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fff98f6316
git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@3693 d0543943-73ff-0310-b7d9-9358b9ac24b2
277 lines
8.7 KiB
C
277 lines
8.7 KiB
C
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is the Netscape Portable Runtime (NSPR).
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 1998-2000
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#include <kernel/OS.h>
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#include "primpl.h"
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/*
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** Create a new condition variable.
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**
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** "lock" is the lock used to protect the condition variable.
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**
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** Condition variables are synchronization objects that threads can use
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** to wait for some condition to occur.
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**
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** This may fail if memory is tight or if some operating system resource
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** is low. In such cases, a NULL will be returned.
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*/
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PR_IMPLEMENT(PRCondVar*)
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PR_NewCondVar (PRLock *lock)
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{
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PRCondVar *cv = PR_NEW( PRCondVar );
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PR_ASSERT( NULL != lock );
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if( NULL != cv )
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{
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cv->lock = lock;
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cv->sem = create_sem(0, "CVSem");
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cv->handshakeSem = create_sem(0, "CVHandshake");
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cv->signalSem = create_sem( 0, "CVSignal");
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cv->signalBenCount = 0;
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cv->ns = cv->nw = 0;
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PR_ASSERT( cv->sem >= B_NO_ERROR );
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PR_ASSERT( cv->handshakeSem >= B_NO_ERROR );
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PR_ASSERT( cv->signalSem >= B_NO_ERROR );
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}
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return cv;
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} /* PR_NewCondVar */
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/*
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** Destroy a condition variable. There must be no thread
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** waiting on the condvar. The caller is responsible for guaranteeing
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** that the condvar is no longer in use.
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**
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*/
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PR_IMPLEMENT(void)
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PR_DestroyCondVar (PRCondVar *cvar)
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{
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status_t result = delete_sem( cvar->sem );
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PR_ASSERT( result == B_NO_ERROR );
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result = delete_sem( cvar->handshakeSem );
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PR_ASSERT( result == B_NO_ERROR );
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result = delete_sem( cvar->signalSem );
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PR_ASSERT( result == B_NO_ERROR );
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PR_DELETE( cvar );
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}
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/*
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** The thread that waits on a condition is blocked in a "waiting on
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** condition" state until another thread notifies the condition or a
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** caller specified amount of time expires. The lock associated with
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** the condition variable will be released, which must have be held
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** prior to the call to wait.
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**
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** Logically a notified thread is moved from the "waiting on condition"
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** state and made "ready." When scheduled, it will attempt to reacquire
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** the lock that it held when wait was called.
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**
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** The timeout has two well known values, PR_INTERVAL_NO_TIMEOUT and
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** PR_INTERVAL_NO_WAIT. The former value requires that a condition be
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** notified (or the thread interrupted) before it will resume from the
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** wait. If the timeout has a value of PR_INTERVAL_NO_WAIT, the effect
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** is to release the lock, possibly causing a rescheduling within the
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** runtime, then immediately attempting to reacquire the lock and resume.
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**
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** Any other value for timeout will cause the thread to be rescheduled
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** either due to explicit notification or an expired interval. The latter
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** must be determined by treating time as one part of the monitored data
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** being protected by the lock and tested explicitly for an expired
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** interval.
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**
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** Returns PR_FAILURE if the caller has not locked the lock associated
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** with the condition variable or the thread was interrupted (PR_Interrupt()).
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** The particular reason can be extracted with PR_GetError().
