nuclear@0: /************************************************************************************
nuclear@0: 
nuclear@0: PublicHeader:   OVR
nuclear@0: Filename    :   OVR_System.h
nuclear@0: Content     :   General kernel initialization/cleanup, including that
nuclear@0:                 of the memory allocator.
nuclear@0: Created     :   September 19, 2012
nuclear@0: Notes       : 
nuclear@0: 
nuclear@0: Copyright   :   Copyright 2014 Oculus VR, LLC All Rights reserved.
nuclear@0: 
nuclear@0: Licensed under the Oculus VR Rift SDK License Version 3.2 (the "License"); 
nuclear@0: you may not use the Oculus VR Rift SDK except in compliance with the License, 
nuclear@0: which is provided at the time of installation or download, or which 
nuclear@0: otherwise accompanies this software in either electronic or hard copy form.
nuclear@0: 
nuclear@0: You may obtain a copy of the License at
nuclear@0: 
nuclear@0: http://www.oculusvr.com/licenses/LICENSE-3.2 
nuclear@0: 
nuclear@0: Unless required by applicable law or agreed to in writing, the Oculus VR SDK 
nuclear@0: distributed under the License is distributed on an "AS IS" BASIS,
nuclear@0: WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
nuclear@0: See the License for the specific language governing permissions and
nuclear@0: limitations under the License.
nuclear@0: 
nuclear@0: ************************************************************************************/
nuclear@0: 
nuclear@0: #ifndef OVR_System_h
nuclear@0: #define OVR_System_h
nuclear@0: 
nuclear@0: #include "OVR_Allocator.h"
nuclear@0: #include "OVR_Log.h"
nuclear@0: #include "OVR_Atomic.h"
nuclear@0: 
nuclear@0: namespace OVR {
nuclear@0: 
nuclear@0: 
nuclear@0: //-----------------------------------------------------------------------------
nuclear@0: // SystemSingleton
nuclear@0: 
nuclear@0: // Subsystems are implemented using the Singleton pattern.
nuclear@0: // To avoid code duplication in all the places where Singletons are defined,
nuclear@0: // The pattern is defined once here and used everywhere.
nuclear@0: 
nuclear@0: class SystemSingletonInternal
nuclear@0: {
nuclear@0:     friend class System;
nuclear@0: 
nuclear@0:     SystemSingletonInternal* NextSingleton;
nuclear@0: 
nuclear@0:     // No copying allowed
nuclear@0:     OVR_NON_COPYABLE(SystemSingletonInternal);
nuclear@0: 
nuclear@0: protected:
nuclear@0:     SystemSingletonInternal() :
nuclear@0:         NextSingleton(0)
nuclear@0:     {
nuclear@0:     }
nuclear@0: 
nuclear@0:     virtual ~SystemSingletonInternal(){}
nuclear@0: 
nuclear@0:     // Call this to register the destroy events
nuclear@0:     // Destroy callbacks will be called in the reverse order they were registered
nuclear@0:     // Note: As a rule of thumb, call this at the end of the singleton class constructor.
nuclear@0:     void PushDestroyCallbacks();
nuclear@0: 
nuclear@0:     // Required: Invoked when the System object is shutting down
nuclear@0:     // Called after threads are stopped
nuclear@0:     // Called before Log, Allocator, and Timer subsystems are stopped
nuclear@0:     // Listeners are called in the opposite order they were registered
nuclear@0:     virtual void OnSystemDestroy() = 0;
nuclear@0: 
nuclear@0:     // Called just before waiting for threads to die
nuclear@0:     // Listeners are called in the opposite order they were registered
nuclear@0:     // Useful to start terminating threads at the right time
nuclear@0:     // Note: The singleton must not delete itself here.
