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