/*

Copyright (C) 2016 Apple Inc. All Rights Reserved.

See LICENSE.txt for this sample’s licensing information

Abstract:

Part of Core Audio Public Utility Classes

*/

#if !defined(__CAGuard_h__)

#define __CAGuard_h__

//==================================================================================================

//  Includes

//=============================================================================

//  Super Class Includes

#include "CAMutex.h"

#if CoreAudio_Debug

//  #define Log_Average_Latency 1

#endif

//==================================================================================================

//  CAGuard

//

//  This is your typical mutex with signalling implemented via pthreads.

//  Lock() will return true if and only if the guard is locked on that call.

//  A thread that already has the guard will receive 'false' if it locks it

//  again. Use of the stack-based CAGuard::Locker class is highly recommended

//  to properly manage the recursive nesting. The Wait calls with timeouts

//  will return true if and only if the timeout period expired. They will

//  return false if they receive notification any other way.

//==================================================================================================

class   CAGuard : public CAMutex

{

//  Construction/Destruction

public:

                    CAGuard(const char* inName);

    virtual         ~CAGuard();

//  Actions

public:

    virtual void    Wait();

    virtual bool    WaitFor(UInt64 inNanos);

    virtual bool    WaitUntil(UInt64 inNanos);

    virtual void    Notify();

    virtual void    NotifyAll();

//  Implementation

protected:

#if TARGET_OS_MAC

    pthread_cond_t  mCondVar;

#else

    HANDLE          mEvent;

#endif

#if Log_Average_Latency

    Float64         mAverageLatencyAccumulator;

    UInt32          mAverageLatencyCount;

#endif

//  Helper class to manage taking and releasing recursively

public:

    class           Locker

    {

    //  Construction/Destruction

    public:

                    Locker(CAGuard& inGuard) : mGuard(inGuard), mNeedsRelease(false) { mNeedsRelease = mGuard.Lock(); }

                    ~Locker() { if(mNeedsRelease) { mGuard.Unlock(); } }

    private:

                    Locker(const Locker&);

        Locker&     operator=(const Locker&);

    //  Actions

    public:

        void        Wait() { mGuard.Wait(); }

        bool        WaitFor(UInt64 inNanos) { return mGuard.WaitFor(inNanos); }

        bool        WaitUntil(UInt64 inNanos) { return mGuard.WaitUntil(inNanos); }

        void        Notify() { mGuard.Notify(); }

        void        NotifyAll() { mGuard.NotifyAll(); }

    //  Implementation

    private:

        CAGuard&    mGuard;

        bool        mNeedsRelease;  

    };

};

#endif