Memcache 中实现消息队列

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;
}
}