Initial commit

Lts/Services/AudioVideoManagement/avs_command_queue.h

@@ -0,0 +1,100 @@
+/**
+  * @RDE_HEADER@
+  * AvsCommandQueue
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Christian Fröbel, NLSE, 2018-02-23
+  */
+
+#pragma once
+
+#include "logger.h"
+#include "avm_export.h"
+#include <QObject>
+#include <QTimer>
+#include <deque>
+#include <memory>
+#include <chrono>
+
+
+namespace LtsUtils
+{
+class IConnection;
+}
+
+namespace AudioVideoManagement
+{
+
+class ICommand;
+
+/**
+ * CommandQueue used by AvaControl and VdControl.
+ * The CommandQueue ensures that each command is sent after the previous command finished.
+ * When a command is not finished within a defined time frame timeout() is signalled.
+ *
+ * @author Christian Fröbel
+ */
+class AVM_COMMON_EXPORT AvsCommandQueue : public QObject
+{
+  Q_OBJECT
+
+public:
+  /**
+   * @param timeout Timeout within which each command must be completed. Use 0 to disable the timeout.
+   */
+  explicit AvsCommandQueue(std::chrono::milliseconds timeout);
+  ~AvsCommandQueue() override;
+
+  void queue(std::unique_ptr<ICommand> cmd, std::unique_ptr<LtsUtils::IConnection> connection);
+  void done();
+
+  ICommand *currentCommand() const;
+  bool currentHasConnection() const;
+  LtsUtils::IConnection *currentConnection() const;
+
+  void flush();
+
+  /**
+   * Tell the Queue that the current command is still alive.
+   * Internal Timeout timer will be reset.
+   */
+  void alive();
+
+  bool isEmpty() const { return m_queue.empty(); }
+
+signals:
+  /**
+   * Signalled whenever the queue is empty again. This can have several reasons:
+   * - The last command finished successfully.
+   * - flush() was called while commands are pending.
+   * - This instance is deleted with pending commands which get flushed then.
+   */
+  void queueEmpty();
+
+  /** Signalled if the current command did not finish within the defined time frame. */
+  void timeout();
+
+private:
+  void nextCommand();
+  void tryReduce();
+
+private:
+  /**
+   * Associates a command with a Qt-connection (signal-signal or signal-slot).
+   * In a scenario where multiple clients use an AvaControl instance
+   * this makes it possible to give the asynchronous response only
+   * to the initiator of the command.
+   */
+  struct CommandWithConn
+  {
+    std::unique_ptr<ICommand>   cmd;
+    std::unique_ptr<LtsUtils::IConnection>   connection;
+  };
+
+  std::deque<CommandWithConn>   m_queue;
+  QTimer                        m_timer;
+  LOGGER_T                      m_logger;
+};
+
+} // namespace AudioVideoManagement