<?php /** * 使用共享内存的PHP循环内存队列实现 * 支持多进程, 支持各种数据类型的存储 * 注: 完成入队或出队操作,尽快使用unset(), 以释放临界区 * * @author [email protected] * @created 2009-12-23 */ 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 = 25600; // 最大共享内存(byte) private $shmId = 0;
private $filePtr = './shmq.ptr';
private $semId = 0; public function __construct() { $shmkey = ftok(__FILE__, 't');
$this->shmId = shmop_open($shmkey, "c", 0644, $this->memSize ); $this->maxQSize = $this->memSize / $this->blockSize;
// 申?一个信号量 $this->semId = sem_get($shmkey, 1); sem_acquire($this->semId); // 申请进入临界区
$this->init(); }
private function init() { if ( file_exists($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; }
$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 ){ // 队空 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); // 出临界区, 释放信号量 } }
/* // 进队操作 $shmq = new ShmQueue(); $data = 'test data'; $shmq->enQueue($data); unset($shmq); // 出队操作 $shmq = new ShmQueue(); $data = $shmq->deQueue(); unset($shmq); */ ?>
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