AOO410/main/sal/osl/os2/mutex.c

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 * 
 * Licensed to the Apache Software Foundation (ASF) under one
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 * 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
 * under the License.
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 *************************************************************/



#include <sys/fmutex.h>

#include "system.h"

#include <osl/mutex.h>
#include <osl/diagnose.h>

/*
    Implementation notes:
    The void* hidden by oslMutex points to an OS/2 mutex semaphore.
*/
typedef struct _oslMutexImpl {
	HMTX				m_Mutex;
	int 				m_Locks;
	ULONG				m_Owner;
	ULONG				m_Requests;
} oslMutexImpl;

// static mutex to control access to private members of oslMutexImpl
static HMTX MutexLock = 0;

/*****************************************************************************/
/* osl_createMutex */
/*****************************************************************************/
oslMutex SAL_CALL osl_createMutex()
{
	oslMutexImpl *pMutexImpl;
    HMTX hMutex;
    APIRET rc;

	pMutexImpl= (oslMutexImpl*)calloc(sizeof(oslMutexImpl), 1);
	OSL_ASSERT(pMutexImpl); /* alloc successful? */
	
    /* create semaphore */
    rc = DosCreateMutexSem( NULL, &pMutexImpl->m_Mutex, 0, FALSE );
    if( rc != 0 )
	{
		free(pMutexImpl);
        return NULL;
	}

	// create static mutex for private members
	if (MutexLock == 0)
		DosCreateMutexSem( NULL, &MutexLock, 0, FALSE );

	return (oslMutex)pMutexImpl;
}

/*****************************************************************************/
/* osl_destroyMutex */
/*****************************************************************************/
void SAL_CALL osl_destroyMutex(oslMutex Mutex)
{
	oslMutexImpl *pMutexImpl = (oslMutexImpl *)Mutex;
	if (pMutexImpl)
	{
		DosCloseMutexSem( pMutexImpl->m_Mutex);
		free(pMutexImpl);
	}
}

/*****************************************************************************/
/* osl_acquireMutex */
/*****************************************************************************/
sal_Bool SAL_CALL osl_acquireMutex(oslMutex Mutex)
{
	oslMutexImpl *pMutexImpl = (oslMutexImpl *)Mutex;
    APIRET rc = 0;
    OSL_ASSERT(Mutex);

	DosRequestMutexSem( MutexLock, SEM_INDEFINITE_WAIT );
	pMutexImpl->m_Requests++;
	DosReleaseMutexSem( MutexLock);

	rc = DosRequestMutexSem( pMutexImpl->m_Mutex, SEM_INDEFINITE_WAIT );

	DosRequestMutexSem( MutexLock, SEM_INDEFINITE_WAIT );
	pMutexImpl->m_Requests--;
	if (pMutexImpl->m_Locks++ == 0)
		pMutexImpl->m_Owner = _gettid();
	DosReleaseMutexSem( MutexLock);

    return( rc == 0 );
}

/*****************************************************************************/
/* osl_tryToAcquireMutex */
/*****************************************************************************/
sal_Bool SAL_CALL osl_tryToAcquireMutex(oslMutex Mutex)
{
	sal_Bool 	 ret = sal_False;
	oslMutexImpl *pMutexImpl = (oslMutexImpl *)Mutex;
    OSL_ASSERT(Mutex);

	DosRequestMutexSem( MutexLock, SEM_INDEFINITE_WAIT );

	if ( ((pMutexImpl->m_Requests == 0) && (pMutexImpl->m_Locks == 0)) ||
		 (pMutexImpl->m_Owner == _gettid()) )
		ret = osl_acquireMutex(Mutex);

	DosReleaseMutexSem( MutexLock);
	
    return ret;
}

/*****************************************************************************/
/* osl_releaseMutex */
/*****************************************************************************/
sal_Bool SAL_CALL osl_releaseMutex(oslMutex Mutex)
{
	oslMutexImpl *pMutexImpl = (oslMutexImpl *)Mutex;
    APIRET rc;
    OSL_ASSERT(Mutex);

	DosRequestMutexSem( MutexLock, SEM_INDEFINITE_WAIT );

	if (--(pMutexImpl->m_Locks) == 0)
		pMutexImpl->m_Owner = 0;

	DosReleaseMutexSem( MutexLock);

    rc = DosReleaseMutexSem( pMutexImpl->m_Mutex);

    return sal_True;
}



/*****************************************************************************/
/* osl_getGlobalMutex */
/*****************************************************************************/

oslMutex g_Mutex = NULL;

oslMutex * SAL_CALL osl_getGlobalMutex(void) 
{
	if (g_Mutex == NULL)
		g_Mutex = osl_createMutex();
	return &g_Mutex;
}