/**************************************************************
 * 
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
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 *************************************************************/


#ifndef _OSL_MUTEX_HXX_
#define _OSL_MUTEX_HXX_

#ifdef __cplusplus

#include <osl/mutex.h>


namespace osl
{     
    /** A mutual exclusion synchronization object
    */
	class Mutex {
    
    public:
		/** Create a thread-local mutex.
			@return 0 if the mutex could not be created, otherwise a handle to the mutex.
            @seealso ::osl_createMutex()
		*/
		Mutex() 
		{
			mutex = osl_createMutex();
		}

		/** Release the OS-structures and free mutex data-structure. 
            @seealso ::osl_destroyMutex()
		*/
		~Mutex()
		{
			osl_destroyMutex(mutex);
		}

		/** Acquire the mutex, block if already acquired by another thread.
			@return sal_False if system-call fails.
            @seealso ::osl_acquireMutex()
		*/
		sal_Bool acquire()
		{
			return osl_acquireMutex(mutex);
		}

		/** Try to acquire the mutex without blocking.
			@return sal_False if it could not be acquired.
            @seealso ::osl_tryToAcquireMutex()
		*/
		sal_Bool tryToAcquire()
		{
			return osl_tryToAcquireMutex(mutex);
		}

		/** Release the mutex.
			@return sal_False if system-call fails.
            @seealso ::osl_releaseMutex()
		*/
		sal_Bool release()
		{
			return osl_releaseMutex(mutex);
		}

        /** Returns a global static mutex object.
            The global and static mutex object can be used to initialize other 
            static objects in a thread safe manner.
            @return the global mutex object
            @seealso ::osl_getGlobalMutex()
        */
		static Mutex * getGlobalMutex()
		{
			return (Mutex *)osl_getGlobalMutex();
		}
        
	private:
        oslMutex mutex;

        /** The underlying oslMutex has no reference count.
        
        Since the underlying oslMutex is not a reference counted object, copy
        constructed Mutex may work on an already destructed oslMutex object.
        
        */
        Mutex(const Mutex&);
        
        /** The underlying oslMutex has no reference count.
        
        When destructed, the Mutex object destroys the undelying oslMutex, 
        which might cause severe problems in case it's a temporary object.
         
        */
        Mutex(oslMutex Mutex);
        
        /** This assignment operator is private for the same reason as
            the copy constructor.
        */
        Mutex& operator= (const Mutex&);
        
        /** This assignment operator is private for the same reason as
            the constructor taking a oslMutex argument.
        */
        Mutex& operator= (oslMutex);
	};

    /** A helper class for mutex objects and interfaces.
    */
	template<class T>
	class Guard
	{
	private:
		Guard( const Guard& );
		const Guard& operator = ( const Guard& );

	protected:
		T * pT;
	public:

        /** Acquires the object specified as parameter.
        */
		Guard(T * pT_) : pT(pT_)
		{
			pT->acquire();
		}

        /** Acquires the object specified as parameter.
        */
		Guard(T & t) : pT(&t)
		{
			pT->acquire();
		}

		/** Releases the mutex or interface. */
		~Guard()
		{
			pT->release();
		}
	};

    /** A helper class for mutex objects and interfaces.
    */
	template<class T>
	class ClearableGuard
	{
	private:
		ClearableGuard( const ClearableGuard& );
		const ClearableGuard& operator = ( const ClearableGuard& );
	protected:
		T * pT;
	public:
		
        /** Acquires the object specified as parameter.
        */
		ClearableGuard(T * pT_) : pT(pT_)
		{
			pT->acquire();
		}

        /** Acquires the object specified as parameter.
        */
		ClearableGuard(T & t) : pT(&t)
		{
			pT->acquire();
		}

		/** Releases the mutex or interface if not already released by clear().
        */
		~ClearableGuard()
		{
			if (pT)
				pT->release();
		}
		
		/** Releases the mutex or interface. 
        */
		void clear()
		{
			if(pT)
			{
				pT->release();
				pT = NULL;
			}
	    }
	};

    /** A helper class for mutex objects and interfaces.
    */
	template< class T >
    class ResettableGuard : public ClearableGuard< T >
    {
    private:
        ResettableGuard(ResettableGuard &); // not defined
        void operator =(ResettableGuard &); // not defined

    protected:
        T* pResetT;
    public:
        /** Acquires the object specified as parameter.
        */
        ResettableGuard( T* pT_ ) :
                ClearableGuard<T>( pT_ ),
                pResetT( pT_ )
        {}
        
        /** Acquires the object specified as parameter.
        */
        ResettableGuard( T& rT ) :
                ClearableGuard<T>( rT ),
                pResetT( &rT )
        {}
        
		/** Re-aquires the mutex or interface.
        */
        void reset()
        {
            if( pResetT )
            {
                this->pT = pResetT;
                this->pT->acquire();
            }
        }
    };

	typedef Guard<Mutex> MutexGuard;
	typedef ClearableGuard<Mutex> ClearableMutexGuard;
	typedef ResettableGuard< Mutex > ResettableMutexGuard;
}

#endif  /* __cplusplus */
#endif	/* _OSL_MUTEX_HXX_ */