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