andre@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
andre@0: /* This Source Code Form is subject to the terms of the Mozilla Public
andre@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
andre@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
andre@0: 
andre@0: #ifndef prsem_h___
andre@0: #define prsem_h___
andre@0: 
andre@0: /*
andre@0: ** API for counting semaphores. Semaphores are counting synchronizing 
andre@0: ** variables based on a lock and a condition variable.  They are lightweight 
andre@0: ** contention control for a given count of resources.
andre@0: */
andre@0: #include "prtypes.h"
andre@0: 
andre@0: PR_BEGIN_EXTERN_C
andre@0: 
andre@0: typedef struct PRSemaphore PRSemaphore;
andre@0: 
andre@0: /*
andre@0: ** Create a new semaphore object.
andre@0: */
andre@0: NSPR_API(PRSemaphore*) PR_NewSem(PRUintn value);
andre@0: 
andre@0: /*
andre@0: ** Destroy the given semaphore object.
andre@0: **
andre@0: */
andre@0: NSPR_API(void) PR_DestroySem(PRSemaphore *sem);
andre@0: 
andre@0: /*
andre@0: ** Wait on a Semaphore.
andre@0: ** 
andre@0: ** This routine allows a calling thread to wait or proceed depending upon the 
andre@0: ** state of the semahore sem. The thread can proceed only if the counter value 
andre@0: ** of the semaphore sem is currently greater than 0. If the value of semaphore 
andre@0: ** sem is positive, it is decremented by one and the routine returns immediately 
andre@0: ** allowing the calling thread to continue. If the value of semaphore sem is 0, 
andre@0: ** the calling thread blocks awaiting the semaphore to be released by another 
andre@0: ** thread.
andre@0: ** 
andre@0: ** This routine can return PR_PENDING_INTERRUPT if the waiting thread 
andre@0: ** has been interrupted.
andre@0: */
andre@0: NSPR_API(PRStatus) PR_WaitSem(PRSemaphore *sem);
andre@0: 
andre@0: /*
andre@0: ** This routine increments the counter value of the semaphore. If other threads 
andre@0: ** are blocked for the semaphore, then the scheduler will determine which ONE 
andre@0: ** thread will be unblocked.
andre@0: */
andre@0: NSPR_API(void) PR_PostSem(PRSemaphore *sem);
andre@0: 
andre@0: /*
andre@0: ** Returns the value of the semaphore referenced by sem without affecting
andre@0: ** the state of the semaphore.  The value represents the semaphore vaule
andre@0: F** at the time of the call, but may not be the actual value when the
andre@0: ** caller inspects it.
andre@0: */
andre@0: NSPR_API(PRUintn) PR_GetValueSem(PRSemaphore *sem);
andre@0: 
andre@0: PR_END_EXTERN_C
andre@0: 
andre@0: #endif /* prsem_h___ */