PHP memcache實現訊息佇列執行個體

現在memcache在伺服器緩衝應用比較廣泛，下面我來介紹memcache實現訊息佇列等待的一個例子，有需要瞭解的朋友可參考。

memche訊息佇列的原理就是在key上做文章，用以做一個連續的數字加上首碼記錄序列化以後訊息或者日誌。然後通過定時程式將內容落地到檔案或者資料庫。

php實現訊息佇列的用處比如在做發送郵件時發送大量郵件很費時間的問題，那麼可以採取隊列。
方便實現隊列的輕量級佇列服務器是：
starling支援memcache協議的輕量級持久化伺服器
https://github.com/starling/starling
Beanstalkd輕量、高效，支援持久化，每秒可處理3000左右的隊列
http://kr.github.com/beanstalkd/
php中也可以使用memcache/memcached來實現訊息佇列。

connect('127.0.0.1', 11211);}return $mc;}/*** mc 計數器,增加計數並返回新的計數* @param string $key   計數器* @param int $offset   計數增量,可為負數.0為不改變計數* @param int $time     時間* @return int/false    失敗是返回false,成功時返回更新計數器後的計數*/static public function set_counter( $key, $offset, $time=0 ){$mc = self::mc_init();$val = $mc->get($key);if( !is_numeric($val)  $val < 0 ){$ret = $mc->set( $key, 0, $time );if( !$ret ) return false;$val = 0;}$offset = intval( $offset );if( $offset > 0 ){return $mc->increment( $key, $offset );}elseif( $offset < 0 ){return $mc->decrement( $key, -$offset );}return $val;}/*** 寫入隊列* @param string $key* @param mixed $value* @return bool*/static public function input( $key, $value ){$mc = self::mc_init();$w_key = self::PREFIX.$key.'W';$v_key = self::PREFIX.$key.self::set_counter($w_key, 1);return $mc->set( $v_key, $value );}/*** 讀取隊列裡的資料* @param string $key* @param int $max  最多讀取條數* @return array*/static public function output( $key, $max=100 ){$out = array();$mc = self::mc_init();$r_key = self::PREFIX.$key.'R';$w_key = self::PREFIX.$key.'W';$r_p   = self::set_counter( $r_key, 0 );//讀指標$w_p   = self::set_counter( $w_key, 0 );//寫指標if( $r_p == 0 ) $r_p = 1;while( $w_p >= $r_p ){if( --$max < 0 ) break;$v_key = self::PREFIX.$key.$r_p;$r_p = self::set_counter( $r_key, 1 );$out[] = $mc->get( $v_key );$mc->delete($v_key);}return $out;}}/**使用方法:QMC::input($key, $value );//寫入隊列$list = QMC::output($key);//讀取隊列*/?>

基於PHP共用記憶體實現的訊息佇列:

shmId = shmop_open($shmkey, "c", 0644, $this->memSize );$this->maxQSize = $this->memSize / $this->blockSize;// 申?一個訊號量$this->semId = sem_get($shmkey, 1);sem_acquire($this->semId); // 申請進入臨界區$this->init();}private function init(){if ( file_exists($this->filePtr) ){$contents = file_get_contents($this->filePtr);$data = explode( '', $contents );if ( isset($data[0]) && isset($data[1])){$this->front = (int)$data[0];$this->rear  = (int)$data[1];}}}public function getLength(){return (($this->rear - $this->front + $this->memSize) % ($this->memSize) )/$this->blockSize;}public function enQueue( $value ){if ( $this->ptrInc($this->rear) == $this->front ){ // 隊滿return false;}$data = $this->encode($value);shmop_write($this->shmId, $data, $this->rear );$this->rear = $this->ptrInc($this->rear);return true;}public function deQueue(){if ( $this->front == $this->rear ){ // 隊空return false;}$value = shmop_read($this->shmId, $this->front, $this->blockSize-1);$this->front = $this->ptrInc($this->front);return $this->decode($value);}private function ptrInc( $ptr ){return ($ptr + $this->blockSize) % ($this->memSize);}private function encode( $value ){$data = serialize($value) . "__eof";echo '';echo strlen($data);echo '';echo $this->blockSize -1;echo '';if ( strlen($data) > $this->blockSize -1 ){throw new Exception(strlen($data)." is overload block size!");}return $data;}private function decode( $value ){$data = explode("__eof", $value);return unserialize($data[0]);}public function __destruct(){$data = $this->front . '' . $this->rear;file_put_contents($this->filePtr, $data);sem_release($this->semId); // 出臨界區, 釋放訊號量}}/*// 進隊操作$shmq = new ShmQueue();$data = 'test data';$shmq->enQueue($data);unset($shmq);// 出隊操作$shmq = new ShmQueue();$data = $shmq->deQueue();unset($shmq);*/?>

