third_party/npapi/npspy/extern/nspr/pripcsem.h

   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) 1999-2000 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: pripcsem.h
  37  *
  38  * Description: named semaphores for interprocess
  39  * synchronization
  40  *
  41  * Unrelated processes obtain access to a shared semaphore
  42  * by specifying its name.
  43  *
  44  * Our goal is to support named semaphores on at least
  45  * Unix and Win32 platforms.  The implementation will use
  46  * one of the three native semaphore APIs: POSIX, System V,
  47  * and Win32.
  48  *
  49  * Because POSIX named semaphores have kernel persistence,
  50  * we are forced to have a delete function in this API.
  51  */
  52
  53 #ifndef pripcsem_h___
  54 #define pripcsem_h___
  55
  56 #include "prtypes.h"
  57 #include "prio.h"
  58
  59 PR_BEGIN_EXTERN_C
  60
  61 /*
  62  * PRSem is an opaque structure that represents a named
  63  * semaphore.
  64  */
  65 typedef struct PRSem PRSem;
  66
  67 /*
  68  * PR_OpenSemaphore --
  69  *
  70  * Create or open a named semaphore with the specified name.
  71  * A handle to the semaphore is returned.
  72  *
  73  * If the named semaphore doesn't exist and the PR_SEM_CREATE
  74  * flag is specified, the named semaphore is created.  The
  75  * created semaphore needs to be removed from the system with
  76  * a PR_DeleteSemaphore call.
  77  *
  78  * If PR_SEM_CREATE is specified, the third argument is the
  79  * access permission bits of the new semaphore (same
  80  * interpretation as the mode argument to PR_Open) and the
  81  * fourth argument is the initial value of the new semaphore.
  82  * If PR_SEM_CREATE is not specified, the third and fourth
  83  * arguments are ignored.
  84  */
  85
  86 #define PR_SEM_CREATE 0x1  /* create if not exist */
  87 #define PR_SEM_EXCL   0x2  /* fail if already exists */
  88
  89 NSPR_API(PRSem *) PR_OpenSemaphore(
  90     const char *name, PRIntn flags, PRIntn mode, PRUintn value);
  91
  92 /*
  93  * PR_WaitSemaphore --
  94  *
  95  * If the value of the semaphore is > 0, decrement the value and return.
  96  * If the value is 0, sleep until the value becomes > 0, then decrement
  97  * the value and return.
  98  *
  99  * The "test and decrement" operation is performed atomically.
 100  */
 101
 102 NSPR_API(PRStatus) PR_WaitSemaphore(PRSem *sem);
 103
 104 /*
 105  * PR_PostSemaphore --
 106  *
 107  * Increment the value of the named semaphore by 1.
 108  */
 109
 110 NSPR_API(PRStatus) PR_PostSemaphore(PRSem *sem);
 111
 112 /*
 113  * PR_CloseSemaphore --
 114  *
 115  * Close a named semaphore handle.
 116  */
 117
 118 NSPR_API(PRStatus) PR_CloseSemaphore(PRSem *sem);
 119
 120 /*
 121  * PR_DeleteSemaphore --
 122  *
 123  * Remove a named semaphore from the system.
 124  */
 125
 126 NSPR_API(PRStatus) PR_DeleteSemaphore(const char *name);
 127
 128 PR_END_EXTERN_C
 129
 130 #endif /* pripcsem_h___ */