The Tor Browser: nsprpub/pr/include/obsolete/prsem.h@44a2da4a2ab2

Replace accessor implementation with direct member state manipulation, by
request https://trac.torproject.org/projects/tor/ticket/9701#comment:32

     1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

     2 /* This Source Code Form is subject to the terms of the Mozilla Public

     3  * License, v. 2.0. If a copy of the MPL was not distributed with this

     4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     6 #ifndef prsem_h___

     7 #define prsem_h___

     9 /*

    10 ** API for counting semaphores. Semaphores are counting synchronizing

    11 ** variables based on a lock and a condition variable.  They are lightweight

    12 ** contention control for a given count of resources.

    13 */

    14 #include "prtypes.h"

    16 PR_BEGIN_EXTERN_C

    18 typedef struct PRSemaphore PRSemaphore;

    20 /*

    21 ** Create a new semaphore object.

    22 */

    23 NSPR_API(PRSemaphore*) PR_NewSem(PRUintn value);

    25 /*

    26 ** Destroy the given semaphore object.

    27 **

    28 */

    29 NSPR_API(void) PR_DestroySem(PRSemaphore *sem);

    31 /*

    32 ** Wait on a Semaphore.

    33 **

    34 ** This routine allows a calling thread to wait or proceed depending upon the

    35 ** state of the semahore sem. The thread can proceed only if the counter value

    36 ** of the semaphore sem is currently greater than 0. If the value of semaphore

    37 ** sem is positive, it is decremented by one and the routine returns immediately

    38 ** allowing the calling thread to continue. If the value of semaphore sem is 0,

    39 ** the calling thread blocks awaiting the semaphore to be released by another

    40 ** thread.

    41 **

    42 ** This routine can return PR_PENDING_INTERRUPT if the waiting thread

    43 ** has been interrupted.

    44 */

    45 NSPR_API(PRStatus) PR_WaitSem(PRSemaphore *sem);

    47 /*

    48 ** This routine increments the counter value of the semaphore. If other threads

    49 ** are blocked for the semaphore, then the scheduler will determine which ONE

    50 ** thread will be unblocked.

    51 */

    52 NSPR_API(void) PR_PostSem(PRSemaphore *sem);

    54 /*

    55 ** Returns the value of the semaphore referenced by sem without affecting

    56 ** the state of the semaphore.  The value represents the semaphore vaule

    57 F** at the time of the call, but may not be the actual value when the

    58 ** caller inspects it.

    59 */

    60 NSPR_API(PRUintn) PR_GetValueSem(PRSemaphore *sem);

    62 PR_END_EXTERN_C

    64 #endif /* prsem_h___ */

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