text: /* Hash Tables Implementation.
   *
   * This file implements in-memory hash tables with insert/del/replace/find/
   * get-random-element operations. Hash tables will auto-resize if needed
   * tables of power of two in size are used, collisions are handled by
   * chaining. See the source code for more information... :)
   *
   * Copyright (c) 2006-2012, Salvatore Sanfilippo <antirez at gmail dot com>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   *   * Redistributions of source code must retain the above copyright notice,
   *     this list of conditions and the following disclaimer.
   *   * Redistributions in binary form must reproduce the above copyright
   *     notice, this list of conditions and the following disclaimer in the
   *     documentation and/or other materials provided with the distribution.
   *   * Neither the name of Redis nor the names of its contributors may be used
   *     to endorse or promote products derived from this software without
   *     specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include <stdint.h>
  
  #ifndef __DICT_H
  #define __DICT_H
  
  #define DICT_OK 0
  #define DICT_ERR 1
  
  /* Unused arguments generate annoying warnings... */
  #define DICT_NOTUSED(V) ((void) V)
  
  typedef struct dictEntry {
      void *key; // key 键
      union {
          void *val;
          uint64_t u64;
          int64_t s64;
          double d;
      } v; // value 值
      struct dictEntry *next; // 下一个
  } dictEntry;
  
  typedef struct dictType {
      uint64_t (*hashFunction)(const void *key);
      void *(*keyDup)(void *privdata, const void *key);
      void *(*valDup)(void *privdata, const void *obj);
      int (*keyCompare)(void *privdata, const void *key1, const void *key2);
      void (*keyDestructor)(void *privdata, void *key);
      void (*valDestructor)(void *privdata, void *obj);
  } dictType;
  
  /* This is our hash table structure. Every dictionary has two of this as we
   * implement incremental rehashing, for the old to the new table. */
  typedef struct dictht {
      /// dictEntry 结构体指针 一维数组 可以理解为 dictEntry * *table
      /// table[i] 存储了位于第i个slot位置的 dictEntry 的结构体指针 table存储的是头结点的地址
      dictEntry **table;
      unsigned long size; /// 一维数组的长度
      unsigned long sizemask;
      unsigned long used; /// hash 表中的元素个数
  } dictht;
  
  typedef struct dict {
      dictType *type;
      void *privdata;
      dictht ht[2]; // 两个 dictht 。一般只使用第一个；扩容时，第一个是老的，第二个是新的，扩容完成后，老的指向新的。
      long rehashidx; /* rehashing not in progress if rehashidx == -1 */ /// 不为-1 表示待rehash的slots的下标
      unsigned long iterators; /* number of iterators currently running */
  } dict;
  
  /* If safe is set to 1 this is a safe iterator, that means, you can call
   * dictAdd, dictFind, and other functions against the dictionary even while
   * iterating. Otherwise it is a non safe iterator, and only dictNext()
   * should be called while iterating. */
  typedef struct dictIterator {
      dict *d;
      long index;
      int table, safe;
      dictEntry *entry, *nextEntry;
      /* unsafe iterator fingerprint for misuse detection. */
      long long fingerprint;
  } dictIterator;
  
  typedef void (dictScanFunction)(void *privdata, const dictEntry *de);
  typedef void (dictScanBucketFunction)(void *privdata, dictEntry **bucketref);
  
  /* This is the initial size of every hash table */
  #define DICT_HT_INITIAL_SIZE     4
  
  /* ------------------------------- Macros ------------------------------------*/
  #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 dictSetDoubleVal(entry, _val_) \
      do { (entry)->v.d = _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 dictGetDoubleVal(he) ((he)->v.d)
  #define dictSlots(d) ((d)->ht[0].size+(d)->ht[1].size)
  #define dictSize(d) ((d)->ht[0].used+(d)->ht[1].used)
  #define dictIsRehashing(d) ((d)->rehashidx != -1)
  
  /* API */
  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, dictEntry **existing);
  dictEntry *dictAddOrFind(dict *d, void *key);
  int dictReplace(dict *d, void *key, void *val);
  int dictDelete(dict *d, const void *key);
  dictEntry *dictUnlink(dict *ht, const void *key);
  void dictFreeUnlinkedEntry(dict *d, dictEntry *he);
  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);
  dictEntry *dictGetFairRandomKey(dict *d);
  unsigned int dictGetSomeKeys(dict *d, dictEntry **des, unsigned int count);
  void dictGetStats(char *buf, size_t bufsize, dict *d);
  uint64_t dictGenHashFunction(const void *key, int len);
  uint64_t dictGenCaseHashFunction(const unsigned char *buf, int len);
  void dictEmpty(dict *d, void(callback)(void*));
  void dictEnableResize(void);
  void dictDisableResize(void);
  int dictRehash(dict *d, int n);
  int dictRehashMilliseconds(dict *d, int ms);
  void dictSetHashFunctionSeed(uint8_t *seed);
  uint8_t *dictGetHashFunctionSeed(void);
  unsigned long dictScan(dict *d, unsigned long v, dictScanFunction *fn, dictScanBucketFunction *bucketfn, void *privdata);
  uint64_t dictGetHash(dict *d, const void *key);
  dictEntry **dictFindEntryRefByPtrAndHash(dict *d, const void *oldptr, uint64_t hash);
  
  /* Hash table types */
  extern dictType dictTypeHeapStringCopyKey;
  extern dictType dictTypeHeapStrings;
  extern dictType dictTypeHeapStringCopyKeyValue;
  
  #endif /* __DICT_H */
  