本文實例講述了PHP實現的memcache環形隊列類。分享給大家供大家參考。具體如下：

這里介紹了PHP實現的memcache環形隊列類。沒咋學過數據結構，因為業務需要，所以只是硬著頭皮模擬的！ 參考PHP memcache 隊列代碼。為使隊列隨時可入可出，且不受int長度越界危險（單鏈采取Head自增的話不作處理有越界可能），所以索性改寫成環形隊列?？赡苓€有BUG，忘見諒！

<?php

/**

* PHP memcache 環形隊列類

* 原作者 LKK/lianq.net

* 修改 FoxHunter

* 因業務需要只保留的隊列中的Pop和Push,修改過期時間為0即永久

*/

class MQueue

{

public static $client;

private $expire; //過期時間,秒,1~2592000,即30天內

private $sleepTime; //等待解鎖時間,微秒

private $queueName; //隊列名稱,唯一值

private $retryNum; //嘗試次數

private $MAXNUM; //最大隊列容量

private $canRewrite; //是否可以覆寫開關，滿出來的內容從頭部開始覆蓋重寫原來的數據

private $HEAD; //下一步要進入的指針位置

private $TAIL; //下一步要進入的指針位置

private $LEN; //隊列現有長度

const LOCK_KEY = '_Fox_MQ_LOCK_'; //鎖存儲標示

const LENGTH_KEY = '_Fox_MQ_LENGTH_'; //隊列現長度存儲標示

const VALU_KEY = '_Fox_MQ_VAL_'; //隊列鍵值存儲標示

const HEAD_KEY = '_Fox_MQ_HEAD_'; //隊列HEAD指針位置標示

const TAIL_KEY = '_Fox_MQ_TAIL_'; //隊列TAIL指針位置標示

/*

* 構造函數

* 對于同一個$queueName，實例化時必須保障構造函數的參數值一致，否則pop和push會導隊列順序混亂

*/

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); //當客戶斷開連接,允許繼續執行

set_time_limit(0); //取消腳本執行延時上限

$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;

}

//獲取隊列首尾指針信息和長度

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原子性加鎖

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) { //嘗試等待N次

return false;

break;

}

}

return $this->access = true;

}

return false;

}

//更新頭部指針指向,指向下一個位置

private function incrHead()

{

//$this->getHeadAndTail(); //獲取最新指針信息 ,由于本方法體均在鎖內調用，其鎖內已調用了此方法，本行注釋

$this->HEAD++; //頭部指針下移

if ($this->HEAD >= $this->MAXNUM) {

$this->HEAD = 0; //邊界值修正

}

;

$this->LEN--; //Head的移動由Pop觸發，所以相當于數量減少

if ($this->LEN < 0) {

$this->LEN = 0; //邊界值修正

}

;

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

}

//更新尾部指針指向，指向下一個位置

private function incrTail()

{

//$this->getHeadAndTail(); //獲取最新指針信息，由于本方法體均在鎖內調用，其鎖內已調用了此方法，本行注釋

$this->TAIL++; //尾部指針下移

if ($this->TAIL >= $this->MAXNUM) {

$this->TAIL = 0; //邊界值修正

}

;

$this->LEN++; //Head的移動由Push觸發，所以相當于數量增加

if ($this->LEN >= $this->MAXNUM) {

$this->LEN = $this->MAXNUM; //邊界值長度修正

}

;

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

}

// 解鎖

private function unLock()

{

memcache_delete(self::$client, $this->queueName . self::LOCK_KEY);

$this->access = false;

}

//判斷是否滿隊列

public function isFull()

{

//外部直接調用的時候由于沒有鎖所以此處的值是個大概值，并不很準確，但是內部調用由于在前面有lock，所以可信

if ($this->canRewrite)

return false;

return $this->LEN == $this->MAXNUM ? true : false;

}

//判斷是否為空

public function isEmpty()

{

//外部直接調用的時候由于沒有鎖所以此處的值是個大概值，并不很準確，但是內部調用由于在前面有lock，所以可信

return $this->LEN == 0 ? true : false;

}

public function getLen()

{

//外部直接調用的時候由于沒有鎖所以此處的值是個大概值，并不很準確，但是內部調用由于在前面有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(); //獲取最新指針信息

if ($this->isFull()) { //只有在非覆寫下才有Full概念

$this->unLock();

return false;

}

if (memcache_set(self::$client, $this->queueName . self::VALU_KEY . $this->TAIL, $data, MEMCACHE_COMPRESSED, $this->expire)) {

//當推送后，發現尾部和頭部重合（此時指針還未移動），且右邊仍有未由Head讀取的數據，那么移動Head指針，避免尾部指針跨越Head

if ($this->TAIL == $this->HEAD && $this->LEN >= 1) {

$this->incrHead();

}

$this->incrTail(); //移動尾部指針

$result = true;

}

$this->unLock();

return $result;

}

/*

* Pop一個值

* @param [length] int 隊列長度

* @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; //默認讀取所有

if ($this->isEmpty()) {

$this->unLock();

return false;

}

//獲取長度超出隊列長度后進行修正

if ($length > $this->LEN)

$length = $this->LEN;

$data = $this->popKeyArray($length);

$this->unLock();

return $data;

}

/*

* pop某段長度的值

* @param [length] int 隊列長度

* @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);

//當提取值后，發現頭部和尾部重合（此時指針還未移動），且右邊沒有數據，即隊列中最后一個數據被完全掏空，此時指針停留在本地不移動，隊列長度變為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讀取出的數據，均移動HEAD指針到下一處待讀取位置

}

}

return $result;

}

/*

* 重置隊列

* * @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緩存數據

* @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;

}

}

希望本文所述對大家的php程序設計有所幫助。