BackgroundMusic/BGMDriver/PublicUtility/CAMutex.h

/*
     File: CAMutex.h 
 Abstract:  Part of CoreAudio Utility Classes  
  Version: 1.0.1 
  
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*/
#ifndef __CAMutex_h__
#define __CAMutex_h__

//==================================================================================================
//	Includes
//==================================================================================================

//	System Includes
#if !defined(__COREAUDIO_USE_FLAT_INCLUDES__)
	#include <CoreAudio/CoreAudioTypes.h>
#else
	#include <CoreAudioTypes.h>
#endif

#if TARGET_OS_MAC
	#include <pthread.h>
#elif TARGET_OS_WIN32
	#include <windows.h>
#else
	#error	Unsupported operating system
#endif

//==================================================================================================
//	A recursive mutex.
//==================================================================================================

class	CAMutex
{
//	Construction/Destruction
public:
					CAMutex(const char* inName);
	virtual			~CAMutex();

//	Actions
public:
	virtual bool	Lock();
	virtual void	Unlock();
	virtual bool	Try(bool& outWasLocked);	// returns true if lock is free, false if not
	
	virtual bool	IsFree() const;
	virtual bool	IsOwnedByCurrentThread() const;
		
//	Implementation
protected:
	const char*		mName;
#if TARGET_OS_MAC
	pthread_t		mOwner;
	pthread_mutex_t	mMutex;
#elif TARGET_OS_WIN32
	UInt32			mOwner;
	HANDLE			mMutex;
#endif

//	Helper class to manage taking and releasing recursively
public:
	class			Locker
	{
	
	//	Construction/Destruction
	public:
					Locker(CAMutex& inMutex) : mMutex(&inMutex), mNeedsRelease(false) { mNeedsRelease = mMutex->Lock(); }
					Locker(const CAMutex& inMutex) : mMutex(const_cast<CAMutex*>(&inMutex)), mNeedsRelease(false) { mNeedsRelease = mMutex->Lock(); }
					Locker(CAMutex* inMutex) : mMutex(inMutex), mNeedsRelease(false) { mNeedsRelease = (mMutex != NULL && mMutex->Lock()); }
						// in this case the mutex can be null
					~Locker() { if(mNeedsRelease) { mMutex->Unlock(); } }
	
	
	private:
					Locker(const Locker&);
		Locker&		operator=(const Locker&);
	
	//	Implementation
	private:
		CAMutex*	mMutex;
		bool		mNeedsRelease;
	
	};

// Unlocker
	class Unlocker
	{
	public:
						Unlocker(CAMutex& inMutex);
						~Unlocker();
		
	private:
		CAMutex&	mMutex;
		bool		mNeedsLock;
		
		// Hidden definitions of copy ctor, assignment operator
		Unlocker(const Unlocker& copy);				// Not implemented
		Unlocker& operator=(const Unlocker& copy);	// Not implemented
	};
	
// you can use this with Try - if you take the lock in try, pass in the outWasLocked var
	class Tryer {
	
	//	Construction/Destruction
	public:
		Tryer (CAMutex &mutex) : mMutex(mutex), mNeedsRelease(false), mHasLock(false) { mHasLock = mMutex.Try (mNeedsRelease); }
		~Tryer () { if (mNeedsRelease) mMutex.Unlock(); }
		
		bool HasLock () const { return mHasLock; }

	private:
					Tryer(const Tryer&);
		Tryer&		operator=(const Tryer&);

	//	Implementation
	private:
		CAMutex &		mMutex;
		bool			mNeedsRelease;
		bool			mHasLock;
	};
};


#endif // __CAMutex_h__