對於一個很大的訊息佇列，頻繁進行進行大資料庫的序列化 和 還原序列化，有太耗費。下面是我用PHP 實現的一個訊息佇列，只需要在尾部插入一個資料，就操作尾部，不用操作整個訊息佇列進行讀取，與操作。但是，這個訊息佇列不是安全執行緒的，我只是盡量的避免了衝突的可能性。如果訊息不是非常的密集，比如幾秒鐘才一個，還是可以考慮這樣使用的。
如果你要實現安全執行緒的，一個建議是通過檔案進行鎖定，然後進行操作。下面是代碼：
代碼如下:

class Memcache_Queue { private $memcache; private $name; private $prefix; function __construct($maxSize, $name, $memcache, $prefix = "__memcache_queue__") { if ($memcache == null) { throw new Exception("memcache object is null, new the object first."); } $this->memcache = $memcache; $this->name = $name; $this->prefix = $prefix; $this->maxSize = $maxSize; $this->front = 0; $this->real = 0; $this->size = 0; } function __get($name) { return $this->get($name); } function __set($name, $value) { $this->add($name, $value); return $this; } function isEmpty() { return $this->size == 0; } function isFull() { return $this->size == $this->maxSize; } function enQueue($data) { if ($this->isFull()) { throw new Exception("Queue is Full"); } $this->increment("size"); $this->set($this->real, $data); $this->set("real", ($this->real + 1) % $this->maxSize); return $this; } function deQueue() { if ($this->isEmpty()) { throw new Exception("Queue is Empty"); } $this->decrement("size"); $this->delete($this->front); $this->set("front", ($this->front + 1) % $this->maxSize); return $this; } function getTop() { return $this->get($this->front); } function getAll() { return $this->getPage(); } function getPage($offset = 0, $limit = 0) { if ($this->isEmpty()  $this->size < $offset) { return null; } $keys[] = $this->getKeyByPos(($this->front + $offset) % $this->maxSize); $num = 1; for ($pos = ($this->front + $offset + 1) % $this->maxSize; $pos != $this->real; $pos = ($pos + 1) % $this->maxSize) { $keys[] = $this->getKeyByPos($pos); $num++; if ($limit > 0 && $limit == $num) { break; } } return array_values($this->memcache->get($keys)); } function makeEmpty() { $keys = $this->getAllKeys(); foreach ($keys as $value) { $this->delete($value); } $this->delete("real"); $this->delete("front"); $this->delete("size"); $this->delete("maxSize"); } private function getAllKeys() { if ($this->isEmpty()) { return array(); } $keys[] = $this->getKeyByPos($this->front); for ($pos = ($this->front + 1) % $this->maxSize; $pos != $this->real; $pos = ($pos + 1) % $this->maxSize) { $keys[] = $this->getKeyByPos($pos); } return $keys; } private function add($pos, $data) { $this->memcache->add($this->getKeyByPos($pos), $data); return $this; } private function increment($pos) { return $this->memcache->increment($this->getKeyByPos($pos)); } private function decrement($pos) { $this->memcache->decrement($this->getKeyByPos($pos)); } private function set($pos, $data) { $this->memcache->set($this->getKeyByPos($pos), $data); return $this; } private function get($pos) { return $this->memcache->get($this->getKeyByPos($pos)); } private function delete($pos) { return $this->memcache->delete($this->getKeyByPos($pos)); } private function getKeyByPos($pos) { return $this->prefix . $this->name . $pos; } }