PHP memcache 环形队列

<?php
 
/**
 * PHP memcache 环形队列类
 * 因业务需要只保留的队列中的Pop和Push,修改过期时间为0即永久
 */
class MQueue
{
    public static $client;
     
    private $expire; //过期时间,秒,1~2592000,即30天内
    private $sleepTime; //等待解锁时间,微秒
    private $queueName; //队列名称,唯一值
    private $retryNum; //尝试次数
    private $MAXNUM; //最大队列容量
    private $canRewrite; //是否可以覆写开关，满出来的内容从头部开始覆盖重写原来的数据
     
    private $HEAD; //下一步要进入的指针位置
    private $TAIL; //下一步要进入的指针位置
    private $LEN; //队列现有长度
     
    const LOCK_KEY = '_Fox_MQ_LOCK_'; //锁存储标示
    const LENGTH_KEY = '_Fox_MQ_LENGTH_'; //队列现长度存储标示
    const VALU_KEY = '_Fox_MQ_VAL_'; //队列键值存储标示
    const HEAD_KEY = '_Fox_MQ_HEAD_'; //队列HEAD指针位置标示
    const TAIL_KEY = '_Fox_MQ_TAIL_'; //队列TAIL指针位置标示
     
    /*
     * 构造函数
     * 对于同一个$queueName，实例化时必须保障构造函数的参数值一致，否则pop和push会导队列顺序混乱
     */
    public function __construct($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); //当客户断开连接,允许继续执行
        set_time_limit(0); //取消脚本执行延时上限
        $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;
         
    }
     
    //获取队列首尾指针信息和长度
    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原子性加锁
    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) { //尝试等待N次
                    return false;
                    break;
                }
            }
            return $this->access = true;
        }
        return false;
    }
     
    //更新头部指针指向,指向下一个位置
    private function incrHead()
    {
        //$this->getHeadAndTail(); //获取最新指针信息 ,由于本方法体均在锁内调用，其锁内已调用了此方法，本行注释
        $this->HEAD++; //头部指针下移
        if ($this->HEAD >= $this->MAXNUM) {
            $this->HEAD = 0; //边界值修正
        }
        ;
        $this->LEN--; //Head的移动由Pop触发，所以相当于数量减少
        if ($this->LEN < 0) {
            $this->LEN = 0; //边界值修正
        }
        ;
        memcache_set(self::$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
         
    }
     
    //更新尾部指针指向，指向下一个位置
    private function incrTail()
    {
         
        //$this->getHeadAndTail(); //获取最新指针信息，由于本方法体均在锁内调用，其锁内已调用了此方法，本行注释
        $this->TAIL++; //尾部指针下移
        if ($this->TAIL >= $this->MAXNUM) {
            $this->TAIL = 0; //边界值修正
        }
        ;
        $this->LEN++; //Head的移动由Push触发，所以相当于数量增加
        if ($this->LEN >= $this->MAXNUM) {
            $this->LEN = $this->MAXNUM; //边界值长度修正
        }
        ;
        memcache_set(self::$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
    }
     
     
    // 解锁
    private function unLock()
    {
        memcache_delete(self::$client, $this->queueName . self::LOCK_KEY);
        $this->access = false;
    }
     
    //判断是否满队列
    public function isFull()
    {
        //外部直接调用的时候由于没有锁所以此处的值是个大概值，并不很准确，但是内部调用由于在前面有lock，所以可信
        if ($this->canRewrite)
            return false;
        return $this->LEN == $this->MAXNUM ? true : false;
    }
     
    //判断是否为空
    public function isEmpty()
    {
        //外部直接调用的时候由于没有锁所以此处的值是个大概值，并不很准确，但是内部调用由于在前面有lock，所以可信
        return $this->LEN == 0 ? true : false;
    }
     
    public function getLen()
    {
        //外部直接调用的时候由于没有锁所以此处的值是个大概值，并不很准确，但是内部调用由于在前面有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(); //获取最新指针信息
         
        if ($this->isFull()) { //只有在非覆写下才有Full概念
            $this->unLock();
            return false;
        }
         
        if (memcache_set(self::$client, $this->queueName . self::VALU_KEY . $this->TAIL, $data, MEMCACHE_COMPRESSED, $this->expire)) {
            //当推送后，发现尾部和头部重合（此时指针还未移动），且右边仍有未由Head读取的数据，那么移动Head指针，避免尾部指针跨越Head
            if ($this->TAIL == $this->HEAD && $this->LEN >= 1) {
                $this->incrHead();
            }
            $this->incrTail(); //移动尾部指针
            $result = true;
        }
         
        $this->unLock();
        return $result;
    }
     
     
    /*
     * Pop一个值
     * @param    [length]    int    队列长度
     * @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; //默认读取所有
         
        if ($this->isEmpty()) {
            $this->unLock();
            return false;
        }
        //获取长度超出队列长度后进行修正
        if ($length > $this->LEN)
            $length = $this->LEN;
         
        $data = $this->popKeyArray($length);
        $this->unLock();
        return $data;
    }
     
     
    /*
     * pop某段长度的值
     * @param    [length]    int    队列长度
     * @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 . $this->HEAD, 0);
            //当提取值后，发现头部和尾部重合（此时指针还未移动），且右边没有数据，即队列中最后一个数据被完全掏空，此时指针停留在本地不移动，队列长度变为0
            if ($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读取出的数据，均移动HEAD指针到下一处待读取位置
            }
        }
        return $result;
    }
     
    /*
     * 重置队列
     * * @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缓存数据
     * @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;
    }
     
     
}
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原文地址：https://www.cnblogs.com/pingliangren/p/5587830.html