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 50 PR_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 63 typedef 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 ***********************************************************************/ 80 NSPR_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 ***********************************************************************/ 91 NSPR_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 ***********************************************************************/ 102 NSPR_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 ***********************************************************************/ 114 NSPR_API(PRStatus) PR_Unlock(PRLock *lock); 115 116 PR_END_EXTERN_C 117 118 #endif /* prlock_h___ */ 119