github.com/insionng/yougam@v0.0.0-20170714101924-2bc18d833463/libraries/pingcap/tidb/kv/bufpool.go (about)

     1  // Copyright 2015 PingCAP, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package kv
    15  
    16  import (
    17  	"sync"
    18  
    19  	"github.com/insionng/yougam/libraries/ngaut/log"
    20  )
    21  
    22  // A cache holds a set of reusable objects.
    23  // The slice is a stack (LIFO).
    24  // If more are needed, the cache creates them by calling new.
    25  type cache struct {
    26  	mu    sync.Mutex
    27  	name  string
    28  	saved []MemBuffer
    29  	// factory
    30  	fact func() MemBuffer
    31  }
    32  
    33  func (c *cache) put(x MemBuffer) {
    34  	c.mu.Lock()
    35  	if len(c.saved) < cap(c.saved) {
    36  		c.saved = append(c.saved, x)
    37  	} else {
    38  		log.Warnf("%s is full, size: %d, you may need to increase pool size", c.name, len(c.saved))
    39  	}
    40  	c.mu.Unlock()
    41  }
    42  
    43  func (c *cache) get() MemBuffer {
    44  	c.mu.Lock()
    45  	n := len(c.saved)
    46  	if n == 0 {
    47  		c.mu.Unlock()
    48  		return c.fact()
    49  	}
    50  	x := c.saved[n-1]
    51  	c.saved = c.saved[0 : n-1]
    52  	c.mu.Unlock()
    53  	return x
    54  }
    55  
    56  func newCache(name string, cap int, fact func() MemBuffer) *cache {
    57  	return &cache{name: name, saved: make([]MemBuffer, 0, cap), fact: fact}
    58  }