Kernel/IPC: Use Ports and Sessions as the fundamental building block of Inter Process Communication.

All handles obtained via srv::GetServiceHandle or svcConnectToPort are references to ClientSessions.
Service modules will wait on the counterpart of those ClientSessions (Called ServerSessions) using svcReplyAndReceive or svcWaitSynchronization[1|N], and will be awoken when a SyncRequest is performed.

HLE Interfaces are now ClientPorts which override the HandleSyncRequest virtual member function to perform command handling immediately.

src/core/hle/kernel/client_session.cpp

@@ -0,0 +1,42 @@
+// Copyright 2016 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "common/assert.h"
+
+#include "core/hle/kernel/client_port.h"
+#include "core/hle/kernel/client_session.h"
+#include "core/hle/kernel/server_session.h"
+#include "core/hle/kernel/kernel.h"
+
+namespace Kernel {
+
+ClientSession::ClientSession() {}
+ClientSession::~ClientSession() {}
+
+ResultVal<SharedPtr<ClientSession>> ClientSession::Create(SharedPtr<ServerSession> server_session, SharedPtr<ClientPort> client_port, std::string name) {
+    SharedPtr<ClientSession> client_session(new ClientSession);
+
+    client_session->name = std::move(name);
+    client_session->server_session = server_session;
+    client_session->client_port = client_port;
+
+    return MakeResult<SharedPtr<ClientSession>>(std::move(client_session));
+}
+
+ResultCode ClientSession::HandleSyncRequest() {
+    // Signal the server session that new data is available
+    ResultCode result = server_session->HandleSyncRequest();
+
+    if (result.IsError())
+        return result;
+
+    // Tell the client port to handle the request in case it's an HLE service.
+    // The client port can be nullptr for port-less sessions (Like for example File and Directory sessions).
+    if (client_port != nullptr)
+        result = client_port->HandleSyncRequest();
+
+    return result;
+}
+
+} // namespace