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:		nsrwlock.h
michael@0: ** Description:	API to basic reader-writer lock functions of NSS.
michael@0: **	These are re-entrant reader writer locks; that is,
michael@0: **	If I hold the write lock, I can ask for it and get it again.
michael@0: **	If I hold the write lock, I can also ask for and get a read lock.
michael@0: **      I can then release the locks in any order (read or write).
michael@0: **	I must release each lock type as many times as I acquired it.
michael@0: **	Otherwise, these are normal reader/writer locks.
michael@0: **
michael@0: ** For deadlock detection, locks should be ranked, and no lock may be aquired
michael@0: ** while I hold a lock of higher rank number.
michael@0: ** If you don't want that feature, always use NSS_RWLOCK_RANK_NONE.
michael@0: ** Lock name is for debugging, and is optional (may be NULL)
michael@0: **/
michael@0: 
michael@0: #ifndef nssrwlk_h___
michael@0: #define nssrwlk_h___
michael@0: 
michael@0: #include "utilrename.h"
michael@0: #include "prtypes.h"
michael@0: #include "nssrwlkt.h"
michael@0: 
michael@0: #define	NSS_RWLOCK_RANK_NONE	0
michael@0: 
michael@0: /* SEC_BEGIN_PROTOS */
michael@0: PR_BEGIN_EXTERN_C
michael@0: 
michael@0: /***********************************************************************
michael@0: ** FUNCTION:    NSSRWLock_New
michael@0: ** DESCRIPTION:
michael@0: **  Returns a pointer to a newly created reader-writer lock object.
michael@0: ** INPUTS:      Lock rank
michael@0: **		Lock name
michael@0: ** OUTPUTS:     void
michael@0: ** RETURN:      NSSRWLock*
michael@0: **   If the lock cannot be created because of resource constraints, NULL
michael@0: **   is returned.
michael@0: **  
michael@0: ***********************************************************************/
michael@0: extern NSSRWLock* NSSRWLock_New(PRUint32 lock_rank, const char *lock_name);
michael@0: 
michael@0: /***********************************************************************
michael@0: ** FUNCTION:    NSSRWLock_AtomicCreate
michael@0: ** DESCRIPTION:
michael@0: **  Given the address of a NULL pointer to a NSSRWLock, 
michael@0: **  atomically initializes that pointer to a newly created NSSRWLock.
michael@0: **  Returns the value placed into that pointer, or NULL.
michael@0: **
michael@0: ** INPUTS:      address of NSRWLock pointer
michael@0: **              Lock rank
michael@0: **		Lock name
michael@0: ** OUTPUTS:     NSSRWLock*
michael@0: ** RETURN:      NSSRWLock*
michael@0: **   If the lock cannot be created because of resource constraints, 
michael@0: **   the pointer will be left NULL.
michael@0: **  
michael@0: ***********************************************************************/
michael@0: extern NSSRWLock *
michael@0: nssRWLock_AtomicCreate( NSSRWLock  ** prwlock, 
michael@0: 			PRUint32      lock_rank, 
michael@0: 			const char *  lock_name);
michael@0: 
michael@0: /***********************************************************************
michael@0: ** FUNCTION:    NSSRWLock_Destroy
michael@0: ** DESCRIPTION:
michael@0: **  Destroys a given RW lock object.
michael@0: ** INPUTS:      NSSRWLock *lock - Lock to be freed.
michael@0: ** OUTPUTS:     void
michael@0: ** RETURN:      None
michael@0: ***********************************************************************/
michael@0: extern void NSSRWLock_Destroy(NSSRWLock *lock);
michael@0: 
michael@0: /***********************************************************************
michael@0: ** FUNCTION:    NSSRWLock_LockRead
michael@0: ** DESCRIPTION:
michael@0: **  Apply a read lock (non-exclusive) on a RWLock
michael@0: ** INPUTS:      NSSRWLock *lock - Lock to be read-locked.
michael@0: ** OUTPUTS:     void
michael@0: ** RETURN:      None
michael@0: ***********************************************************************/
michael@0: extern void NSSRWLock_LockRead(NSSRWLock *lock);
michael@0: 
michael@0: /***********************************************************************
michael@0: ** FUNCTION:    NSSRWLock_LockWrite
michael@0: ** DESCRIPTION:
michael@0: **  Apply a write lock (exclusive) on a RWLock
michael@0: ** INPUTS:      NSSRWLock *lock - Lock to write-locked.
michael@0: ** OUTPUTS:     void
michael@0: ** RETURN:      None
michael@0: ***********************************************************************/
michael@0: extern void NSSRWLock_LockWrite(NSSRWLock *lock);
michael@0: 
michael@0: /***********************************************************************
michael@0: ** FUNCTION:    NSSRWLock_UnlockRead
michael@0: ** DESCRIPTION:
michael@0: **  Release a Read lock. Unlocking an unlocked lock has undefined results.
michael@0: ** INPUTS:      NSSRWLock *lock - Lock to unlocked.
michael@0: ** OUTPUTS:     void
michael@0: ** RETURN:      void
michael@0: ***********************************************************************/
michael@0: extern void NSSRWLock_UnlockRead(NSSRWLock *lock);
michael@0: 
michael@0: /***********************************************************************
michael@0: ** FUNCTION:    NSSRWLock_UnlockWrite
michael@0: ** DESCRIPTION:
michael@0: **  Release a Write lock. Unlocking an unlocked lock has undefined results.
michael@0: ** INPUTS:      NSSRWLock *lock - Lock to unlocked.
michael@0: ** OUTPUTS:     void
michael@0: ** RETURN:      void
michael@0: ***********************************************************************/
michael@0: extern void NSSRWLock_UnlockWrite(NSSRWLock *lock);
michael@0: 
michael@0: /***********************************************************************
michael@0: ** FUNCTION:    NSSRWLock_HaveWriteLock
michael@0: ** DESCRIPTION:
michael@0: **  Tells caller whether the current thread holds the write lock, or not.
michael@0: ** INPUTS:      NSSRWLock *lock - Lock to test.
michael@0: ** OUTPUTS:     void
michael@0: ** RETURN:      PRBool	PR_TRUE IFF the current thread holds the write lock.
michael@0: ***********************************************************************/
michael@0: 
michael@0: extern PRBool NSSRWLock_HaveWriteLock(NSSRWLock *rwlock);
michael@0: 
michael@0: /* SEC_END_PROTOS */
michael@0: PR_END_EXTERN_C
michael@0: 
michael@0: #endif /* nsrwlock_h___ */