Redis字典扩张算法

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/* This is the initial size of every hash table */

#define DICT_HT_INITIAL_SIZE     4

/* Our hash table capability is a power of two */

static unsigned long _dictNextPower(unsigned long size)

{

    unsigned long i = DICT_HT_INITIAL_SIZE;



    if (size >= LONG_MAX) return LONG_MAX + 1LU;

    while(1) {

        if (i >= size)

            return i;

        i *= 2;

    }

}