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/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is the Netscape security libraries.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1994-2000
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
** File: nsrwlock.h
** Description: API to basic reader-writer lock functions of NSS.
** These are re-entrant reader writer locks; that is,
** If I hold the write lock, I can ask for it and get it again.
** If I hold the write lock, I can also ask for and get a read lock.
** I can then release the locks in any order (read or write).
** I must release each lock type as many times as I acquired it.
** Otherwise, these are normal reader/writer locks.
**
** For deadlock detection, locks should be ranked, and no lock may be aquired
** while I hold a lock of higher rank number.
** If you don't want that feature, always use NSS_RWLOCK_RANK_NONE.
** Lock name is for debugging, and is optional (may be NULL)
**/
#ifndef nssrwlk_h___
#define nssrwlk_h___
#include "prtypes.h"
#include "nssrwlkt.h"
#define NSS_RWLOCK_RANK_NONE 0
/* SEC_BEGIN_PROTOS */
PR_BEGIN_EXTERN_C
/***********************************************************************
** FUNCTION: NSSRWLock_New
** DESCRIPTION:
** Returns a pointer to a newly created reader-writer lock object.
** INPUTS: Lock rank
** Lock name
** OUTPUTS: void
** RETURN: NSSRWLock*
** If the lock cannot be created because of resource constraints, NULL
** is returned.
**
***********************************************************************/
PR_EXTERN(NSSRWLock*) NSSRWLock_New(PRUint32 lock_rank, const char *lock_name);
/***********************************************************************
** FUNCTION: NSSRWLock_AtomicCreate
** DESCRIPTION:
** Given the address of a NULL pointer to a NSSRWLock,
** atomically initializes that pointer to a newly created NSSRWLock.
** Returns the value placed into that pointer, or NULL.
**
** INPUTS: address of NSRWLock pointer
** Lock rank
** Lock name
** OUTPUTS: NSSRWLock*
** RETURN: NSSRWLock*
** If the lock cannot be created because of resource constraints,
** the pointer will be left NULL.
**
***********************************************************************/
PR_EXTERN(NSSRWLock *)
nssRWLock_AtomicCreate( NSSRWLock ** prwlock,
PRUint32 lock_rank,
const char * lock_name);
/***********************************************************************
** FUNCTION: NSSRWLock_Destroy
** DESCRIPTION:
** Destroys a given RW lock object.
** INPUTS: NSSRWLock *lock - Lock to be freed.
** OUTPUTS: void
** RETURN: None
***********************************************************************/
PR_EXTERN(void) NSSRWLock_Destroy(NSSRWLock *lock);
/***********************************************************************
** FUNCTION: NSSRWLock_LockRead
** DESCRIPTION:
** Apply a read lock (non-exclusive) on a RWLock
** INPUTS: NSSRWLock *lock - Lock to be read-locked.
** OUTPUTS: void
** RETURN: None
***********************************************************************/
PR_EXTERN(void) NSSRWLock_LockRead(NSSRWLock *lock);
/***********************************************************************
** FUNCTION: NSSRWLock_LockWrite
** DESCRIPTION:
** Apply a write lock (exclusive) on a RWLock
** INPUTS: NSSRWLock *lock - Lock to write-locked.
** OUTPUTS: void
** RETURN: None
***********************************************************************/
PR_EXTERN(void) NSSRWLock_LockWrite(NSSRWLock *lock);
/***********************************************************************
** FUNCTION: NSSRWLock_UnlockRead
** DESCRIPTION:
** Release a Read lock. Unlocking an unlocked lock has undefined results.
** INPUTS: NSSRWLock *lock - Lock to unlocked.
** OUTPUTS: void
** RETURN: void
***********************************************************************/
PR_EXTERN(void) NSSRWLock_UnlockRead(NSSRWLock *lock);
/***********************************************************************
** FUNCTION: NSSRWLock_UnlockWrite
** DESCRIPTION:
** Release a Write lock. Unlocking an unlocked lock has undefined results.
** INPUTS: NSSRWLock *lock - Lock to unlocked.
** OUTPUTS: void
** RETURN: void
***********************************************************************/
PR_EXTERN(void) NSSRWLock_UnlockWrite(NSSRWLock *lock);
/***********************************************************************
** FUNCTION: NSSRWLock_HaveWriteLock
** DESCRIPTION:
** Tells caller whether the current thread holds the write lock, or not.
** INPUTS: NSSRWLock *lock - Lock to test.
** OUTPUTS: void
** RETURN: PRBool PR_TRUE IFF the current thread holds the write lock.
***********************************************************************/
PR_EXTERN(PRBool) NSSRWLock_HaveWriteLock(NSSRWLock *rwlock);
/* SEC_END_PROTOS */
PR_END_EXTERN_C
#endif /* nsrwlock_h___ */
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