DockerCLI/vendor/google.golang.org/grpc/shared_buffer_pool.go

155 lines
3.6 KiB
Go

/*
*
* Copyright 2023 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package grpc
import "sync"
// SharedBufferPool is a pool of buffers that can be shared, resulting in
// decreased memory allocation. Currently, in gRPC-go, it is only utilized
// for parsing incoming messages.
//
// # Experimental
//
// Notice: This API is EXPERIMENTAL and may be changed or removed in a
// later release.
type SharedBufferPool interface {
// Get returns a buffer with specified length from the pool.
//
// The returned byte slice may be not zero initialized.
Get(length int) []byte
// Put returns a buffer to the pool.
Put(*[]byte)
}
// NewSharedBufferPool creates a simple SharedBufferPool with buckets
// of different sizes to optimize memory usage. This prevents the pool from
// wasting large amounts of memory, even when handling messages of varying sizes.
//
// # Experimental
//
// Notice: This API is EXPERIMENTAL and may be changed or removed in a
// later release.
func NewSharedBufferPool() SharedBufferPool {
return &simpleSharedBufferPool{
pools: [poolArraySize]simpleSharedBufferChildPool{
newBytesPool(level0PoolMaxSize),
newBytesPool(level1PoolMaxSize),
newBytesPool(level2PoolMaxSize),
newBytesPool(level3PoolMaxSize),
newBytesPool(level4PoolMaxSize),
newBytesPool(0),
},
}
}
// simpleSharedBufferPool is a simple implementation of SharedBufferPool.
type simpleSharedBufferPool struct {
pools [poolArraySize]simpleSharedBufferChildPool
}
func (p *simpleSharedBufferPool) Get(size int) []byte {
return p.pools[p.poolIdx(size)].Get(size)
}
func (p *simpleSharedBufferPool) Put(bs *[]byte) {
p.pools[p.poolIdx(cap(*bs))].Put(bs)
}
func (p *simpleSharedBufferPool) poolIdx(size int) int {
switch {
case size <= level0PoolMaxSize:
return level0PoolIdx
case size <= level1PoolMaxSize:
return level1PoolIdx
case size <= level2PoolMaxSize:
return level2PoolIdx
case size <= level3PoolMaxSize:
return level3PoolIdx
case size <= level4PoolMaxSize:
return level4PoolIdx
default:
return levelMaxPoolIdx
}
}
const (
level0PoolMaxSize = 16 // 16 B
level1PoolMaxSize = level0PoolMaxSize * 16 // 256 B
level2PoolMaxSize = level1PoolMaxSize * 16 // 4 KB
level3PoolMaxSize = level2PoolMaxSize * 16 // 64 KB
level4PoolMaxSize = level3PoolMaxSize * 16 // 1 MB
)
const (
level0PoolIdx = iota
level1PoolIdx
level2PoolIdx
level3PoolIdx
level4PoolIdx
levelMaxPoolIdx
poolArraySize
)
type simpleSharedBufferChildPool interface {
Get(size int) []byte
Put(any)
}
type bufferPool struct {
sync.Pool
defaultSize int
}
func (p *bufferPool) Get(size int) []byte {
bs := p.Pool.Get().(*[]byte)
if cap(*bs) < size {
p.Pool.Put(bs)
return make([]byte, size)
}
return (*bs)[:size]
}
func newBytesPool(size int) simpleSharedBufferChildPool {
return &bufferPool{
Pool: sync.Pool{
New: func() any {
bs := make([]byte, size)
return &bs
},
},
defaultSize: size,
}
}
// nopBufferPool is a buffer pool just makes new buffer without pooling.
type nopBufferPool struct {
}
func (nopBufferPool) Get(length int) []byte {
return make([]byte, length)
}
func (nopBufferPool) Put(*[]byte) {
}