michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /*
michael@0: ** File:		prlock.h
michael@0: ** Description:	API to basic locking functions of NSPR.
michael@0: **
michael@0: **
michael@0: ** NSPR provides basic locking mechanisms for thread synchronization.  Locks 
michael@0: ** are lightweight resource contention controls that prevent multiple threads 
michael@0: ** from accessing something (code/data) simultaneously.
michael@0: **/
michael@0: 
michael@0: #ifndef prlock_h___
michael@0: #define prlock_h___
michael@0: 
michael@0: #include "prtypes.h"
michael@0: 
michael@0: PR_BEGIN_EXTERN_C
michael@0: 
michael@0: /**********************************************************************/
michael@0: /************************* TYPES AND CONSTANTS ************************/
michael@0: /**********************************************************************/
michael@0: 
michael@0: /*
michael@0:  * PRLock --
michael@0:  *
michael@0:  *     NSPR represents the lock as an opaque entity to the client of the
michael@0:  *	   API.  All routines operate on a pointer to this opaque entity.
michael@0:  */
michael@0: 
michael@0: typedef struct PRLock PRLock;
michael@0: 
michael@0: /**********************************************************************/
michael@0: /****************************** FUNCTIONS *****************************/
michael@0: /**********************************************************************/
michael@0: 
michael@0: /***********************************************************************
michael@0: ** FUNCTION:    PR_NewLock
michael@0: ** DESCRIPTION:
michael@0: **  Returns a pointer to a newly created opaque lock object.
michael@0: ** INPUTS:      void
michael@0: ** OUTPUTS:     void
michael@0: ** RETURN:      PRLock*
michael@0: **   If the lock can not be created because of resource constraints, NULL
michael@0: **   is returned.
michael@0: **  
michael@0: ***********************************************************************/
michael@0: NSPR_API(PRLock*) PR_NewLock(void);
michael@0: 
michael@0: /***********************************************************************
michael@0: ** FUNCTION:    PR_DestroyLock
michael@0: ** DESCRIPTION:
michael@0: **  Destroys a given opaque lock object.
michael@0: ** INPUTS:      PRLock *lock
michael@0: **              Lock to be freed.
michael@0: ** OUTPUTS:     void
michael@0: ** RETURN:      None
michael@0: ***********************************************************************/
michael@0: NSPR_API(void) PR_DestroyLock(PRLock *lock);
michael@0: 
michael@0: /***********************************************************************
michael@0: ** FUNCTION:    PR_Lock
michael@0: ** DESCRIPTION:
michael@0: **  Lock a lock.
michael@0: ** INPUTS:      PRLock *lock
michael@0: **              Lock to locked.
michael@0: ** OUTPUTS:     void
michael@0: ** RETURN:      None
michael@0: ***********************************************************************/
michael@0: NSPR_API(void) PR_Lock(PRLock *lock);
michael@0: 
michael@0: /***********************************************************************
michael@0: ** FUNCTION:    PR_Unlock
michael@0: ** DESCRIPTION:
michael@0: **  Unlock a lock.  Unlocking an unlocked lock has undefined results.
michael@0: ** INPUTS:      PRLock *lock
michael@0: **              Lock to unlocked.
michael@0: ** OUTPUTS:     void
michael@0: ** RETURN:      PR_STATUS
michael@0: **              Returns PR_FAILURE if the caller does not own the lock.
michael@0: ***********************************************************************/
michael@0: NSPR_API(PRStatus) PR_Unlock(PRLock *lock);
michael@0: 
michael@0: /***********************************************************************
michael@0: ** MACRO:    PR_ASSERT_CURRENT_THREAD_OWNS_LOCK
michael@0: ** DESCRIPTION:
michael@0: **  If the current thread owns |lock|, this assertion is guaranteed to
michael@0: **  succeed.  Otherwise, the behavior of this function is undefined.
michael@0: ** INPUTS:      PRLock *lock
michael@0: **              Lock to assert ownership of.
michael@0: ** OUTPUTS:     void
michael@0: ** RETURN:      None
michael@0: ***********************************************************************/
michael@0: #if defined(DEBUG) || defined(FORCE_PR_ASSERT)
michael@0: #define PR_ASSERT_CURRENT_THREAD_OWNS_LOCK(/* PrLock* */ lock) \
michael@0:     PR_AssertCurrentThreadOwnsLock(lock)
michael@0: #else
michael@0: #define PR_ASSERT_CURRENT_THREAD_OWNS_LOCK(/* PrLock* */ lock)
michael@0: #endif
michael@0: 
michael@0: /* Don't call this function directly. */
michael@0: NSPR_API(void) PR_AssertCurrentThreadOwnsLock(PRLock *lock);
michael@0: 
michael@0: PR_END_EXTERN_C
michael@0: 
michael@0: #endif /* prlock_h___ */