githaven/vendor/github.com/pingcap/tidb/kv/bufpool.go

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// Copyright 2015 PingCAP, 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package kv
import (
"sync"
"github.com/ngaut/log"
)
// A cache holds a set of reusable objects.
// The slice is a stack (LIFO).
// If more are needed, the cache creates them by calling new.
type cache struct {
mu sync.Mutex
name string
saved []MemBuffer
// factory
fact func() MemBuffer
}
func (c *cache) put(x MemBuffer) {
c.mu.Lock()
if len(c.saved) < cap(c.saved) {
c.saved = append(c.saved, x)
} else {
log.Warnf("%s is full, size: %d, you may need to increase pool size", c.name, len(c.saved))
}
c.mu.Unlock()
}
func (c *cache) get() MemBuffer {
c.mu.Lock()
n := len(c.saved)
if n == 0 {
c.mu.Unlock()
return c.fact()
}
x := c.saved[n-1]
c.saved = c.saved[0 : n-1]
c.mu.Unlock()
return x
}
func newCache(name string, cap int, fact func() MemBuffer) *cache {
return &cache{name: name, saved: make([]MemBuffer, 0, cap), fact: fact}
}