PHP实现的memcache环形队列类实例

本文实例讲述了PHP实现的memcache环形队列类。分享给大家供大家参考。具体如下：

这里介绍了PHP实现的memcache环形队列类。没咋学过数据结构，因为业务需要，所以只是硬着头皮模拟的！ 参考PHP memcache 队列代码。为使队列随时可入可出，且不受int长度越界危险（单链采取Head自增的话不作处理有越界可能），所以索性改写成环形队列。可能还有BUG，忘见谅！

'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 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 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 && $this->LEN LEN = 0;    memcache_set(self::$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 $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; }}

希望本文所述对大家的php程序设计有所帮助。