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