nuclear@0:     virtual void OnThreadDestroy() {}
nuclear@0: };
nuclear@0: 
nuclear@0: // Singletons derive from this class
nuclear@0: template<class T>
nuclear@0: class SystemSingletonBase : public SystemSingletonInternal
nuclear@0: {
nuclear@0:     static AtomicPtr<T> SingletonInstance;
nuclear@0:     static T* SlowGetInstance();
nuclear@0: 
nuclear@0: protected:
nuclear@0:     ~SystemSingletonBase()
nuclear@0:     {
nuclear@0:         // Make sure the instance gets set to zero on dtor
nuclear@0:         if (SingletonInstance == this)
nuclear@0:             SingletonInstance = 0;
nuclear@0:     }
nuclear@0: 
nuclear@0: public:
nuclear@0:     static OVR_FORCE_INLINE T* GetInstance()
nuclear@0:     {
nuclear@0:         // Fast version
nuclear@0:         // Note: The singleton instance is stored in an AtomicPtr<> to allow it to be accessed
nuclear@0:         // atomically from multiple threads without locks.
nuclear@0:         T* instance = SingletonInstance;
nuclear@0:         return instance ? instance : SlowGetInstance();
nuclear@0:     }
nuclear@0: };
nuclear@0: 
nuclear@0: // For reference, see N3337 14.5.1.3 (Static data members of class templates):
nuclear@0: template<class T> OVR::AtomicPtr<T> OVR::SystemSingletonBase<T>::SingletonInstance;
nuclear@0: 
nuclear@0: // Place this in the singleton class in the header file
nuclear@0: #define OVR_DECLARE_SINGLETON(T) \
nuclear@0:     friend class OVR::SystemSingletonBase<T>; \
nuclear@0: private: \
nuclear@0:     T(); \
nuclear@0:     virtual ~T(); \
nuclear@0:     virtual void OnSystemDestroy();
nuclear@0: 
nuclear@0: // Place this in the singleton class source file
nuclear@0: #define OVR_DEFINE_SINGLETON(T) \
nuclear@0:     namespace OVR { \
nuclear@0:     template<> T* SystemSingletonBase<T>::SlowGetInstance() \
nuclear@0:     { \
nuclear@0:         static OVR::Lock lock; \
nuclear@0:         OVR::Lock::Locker locker(&lock); \
nuclear@0:         if (!SingletonInstance) SingletonInstance = new T; \
nuclear@0:         return SingletonInstance; \
nuclear@0:     } \
nuclear@0:     }
nuclear@0: 
nuclear@0: 
nuclear@0: // ***** System Core Initialization class
nuclear@0: 
nuclear@0: // System initialization must take place before any other OVR_Kernel objects are used;
nuclear@0: // this is done my calling System::Init(). Among other things, this is necessary to
nuclear@0: // initialize the memory allocator. Similarly, System::Destroy must be
nuclear@0: // called before program exist for proper cleanup. Both of these tasks can be achieved by
nuclear@0: // simply creating System object first, allowing its constructor/destructor do the work.
nuclear@0: 
nuclear@0: // TBD: Require additional System class for Oculus Rift API?
nuclear@0: 
nuclear@0: class System
nuclear@0: {
nuclear@0: public:
nuclear@0:     // System constructor expects allocator to be specified, if it is being substituted.
nuclear@0:     System(Log* log = Log::ConfigureDefaultLog(LogMask_Debug),
nuclear@0:            Allocator* palloc = DefaultAllocator::InitSystemSingleton())
nuclear@0:     {
nuclear@0:         Init(log, palloc);
nuclear@0:     }
nuclear@0:     ~System()
nuclear@0:     {
nuclear@0:         Destroy();
nuclear@0:     }
nuclear@0: 
nuclear@0: 	static void OVR_CDECL DirectDisplayInitialize();
nuclear@0:     static bool OVR_CDECL DirectDisplayEnabled();
nuclear@0: 
nuclear@0:     // Returns 'true' if system was properly initialized.
nuclear@0:     static bool OVR_CDECL IsInitialized();
nuclear@0: 
nuclear@0:     // Initializes System core.  Users can override memory implementation by passing
nuclear@0:     // a different Allocator here.
nuclear@0:     static void OVR_CDECL Init(Log* log = Log::ConfigureDefaultLog(LogMask_Debug),
nuclear@0:                                Allocator *palloc = DefaultAllocator::InitSystemSingleton());
nuclear@0: 
nuclear@0: 	// De-initializes System more, finalizing the threading system and destroying
nuclear@0:     // the global memory allocator.
nuclear@0:     static void OVR_CDECL Destroy();
nuclear@0: };
nuclear@0: 
nuclear@0: 
nuclear@0: } // namespace OVR
nuclear@0: 
nuclear@0: #endif