php Memcache 中实现消息队列

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：

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;
}
}