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| 1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ |
| 2 /* ***** BEGIN LICENSE BLOCK ***** |
| 3 * Version: MPL 1.1/GPL 2.0/LGPL 2.1 |
| 4 * |
| 5 * The contents of this file are subject to the Mozilla Public License Version |
| 6 * 1.1 (the "License"); you may not use this file except in compliance with |
| 7 * the License. You may obtain a copy of the License at |
| 8 * http://www.mozilla.org/MPL/ |
| 9 * |
| 10 * Software distributed under the License is distributed on an "AS IS" basis, |
| 11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License |
| 12 * for the specific language governing rights and limitations under the |
| 13 * License. |
| 14 * |
| 15 * The Original Code is the Netscape Portable Runtime (NSPR). |
| 16 * |
| 17 * The Initial Developer of the Original Code is |
| 18 * Netscape Communications Corporation. |
| 19 * Portions created by the Initial Developer are Copyright (C) 1999-2000 |
| 20 * the Initial Developer. All Rights Reserved. |
| 21 * |
| 22 * Contributor(s): |
| 23 * |
| 24 * Alternatively, the contents of this file may be used under the terms of |
| 25 * either the GNU General Public License Version 2 or later (the "GPL"), or |
| 26 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), |
| 27 * in which case the provisions of the GPL or the LGPL are applicable instead |
| 28 * of those above. If you wish to allow use of your version of this file only |
| 29 * under the terms of either the GPL or the LGPL, and not to allow others to |
| 30 * use your version of this file under the terms of the MPL, indicate your |
| 31 * decision by deleting the provisions above and replace them with the notice |
| 32 * and other provisions required by the GPL or the LGPL. If you do not delete |
| 33 * the provisions above, a recipient may use your version of this file under |
| 34 * the terms of any one of the MPL, the GPL or the LGPL. |
| 35 * |
| 36 * ***** END LICENSE BLOCK ***** */ |
| 37 |
| 38 /* |
| 39 * File: pripcsem.h |
| 40 * |
| 41 * Description: named semaphores for interprocess |
| 42 * synchronization |
| 43 * |
| 44 * Unrelated processes obtain access to a shared semaphore |
| 45 * by specifying its name. |
| 46 * |
| 47 * Our goal is to support named semaphores on at least |
| 48 * Unix and Win32 platforms. The implementation will use |
| 49 * one of the three native semaphore APIs: POSIX, System V, |
| 50 * and Win32. |
| 51 * |
| 52 * Because POSIX named semaphores have kernel persistence, |
| 53 * we are forced to have a delete function in this API. |
| 54 */ |
| 55 |
| 56 #ifndef pripcsem_h___ |
| 57 #define pripcsem_h___ |
| 58 |
| 59 #include "prtypes.h" |
| 60 #include "prio.h" |
| 61 |
| 62 PR_BEGIN_EXTERN_C |
| 63 |
| 64 /* |
| 65 * PRSem is an opaque structure that represents a named |
| 66 * semaphore. |
| 67 */ |
| 68 typedef struct PRSem PRSem; |
| 69 |
| 70 /* |
| 71 * PR_OpenSemaphore -- |
| 72 * |
| 73 * Create or open a named semaphore with the specified name. |
| 74 * A handle to the semaphore is returned. |
| 75 * |
| 76 * If the named semaphore doesn't exist and the PR_SEM_CREATE |
| 77 * flag is specified, the named semaphore is created. The |
| 78 * created semaphore needs to be removed from the system with |
| 79 * a PR_DeleteSemaphore call. |
| 80 * |
| 81 * If PR_SEM_CREATE is specified, the third argument is the |
| 82 * access permission bits of the new semaphore (same |
| 83 * interpretation as the mode argument to PR_Open) and the |
| 84 * fourth argument is the initial value of the new semaphore. |
| 85 * If PR_SEM_CREATE is not specified, the third and fourth |
| 86 * arguments are ignored. |
| 87 */ |
| 88 |
| 89 #define PR_SEM_CREATE 0x1 /* create if not exist */ |
| 90 #define PR_SEM_EXCL 0x2 /* fail if already exists */ |
| 91 |
| 92 NSPR_API(PRSem *) PR_OpenSemaphore( |
| 93 const char *name, PRIntn flags, PRIntn mode, PRUintn value); |
| 94 |
| 95 /* |
| 96 * PR_WaitSemaphore -- |
| 97 * |
| 98 * If the value of the semaphore is > 0, decrement the value and return. |
| 99 * If the value is 0, sleep until the value becomes > 0, then decrement |
| 100 * the value and return. |
| 101 * |
| 102 * The "test and decrement" operation is performed atomically. |
| 103 */ |
| 104 |
| 105 NSPR_API(PRStatus) PR_WaitSemaphore(PRSem *sem); |
| 106 |
| 107 /* |
| 108 * PR_PostSemaphore -- |
| 109 * |
| 110 * Increment the value of the named semaphore by 1. |
| 111 */ |
| 112 |
| 113 NSPR_API(PRStatus) PR_PostSemaphore(PRSem *sem); |
| 114 |
| 115 /* |
| 116 * PR_CloseSemaphore -- |
| 117 * |
| 118 * Close a named semaphore handle. |
| 119 */ |
| 120 |
| 121 NSPR_API(PRStatus) PR_CloseSemaphore(PRSem *sem); |
| 122 |
| 123 /* |
| 124 * PR_DeleteSemaphore -- |
| 125 * |
| 126 * Remove a named semaphore from the system. |
| 127 */ |
| 128 |
| 129 NSPR_API(PRStatus) PR_DeleteSemaphore(const char *name); |
| 130 |
| 131 PR_END_EXTERN_C |
| 132 |
| 133 #endif /* pripcsem_h___ */ |
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