why? i dunno… just because… just a toy…

no sql, no flat file, no write permissions required anywhere, no fuss

class mc_chat {

        var $chan = null;
        var $mc = null;
        var $ret = 5;

        function __construct($memcached, $channel, $retention=5) {
                $this->mc = $memcached;
                $this->chan = $channel;
                $this->ret = $retention;
        }

        function messages( $from=0 ) {
                $max = (int)$this->mc->get("$this->chan:max:posted");
                $min = (int)$this->mc->get("$this->chan:min:posted");
                $messages = array();
                for ( $i=$min; $i< =$max; $i++ ) {
                        if ( $i < $from )
                                continue;
                        $m = $this->get($i);
                        if ( $m['user'] && $m['message'] )
                                $messages[$i] = $m;
                }
                return $messages;
        }

        function get($id) {
                return array(
                        'user' =>(string)$this->mc->get("$this->chan:msg:$id:user"),
                        'message' => (string)$this->mc->get("$this->chan:msg:$id"),
                );
        }

        function add($user, $message) {
                $id = (int)$this->mc->increment("$this->chan:max:posted");
                if ( !$id ) {
                        $id=1;
                        $this->mc->set("$this->chan:max:posted", 1);
                }
                $this->mc->set("$this->chan:msg:$id:user", (string)$user);
                $this->mc->set("$this->chan:msg:$id", (string)$message);
                if ( $id >= $this->ret ) {
                        if ( !$this->mc->increment("$this->chan:min:posted") )
                                $this->mc->set("$this->chan:min:posted", 1);
                }

        }

}

$mc = new Memcache;
$mc->connect('localhost', 11211);
$keep_messages = 10;
$chatter_id = 1;
$chat = new mc_chat($mc, 'chat-room-id', $keep_messages);
$chat->add($chatter_id, date("r").": $chatter_id : foo");
$chat->messages(37); // messages only above id=37
$chat->messages(); // all the latest messages