mirror of
https://github.com/42wim/matterbridge.git
synced 2024-12-21 10:32:35 +01:00
152 lines
2.9 KiB
Go
152 lines
2.9 KiB
Go
package bytebufferpool
|
|
|
|
import (
|
|
"sort"
|
|
"sync"
|
|
"sync/atomic"
|
|
)
|
|
|
|
const (
|
|
minBitSize = 6 // 2**6=64 is a CPU cache line size
|
|
steps = 20
|
|
|
|
minSize = 1 << minBitSize
|
|
maxSize = 1 << (minBitSize + steps - 1)
|
|
|
|
calibrateCallsThreshold = 42000
|
|
maxPercentile = 0.95
|
|
)
|
|
|
|
// Pool represents byte buffer pool.
|
|
//
|
|
// Distinct pools may be used for distinct types of byte buffers.
|
|
// Properly determined byte buffer types with their own pools may help reducing
|
|
// memory waste.
|
|
type Pool struct {
|
|
calls [steps]uint64
|
|
calibrating uint64
|
|
|
|
defaultSize uint64
|
|
maxSize uint64
|
|
|
|
pool sync.Pool
|
|
}
|
|
|
|
var defaultPool Pool
|
|
|
|
// Get returns an empty byte buffer from the pool.
|
|
//
|
|
// Got byte buffer may be returned to the pool via Put call.
|
|
// This reduces the number of memory allocations required for byte buffer
|
|
// management.
|
|
func Get() *ByteBuffer { return defaultPool.Get() }
|
|
|
|
// Get returns new byte buffer with zero length.
|
|
//
|
|
// The byte buffer may be returned to the pool via Put after the use
|
|
// in order to minimize GC overhead.
|
|
func (p *Pool) Get() *ByteBuffer {
|
|
v := p.pool.Get()
|
|
if v != nil {
|
|
return v.(*ByteBuffer)
|
|
}
|
|
return &ByteBuffer{
|
|
B: make([]byte, 0, atomic.LoadUint64(&p.defaultSize)),
|
|
}
|
|
}
|
|
|
|
// Put returns byte buffer to the pool.
|
|
//
|
|
// ByteBuffer.B mustn't be touched after returning it to the pool.
|
|
// Otherwise data races will occur.
|
|
func Put(b *ByteBuffer) { defaultPool.Put(b) }
|
|
|
|
// Put releases byte buffer obtained via Get to the pool.
|
|
//
|
|
// The buffer mustn't be accessed after returning to the pool.
|
|
func (p *Pool) Put(b *ByteBuffer) {
|
|
idx := index(len(b.B))
|
|
|
|
if atomic.AddUint64(&p.calls[idx], 1) > calibrateCallsThreshold {
|
|
p.calibrate()
|
|
}
|
|
|
|
maxSize := int(atomic.LoadUint64(&p.maxSize))
|
|
if maxSize == 0 || cap(b.B) <= maxSize {
|
|
b.Reset()
|
|
p.pool.Put(b)
|
|
}
|
|
}
|
|
|
|
func (p *Pool) calibrate() {
|
|
if !atomic.CompareAndSwapUint64(&p.calibrating, 0, 1) {
|
|
return
|
|
}
|
|
|
|
a := make(callSizes, 0, steps)
|
|
var callsSum uint64
|
|
for i := uint64(0); i < steps; i++ {
|
|
calls := atomic.SwapUint64(&p.calls[i], 0)
|
|
callsSum += calls
|
|
a = append(a, callSize{
|
|
calls: calls,
|
|
size: minSize << i,
|
|
})
|
|
}
|
|
sort.Sort(a)
|
|
|
|
defaultSize := a[0].size
|
|
maxSize := defaultSize
|
|
|
|
maxSum := uint64(float64(callsSum) * maxPercentile)
|
|
callsSum = 0
|
|
for i := 0; i < steps; i++ {
|
|
if callsSum > maxSum {
|
|
break
|
|
}
|
|
callsSum += a[i].calls
|
|
size := a[i].size
|
|
if size > maxSize {
|
|
maxSize = size
|
|
}
|
|
}
|
|
|
|
atomic.StoreUint64(&p.defaultSize, defaultSize)
|
|
atomic.StoreUint64(&p.maxSize, maxSize)
|
|
|
|
atomic.StoreUint64(&p.calibrating, 0)
|
|
}
|
|
|
|
type callSize struct {
|
|
calls uint64
|
|
size uint64
|
|
}
|
|
|
|
type callSizes []callSize
|
|
|
|
func (ci callSizes) Len() int {
|
|
return len(ci)
|
|
}
|
|
|
|
func (ci callSizes) Less(i, j int) bool {
|
|
return ci[i].calls > ci[j].calls
|
|
}
|
|
|
|
func (ci callSizes) Swap(i, j int) {
|
|
ci[i], ci[j] = ci[j], ci[i]
|
|
}
|
|
|
|
func index(n int) int {
|
|
n--
|
|
n >>= minBitSize
|
|
idx := 0
|
|
for n > 0 {
|
|
n >>= 1
|
|
idx++
|
|
}
|
|
if idx >= steps {
|
|
idx = steps - 1
|
|
}
|
|
return idx
|
|
}
|