forked from gravitational/teleport
/
slice.go
124 lines (110 loc) · 3.14 KB
/
slice.go
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// Copyright 2021 Gravitational, Inc
//
// 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 utils
import (
"bytes"
"sync"
)
// SlicePool manages a pool of slices
// in attempts to manage memory in go more efficiently
// and avoid frequent allocations
type SlicePool interface {
// Zero zeroes slice
Zero(b []byte)
// Get returns a new or already allocated slice
Get() []byte
// Put returns slice back to the pool
Put(b []byte)
// Size returns a slice size
Size() int64
}
// NewSliceSyncPool returns a new slice pool, using sync.Pool
// of pre-allocated or newly allocated slices of the predefined size and capacity
func NewSliceSyncPool(sliceSize int64) *SliceSyncPool {
s := &SliceSyncPool{
sliceSize: sliceSize,
zeroSlice: make([]byte, sliceSize),
}
s.New = func() interface{} {
slice := make([]byte, s.sliceSize)
return &slice
}
return s
}
// SliceSyncPool is a sync pool of slices (usually large)
// of the same size to optimize memory usage, see sync.Pool for more details
type SliceSyncPool struct {
sync.Pool
sliceSize int64
zeroSlice []byte
}
// Zero zeroes slice of any length
func (s *SliceSyncPool) Zero(b []byte) {
if len(b) <= len(s.zeroSlice) {
// zero all bytes in the slice to avoid
// data lingering in memory
copy(b, s.zeroSlice[:len(b)])
} else {
// use working, but less optimal implementation
for i := 0; i < len(b); i++ {
b[i] = 0
}
}
}
// Get returns a new or already allocated slice
func (s *SliceSyncPool) Get() []byte {
pslice := s.Pool.Get().(*[]byte)
return *pslice
}
// Put returns slice back to the pool
func (s *SliceSyncPool) Put(b []byte) {
s.Zero(b)
s.Pool.Put(&b)
}
// Size returns a slice size
func (s *SliceSyncPool) Size() int64 {
return s.sliceSize
}
// NewBufferSyncPool returns a new instance of sync pool of bytes.Buffers
// that creates new buffers with preallocated underlying buffer of size
func NewBufferSyncPool(size int64) *BufferSyncPool {
return &BufferSyncPool{
size: size,
Pool: sync.Pool{
New: func() interface{} {
return bytes.NewBuffer(make([]byte, size))
},
},
}
}
// BufferSyncPool is a sync pool of bytes.Buffer
type BufferSyncPool struct {
sync.Pool
size int64
}
// Put resets the buffer (does not free the memory)
// and returns it back to the pool. Users should be careful
// not to use the buffer (e.g. via Bytes) after it was returned
func (b *BufferSyncPool) Put(buf *bytes.Buffer) {
buf.Reset()
b.Pool.Put(buf)
}
// Get returns a new or already allocated buffer
func (b *BufferSyncPool) Get() *bytes.Buffer {
return b.Pool.Get().(*bytes.Buffer)
}
// Size returns default allocated buffer size
func (b *BufferSyncPool) Size() int64 {
return b.size
}