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：
這裡介紹了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。可能還有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 $LEN; //隊列現有長度
const LOCK_KEY = '_Fox_MQ_LOCK_'; //鎖存儲標示
const LENGTH_KEY = '_Fox_MQ_LENGTH_'; //隊列現長度存儲標示
const VALU_KEY = '_Fox_MQ_VAL_'; //隊列鍵值存儲標示
const HEAD_KEY = '_Fox_MQ_HEAD_'; //隊列HEAD指針位置標示
const TAIL_KEY = '_Fox_MQ_TAIL_'; //隊列TAIL指針位置標示
/*
* 構造函數
* 對於同一個$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 ,由於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
}
;
$this->LEN--; //Head的移動由Pop觸發，所以相當於數量減少
if ($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，由於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
}
;
$this->LEN++; //Head的移動由Push觸發，所以相當於數量增加
if ($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);
$this->access = false;
}
//判斷是否滿隊列
public function isFull()
{
//外部直接調用的時候由於沒有鎖所以此處的值是個大概值，並不很准確，但是內部調用由於在前面有lock，所以可信
if ($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於沒有鎖所以此處的值是個大概值，並不很准確，但是內部調用由於在前面有lock，所以可信
return $this->LEN == 0 ? true : false;
}
public function getLen()
{
//外部直接調用的時候由於沒有鎖所以此處的值是個大概值，並不很准確，但是內部調用由於在前面有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, $this->expire)) {
//當推送後，發現尾部和頭部重合（此時指針還未移動），且右邊仍有未由Head讀取的數據，那麼移動Head指針，避免尾部指針跨越Head
if ($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()) {
$this->unLock();
return false;
}
//獲取長度超出隊列長度後進行修正
if ($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 . $this->HEAD, 0);
//當提取值後，發現頭部和尾部重合（此時指針還未移動），且右邊沒有數據，即隊列中最後一個數據被完全掏空，此時指針停留在本地不移動，隊列長度變為0
if ($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。
