Initial commit

Lts/Plugins/AudioVideoManagement/Data/avs_session_context.h

@@ -0,0 +1,134 @@
+/**
+  * @RDE_HEADER@
+  * AvsSessionContext
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Christian Fröbel, SLSE, 2017-08-03
+  */
+
+#pragma once
+
+#include <AudioVideoManagement/ava_types.h>
+#include <QString>
+#include <memory>
+#include <functional>
+
+namespace OperatorManagement
+{
+namespace Interface
+{
+class Dtc;
+}
+}
+
+
+namespace AudioVideoManagement
+{
+
+namespace Interface
+{
+class Dtc;
+}
+
+class AvaSession;
+class AvaState;
+class StreamNameMapping;
+class AvsMenus;
+class VdSession;
+class AvmExerciseContextHandle;
+class AvsApp;
+class PlaybackApp;
+
+/**
+ * AvsSessionContext ensures that there can only be one communication
+ * channel to AVS_Workstation and AVS_Export with a defined exercise context at
+ * any given time.
+ * AvsSessionContext must not be used with the global exercise (exerciseId 0).
+ *
+ * The application can have many users of the communication channels at the same time.
+ * The reason for this is that the AvmDataPlugin will be instantiated for every
+ * exercise (also live and replay) and possibly multiple times for an exercise.
+ * All these users shall share the same communication channels.
+ * But all parallel users must use the same exercise context.
+ *
+ * AvsSessionContext creates the communication channels (AvaSession, VdSession) when the first user
+ * calls acquire(). Subsequent users can get access to the same channels by also
+ * calling acquire() -- but the exercise context must match.
+ * When a user no longer needs these communication channels it calls release().
+ * When all users released the communication channels, they will be deleted.
+ * After that another user can call acquire() with a different exercise context.
+ *
+ * Use AvsSessionContextHandle to automatically acquire() and release()
+ * the communication channel.
+ * 
+ * See AvmExerciseContext for a visualization of lifetimes of Apps, PluginInterface-instances
+ * and ExerciseContext.
+ * 
+ * @see AvmExerciseContext
+ * @author Christian Fröbel
+ */
+class AvsSessionContext
+{
+public:
+  /**
+   * Small helper struct that holds all parts that make up a session.
+   * Only useful for AvsSessionContextHandle in order to access those parts.
+   */
+  struct Composite;
+
+  AvsSessionContext();
+  ~AvsSessionContext();
+
+  /**
+   * Check whether a AvsSessionContext with the given exerciseId can be acquired.
+   * Yields true when no AvsSessionContext was created yet or when the currently active
+   * AvsSessionContext is for the same exericse.
+   */
+  bool canAcquire(int exerciseId) const;
+
+  /**
+   * Need not to be called directly; use AvsSessionContextHandle instead.
+   */
+  ///@{
+  Composite *acquire(int exerciseId, int operatorId, const QString &langCode, AvaGuiStyle, const AvmExerciseContextHandle &exerciseContextHandle);
+  void release(Composite *composite);
+  ///@}
+
+private:
+  std::unique_ptr<Composite>   m_composite;
+  int                          m_refCount{0};
+};
+
+
+/**
+ * Helper class to automatically call AvsSessionContext::acquire()
+ * and AvsSessionContext::release() in the ctor and dtor respectively.
+ * Instances can be moved but not copied.
+ */
+class AvsSessionContextHandle
+{
+public:
+  AvsSessionContextHandle() = default;
+  AvsSessionContextHandle(AvsSessionContext *context, int exerciseId, int operatorId, const QString &langCode, AvaGuiStyle, const AvmExerciseContextHandle &exerciseContextHandle);
+
+  operator bool() const { return m_composite.get(); }
+
+  AvaSession *avaSession() const;
+  AvaState *avaState() const;
+  AvsMenus *menus() const;
+
+  VdSession *vdSession() const;
+
+  AvsApp      *liveVideoApp() const;
+  PlaybackApp *videoPlaybackApp() const;
+  PlaybackApp *audioPlaybackApp() const;
+  PlaybackApp *videoPresentationApp() const;
+  PlaybackApp *audioPresentationApp() const;
+
+private:
+  using Releaser = std::function<void (AvsSessionContext::Composite *)>;
+  std::unique_ptr<AvsSessionContext::Composite, Releaser>   m_composite;
+};
+
+} // namespace AudioVideoManagement