AOO410/main/framework/inc/threadhelp/irwlock.h

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#ifndef __FRAMEWORK_THREADHELP_IRWLOCK_H_
#define __FRAMEWORK_THREADHELP_IRWLOCK_H_

//_________________________________________________________________________________________________________________
//	includes
//_________________________________________________________________________________________________________________

//_________________________________________________________________________________________________________________
//	namespace
//_________________________________________________________________________________________________________________

namespace framework{

//_________________________________________________________________________________________________________________
//	declarations
//_________________________________________________________________________________________________________________

/*-************************************************************************************************************//**
	@descr			A guard (specialy a write guard) support different internal working states.
					His lock can set for reading or writing/reading! Or he was unlocked by user ...
*//*-*************************************************************************************************************/
enum ELockMode
{
	E_NOLOCK	,
	E_READLOCK	,
	E_WRITELOCK
};

/*-************************************************************************************************************//**
	@descr			We implement two guards for using an rw-lock. But if you wish to implement
					different rw-locks to you will have problems by using with same guard implementation!
					Thats why we define this "pure virtual base class" ...
					All rw-locks must support this base interface for working and all guard must use this one too!
*//*-*************************************************************************************************************/
class IRWLock
{
	//-------------------------------------------------------------------------------------------------------------
	//	public methods
	//-------------------------------------------------------------------------------------------------------------
	public:

		/*-****************************************************************************************************//**
			@descr		These functions must be supported by a derived class!
							acquireReadAccess()		-try to register thread as reader
							releaseReadAccess()		-unregister thread as reader
							acquireWriteAccess()	-try to register thread as writer
							releaseWriteAccess()	-unregister thread as writer
							downgradeWriteAccess()	-make writer to reader
		*//*-*****************************************************************************************************/
        virtual void acquireReadAccess    () =0;
        virtual void releaseReadAccess    () =0;
        virtual void acquireWriteAccess   () =0;
        virtual void releaseWriteAccess   () =0;
        virtual void downgradeWriteAccess () =0;

};		//	class IRWLock

}		//	namespace framework

#endif	//	#ifndef __FRAMEWORK_THREADHELP_IRWLOCK_H_