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PHP实现的memcache环形队列类实例

2015-07-29 09:53作者：fang

本文实例讲述了PHP实现的memcache环形队列类。分享给大家供大家参考。具体如下：

这里介绍了PHP实现的memcache环形队列类。没咋学过数据结构，因为业务需要，所以只是硬着头皮模拟的！ 参考PHP memcache 队列代码。为使队列随时可入可出，且不受int长度越界危险（单链采取Head自增的话不作处理有越界可能），所以索性改写成环形队列。可能还有BUG，忘见谅！

<?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;

}

}

希望本文所述对大家的php程序设计有所帮助。

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