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+/************************************************************************************
+
+PublicHeader: None
+Filename : OVR_ThreadCommandQueue.h
+Content : Command queue for operations executed on a thread
+Created : October 29, 2012
+Author : Michael Antonov
+
+Copyright : Copyright 2014 Oculus VR, LLC All Rights reserved.
+
+Licensed under the Oculus VR Rift SDK License Version 3.2 (the "License");
+you may not use the Oculus VR Rift SDK except in compliance with the License,
+which is provided at the time of installation or download, or which
+otherwise accompanies this software in either electronic or hard copy form.
+
+You may obtain a copy of the License at
+
+http://www.oculusvr.com/licenses/LICENSE-3.2
+
+Unless required by applicable law or agreed to in writing, the Oculus VR SDK
+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.
+
+************************************************************************************/
+
+#ifndef OVR_ThreadCommandQueue_h
+#define OVR_ThreadCommandQueue_h
+
+#include "../Kernel/OVR_Types.h"
+#include "../Kernel/OVR_List.h"
+#include "../Kernel/OVR_Atomic.h"
+#include "../Kernel/OVR_Threads.h"
+
+namespace OVR {
+
+class ThreadCommand;
+class ThreadCommandQueue;
+
+
+//-------------------------------------------------------------------------------------
+// ***** ThreadCommand
+
+// ThreadCommand is a base class implementation for commands stored in ThreadCommandQueue.
+class ThreadCommand
+{
+public:
+ // NotifyEvent is used by ThreadCommandQueue::PushCallAndWait to notify the
+ // calling (producer) thread when command is completed or queue slot is available.
+ class NotifyEvent : public ListNode<NotifyEvent>, public NewOverrideBase
+ {
+ Event E;
+ public:
+ NotifyEvent() { }
+
+ void Wait() { E.Wait(); }
+ void PulseEvent() { E.PulseEvent(); }
+ };
+
+ // ThreadCommand::PopBuffer is temporary storage for a command popped off
+ // by ThreadCommandQueue::PopCommand.
+ class PopBuffer
+ {
+ enum { MaxSize = 256 };
+
+ size_t Size;
+ union {
+ uint8_t Buffer[MaxSize];
+ size_t Align;
+ };
+
+ ThreadCommand* toCommand() const { return (ThreadCommand*)Buffer; }
+
+ public:
+ PopBuffer() : Size(0) { }
+ ~PopBuffer();
+
+ void InitFromBuffer(void* data);
+
+ bool HasCommand() const { return Size != 0; }
+ size_t GetSize() const { return Size; }
+ bool NeedsWait() const { return toCommand()->NeedsWait(); }
+ NotifyEvent* GetEvent() const { return toCommand()->pEvent; }
+
+ // Execute the command and also notifies caller to finish waiting,
+ // if necessary.
+ void Execute();
+ };
+
+ uint16_t Size;
+ bool WaitFlag;
+ bool ExitFlag; // Marks the last exit command.
+ NotifyEvent* pEvent;
+
+ ThreadCommand(size_t size, bool waitFlag, bool exitFlag = false)
+ : Size((uint16_t)size), WaitFlag(waitFlag), ExitFlag(exitFlag), pEvent(0) { }
+ virtual ~ThreadCommand() { }
+
+ bool NeedsWait() const { return WaitFlag; }
+ size_t GetSize() const { return Size; }
+
+ virtual void Execute() const = 0;
+ // Copy constructor used for serializing this to memory buffer.
+ virtual ThreadCommand* CopyConstruct(void* p) const = 0;
+};
+
+
+//-------------------------------------------------------------------------------------
+
+// CleanType is a template that strips 'const' and '&' modifiers from the argument type;
+// for example, typename CleanType<A&>::Type is equivalent to A.
+template<class T> struct CleanType { typedef T Type; };
+template<class T> struct CleanType<T&> { typedef T Type; };
+template<class T> struct CleanType<const T> { typedef T Type; };
+template<class T> struct CleanType<const T&> { typedef T Type; };
+
+// SelfType is a template that yields the argument type. This helps avoid conflicts with
+// automatic template argument deduction for function calls when identical argument
+// is already defined.
+template<class T> struct SelfType { typedef T Type; };
+
+
+
+//-------------------------------------------------------------------------------------
+// ThreadCommand specializations for member functions with different number of
+// arguments and argument types.
+
+// Used to return nothing from a ThreadCommand, to avoid problems with 'void'.
