How to implement ring queue in PHP based on memcache

This article mainly introduces the method of implementing ring queue in PHP based on memcache. Interested friends can refer to it. I hope it will be helpful to everyone.

The code is as follows:

<?php
/**
 * PHP memcache 环形队列类
 * 原作者 LKK/lianq.net
 * 修改 FoxHunter
 * 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 $LEN; //队列现有长度
 const LOCK_KEY = &#39;_Fox_MQ_LOCK_&#39;; //锁存储标示
 const LENGTH_KEY = &#39;_Fox_MQ_LENGTH_&#39;; //队列现长度存储标示
 const VALU_KEY = &#39;_Fox_MQ_VAL_&#39;; //队列键值存储标示
 const HEAD_KEY = &#39;_Fox_MQ_HEAD_&#39;; //队列HEAD指针位置标示
 const TAIL_KEY = &#39;_Fox_MQ_TAIL_&#39;; //队列TAIL指针位置标示
 /*
  * 构造函数
  * 对于同一个$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 = &#39;&#39;, $maxqueue = 1, $canRewrite = false, $expire = 0, $config = &#39;&#39;)
 {
  if (empty($config)) {
   self::$client = memcache_pconnect(&#39;127.0.0.1&#39;, 11211);
  } elseif (is_array($config)) { //array(&#39;host&#39;=>&#39;127.0.0.1&#39;,&#39;port&#39;=>&#39;11211&#39;)
   self::$client = memcache_pconnect($config[&#39;host&#39;], $config[&#39;port&#39;]);
  } elseif (is_string($config)) { //"127.0.0.1:11211"
   $tmp   = explode(&#39;:&#39;, $config);
   $conf[&#39;host&#39;] = isset($tmp[0]) ? $tmp[0] : &#39;127.0.0.1&#39;;
   $conf[&#39;port&#39;] = isset($tmp[1]) ? $tmp[1] : &#39;11211&#39;;
   self::$client = memcache_pconnect($conf[&#39;host&#39;], $conf[&#39;port&#39;]);
  }
  if (!self::$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 = &#39;&#39;)
 {
  $result = false;
  if (empty($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;
 }
}

Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study.

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