Add protocol property to the transport

Transport should be protocol aware because it should be possible to
switch the protocol if the operation is supported, for example for upgrading
HTTP to web sockets or HTTP 1.1 to HTTP/2.

source/tanya/async/event/iocp.d

@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 /**
- * Copyright: Eugene Wissner 2016.
+ * Copyright: Eugene Wissner 2016-2017.
  * License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
  *                  Mozilla Public License, v. 2.0).
  * Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)

source/tanya/async/event/selector.d

@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 /**
- * Copyright: Eugene Wissner 2016.
+ * Copyright: Eugene Wissner 2016-2017.
  * License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
  *                  Mozilla Public License, v. 2.0).
  * Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
@@ -13,6 +13,7 @@ module tanya.async.event.selector;
 version (Posix):
 
 import tanya.async.loop;
+import tanya.async.protocol;
 import tanya.async.transport;
 import tanya.async.watcher;
 import tanya.container.buffer;
@@ -28,6 +29,8 @@ class SelectorStreamTransport : StreamTransport
 {
 	private ConnectedSocket socket_;
 
+	private Protocol protocol_;
+
 	/// Input buffer.
 	package WriteBuffer!ubyte input;
 
@@ -40,22 +43,64 @@ class SelectorStreamTransport : StreamTransport
 	 * Params:
 	 * 	loop     = Event loop.
 	 * 	socket   = Socket.
+	 * 	protocol = Application protocol.
+	 *
+	 * Precondition: $(D_INLINECODE loop !is null
+	 *                           && socket !is null
+	 *                           && protocol !is null)
 	 */
-	this(SelectorLoop loop, ConnectedSocket socket) @nogc
+	this(SelectorLoop loop, ConnectedSocket socket, Protocol protocol) @nogc
+	in 
+	{
+		assert(loop !is null);
+		assert(socket !is null);
+		assert(protocol !is null);
+	}
+	body
 	{
 		socket_ = socket;
 		this.loop = loop;
+		protocol_ = protocol;
 		input = WriteBuffer!ubyte(8192, MmapPool.instance);
 	}
 
 	/**
 	 * Returns: Transport socket.
 	 */
-	inout(ConnectedSocket) socket() inout pure nothrow @safe @nogc
+	ConnectedSocket socket() pure nothrow @safe @nogc
 	{
 		return socket_;
 	}
 
+	/**
+	 * Returns: Application protocol.
+	 */
+	@property Protocol protocol() pure nothrow @safe @nogc
+	{
+		return protocol_;
+	}
+
+	/**
+	 * Switches the protocol.
+	 *
+	 * The protocol is deallocated by the event loop, it should currently be
+	 * allocated with $(D_PSYMBOL MmapPool).
+	 *
+	 * Params:
+	 * 	protocol = Application protocol.
+	 *
+	 * Precondition: $(D_INLINECODE protocol !is null)
+	 */
+	@property void protocol(Protocol protocol) pure nothrow @safe @nogc
+	in
+	{
+		assert(protocol !is null);
+	}
+	body
+	{
+		protocol_ = protocol;
+	}
+
 	/**
 	 * Write some data to the transport.
 	 *
@@ -224,7 +269,8 @@ abstract class SelectorLoop : Loop
 			}
 
 			IOWatcher io;
-			auto transport = MmapPool.instance.make!SelectorStreamTransport(this, client);
+			auto protocol = connection.protocol;
+			auto transport = MmapPool.instance.make!SelectorStreamTransport(this, client, protocol);
 
 			if (connections.length > client.handle)
 			{
@@ -236,13 +282,12 @@ abstract class SelectorLoop : Loop
 			}
 			if (io is null)
 			{
-				io = MmapPool.instance.make!IOWatcher(transport,
-				                                      connection.protocol);
+				io = MmapPool.instance.make!IOWatcher(transport, protocol);
 				connections[client.handle] = io;
 			}
 			else
 			{
-				io(transport, connection.protocol);
+				io(transport, protocol);
 			}
 
 			reify(io, EventMask(Event.none), EventMask(Event.read, Event.write));