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/gecko_api/include/obsolete/prsem.h

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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) 1998-2000
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#ifndef prsem_h___
39#define prsem_h___
40
41/*
42** API for counting semaphores. Semaphores are counting synchronizing 
43** variables based on a lock and a condition variable.  They are lightweight 
44** contention control for a given count of resources.
45*/
46#include "prtypes.h"
47
48PR_BEGIN_EXTERN_C
49
50typedef struct PRSemaphore PRSemaphore;
51
52/*
53** Create a new semaphore object.
54*/
55NSPR_API(PRSemaphore*) PR_NewSem(PRUintn value);
56
57/*
58** Destroy the given semaphore object.
59**
60*/
61NSPR_API(void) PR_DestroySem(PRSemaphore *sem);
62
63/*
64** Wait on a Semaphore.
65** 
66** This routine allows a calling thread to wait or proceed depending upon the 
67** state of the semahore sem. The thread can proceed only if the counter value 
68** of the semaphore sem is currently greater than 0. If the value of semaphore 
69** sem is positive, it is decremented by one and the routine returns immediately 
70** allowing the calling thread to continue. If the value of semaphore sem is 0, 
71** the calling thread blocks awaiting the semaphore to be released by another 
72** thread.
73** 
74** This routine can return PR_PENDING_INTERRUPT if the waiting thread 
75** has been interrupted.
76*/
77NSPR_API(PRStatus) PR_WaitSem(PRSemaphore *sem);
78
79/*
80** This routine increments the counter value of the semaphore. If other threads 
81** are blocked for the semaphore, then the scheduler will determine which ONE 
82** thread will be unblocked.
83*/
84NSPR_API(void) PR_PostSem(PRSemaphore *sem);
85
86/*
87** Returns the value of the semaphore referenced by sem without affecting
88** the state of the semaphore.  The value represents the semaphore vaule
89F** at the time of the call, but may not be the actual value when the
90** caller inspects it.
91*/
92NSPR_API(PRUintn) PR_GetValueSem(PRSemaphore *sem);
93
94PR_END_EXTERN_C
95
96#endif /* prsem_h___ */