implement tcp handler and pass reason to callback

include/amqpcpp/connectionhandler.h

@@ -204,8 +204,9 @@ public:
      *  disk space, another notification will not be sent.
      *
      *  @param  connection      The connection that was blocked
+     *  @param  reason          Why was the connection blocked
      */
-    virtual void onBlocked(Connection *connection) 
+    virtual void onBlocked(Connection *connection, const char *reason) 
     {
         // make sure compilers dont complain about unused parameters
         (void) connection;

include/amqpcpp/connectionimpl.h

@@ -430,11 +430,12 @@ public:
 
     /**
      *  Report that the connection is blocked
+     *  @param  reason
      */
-    void reportBlocked()
+    void reportBlocked(const char *reason)
     {
         // inform the handler
-        _handler->onBlocked(_parent);
+        _handler->onBlocked(_parent, reason);
     }
 
     /**

include/amqpcpp/linux_tcp/tcpconnection.h

@@ -117,6 +117,27 @@ private:
      */
     virtual void onClosed(Connection *connection) override;
 
+    /**
+     *  Method that is called when the AMQP connection was blocked.
+     *  @param  connection      The connection that was blocked
+     *  @param  reason          Why was the connection blocked
+     */
+    virtual void onBlocked(Connection *connection, const char *reason) override
+    {
+        // pass to user space
+        if (_handler) _handler->onBlocked(this, reason);
+    }
+
+    /**
+     *  Method that is called when the AMQP connection is no longer blocked.
+     *  @param  connection      The connection that is no longer blocked
+     */
+    virtual void onUnblocked(Connection *connection) 
+    { 
+        // pass to user space
+        if (_handler) _handler->onUnblocked(this);
+    }
+
     /**
      *  Method that is called when the tcp connection has been established
      *  @param  state

include/amqpcpp/linux_tcp/tcphandler.h

@@ -191,6 +191,39 @@ public:
         (void) connection;
     }
 
+    /**
+     *  Method that is called when the AMQP connection was blocked.
+     * 
+     *  This method is called, when the server connection gets blocked for the first
+     *  time due to the broker running low on a resource (memory or disk). For
+     *  example, when a RabbitMQ node detects that it is low on RAM, it sends a
+     *  notification to all connected publishing clients supporting this feature.
+     *  If before the connections are unblocked the node also starts running low on
+     *  disk space, another notification will not be sent.
+     *
+     *  @param  connection      The connection that was blocked
+     *  @param  reason          Why was the connection blocked
+     */
+    virtual void onBlocked(TcpConnection *connection, const char *reason)
+    {
+        // make sure compilers dont complain about unused parameters
+        (void) connection;
+    }
+
+    /**
+     *  Method that is called when the AMQP connection is no longer blocked.
+     * 
+     *  This method is called when all resource alarms have cleared and the
+     *  connection is fully unblocked.
+     *
+     *  @param  connection      The connection that is no longer blocked
+     */
+    virtual void onUnblocked(TcpConnection *connection) 
+    { 
+        // make sure compilers dont complain about unused parameters
+        (void) connection;
+    }
+
     /**
      *  Method that is called when the TCP connection is lost or closed. This
      *  is always called if you have also received a call to onConnected().

src/connectionblockframe.h

@@ -94,7 +94,7 @@ public:
     virtual bool process(ConnectionImpl *connection) override
     {
         // report that it is blocked
-        connection->reportBlocked();
+        connection->reportBlocked(this->reason().c_str());
         
         // done
         return true;