1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2/*
3 * The contents of this file are subject to the Mozilla Public
4 * License Version 1.1 (the "License"); you may not use this file
5 * except in compliance with the License. You may obtain a copy of
6 * the License at http://www.mozilla.org/MPL/
7 *
8 * Software distributed under the License is distributed on an "AS
9 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
10 * implied. See the License for the specific language governing
11 * rights and limitations under the License.
12 *
13 * The Original Code is the Netscape Portable Runtime (NSPR).
14 *
15 * The Initial Developer of the Original Code is Netscape
16 * Communications Corporation.  Portions created by Netscape are
17 * Copyright (C) 1998-2000 Netscape Communications Corporation.  All
18 * Rights Reserved.
19 *
20 * Contributor(s):
21 *
22 * Alternatively, the contents of this file may be used under the
23 * terms of the GNU General Public License Version 2 or later (the
24 * "GPL"), in which case the provisions of the GPL are applicable
25 * instead of those above.  If you wish to allow use of your
26 * version of this file only under the terms of the GPL and not to
27 * allow others to use your version of this file under the MPL,
28 * indicate your decision by deleting the provisions above and
29 * replace them with the notice and other provisions required by
30 * the GPL.  If you do not delete the provisions above, a recipient
31 * may use your version of this file under either the MPL or the
32 * GPL.
33 */
34
35/*
36** File:		prrwlock.h
37** Description:	API to basic reader-writer lock functions of NSPR.
38**
39**/
40
41#ifndef prrwlock_h___
42#define prrwlock_h___
43
44#include "prtypes.h"
45
46PR_BEGIN_EXTERN_C
47
48/*
49 * PRRWLock --
50 *
51 *	The reader writer lock, PRRWLock, is an opaque object to the clients
52 *	of NSPR.  All routines operate on a pointer to this opaque entity.
53 */
54
55
56typedef struct PRRWLock PRRWLock;
57
58#define	PR_RWLOCK_RANK_NONE	0
59
60
61/***********************************************************************
62** FUNCTION:    PR_NewRWLock
63** DESCRIPTION:
64**  Returns a pointer to a newly created reader-writer lock object.
65** INPUTS:      Lock rank
66**				Lock name
67** OUTPUTS:     void
68** RETURN:      PRRWLock*
69**   If the lock cannot be created because of resource constraints, NULL
70**   is returned.
71**
72***********************************************************************/
73NSPR_API(PRRWLock*) PR_NewRWLock(PRUint32 lock_rank, const char *lock_name);
74
75/***********************************************************************
76** FUNCTION:    PR_DestroyRWLock
77** DESCRIPTION:
78**  Destroys a given RW lock object.
79** INPUTS:      PRRWLock *lock - Lock to be freed.
80** OUTPUTS:     void
81** RETURN:      None
82***********************************************************************/
83NSPR_API(void) PR_DestroyRWLock(PRRWLock *lock);
84
85/***********************************************************************
86** FUNCTION:    PR_RWLock_Rlock
87** DESCRIPTION:
88**  Apply a read lock (non-exclusive) on a RWLock
89** INPUTS:      PRRWLock *lock - Lock to be read-locked.
90** OUTPUTS:     void
91** RETURN:      None
92***********************************************************************/
93NSPR_API(void) PR_RWLock_Rlock(PRRWLock *lock);
94
95/***********************************************************************
96** FUNCTION:    PR_RWLock_Wlock
97** DESCRIPTION:
98**  Apply a write lock (exclusive) on a RWLock
99** INPUTS:      PRRWLock *lock - Lock to write-locked.
100** OUTPUTS:     void
101** RETURN:      None
102***********************************************************************/
103NSPR_API(void) PR_RWLock_Wlock(PRRWLock *lock);
104
105/***********************************************************************
106** FUNCTION:    PR_RWLock_Unlock
107** DESCRIPTION:
108**  Release a RW lock. Unlocking an unlocked lock has undefined results.
109** INPUTS:      PRRWLock *lock - Lock to unlocked.
110** OUTPUTS:     void
111** RETURN:      void
112***********************************************************************/
113NSPR_API(void) PR_RWLock_Unlock(PRRWLock *lock);
114
115PR_END_EXTERN_C
116
117#endif /* prrwlock_h___ */
118