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:		prlock.h
37** Description:	API to basic locking functions of NSPR.
38**
39**
40** NSPR provides basic locking mechanisms for thread synchronization.  Locks
41** are lightweight resource contention controls that prevent multiple threads
42** from accessing something (code/data) simultaneously.
43**/
44
45#ifndef prlock_h___
46#define prlock_h___
47
48#include "prtypes.h"
49
50PR_BEGIN_EXTERN_C
51
52/**********************************************************************/
53/************************* TYPES AND CONSTANTS ************************/
54/**********************************************************************/
55
56/*
57 * PRLock --
58 *
59 *     NSPR represents the lock as an opaque entity to the client of the
60 *	   API.  All routines operate on a pointer to this opaque entity.
61 */
62
63typedef struct PRLock PRLock;
64
65/**********************************************************************/
66/****************************** FUNCTIONS *****************************/
67/**********************************************************************/
68
69/***********************************************************************
70** FUNCTION:    PR_NewLock
71** DESCRIPTION:
72**  Returns a pointer to a newly created opaque lock object.
73** INPUTS:      void
74** OUTPUTS:     void
75** RETURN:      PRLock*
76**   If the lock can not be created because of resource constraints, NULL
77**   is returned.
78**
79***********************************************************************/
80NSPR_API(PRLock*) PR_NewLock(void);
81
82/***********************************************************************
83** FUNCTION:    PR_DestroyLock
84** DESCRIPTION:
85**  Destroys a given opaque lock object.
86** INPUTS:      PRLock *lock
87**              Lock to be freed.
88** OUTPUTS:     void
89** RETURN:      None
90***********************************************************************/
91NSPR_API(void) PR_DestroyLock(PRLock *lock);
92
93/***********************************************************************
94** FUNCTION:    PR_Lock
95** DESCRIPTION:
96**  Lock a lock.
97** INPUTS:      PRLock *lock
98**              Lock to locked.
99** OUTPUTS:     void
100** RETURN:      None
101***********************************************************************/
102NSPR_API(void) PR_Lock(PRLock *lock);
103
104/***********************************************************************
105** FUNCTION:    PR_Unlock
106** DESCRIPTION:
107**  Unlock a lock.  Unlocking an unlocked lock has undefined results.
108** INPUTS:      PRLock *lock
109**              Lock to unlocked.
110** OUTPUTS:     void
111** RETURN:      PR_STATUS
112**              Returns PR_FAILURE if the caller does not own the lock.
113***********************************************************************/
114NSPR_API(PRStatus) PR_Unlock(PRLock *lock);
115
116PR_END_EXTERN_C
117
118#endif /* prlock_h___ */
119