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65 lines
2.0 KiB
C
65 lines
2.0 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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#ifndef prsem_h___
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#define prsem_h___
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/*
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** API for counting semaphores. Semaphores are counting synchronizing
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** variables based on a lock and a condition variable. They are lightweight
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** contention control for a given count of resources.
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*/
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#include "prtypes.h"
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PR_BEGIN_EXTERN_C
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typedef struct PRSemaphore PRSemaphore;
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/*
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** Create a new semaphore object.
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*/
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NSPR_API(PRSemaphore*) PR_NewSem(PRUintn value);
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/*
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** Destroy the given semaphore object.
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**
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*/
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NSPR_API(void) PR_DestroySem(PRSemaphore *sem);
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/*
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** Wait on a Semaphore.
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**
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** This routine allows a calling thread to wait or proceed depending upon the
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** state of the semahore sem. The thread can proceed only if the counter value
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** of the semaphore sem is currently greater than 0. If the value of semaphore
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** sem is positive, it is decremented by one and the routine returns immediately
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** allowing the calling thread to continue. If the value of semaphore sem is 0,
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** the calling thread blocks awaiting the semaphore to be released by another
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** thread.
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**
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** This routine can return PR_PENDING_INTERRUPT if the waiting thread
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** has been interrupted.
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*/
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NSPR_API(PRStatus) PR_WaitSem(PRSemaphore *sem);
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/*
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** This routine increments the counter value of the semaphore. If other threads
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** are blocked for the semaphore, then the scheduler will determine which ONE
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** thread will be unblocked.
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*/
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NSPR_API(void) PR_PostSem(PRSemaphore *sem);
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/*
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** Returns the value of the semaphore referenced by sem without affecting
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** the state of the semaphore. The value represents the semaphore vaule
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F** at the time of the call, but may not be the actual value when the
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** caller inspects it.
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*/
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NSPR_API(PRUintn) PR_GetValueSem(PRSemaphore *sem);
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PR_END_EXTERN_C
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#endif /* prsem_h___ */
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