CAMutex.h

/*  Copyright © 2007 Apple Inc. All Rights Reserved.
    
    Disclaimer: IMPORTANT:  This Apple software is supplied to you by 
            Apple Inc. ("Apple") in consideration of your agreement to the
            following terms, and your use, installation, modification or
            redistribution of this Apple software constitutes acceptance of these
            terms.  If you do not agree with these terms, please do not use,
            install, modify or redistribute this Apple software.
            
            In consideration of your agreement to abide by the following terms, and
            subject to these terms, Apple grants you a personal, non-exclusive
            license, under Apple's copyrights in this original Apple software (the
            "Apple Software"), to use, reproduce, modify and redistribute the Apple
            Software, with or without modifications, in source and/or binary forms;
            provided that if you redistribute the Apple Software in its entirety and
            without modifications, you must retain this notice and the following
            text and disclaimers in all such redistributions of the Apple Software. 
            Neither the name, trademarks, service marks or logos of Apple Inc. 
            may be used to endorse or promote products derived from the Apple
            Software without specific prior written permission from Apple.  Except
            as expressly stated in this notice, no other rights or licenses, express
            or implied, are granted by Apple herein, including but not limited to
            any patent rights that may be infringed by your derivative works or by
            other works in which the Apple Software may be incorporated.
            
            The Apple Software is provided by Apple on an "AS IS" basis.  APPLE
            MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
            THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS
            FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND
            OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.
            
            IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL
            OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
            SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
            INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,
            MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED
            AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),
            STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE
            POSSIBILITY OF SUCH DAMAGE.
*/
#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() { if(mNeedsRelease) { mMutex.Unlock(); } }
    
    private:
                    Locker(const Locker&);
        Locker&     operator=(const Locker&);
    
    //  Implementation
    private:
        CAMutex&    mMutex;
        bool        mNeedsRelease;
    
    };
    
        // 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__