Memcache 一般用于缓存服务。但是很多时候,比如一个消息广播系统,需要一个消息队列。直接从数据库取消息,负载往往不行。如果将整个消息队列用一个key缓存到memcache里面.对于一个很大的消息队列,频繁进行进行大数据库的序列化 和 反序列化,有太耗费。下面是我用PHP 实现的一个消息队列,只需要在尾部插入一个数据,就操作尾部,不用操作整个消息队列进行读取,与操作。但是,这个消息队列不是线程安全的,我只是尽量的避免了冲突的可能性。如果消息不是非常的密集,比如几秒钟才一个,还是可以考虑这样使用的。如果你要实现线程安全的,一个建议是通过文件进行锁定,然后进行操作。下面是代码:复制代码 代码如下:class Memcache_Queue{private $memcache;private $name;private $prefix;function __construct($maxSize, $name, $memcache, $prefix = "__memcache_queue__"){if ($memcache == null) {throw new Exception("memcache object is null, new the object first.");}$this->memcache = $memcache;$this->name = $name;$this->prefix = $prefix;$this->maxSize = $maxSize;$this->front = 0;$this->real = 0;$this->size = 0;}function __get($name){return $this->get($name);}function __set($name, $value){$this->add($name, $value);return $this;}function isEmpty(){return $this->size == 0;}function isFull(){return $this->size == $this->maxSize;}function enQueue($data){if ($this->isFull()) {throw new Exception("Queue is Full");}$this->increment("size");$this->set($this->real, $data);$this->set("real", ($this->real + 1) % $this->maxSize);return $this;}function deQueue(){if ($this->isEmpty()) {throw new Exception("Queue is Empty");}$this->decrement("size");$this->delete($this->front);$this->set("front", ($this->front + 1) % $this->maxSize);return $this;}function getTop(){return $this->get($this->front);}function getAll(){return $this->getPage();}function getPage($offset = 0, $limit = 0){if ($this->isEmpty() || $this->size < $offset) {return null;}$keys[] = $this->getKeyByPos(($this->front + $offset) % $this->maxSize);$num = 1;for ($pos = ($this->front + $offset + 1) % $this->maxSize; $pos != $this->real; $pos = ($pos + 1) % $this->maxSize){$keys[] = $this->getKeyByPos($pos);$num++;if ($limit > 0 & $limit == $num) {break;}}return array_values($this->memcache->get($keys));}function makeEmpty(){$keys = $this->getAllKeys();foreach ($keys as $value) {$this->delete($value);}$this->delete("real");$this->delete("front");$this->delete("size");$this->delete("maxSize");}private function getAllKeys(){if ($this->isEmpty()){return array();}$keys[] = $this->getKeyByPos($this->front);for ($pos = ($this->front + 1) % $this->maxSize; $pos != $this->real; $pos = ($pos + 1) % $this->maxSize){$keys[] = $this->getKeyByPos($pos);}return $keys;}private function add($pos, $data){$this->memcache->add($this->getKeyByPos($pos), $data);return $this;}private function increment($pos){return $this->memcache->increment($this->getKeyByPos($pos));}private function decrement($pos){$this->memcache->decrement($this->getKeyByPos($pos));}private function set($pos, $data){$this->memcache->set($this->getKeyByPos($pos), $data);return $this;}private function get($pos){return $this->memcache->get($this->getKeyByPos($pos));}private function delete($pos){return $this->memcache->delete($this->getKeyByPos($pos));}private function getKeyByPos($pos){return $this->prefix . $this->name . $pos;}}
本文章来至源码世界 http://www.ymsky.net/views/73640.shtml