = dictAddRaw(dict,mykey);
* if (entry != NULL) dictSetSignedIntegerVal(entry,1000);
*
* Return values:
*
* If key already exists NULL is returned.
* If key was added, the hash entry is returned to be manipulated by the caller.
*/
dictEntry *dictAddRaw(dict *d, void *key)
{
int index;
dictEntry *entry;
dictht *ht;
if (dictIsRehashing(d)) _dictRehashStep(d);
/* Get the index of the new element, or -1 if
* the element already exists. */
if ((index = _dictKeyIndex(d, key)) == -1)
return NULL;
/* Allocate the memory and store the new entry */
ht = dictIsRehashing(d) ? &d->ht[1] : &d->ht[0];
entry = zmalloc(sizeof(*entry));
entry->next = ht->table[index];
ht->table[index] = entry;
ht->used++;
/* Set the hash entry fields. */
//使用dictType中的keyDup函数
dictSetKey(d, entry, key);
return entry;
}
/* 添加元素的底层实现函数(由 dictAdd 调用)
*
* 新元素的添加操作被分为两步：
* 1) 创建节点并设置节点的 key ，然后返回节点
* 2) 设置节点的值
* 这个函数执行第一步，第二步由函数 dictSetVal 进行
*
* Args:
* d 字典
* key 新节点的关键字
*
* Returns:
* NULL 关键字已经存在
* entry 设置了关键字的新节点，返回给调用者进行进一步的处理
*/
dictEntry *dictAddRaw(dict *d, void *key)
{
int index;
dictEntry *entry;
dictht *ht;
// 检查字典(的哈希表)能否执行 rehash 操作
// 如果可以的话，执行平摊 rehash 操作
if (dictIsRehashing(d)) _dictRehashStep(d);
// 计算 key 的 index 值
// 如果 key 已经存在，_dictKeyIndex 返回 -1
if ((index = _dictKeyIndex(d, key)) == -1)
return NULL;
// 如果字典正在进行 rehash ，那么将新元素添加到 1 号哈希表，
// 否则，使用 0 号哈希表
ht = dictIsRehashing(d) ? &d->ht[1] : &d->ht[0];
entry = zmalloc(sizeof(*entry)); // 为新节点分配内存
entry->next = ht->table[index]; // 调整节点的 next 指针
ht->table[index] = entry; // 然后将新节点设为链头
ht->used++; // 更新正在使用的节点数量
// 设置节点的 key 域
dictSetKey(d, entry, key);
return entry; // 返回新节点
}
/* Add the specified value into a set.
*
* If the value was already member of the set, nothing is done and 0 is
* returned, otherwise the new element is added and 1 is returned. */
int setTypeAdd(robj *subject, sds value) {
long long llval;
if (subject->encoding == OBJ_ENCODING_HT) {
dict *ht = subject->ptr;
dictEntry *de = dictAddRaw(ht,value);
if (de) {
dictSetKey(ht,de,sdsdup(value));
dictSetVal(ht,de,NULL);
return 1;
}
} else if (subject->encoding == OBJ_ENCODING_INTSET) {
if (isSdsRepresentableAsLongLong(value,&llval) == C_OK) {
uint8_t success = 0;
subject->ptr = intsetAdd(subject->ptr,llval,&success);
if (success) {
/* Convert to regular set when the intset contains
* too many entries. */
if (intsetLen(subject->ptr) > server.set_max_intset_entries)
setTypeConvert(subject,OBJ_ENCODING_HT);
return 1;
}
} else {
/* Failed to get integer from object, convert to regular set. */
setTypeConvert(subject,OBJ_ENCODING_HT);
/* The set *was* an intset and this value is not integer
* encodable, so dictAdd should always work. */
serverAssert(dictAdd(subject->ptr,sdsdup(value),NULL) == DICT_OK);
return 1;
}
} else {
serverPanic("Unknown set encoding");
}
return 0;
}
