add graceful stop

Connection/TcpConnection.php

@@ -874,6 +874,19 @@ class TcpConnection extends ConnectionInterface
      */
     public function __destruct()
     {
+        static $mod;
         self::$statistics['connection_count']--;
+        if(Worker::getGracefulStop() && Worker::getStatus() === Worker::STATUS_SHUTDOWN){
+            if(!isset($mod)){
+                $mod=round((self::$statistics['connection_count']+1)/3);
+            }
+            if(0 === self::$statistics['connection_count']%$mod){
+                Worker::log('worker('.posix_getpid().') remains '.self::$statistics['connection_count'].' connection(s)'."\r");
+            }
+            if(0 === self::$statistics['connection_count']){
+                Worker::$globalEvent->destroy();
+                exit(0);
+            }
+        }
     }
 }