redis数据结构存储Dict设计细节（redis的设计与实现笔记）

typedef struct dictEntry {//字典的节点  
    void *key;  
    union {//使用的联合体  
        void *val;  
        uint64_t u64;//这两个参数很有用  
        int64_t s64;  
    } v;  
    struct dictEntry *next;//下一个节点指针  
} dictEntry;  
  
typedef struct dictType {  
    unsigned int (*hashFunction)(const void *key); //hash函数指针  
    void *(*keyDup)(void *privdata, const void *key); //键复制函数指针  
    void *(*valDup)(void *privdata, const void *obj); //值复制函数指针  
    int (*keyCompare)(void *privdata, const void *key1, const void *key2); //键比较函数指针  
    void (*keyDestructor)(void *privdata, void *key); //键构造函数指针  
    void (*valDestructor)(void *privdata, void *obj); //值构造函数指针  
} 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 { //字典hash table  
    dictEntry **table;//可以看做字典数组，俗称桶bucket  
    unsigned long size; //指针数组的大小，即桶的层数  
    unsigned long sizemask;  
    unsigned long used; //字典中当前的节点数目  
} dictht;  
  
typedef struct dict {  
    dictType *type;  
    void *privdata; //私有数据  
    dictht ht[2];   //两个hash table  
    int rehashidx; /* rehashing not in progress if rehashidx == -1 */ //rehash 索引  
    int iterators; /* number of iterators currently running */ //当前该字典迭代器个数  
} dict;