Message Queue in Memcache

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;
}
}