CAGuard.h

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#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