prucv.c

Netscape NSPR库源码

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/MPL/
 * 
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 * 
 * The Original Code is the Netscape Portable Runtime (NSPR).
 * 
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are 
 * Copyright (C) 1998-2000 Netscape Communications Corporation.  All
 * Rights Reserved.
 * 
 * Contributor(s):
 * 
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU General Public License Version 2 or later (the
 * "GPL"), in which case the provisions of the GPL are applicable 
 * instead of those above.  If you wish to allow use of your 
 * version of this file only under the terms of the GPL and not to
 * allow others to use your version of this file under the MPL,
 * indicate your decision by deleting the provisions above and
 * replace them with the notice and other provisions required by
 * the GPL.  If you do not delete the provisions above, a recipient
 * may use your version of this file under either the MPL or the
 * GPL.
 */


#include "primpl.h"
#include "prinrval.h"
#include "prtypes.h"

#if defined(WIN95)
/*
** Some local variables report warnings on Win95 because the code paths 
** using them are conditioned on HAVE_CUSTOME_USER_THREADS.
** The pragma suppresses the warning.
** 
*/
#pragma warning(disable : 4101)
#endif


/*
** Notify one thread that it has finished waiting on a condition variable
** Caller must hold the _PR_CVAR_LOCK(cv)
*/
PRBool _PR_NotifyThread (PRThread *thread, PRThread *me)
{
    PRBool rv;

    PR_ASSERT(_PR_IS_NATIVE_THREAD(me) || _PR_MD_GET_INTSOFF() != 0);

    _PR_THREAD_LOCK(thread);
    PR_ASSERT(!(thread->flags & _PR_IDLE_THREAD));
    if ( !_PR_IS_NATIVE_THREAD(thread) ) {
        if (thread->wait.cvar != NULL) {
            thread->wait.cvar = NULL;

            _PR_SLEEPQ_LOCK(thread->cpu);
            /* The notify and timeout can collide; in which case both may
             * attempt to delete from the sleepQ; only let one do it.
             */
            if (thread->flags & (_PR_ON_SLEEPQ|_PR_ON_PAUSEQ))
                _PR_DEL_SLEEPQ(thread, PR_TRUE);
            _PR_SLEEPQ_UNLOCK(thread->cpu);

	    if (thread->flags & _PR_SUSPENDING) {
		/*
		 * set thread state to SUSPENDED; a Resume operation
		 * on the thread will move it to the runQ
		 */
            	thread->state = _PR_SUSPENDED;
		_PR_MISCQ_LOCK(thread->cpu);
		_PR_ADD_SUSPENDQ(thread, thread->cpu);
		_PR_MISCQ_UNLOCK(thread->cpu);
            	_PR_THREAD_UNLOCK(thread);
	    } else {
            	/* Make thread runnable */
            	thread->state = _PR_RUNNABLE;
            	_PR_THREAD_UNLOCK(thread);

                _PR_AddThreadToRunQ(me, thread);
                _PR_MD_WAKEUP_WAITER(thread);
            }

            rv = PR_TRUE;
        } else {
            /* Thread has already been notified */
            _PR_THREAD_UNLOCK(thread);
            rv = PR_FALSE;
        }
    } else { /* If the thread is a native thread */
        if (thread->wait.cvar) {
            thread->wait.cvar = NULL;

	    if (thread->flags & _PR_SUSPENDING) {
		/*
		 * set thread state to SUSPENDED; a Resume operation
		 * on the thread will enable the thread to run
		 */
            	thread->state = _PR_SUSPENDED;
	     } else
            	thread->state = _PR_RUNNING;
            _PR_THREAD_UNLOCK(thread);
            _PR_MD_WAKEUP_WAITER(thread);
            rv = PR_TRUE;
        } else {
            _PR_THREAD_UNLOCK(thread);
            rv = PR_FALSE;
        }    
    }    

    return rv;
}

/*
 * Notify thread waiting on cvar; called when thread is interrupted
 * 	The thread lock is held on entry and released before return
 */
void _PR_NotifyLockedThread (PRThread *thread)
{
    PRThread *me = _PR_MD_CURRENT_THREAD();
    PRCondVar *cvar;
    PRThreadPriority pri;

    if ( !_PR_IS_NATIVE_THREAD(me))
    	PR_ASSERT(_PR_MD_GET_INTSOFF() != 0);

    cvar = thread->wait.cvar;
    thread->wait.cvar = NULL;
    _PR_THREAD_UNLOCK(thread);

