字典

哈希表

struct dict {
    dictType *type;

    dictEntry **ht_table[2];
    unsigned long ht_used[2];

    long rehashidx; /* rehashing not in progress if rehashidx == -1 */

    /* Keep small vars at end for optimal (minimal) struct padding */
    unsigned pauserehash : 15; /* If >0 rehashing is paused */

    unsigned useStoredKeyApi : 1; /* See comment of storedHashFunction above */
    signed char ht_size_exp[2]; /* exponent of size. (size = 1<<exp) */
    int16_t pauseAutoResize;  /* If >0 automatic resizing is disallowed (<0 indicates coding error) */
    void *metadata[];
};

struct dictEntry {
    void *key;
    union {
        void *val;
        uint64_t u64;
        int64_t s64;
        double d;
    } v;
    struct dictEntry *next;     /* Next entry in the same hash bucket. */
};

• hash算法使用：MurmurHash2
• 冲突解决：拉链法，添加到表头
• rehash:
  • old复制到new
  • 渐进式hash