本篇文章主要介绍PHP基于memcache实现环形队列的方法，感兴趣的朋友参考下，希望对大家有所帮助。
代码如下：
<?php
/**
* PHP memcache 环形队列类
* 原作者 LKK/lianq.net
* 修改 FoxHunter
* 因业务需要只保留的队列中的Pop和Push,修改过期时间为0即永久
*/
class MQueue
{
public static $client;
private $expire; //过期时间,秒,1~2592000,即30天内
private $sleepTime; //等待解锁时间,微秒
private $queueName; //队列名称,唯一值
private $retryNum; //尝试次数
private $MAXNUM; //最大队列容量
private $canRewrite; //是否可以覆写开关，满出来的内容从头部开始覆盖重写原来的数据
private $HEAD; //下一步要进入的指针位置
private $TAIL; //下一步要进入的指针位置
private $LEN; //队列现有长度
const LOCK_KEY = '_Fox_MQ_LOCK_'; //锁存储标示
const LENGTH_KEY = '_Fox_MQ_LENGTH_'; //队列现长度存储标示
const VALU_KEY = '_Fox_MQ_VAL_'; //队列键值存储标示
const HEAD_KEY = '_Fox_MQ_HEAD_'; //队列HEAD指针位置标示
const TAIL_KEY = '_Fox_MQ_TAIL_'; //队列TAIL指针位置标示
/*
* 构造函数
* 对于同一个$queueName，实例化时必须保障构造函数的参数值一致，否则pop和push会导队列顺序混乱
*/
public function __construct($queueName = '', $maxqueue = 1, $canRewrite = false, $expire = 0, $config = '')
{
if (empty($config)) {
self::$client = memcache_pconnect('127.0.0.1', 11211);
} elseif (is_array($config)) { //array('host'=>'127.0.0.1','port'=>'11211')
self::$client = memcache_pconnect($config['host'], $config['port']);
} elseif (is_string($config)) { //"127.0.0.1:11211"
$tmp = explode(':', $config);
$conf['host'] = isset($tmp[0]) ? $tmp[0] : '127.0.0.1';
$conf['port'] = isset($tmp[1]) ? $tmp[1] : '11211';
self::$client = memcache_pconnect($conf['host'], $conf['port']);
}
if (!self::$client)
return false;
ignore_user_abort(true); //当客户断开连接,允许继续执行
set_time_limit(0); //取消脚本执行延时上限
$this->access = false;
$this->sleepTime = 1000;
$expire = (empty($expire)) ? 0 : (int) $expire + 1;
$this->expire = $expire;
$this->queueName = $queueName;
$this->retryNum = 20000;
$this->MAXNUM = $maxqueue != null ? $maxqueue : 1;
$this->canRewrite = $canRewrite;
$this->getHeadAndTail();
if (!isset($this->HEAD) || empty($this->HEAD))
$this->HEAD = 0;
if (!isset($this->TAIL) || empty($this->TAIL))
$this->TAIL = 0;
if (!isset($this->LEN) || empty($this->LEN))
$this->LEN = 0;
}
//获取队列首尾指针信息和长度
private function getHeadAndTail()
{
$this->HEAD = (int) memcache_get(self::$client, $this->queueName . self::HEAD_KEY);
$this->TAIL = (int) memcache_get(self::$client, $this->queueName . self::TAIL_KEY);
$this->LEN = (int) memcache_get(self::$client, $this->queueName . self::LENGTH_KEY);
}
// 利用memcache_add原子性加锁
private function lock()
{
if ($this->access === false) {
$i = 0;
while (!memcache_add(self::$client, $this->queueName . self::LOCK_KEY, 1, false, $this->expire)) {
usleep($this->sleepTime);
@$i++;
if ($i > $this->retryNum) { //尝试等待N次
return false;
break;
}
}
return $this->access = true;
}
return false;
}
//更新头部指针指向,指向下一个位置
private function incrHead()
{
//$this->getHeadAndTail(); //获取最新指针信息 ,由于本方法体均在锁内调用，其锁内已调用了此方法，本行注释
$this->HEAD++; //头部指针下移
if ($this->HEAD >= $this->MAXNUM) {
$this->HEAD = 0; //边界值修正
}
;
$this->LEN--; //Head的移动由Pop触发，所以相当于数量减少
if ($this->LEN < 0) {
$this->LEN = 0; //边界值修正
}
;
memcache_set(self::$client, $this->queueName . self::HEAD_KEY, $this->HEAD, false, $this->expire); //更新
memcache_set(self::$client, $this->queueName . self::LENGTH_KEY, $this->LEN, false, $this->expire); //更新
}
//更新尾部指针指向，指向下一个位置
private function incrTail()
{
//$this->getHeadAndTail(); //获取最新指针信息，由于本方法体均在锁内调用，其锁内已调用了此方法，本行注释
$this->TAIL++; //尾部指针下移
if ($this->TAIL >= $this->MAXNUM) {
$this->TAIL = 0; //边界值修正
}
;
$this->LEN++; //Head的移动由Push触发，所以相当于数量增加
if ($this->LEN >= $this->MAXNUM) {
$this->LEN = $this->MAXNUM; //边界值长度修正
}
;
memcache_set(self::$client, $this->queueName . self::TAIL_KEY, $this->TAIL, false, $this->expire); //更新
