php实现的消息队列类

<?php

/**
* Created by PhpStorm.
* User: lin
* Date: 2017/6/9
* Time: 11:19
* 实现php共享内存消息队列
*/
class ShmQueue
{
private $maxQSize = 0;//队列最大长度
private $front = 0;//队头指针
private $rear = 0; //队尾指针
private $blockSize = 256;  // 块的大小(byte)
private $memSize = 1280;  // 最大共享内存(byte)
private $shmId = 0;//根据这个id可以操作该共享内存片段
private $filePtr = APP_PATH.'public/shmq.ptr';
private $semId = 0;
public function __construct()
{
$shmkey = ftok(__FILE__, 't');//产生系统id
$this->shmId = shmop_open($shmkey, "c", 0644, $this->memSize );//创建一个内存段
$this->maxQSize = $this->memSize / $this->blockSize;
// 申請一个信号量
$this->semId = sem_get($shmkey, 1);
sem_acquire($this->semId); // 申请进入临界
$this->init();
}
private function init()
{
if ( file_exists($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 ){ // 队满
return false;
}
//echo $this->front;
$data = $this->encode($value);
shmop_write($this->shmId, $data, $this->rear );
$this->rear = $this->ptrInc($this->rear);
return  $this->decode($data);
}
public function deQueue()
{
if ( $this->front == $this->rear ){ // 队空
throw new Exception(" block size is null!");
}
$value = shmop_read($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 $data;
}
public function exist($value){//判断队头的数据

$data = shmop_read($this->shmId, $this->front, $this->blockSize-1);
if($value == $this->decode($data)){
return 1;
}
return 0;
}
private function decode( $value )
{
//return $value;
$data = explode("__eof", $value);
return unserialize($data[0]);
}
public function __destruct()
{
//保存队头和队尾指针
$data = $this->front . '|' . $this->rear;
file_put_contents($this->filePtr, $data);
sem_release($this->semId); // 出临界区, 释放信号量
}

}

$shmq = new ShmQueue();
入队:
$data = 125;
$shmq->enQueue($data);

出队:
$shmq->deQueue();