    _PR_CVAR_LOCK(cvar);
    _PR_THREAD_LOCK(thread);

    if (!_PR_IS_NATIVE_THREAD(thread)) {
            _PR_SLEEPQ_LOCK(thread->cpu);
            /* The notify and timeout can collide; in which case both may
             * attempt to delete from the sleepQ; only let one do it.
             */
            if (thread->flags & (_PR_ON_SLEEPQ|_PR_ON_PAUSEQ))
                _PR_DEL_SLEEPQ(thread, PR_TRUE);
            _PR_SLEEPQ_UNLOCK(thread->cpu);

	    /* Make thread runnable */
	    pri = thread->priority;
	    thread->state = _PR_RUNNABLE;

	    PR_ASSERT(!(thread->flags & _PR_IDLE_THREAD));

            _PR_AddThreadToRunQ(me, thread);
            _PR_THREAD_UNLOCK(thread);

            _PR_MD_WAKEUP_WAITER(thread);
    } else {
	    if (thread->flags & _PR_SUSPENDING) {
		/*
		 * set thread state to SUSPENDED; a Resume operation
		 * on the thread will enable the thread to run
		 */
            	thread->state = _PR_SUSPENDED;
	     } else
            	thread->state = _PR_RUNNING;
            _PR_THREAD_UNLOCK(thread);
            _PR_MD_WAKEUP_WAITER(thread);
    }    

    _PR_CVAR_UNLOCK(cvar);
    return;
}

/*
** Make the given thread wait for the given condition variable
*/
PRStatus _PR_WaitCondVar(
    PRThread *thread, PRCondVar *cvar, PRLock *lock, PRIntervalTime timeout)
{
    PRIntn is;
    PRStatus rv = PR_SUCCESS;

    PR_ASSERT(thread == _PR_MD_CURRENT_THREAD());
    PR_ASSERT(!(thread->flags & _PR_IDLE_THREAD));

#ifdef _PR_GLOBAL_THREADS_ONLY
    if (_PR_PENDING_INTERRUPT(thread)) {
        PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
        thread->flags &= ~_PR_INTERRUPT;
        return PR_FAILURE;
    }

    thread->wait.cvar = cvar;
    lock->owner = NULL;
    _PR_MD_WAIT_CV(&cvar->md,&lock->ilock, timeout);
    thread->wait.cvar = NULL;
    lock->owner = thread;
    if (_PR_PENDING_INTERRUPT(thread)) {
        PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
        thread->flags &= ~_PR_INTERRUPT;
        return PR_FAILURE;
    }

    return PR_SUCCESS;
#else  /* _PR_GLOBAL_THREADS_ONLY */

    if ( !_PR_IS_NATIVE_THREAD(thread))
    	_PR_INTSOFF(is);

    _PR_CVAR_LOCK(cvar);
    _PR_THREAD_LOCK(thread);

    if (_PR_PENDING_INTERRUPT(thread)) {
        PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
        thread->flags &= ~_PR_INTERRUPT;
    	_PR_CVAR_UNLOCK(cvar);
    	_PR_THREAD_UNLOCK(thread);
    	if ( !_PR_IS_NATIVE_THREAD(thread))
    		_PR_INTSON(is);
        return PR_FAILURE;
    }

    thread->state = _PR_COND_WAIT;
    thread->wait.cvar = cvar;

