EstimateBucketMemoryUsage returns the estimated memory usage of a bucket in a map.

GetBytesFromPtr return a bytes array from the given ptr and length.

Slice converts string to slice without copy.

String converts slice to MutableString without copy.

DefBucketMemoryUsageForMapIntToPtr = bucketSize*(1+unsafe.Sizeof(uint64) + unsafe.Sizeof(pointer))+2*ptrSize.

DefBucketMemoryUsageForMapStringToAny = bucketSize*(1+unsafe.Sizeof(string) + unsafe.Sizeof(interface{}))+2*ptrSize.

DefBucketMemoryUsageForMapStrToSlice = bucketSize*(1+unsafe.Sizeof(string) + unsafe.Sizeof(slice))+2*ptrSize ref https://github.com/golang/go/blob/go1.15.6/src/reflect/type.go#L2162.

DefBucketMemoryUsageForSetFloat64 = bucketSize*(1+unsafe.Sizeof(float64) + unsafe.Sizeof(struct{}))+2*ptrSize.

DefBucketMemoryUsageForSetInt64 = bucketSize*(1+unsafe.Sizeof(int64) + unsafe.Sizeof(struct{}))+2*ptrSize.

DefBucketMemoryUsageForSetString = bucketSize*(1+unsafe.Sizeof(string) + unsafe.Sizeof(struct{}))+2*ptrSize.

LoadFactorDen is the denominator of load factor.

LoadFactorNum is the numerator of load factor.

MutableString can be used as string via string(MutableString) without performance loss.