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Stop pre-computing log2 values in allocator.go #11

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Stop pre-computing log2 values in allocator.go #11

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25 changes: 5 additions & 20 deletions z/allocator.go
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,6 @@ package z
import (
"bytes"
"fmt"
"math"
"math/bits"
"math/rand"
"strings"
Expand Down Expand Up @@ -49,7 +48,6 @@ type Allocator struct {
var allocsMu *sync.Mutex
var allocRef uint64
var allocs map[uint64]*Allocator
var calculatedLog2 []int

func init() {
allocsMu = new(sync.Mutex)
Expand All @@ -58,11 +56,6 @@ func init() {
// Set up a unique Ref per process.
rand.Seed(time.Now().UnixNano())
allocRef = uint64(rand.Int63n(1<<16)) << 48

calculatedLog2 = make([]int, 1025)
for i := 1; i <= 1024; i++ {
calculatedLog2[i] = int(math.Log2(float64(i)))
}
}

// NewAllocator creates an allocator starting with the given size.
Expand All @@ -78,8 +71,9 @@ func NewAllocator(sz int, tag string) *Allocator {
buffers: make([][]byte, 64),
Tag: tag,
}
l2 := uint64(log2(sz))
if bits.OnesCount64(uint64(sz)) > 1 {
szu := uint(sz)
l2 := uint64(log2(szu))
if bits.OnesCount(szu) > 1 {
l2 += 1
}
a.buffers[0] = Calloc(1<<l2, a.Tag)
Expand Down Expand Up @@ -157,17 +151,8 @@ func (a *Allocator) Size() int {
panic("Size should not reach here")
}

func log2(sz int) int {
if sz < len(calculatedLog2) {
return calculatedLog2[sz]
}
pow := 10
sz >>= 10
for sz > 1 {
sz >>= 1
pow++
}
return pow
func log2(sz uint) int {
return bits.Len(sz) - 1
}

func (a *Allocator) Allocated() uint64 {
Expand Down