C++实现平方的安全方法（redis的实现）

/* Our hash table capability is a power of two */
static unsigned long _dictNextPower(unsigned long size)
{
unsigned long i = DICT_HT_INITIAL_SIZE; //DICT_HT_INITIAL_SIZE=4

if (size >= LONG_MAX) return LONG_MAX;
while(1) {
if (i >= size)
return i;
i *= 2;
}
}