Added handling of heartbeat message

Author: bstoney

src/Handlers/HbMessagesHandler.php

@@ -3,22 +3,32 @@
 
 namespace Litipk\JupyterPHP\Handlers;
 
-
+use Litipk\JupyterPHP\JupyterBroker;
 use Monolog\Logger;
-
+use React\ZMQ\SocketWrapper;
 
 final class HbMessagesHandler
 {
     /** @var Logger */
     private $logger;
 
-    public function __construct(Logger $logger)
+    /** @var SocketWrapper */
+    private $hbSocket;
+
+    public function __construct(SocketWrapper $hbSocket, Logger $logger)
     {
         $this->logger = $logger;
+        $this->hbSocket = $hbSocket;
     }
 
     public function __invoke($msg)
     {
         $this->logger->debug('Received message', ['processId' => getmypid(), 'msg' => $msg]);
+
+        if (['ping'] == $msg) {
+            $this->hbSocket->send($msg);
+        } else {
+            $this->logger->error('Unknown message', ['processId' => getmypid(), 'msg' => $msg]);
+        }
     }
-}
+}

src/KernelCore.php

@@ -60,7 +60,7 @@ public function __construct(JupyterBroker $jupyterBroker, array $connUris, Logge
     {
         $this->broker = $jupyterBroker;
         $this->logger = $logger;
-        
+
         $this->initSockets($connUris);
         $this->registerHandlers();
     }
@@ -74,7 +74,7 @@ public function run()
     }
 
     /**
-     * @param array[string]string $connUris
+     * @param array [string]string $connUris
      */
     private function initSockets(array $connUris)
     {
@@ -111,7 +111,7 @@ private function registerHandlers()
         );
         $this->hbSocket->on(
             'messages',
-            new HbMessagesHandler($this->logger->withName('HbMessagesHandler'))
+            new HbMessagesHandler($this->hbSocket, $this->logger->withName('HbMessagesHandler'))
         );
         $this->iopubSocket->on(
             'messages',