From ec79e495a168fdc562056bdf48a7d0c0d3040cea Mon Sep 17 00:00:00 2001
From: Krzysztof Jackiewicz <k.jackiewicz@samsung.com>
Date: Wed, 17 Jun 2015 14:17:57 +0200
Subject: [PATCH] Add MessageService

[Feature] Inter-service communication development
[Solution] Add MessageService and ThreadMessageService classes to
support/simplify transferring inter service messages between services/threads.

[Verification] Verify together with next commit

Change-Id: Id205e299ffc186a5e6eae6563d9804ce61fdec21
---
 src/manager/main/message-service.h | 161 +++++++++++++++++++++++++++++++++++++
 1 file changed, 161 insertions(+)
 create mode 100644 src/manager/main/message-service.h

diff --git a/src/manager/main/message-service.h b/src/manager/main/message-service.h
new file mode 100644
index 0000000..65512c0
--- /dev/null
+++ b/src/manager/main/message-service.h
@@ -0,0 +1,161 @@
+/*
+ *  Copyright (c) 2000 - 2015 Samsung Electronics Co., Ltd All Rights Reserved
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License
+ */
+/*
+ * @file       message-service.h
+ * @author     Krzysztof Jackiewicz (k.jackiewicz@samsung.com)
+ * @version    1.0
+ */
+
+#pragma once
+
+#include <mutex>
+#include <list>
+#include <utility>
+#include <thread-service.h>
+#include <noncopyable.h>
+#include <dpl/log/log.h>
+
+namespace CKM {
+
+/*
+ * MessageService framework is a wrapper for inter service communication with use of
+ * CommunicationManager. It allows registering a service as a listener in CommunicationManager and
+ * provides thread safe message handling. The message received from communication manager in
+ * SENDER THREAD is passed to RECEIVER THREAD. The RECEIVER THREAD is notified with
+ * ServiceThread::CreateEvent which in turn calls provided callback in this thread.
+ */
+
+template <typename ...Msgs>
+class MessageService;
+
+
+// aggregating template
+template <typename Msg, typename ...Msgs>
+class MessageService<Msg, Msgs...> : public MessageService<Msg>, public MessageService<Msgs...>
+{
+protected:
+    // RECEIVER THREAD
+    template <typename Mgr>
+    void Register(Mgr& mgr) {
+        MessageService<Msg>::Register(mgr);
+        MessageService<Msgs...>::Register(mgr);
+    }
+    // RECEIVER THREAD
+    void CheckMessages() {
+        MessageService<Msg>::CheckMessages();
+        MessageService<Msgs...>::CheckMessages();
+    }
+};
+
+
+// single Message type (Msg) handler
+template <typename Msg>
+class MessageService<Msg>
+{
+public:
+    MessageService() {}
+    virtual ~MessageService() {}
+    NONCOPYABLE(MessageService);
+
+protected:
+    // RECEIVER THREAD: register as a listener of Msg
+    template <typename Mgr>
+    void Register(Mgr& mgr);
+
+    // SENDER THREAD: notify about new message
+    virtual void Notify() = 0;
+
+    // RECEIVER THREAD: check if there are new messages and process each of them
+    void CheckMessages();
+
+    // RECEIVER THREAD: process single message
+    virtual void ProcessMessage(Msg msg) = 0;
+
+private:
+    // SENDER THREAD: add message to the list
+    void AddMessage(const Msg& msg);
+
+    std::mutex m_messagesMutex;
+    std::list<Msg> m_messages;
+};
+
+template <typename Msg>
+template <typename Mgr>
+void MessageService<Msg>::Register(Mgr& mgr)
+{
+    mgr.Register<Msg>([this](const Msg& msg) { this->AddMessage(msg); });
+}
+
+template <typename Msg>
+void MessageService<Msg>::AddMessage(const Msg& msg)
+{
+    m_messagesMutex.lock();
+    m_messages.push_back(msg);
+    m_messagesMutex.unlock();
+    Notify(); // notify about added message
+}
+
+template <typename Msg>
+void MessageService<Msg>::CheckMessages()
+{
+    while(true) {
+        m_messagesMutex.lock();
+        if (m_messages.empty()) {
+            m_messagesMutex.unlock();
+            break;
+        }
+        // move out the first message
+        Msg message = std::move(m_messages.front());
+        m_messages.pop_front();
+        m_messagesMutex.unlock();
+
+        try {
+            ProcessMessage(std::move(message));
+        } catch(...) {
+            LogError("Uncaught exception in ProcessMessage");
+        }
+    }
+}
+
+
+// thread based service with messages support
+template <typename ...Msgs>
+class ThreadMessageService : public ThreadService, public MessageService<Msgs...>
+{
+public:
+    ThreadMessageService() {}
+    virtual ~ThreadMessageService() {}
+    NONCOPYABLE(ThreadMessageService);
+
+    // RECEIVER THREAD: register as a listener of all supported messages
+    template <typename Mgr>
+    void Register(Mgr& mgr) {
+        MessageService<Msgs...>::Register(mgr);
+    }
+
+private:
+    // SENDER THREAD: adds callback to RECEIVER THREAD event queue and wakes it
+    virtual void Notify() {
+        CreateEvent([this]() { this->CheckMessages(); });
+    }
+
+    // RECEIVER THREAD
+    void CheckMessages() {
+        MessageService<Msgs...>::CheckMessages();
+    }
+};
+
+} /* namespace CKM */
-- 
2.7.4