88 lines
2.0 KiB
Go
88 lines
2.0 KiB
Go
// Copyright 2017 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package pool
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import (
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"fmt"
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"reflect"
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"sync"
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)
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// Pool is a bucketed pool for variably sized byte slices.
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type Pool struct {
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buckets []sync.Pool
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sizes []int
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// make is the function used to create an empty slice when none exist yet.
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make func(int) interface{}
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}
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// New returns a new Pool with size buckets for minSize to maxSize
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// increasing by the given factor.
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func New(minSize, maxSize int, factor float64, makeFunc func(int) interface{}) *Pool {
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if minSize < 1 {
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panic("invalid minimum pool size")
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}
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if maxSize < 1 {
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panic("invalid maximum pool size")
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}
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if factor < 1 {
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panic("invalid factor")
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}
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var sizes []int
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for s := minSize; s <= maxSize; s = int(float64(s) * factor) {
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sizes = append(sizes, s)
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}
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p := &Pool{
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buckets: make([]sync.Pool, len(sizes)),
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sizes: sizes,
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make: makeFunc,
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}
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return p
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}
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// Get returns a new byte slices that fits the given size.
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func (p *Pool) Get(sz int) interface{} {
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for i, bktSize := range p.sizes {
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if sz > bktSize {
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continue
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}
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b := p.buckets[i].Get()
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if b == nil {
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b = p.make(bktSize)
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}
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return b
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}
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return p.make(sz)
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}
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// Put adds a slice to the right bucket in the pool.
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func (p *Pool) Put(s interface{}) {
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slice := reflect.ValueOf(s)
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if slice.Kind() != reflect.Slice {
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panic(fmt.Sprintf("%+v is not a slice", slice))
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}
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for i, size := range p.sizes {
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if slice.Cap() > size {
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continue
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}
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p.buckets[i].Put(slice.Slice(0, 0).Interface())
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return
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}
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}
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