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*/
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PR_IMPLEMENT(PRStatus)
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PR_WaitCondVar (PRCondVar *cvar, PRIntervalTime timeout)
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{
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status_t err;
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if( timeout == PR_INTERVAL_NO_WAIT )
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{
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PR_Unlock( cvar->lock );
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PR_Lock( cvar->lock );
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return PR_SUCCESS;
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}
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if( atomic_add( &cvar->signalBenCount, 1 ) > 0 )
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{
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if (acquire_sem(cvar->signalSem) == B_INTERRUPTED)
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{
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atomic_add( &cvar->signalBenCount, -1 );
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return PR_FAILURE;
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}
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}
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cvar->nw += 1;
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if( atomic_add( &cvar->signalBenCount, -1 ) > 1 )
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{
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release_sem_etc(cvar->signalSem, 1, B_DO_NOT_RESCHEDULE);
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}
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PR_Unlock( cvar->lock );
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if( timeout==PR_INTERVAL_NO_TIMEOUT )
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{
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err = acquire_sem(cvar->sem);
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}
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else
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{
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err = acquire_sem_etc(cvar->sem, 1, B_RELATIVE_TIMEOUT, PR_IntervalToMicroseconds(timeout) );
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}
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if( atomic_add( &cvar->signalBenCount, 1 ) > 0 )
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{
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while (acquire_sem(cvar->signalSem) == B_INTERRUPTED);
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}
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if (cvar->ns > 0)
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{
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release_sem_etc(cvar->handshakeSem, 1, B_DO_NOT_RESCHEDULE);
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cvar->ns -= 1;
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}
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cvar->nw -= 1;
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if( atomic_add( &cvar->signalBenCount, -1 ) > 1 )
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{
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release_sem_etc(cvar->signalSem, 1, B_DO_NOT_RESCHEDULE);
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}
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PR_Lock( cvar->lock );
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if(err!=B_NO_ERROR)
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{
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return PR_FAILURE;
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}
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return PR_SUCCESS;
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}
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/*
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** Notify ONE thread that is currently waiting on 'cvar'. Which thread is
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** dependent on the implementation of the runtime. Common sense would dictate
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** that all threads waiting on a single condition have identical semantics,
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** therefore which one gets notified is not significant.
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**
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** The calling thead must hold the lock that protects the condition, as
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** well as the invariants that are tightly bound to the condition, when
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** notify is called.
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**
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** Returns PR_FAILURE if the caller has not locked the lock associated
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** with the condition variable.
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*/
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PR_IMPLEMENT(PRStatus)
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PR_NotifyCondVar (PRCondVar *cvar)
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{
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status_t err ;
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if( atomic_add( &cvar->signalBenCount, 1 ) > 0 )
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{
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if (acquire_sem(cvar->signalSem) == B_INTERRUPTED)
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{
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atomic_add( &cvar->signalBenCount, -1 );
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return PR_FAILURE;
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}
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}
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if (cvar->nw > cvar->ns)
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{
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cvar->ns += 1;
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release_sem_etc(cvar->sem, 1, B_DO_NOT_RESCHEDULE);
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if( atomic_add( &cvar->signalBenCount, -1 ) > 1 )
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{
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release_sem_etc(cvar->signalSem, 1, B_DO_NOT_RESCHEDULE);
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}
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while (acquire_sem(cvar->handshakeSem) == B_INTERRUPTED)
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{
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err = B_INTERRUPTED;
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}
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}
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else
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{
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if( atomic_add( &cvar->signalBenCount, -1 ) > 1 )
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{
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release_sem_etc(cvar->signalSem, 1, B_DO_NOT_RESCHEDULE);
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}
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}
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return PR_SUCCESS;
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}
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/*
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** Notify all of the threads waiting on the condition variable. The order
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** that the threads are notified is indeterminant. The lock that protects
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** the condition must be held.
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**
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** Returns PR_FAILURE if the caller has not locked the lock associated
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** with the condition variable.
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*/
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PR_IMPLEMENT(PRStatus)
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PR_NotifyAllCondVar (PRCondVar *cvar)
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{
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int32 handshakes;
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status_t err = B_OK;
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if( atomic_add( &cvar->signalBenCount, 1 ) > 0 )
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{
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if (acquire_sem(cvar->signalSem) == B_INTERRUPTED)
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{
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atomic_add( &cvar->signalBenCount, -1 );
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return PR_FAILURE;
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}
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}
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if (cvar->nw > cvar->ns)
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{
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handshakes = cvar->nw - cvar->ns;
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cvar->ns = cvar->nw;
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release_sem_etc(cvar->sem, handshakes, B_DO_NOT_RESCHEDULE);
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if( atomic_add( &cvar->signalBenCount, -1 ) > 1 )
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{
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release_sem_etc(cvar->signalSem, 1, B_DO_NOT_RESCHEDULE);
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}
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while (acquire_sem_etc(cvar->handshakeSem, handshakes, 0, 0) == B_INTERRUPTED)
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{
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err = B_INTERRUPTED;
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}
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}
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else
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{
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if( atomic_add( &cvar->signalBenCount, -1 ) > 1 )
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{
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release_sem_etc(cvar->signalSem, 1, B_DO_NOT_RESCHEDULE);
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}
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}
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return PR_SUCCESS;
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}
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