typedef struct dict {
dictType *type;  //定义了字典需要的函数
void *privdata;
dictht ht[2];     //哈希表结构
int rehashidx; //下一个需要扩容的字典编号，若rehashidx == -1 则不会进行重新散列。
int iterators; //当前正在运行的迭代器数目
} dict;

typedef struct dictType {
unsigned int (*hashFunction)(const void *key);        //hash函数
void *(*keyDup)(void *privdata, const void *key);    //键复制
void *(*valDup)(void *privdata, const void *obj);     //值复制
int (*keyCompare)(void *privdata, const void *key1, const void *key2);  //key比较
void (*keyDestructor)(void *privdata, void *key);    //key析构
void (*valDestructor)(void *privdata, void *obj);     //value析构
} dictType;

typedef struct dictht {
dictEntry **table;
unsigned long size;                 //桶的大小，是2的指数
unsigned long sizemask;         //sizemask=size-1，方便取模（i%sizemask 开放链地址法处理hash冲突）。
unsigned long used;               //哈希表中的记录数
} dictht;

typedef struct dictEntry {
void *key;                           // 键
union {                              //值的共用体
void *val;
uint64_t u64;
int64_t s64;
} v;
struct dictEntry *next;
} dictEntry;

typedef struct dictIterator {
dict *d;
int table, index, safe;
dictEntry *entry, *nextEntry;
long long fingerprint; /* unsafe iterator fingerprint for misuse detection */
} dictIterator;

#define dictFreeVal(d, entry) \
if ((d)->type->valDestructor) \
(d)->type->valDestructor((d)->privdata, (entry)->v.val)#define dictSetVal(d, entry, _val_) do { \
if ((d)->type->valDup) \
entry->v.val = (d)->type->valDup((d)->privdata, _val_); \
else \
entry->v.val = (_val_); \
} while(0)#define dictSetSignedIntegerVal(entry, _val_) \
do { entry->v.s64 = _val_; } while(0)#define dictSetUnsignedIntegerVal(entry, _val_) \
do { entry->v.u64 = _val_; } while(0)#define dictFreeKey(d, entry) \
if ((d)->type->keyDestructor) \
(d)->type->keyDestructor((d)->privdata, (entry)->key)#define dictSetKey(d, entry, _key_) do { \
if ((d)->type->keyDup) \
entry->key = (d)->type->keyDup((d)->privdata, _key_); \
else \
entry->key = (_key_); \
} while(0)#define dictCompareKeys(d, key1, key2) \
(((d)->type->keyCompare) ? \
(d)->type->keyCompare((d)->privdata, key1, key2) : \
(key1) == (key2))#define dictHashKey(d, key) (d)->type->hashFunction(key)
#define dictGetKey(he) ((he)->key)
#define dictGetVal(he) ((he)->v.val)
#define dictGetSignedIntegerVal(he) ((he)->v.s64)
#define dictGetUnsignedIntegerVal(he) ((he)->v.u64)
#define dictSlots(d) ((d)->ht[0].size+(d)->ht[1].size)
#define dictSize(d) ((d)->ht[0].used+(d)->ht[1].used)
#define dictIsRehashing(ht) ((ht)->rehashidx != -1)

dict *dictCreate(dictType *type, void *privDataPtr);
int dictExpand(dict *d, unsigned long size);
int dictAdd(dict *d, void *key, void *val);
dictEntry *dictAddRaw(dict *d, void *key);
int dictReplace(dict *d, void *key, void *val);
dictEntry *dictReplaceRaw(dict *d, void *key);
int dictDelete(dict *d, const void *key);
int dictDeleteNoFree(dict *d, const void *key);
void dictRelease(dict *d);
dictEntry * dictFind(dict *d, const void *key);
void *dictFetchValue(dict *d, const void *key);
int dictResize(dict *d);
dictIterator *dictGetIterator(dict *d);
dictIterator *dictGetSafeIterator(dict *d);
dictEntry *dictNext(dictIterator *iter);
void dictReleaseIterator(dictIterator *iter);
dictEntry *dictGetRandomKey(dict *d);
void dictPrintStats(dict *d);
unsigned int dictGenHashFunction(const void *key, int len);
unsigned int dictGenCaseHashFunction(const unsigned char *buf, int len);
void dictEmpty(dict *d);
void dictEnableResize(void);
void dictDisableResize(void);
int dictRehash(dict *d, int n);
int dictRehashMilliseconds(dict *d, int ms);
void dictSetHashFunctionSeed(unsigned int initval);
unsigned int dictGetHashFunctionSeed(void);

 /* 哈希表类型*/extern dictType dictTypeHeapStringCopyKey;
extern dictType dictTypeHeapStrings;
extern dictType dictTypeHeapStringCopyKeyValue;

/* Resize the table to the minimal size that contains all the elements,* but with the invariant of a USED/BUCKETS ratio near to <= 1 */
int dictResize(dict *d)
{int minimal;if (!dict_can_resize || dictIsRehashing(d)) return DICT_ERR;minimal = d->ht[0].used;if (minimal < DICT_HT_INITIAL_SIZE)minimal = DICT_HT_INITIAL_SIZE;return dictExpand(d, minimal);
}

/* Expand or create the hash table */
int dictExpand(dict *d, unsigned long size)
{dictht n; /* the new hash table */unsigned long realsize = _dictNextPower(size);/* the size is invalid if it is smaller than the number of* elements already inside the hash table */if (dictIsRehashing(d) || d->ht[0].used > size)return DICT_ERR;/* Allocate the new hash table and initialize all pointers to NULL */n.size = realsize;n.sizemask = realsize-1;n.table = zcalloc(realsize*sizeof(dictEntry*));n.used = 0;/* Is this the first initialization? If so it's not really a rehashing* we just set the first hash table so that it can accept keys. */if (d->ht[0].table == NULL) {d->ht[0] = n;return DICT_OK;}/* Prepare a second hash table for incremental rehashing */d->ht[1] = n;d->rehashidx = 0;return DICT_OK;
}

/* Rehash for an amount of time between ms milliseconds and ms+1 milliseconds */
int dictRehashMilliseconds(dict *d, int ms) {long long start = timeInMilliseconds();int rehashes = 0;while(dictRehash(d,100)) {rehashes += 100;if (timeInMilliseconds()-start > ms) break;}return rehashes;
}