memcache_set(self::$client, $this->queueName . self::LENGTH_KEY, $this->LEN, false, $this->expire); //更新
}
// 解锁
private function unLock()
{
memcache_delete(self::$client, $this->queueName . self::LOCK_KEY);
$this->access = false;
}
//判断是否满队列
public function isFull()
{
//外部直接调用的时候由于没有锁所以此处的值是个大概值，并不很准确，但是内部调用由于在前面有lock，所以可信
if ($this->canRewrite)
return false;
return $this->LEN == $this->MAXNUM ? true : false;
}
//判断是否为空
public function isEmpty()
{
//外部直接调用的时候由于没有锁所以此处的值是个大概值，并不很准确，但是内部调用由于在前面有lock，所以可信
return $this->LEN == 0 ? true : false;
}
public function getLen()
{
//外部直接调用的时候由于没有锁所以此处的值是个大概值，并不很准确，但是内部调用由于在前面有lock，所以可信
return $this->LEN;
}
/*
* push值
* @param mixed 值
* @return bool
*/
public function push($data = '')
{
$result = false;
if (empty($data))
return $result;
if (!$this->lock()) {
return $result;
}
$this->getHeadAndTail(); //获取最新指针信息
if ($this->isFull()) { //只有在非覆写下才有Full概念
$this->unLock();
return false;
}
if (memcache_set(self::$client, $this->queueName . self::VALU_KEY . $this->TAIL, $data, MEMCACHE_COMPRESSED, $this->expire)) {
//当推送后，发现尾部和头部重合（此时指针还未移动），且右边仍有未由Head读取的数据，那么移动Head指针，避免尾部指针跨越Head
if ($this->TAIL == $this->HEAD && $this->LEN >= 1) {
$this->incrHead();
}
$this->incrTail(); //移动尾部指针
$result = true;
}
$this->unLock();
return $result;
}
/*
* Pop一个值
* @param [length] int 队列长度
* @return array
*/
public function pop($length = 0)
{
if (!is_numeric($length))
return false;
if (!$this->lock())
return false;
$this->getHeadAndTail();
if (empty($length))
$length = $this->LEN; //默认读取所有
if ($this->isEmpty()) {
$this->unLock();
return false;
}
//获取长度超出队列长度后进行修正
if ($length > $this->LEN)
$length = $this->LEN;
$data = $this->popKeyArray($length);
$this->unLock();
return $data;
}
/*
* pop某段长度的值
* @param [length] int 队列长度
* @return array
*/
private function popKeyArray($length)
{
$result = array();
if (empty($length))
return $result;
for ($k = 0; $k < $length; $k++) {
$result[] = @memcache_get(self::$client, $this->queueName . self::VALU_KEY . $this->HEAD);
@memcache_delete(self::$client, $this->queueName . self::VALU_KEY . $this->HEAD, 0);
//当提取值后，发现头部和尾部重合（此时指针还未移动），且右边没有数据，即队列中最后一个数据被完全掏空，此时指针停留在本地不移动，队列长度变为0
if ($this->TAIL == $this->HEAD && $this->LEN <= 1) {
$this->LEN = 0;
memcache_set(self::$client, $this->queueName . self::LENGTH_KEY, $this->LEN, false, $this->expire); //更新
break;
} else {
$this->incrHead(); //首尾未重合，或者重合但是仍有未读取出的数据，均移动HEAD指针到下一处待读取位置
}
}
return $result;
}
/*
* 重置队列
* * @return NULL
*/
private function reset($all = false)
{
if ($all) {
memcache_delete(self::$client, $this->queueName . self::HEAD_KEY, 0);
memcache_delete(self::$client, $this->queueName . self::TAIL_KEY, 0);
memcache_delete(self::$client, $this->queueName . self::LENGTH_KEY, 0);
} else {
$this->HEAD = $this->TAIL = $this->LEN = 0;
memcache_set(self::$client, $this->queueName . self::HEAD_KEY, 0, false, $this->expire);
memcache_set(self::$client, $this->queueName . self::TAIL_KEY, 0, false, $this->expire);
memcache_set(self::$client, $this->queueName . self::LENGTH_KEY, 0, false, $this->expire);
}
}
/*
* 清除所有memcache缓存数据
* @return NULL
*/
public function memFlush()
{
memcache_flush(self::$client);
}
public function clear($all = false)
{
if (!$this->lock())
return false;
$this->getHeadAndTail();
$Head = $this->HEAD;
$Length = $this->LEN;
$curr = 0;
for ($i = 0; $i < $Length; $i++) {
$curr = $this->$Head + $i;
if ($curr >= $this->MAXNUM) {
$this->HEAD = $curr = 0;
}
@memcache_delete(self::$client, $this->queueName . self::VALU_KEY . $curr, 0);
}
$this->unLock();
$this->reset($all);
return true;
}
}总结：以上就是本篇文的全部内容，希望能对大家的学习有所帮助。
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