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 46 PR_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 56 typedef 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 ***********************************************************************/ 73 NSPR_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 ***********************************************************************/ 83 NSPR_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 ***********************************************************************/ 93 NSPR_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 ***********************************************************************/ 103 NSPR_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 ***********************************************************************/ 113 NSPR_API(void) PR_RWLock_Unlock(PRRWLock *lock); 114 115 PR_END_EXTERN_C 116 117 #endif /* prrwlock_h___ */ 118