mirror of
https://github.com/MetaCubeX/mihomo.git
synced 2024-12-25 19:55:38 +08:00
74 lines
1.6 KiB
Go
74 lines
1.6 KiB
Go
package pool
|
|
|
|
// Inspired by https://github.com/xtaci/smux/blob/master/alloc.go
|
|
|
|
import (
|
|
"errors"
|
|
"math/bits"
|
|
"sync"
|
|
)
|
|
|
|
var defaultAllocator = NewAllocator()
|
|
|
|
// Allocator for incoming frames, optimized to prevent overwriting after zeroing
|
|
type Allocator struct {
|
|
buffers []sync.Pool
|
|
}
|
|
|
|
// NewAllocator initiates a []byte allocator for frames less than 65536 bytes,
|
|
// the waste(memory fragmentation) of space allocation is guaranteed to be
|
|
// no more than 50%.
|
|
func NewAllocator() *Allocator {
|
|
alloc := new(Allocator)
|
|
alloc.buffers = make([]sync.Pool, 17) // 1B -> 64K
|
|
for k := range alloc.buffers {
|
|
i := k
|
|
alloc.buffers[k].New = func() any {
|
|
return make([]byte, 1<<uint32(i))
|
|
}
|
|
}
|
|
return alloc
|
|
}
|
|
|
|
// Get a []byte from pool with most appropriate cap
|
|
func (alloc *Allocator) Get(size int) []byte {
|
|
switch {
|
|
case size < 0:
|
|
panic("alloc.Get: len out of range")
|
|
case size == 0:
|
|
return nil
|
|
case size > 65536:
|
|
return make([]byte, size)
|
|
default:
|
|
bits := msb(size)
|
|
if size == 1<<bits {
|
|
return alloc.buffers[bits].Get().([]byte)[:size]
|
|
}
|
|
|
|
return alloc.buffers[bits+1].Get().([]byte)[:size]
|
|
}
|
|
}
|
|
|
|
// Put returns a []byte to pool for future use,
|
|
// which the cap must be exactly 2^n
|
|
func (alloc *Allocator) Put(buf []byte) error {
|
|
if cap(buf) == 0 || cap(buf) > 65536 {
|
|
return nil
|
|
}
|
|
|
|
bits := msb(cap(buf))
|
|
if cap(buf) != 1<<bits {
|
|
return errors.New("allocator Put() incorrect buffer size")
|
|
}
|
|
|
|
//nolint
|
|
//lint:ignore SA6002 ignore temporarily
|
|
alloc.buffers[bits].Put(buf)
|
|
return nil
|
|
}
|
|
|
|
// msb return the pos of most significant bit
|
|
func msb(size int) uint16 {
|
|
return uint16(bits.Len32(uint32(size)) - 1)
|
|
}
|