+struct Void
+{
+ Void() {}
+ Void(int) {}
+};
+
+// ThreadCommand for member function with 0 arguments.
+template<class C, class R>
+class ThreadCommandMF0 : public ThreadCommand
+{
+ typedef R (C::*FnPtr)();
+ C* pClass;
+ FnPtr pFn;
+ R* pRet;
+
+ void executeImpl() const
+ {
+ pRet ? (void)(*pRet = (pClass->*pFn)()) :
+ (void)(pClass->*pFn)();
+ }
+
+public:
+ ThreadCommandMF0(C* pclass, FnPtr fn, R* ret, bool needsWait)
+ : ThreadCommand(sizeof(ThreadCommandMF0), needsWait),
+ pClass(pclass), pFn(fn), pRet(ret) { }
+
+ virtual void Execute() const { executeImpl(); }
+ virtual ThreadCommand* CopyConstruct(void* p) const
+ { return Construct<ThreadCommandMF0>(p, *this); }
+};
+
+
+// ThreadCommand for member function with 1 argument.
+template<class C, class R, class A0>
+class ThreadCommandMF1 : public ThreadCommand
+{
+ typedef R (C::*FnPtr)(A0);
+ C* pClass;
+ FnPtr pFn;
+ R* pRet;
+ typename CleanType<A0>::Type AVal0;
+
+ void executeImpl() const
+ {
+ pRet ? (void)(*pRet = (pClass->*pFn)(AVal0)) :
+ (void)(pClass->*pFn)(AVal0);
+ }
+
+public:
+ ThreadCommandMF1(C* pclass, FnPtr fn, R* ret, A0 a0, bool needsWait)
+ : ThreadCommand(sizeof(ThreadCommandMF1), needsWait),
+ pClass(pclass), pFn(fn), pRet(ret), AVal0(a0) { }
+
+ virtual void Execute() const { executeImpl(); }
+ virtual ThreadCommand* CopyConstruct(void* p) const
+ { return Construct<ThreadCommandMF1>(p, *this); }
+};
+
+// ThreadCommand for member function with 2 arguments.
+template<class C, class R, class A0, class A1>
+class ThreadCommandMF2 : public ThreadCommand
+{
+ typedef R (C::*FnPtr)(A0, A1);
+ C* pClass;
+ FnPtr pFn;
+ R* pRet;
+ typename CleanType<A0>::Type AVal0;
+ typename CleanType<A1>::Type AVal1;
+
+ void executeImpl() const
+ {
+ pRet ? (void)(*pRet = (pClass->*pFn)(AVal0, AVal1)) :
+ (void)(pClass->*pFn)(AVal0, AVal1);
+ }
+
+public:
+ ThreadCommandMF2(C* pclass, FnPtr fn, R* ret, A0 a0, A1 a1, bool needsWait)
+ : ThreadCommand(sizeof(ThreadCommandMF2), needsWait),
+ pClass(pclass), pFn(fn), pRet(ret), AVal0(a0), AVal1(a1) { }
+
+ virtual void Execute() const { executeImpl(); }
+ virtual ThreadCommand* CopyConstruct(void* p) const
+ { return Construct<ThreadCommandMF2>(p, *this); }
+};
+
+
+//-------------------------------------------------------------------------------------
+// ***** ThreadCommandQueue
+
+// ThreadCommandQueue is a queue of executable function-call commands intended to be
+// serviced by a single consumer thread. Commands are added to the queue with PushCall
+// and removed with PopCall; they are processed in FIFO order. Multiple producer threads
+// are supported and will be blocked if internal data buffer is full.
+
+class ThreadCommandQueue
+{
+public:
+
+ ThreadCommandQueue();
+ virtual ~ThreadCommandQueue();
+
+
+ // Pops the next command from the thread queue, if any is available.
+ // The command should be executed by calling popBuffer->Execute().
+ // Returns 'false' if no command is available at the time of the call.
+ bool PopCommand(ThreadCommand::PopBuffer* popBuffer);
+
+ // Generic implementaion of PushCommand; enqueues a command for execution.
+ // Returns 'false' if push failed, usually indicating thread shutdown.
+ bool PushCommand(const ThreadCommand& command);
+
+ //
+ void PushExitCommand(bool wait);
+
+ // Returns 'true' once ExitCommand has been processed, so the thread can shut down.
+ bool IsExiting() const;
+
+
+ // These two virtual functions serve as notifications for derived
+ // thread waiting.
