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102 lines
2.6 KiB
C
102 lines
2.6 KiB
C
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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* File: pripcsem.h
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*
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* Description: named semaphores for interprocess
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* synchronization
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*
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* Unrelated processes obtain access to a shared semaphore
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* by specifying its name.
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*
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* Our goal is to support named semaphores on at least
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* Unix and Win32 platforms. The implementation will use
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* one of the three native semaphore APIs: POSIX, System V,
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* and Win32.
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*
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* Because POSIX named semaphores have kernel persistence,
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* we are forced to have a delete function in this API.
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*/
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#ifndef pripcsem_h___
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#define pripcsem_h___
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#include "prtypes.h"
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#include "prio.h"
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PR_BEGIN_EXTERN_C
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/*
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* PRSem is an opaque structure that represents a named
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* semaphore.
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*/
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typedef struct PRSem PRSem;
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/*
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* PR_OpenSemaphore --
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*
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* Create or open a named semaphore with the specified name.
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* A handle to the semaphore is returned.
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*
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* If the named semaphore doesn't exist and the PR_SEM_CREATE
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* flag is specified, the named semaphore is created. The
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* created semaphore needs to be removed from the system with
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* a PR_DeleteSemaphore call.
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*
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* If PR_SEM_CREATE is specified, the third argument is the
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* access permission bits of the new semaphore (same
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* interpretation as the mode argument to PR_Open) and the
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* fourth argument is the initial value of the new semaphore.
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* If PR_SEM_CREATE is not specified, the third and fourth
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* arguments are ignored.
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*/
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#define PR_SEM_CREATE 0x1 /* create if not exist */
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#define PR_SEM_EXCL 0x2 /* fail if already exists */
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NSPR_API(PRSem *) PR_OpenSemaphore(
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const char *name, PRIntn flags, PRIntn mode, PRUintn value);
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/*
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* PR_WaitSemaphore --
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*
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* If the value of the semaphore is > 0, decrement the value and return.
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* If the value is 0, sleep until the value becomes > 0, then decrement
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* the value and return.
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*
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* The "test and decrement" operation is performed atomically.
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*/
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NSPR_API(PRStatus) PR_WaitSemaphore(PRSem *sem);
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/*
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* PR_PostSemaphore --
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*
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* Increment the value of the named semaphore by 1.
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*/
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NSPR_API(PRStatus) PR_PostSemaphore(PRSem *sem);
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/*
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* PR_CloseSemaphore --
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*
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* Close a named semaphore handle.
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*/
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NSPR_API(PRStatus) PR_CloseSemaphore(PRSem *sem);
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/*
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* PR_DeleteSemaphore --
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*
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* Remove a named semaphore from the system.
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*/
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NSPR_API(PRStatus) PR_DeleteSemaphore(const char *name);
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PR_END_EXTERN_C
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#endif /* pripcsem_h___ */
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