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