+ virtual void OnPushNonEmpty_Locked() { }
+ virtual void OnPopEmpty_Locked() { }
+
+
+ // *** PushCall with no result
+
+ // Enqueue a member function of 'this' class to be called on consumer thread.
+ // By default the function returns immediately; set 'wait' argument to 'true' to
+ // wait for completion.
+ template<class C, class R>
+ bool PushCall(R (C::*fn)(), bool wait = false)
+ { return PushCommand(ThreadCommandMF0<C,R>(static_cast<C*>(this), fn, 0, wait)); }
+ template<class C, class R, class A0>
+ bool PushCall(R (C::*fn)(A0), typename SelfType<A0>::Type a0, bool wait = false)
+ { return PushCommand(ThreadCommandMF1<C,R,A0>(static_cast<C*>(this), fn, 0, a0, wait)); }
+ template<class C, class R, class A0, class A1>
+ bool PushCall(R (C::*fn)(A0, A1),
+ typename SelfType<A0>::Type a0, typename SelfType<A1>::Type a1, bool wait = false)
+ { return PushCommand(ThreadCommandMF2<C,R,A0,A1>(static_cast<C*>(this), fn, 0, a0, a1, wait)); }
+ // Enqueue a specified member function call of class C.
+ // By default the function returns immediately; set 'wait' argument to 'true' to
+ // wait for completion.
+ template<class C, class R>
+ bool PushCall(C* p, R (C::*fn)(), bool wait = false)
+ { return PushCommand(ThreadCommandMF0<C,R>(p, fn, 0, wait)); }
+ template<class C, class R, class A0>
+ bool PushCall(C* p, R (C::*fn)(A0), typename SelfType<A0>::Type a0, bool wait = false)
+ { return PushCommand(ThreadCommandMF1<C,R,A0>(p, fn, 0, a0, wait)); }
+ template<class C, class R, class A0, class A1>
+ bool PushCall(C* p, R (C::*fn)(A0, A1),
+ typename SelfType<A0>::Type a0, typename SelfType<A1>::Type a1, bool wait = false)
+ { return PushCommand(ThreadCommandMF2<C,R,A0,A1>(p, fn, 0, a0, a1, wait)); }
+
+
+ // *** PushCall with Result
+
+ // Enqueue a member function of 'this' class call and wait for call to complete
+ // on consumer thread before returning.
+ template<class C, class R>
+ bool PushCallAndWaitResult(R (C::*fn)(), R* ret)
+ { return PushCommand(ThreadCommandMF0<C,R>(static_cast<C*>(this), fn, ret, true)); }
+ template<class C, class R, class A0>
+ bool PushCallAndWaitResult(R (C::*fn)(A0), R* ret, typename SelfType<A0>::Type a0)
+ { return PushCommand(ThreadCommandMF1<C,R,A0>(static_cast<C*>(this), fn, ret, a0, true)); }
+ template<class C, class R, class A0, class A1>
+ bool PushCallAndWaitResult(R (C::*fn)(A0, A1), R* ret,
+ typename SelfType<A0>::Type a0, typename SelfType<A1>::Type a1)
+ { return PushCommand(ThreadCommandMF2<C,R,A0,A1>(static_cast<C*>(this), fn, ret, a0, a1, true)); }
+ // Enqueue a member function call for class C and wait for the call to complete
+ // on consumer thread before returning.
+ template<class C, class R>
+ bool PushCallAndWaitResult(C* p, R (C::*fn)(), R* ret)
+ { return PushCommand(ThreadCommandMF0<C,R>(p, fn, ret, true)); }
+ template<class C, class R, class A0>
+ bool PushCallAndWaitResult(C* p, R (C::*fn)(A0), R* ret, typename SelfType<A0>::Type a0)
+ { return PushCommand(ThreadCommandMF1<C,R,A0>(p, fn, ret, a0, true)); }
+ template<class C, class R, class A0, class A1>
+ bool PushCallAndWaitResult(C* p, R (C::*fn)(A0, A1), R* ret,
+ typename SelfType<A0>::Type a0, typename SelfType<A1>::Type a1)
+ { return PushCommand(ThreadCommandMF2<C,R,A0,A1>(p, fn, ret, a0, a1, true)); }
+
+private:
+ class ThreadCommandQueueImpl* pImpl;
+};
+
+
+} // namespace OVR
+
+#endif // OVR_ThreadCommandQueue_h
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