The Tor Browser: nsprpub/pr/src/bthreads/btsem.c@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

     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 #include <kernel/OS.h>

     8 #include "primpl.h"

    10 /*

    11 ** Create a new semaphore object.

    12 */

    13 PR_IMPLEMENT(PRSemaphore*)

    14     PR_NewSem (PRUintn value)

    15 {

    16 	PRSemaphore *semaphore;

    18 	if (!_pr_initialized) _PR_ImplicitInitialization();

    20 	semaphore = PR_NEWZAP(PRSemaphore);

    21 	if (NULL != semaphore) {

    22 		if ((semaphore->sem = create_sem(value, "nspr_sem")) < B_NO_ERROR)

    23 			return NULL;

    24 		else

    25 			return semaphore;

    26 	}

    27 	return NULL;

    28 }

    30 /*

    31 ** Destroy the given semaphore object.

    32 **

    33 */

    34 PR_IMPLEMENT(void)

    35     PR_DestroySem (PRSemaphore *sem)

    36 {

    37 	status_t result;

    39 	PR_ASSERT(sem != NULL);

    40 	result = delete_sem(sem->sem);

    41 	PR_ASSERT(result == B_NO_ERROR);

    42 	PR_DELETE(sem);

    43 }

    45 /*

    46 ** Wait on a Semaphore.

    47 **

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

    49 ** the state of the semahore sem. The thread can proceed only if the

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

    51 ** value of semaphore sem is positive, it is decremented by one and the

    52 ** routine returns immediately allowing the calling thread to continue. If

    53 ** the value of semaphore sem is 0, the calling thread blocks awaiting the

    54 ** semaphore to be released by another thread.

    55 **

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

    57 ** has been interrupted.

    58 */

    59 PR_IMPLEMENT(PRStatus)

    60     PR_WaitSem (PRSemaphore *sem)

    61 {

    62 	PR_ASSERT(sem != NULL);

    63 	if (acquire_sem(sem->sem) == B_NO_ERROR)

    64 		return PR_SUCCESS;

    65 	else

    66 		return PR_FAILURE;

    67 }

    69 /*

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

    71 ** threads are blocked for the semaphore, then the scheduler will

    72 ** determine which ONE thread will be unblocked.

    73 */

    74 PR_IMPLEMENT(void)

    75     PR_PostSem (PRSemaphore *sem)

    76 {

    77 	status_t result;

    79 	PR_ASSERT(sem != NULL);

    80 	result = release_sem_etc(sem->sem, 1, B_DO_NOT_RESCHEDULE);

    81 	PR_ASSERT(result == B_NO_ERROR);

    82 }

    84 /*

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

    86 ** the state of the semaphore.  The value represents the semaphore value

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

    88 ** caller inspects it.

    89 */

    90 PR_IMPLEMENT(PRUintn)

    91     PR_GetValueSem (PRSemaphore *sem)

    92 {

    93 	sem_info	info;

    95 	PR_ASSERT(sem != NULL);

    96 	get_sem_info(sem->sem, &info);

    97 	return info.count;

    98 }

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