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1.1 root 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___ */
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