    /*
    ** Put the caller thread on the condition variable's wait Q
    */
    PR_APPEND_LINK(&thread->waitQLinks, &cvar->condQ);

    /* Note- for global scope threads, we don't put them on the
     *       global sleepQ, so each global thread must put itself
     *       to sleep only for the time it wants to.
     */
    if ( !_PR_IS_NATIVE_THREAD(thread) ) {
        _PR_SLEEPQ_LOCK(thread->cpu);
        _PR_ADD_SLEEPQ(thread, timeout);
        _PR_SLEEPQ_UNLOCK(thread->cpu);
    }
    _PR_CVAR_UNLOCK(cvar);
    _PR_THREAD_UNLOCK(thread);
   
    /* 
    ** Release lock protecting the condition variable and thereby giving time 
    ** to the next thread which can potentially notify on the condition variable
    */
    PR_Unlock(lock);

    PR_LOG(_pr_cvar_lm, PR_LOG_MIN,
	   ("PR_Wait: cvar=%p waiting for %d", cvar, timeout));

    rv = _PR_MD_WAIT(thread, timeout);

    _PR_CVAR_LOCK(cvar);
    PR_REMOVE_LINK(&thread->waitQLinks);
    _PR_CVAR_UNLOCK(cvar);

    PR_LOG(_pr_cvar_lm, PR_LOG_MIN,
	   ("PR_Wait: cvar=%p done waiting", cvar));

    if ( !_PR_IS_NATIVE_THREAD(thread))
    	_PR_INTSON(is);

    /* Acquire lock again that we had just relinquished */
    PR_Lock(lock);

    if (_PR_PENDING_INTERRUPT(thread)) {
        PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
        thread->flags &= ~_PR_INTERRUPT;
        return PR_FAILURE;
    }

    return rv;
#endif  /* _PR_GLOBAL_THREADS_ONLY */
}

void _PR_NotifyCondVar(PRCondVar *cvar, PRThread *me)
{
#ifdef _PR_GLOBAL_THREADS_ONLY
    _PR_MD_NOTIFY_CV(&cvar->md, &cvar->lock->ilock);
#else  /* _PR_GLOBAL_THREADS_ONLY */

    PRCList *q;
    PRIntn is;

    if ( !_PR_IS_NATIVE_THREAD(me))
    	_PR_INTSOFF(is);
    PR_ASSERT(_PR_IS_NATIVE_THREAD(me) || _PR_MD_GET_INTSOFF() != 0);

    _PR_CVAR_LOCK(cvar);
    q = cvar->condQ.next;
    while (q != &cvar->condQ) {
#ifndef XP_MAC
        PR_LOG(_pr_cvar_lm, PR_LOG_MIN, ("_PR_NotifyCondVar: cvar=%p", cvar));
#endif
        if (_PR_THREAD_CONDQ_PTR(q)->wait.cvar)  {
            if (_PR_NotifyThread(_PR_THREAD_CONDQ_PTR(q), me) == PR_TRUE)
                break;
        }
        q = q->next;
    }
    _PR_CVAR_UNLOCK(cvar);

    if ( !_PR_IS_NATIVE_THREAD(me))
    	_PR_INTSON(is);

#endif  /* _PR_GLOBAL_THREADS_ONLY */
}

/*
** Cndition variable debugging log info.
*/
PRUint32 _PR_CondVarToString(PRCondVar *cvar, char *buf, PRUint32 buflen)
{
    PRUint32 nb;

    if (cvar->lock->owner) {
	nb = PR_snprintf(buf, buflen, "[%p] owner=%ld[%p]",
			 cvar, cvar->lock->owner->id, cvar->lock->owner);
    } else {
	nb = PR_snprintf(buf, buflen, "[%p]", cvar);
    }
    return nb;
}

/*
** Expire condition variable waits that are ready to expire. "now" is the current
** time.
*/
void _PR_ClockInterrupt(void)
{
    PRThread *thread, *me = _PR_MD_CURRENT_THREAD();
    _PRCPU *cpu = me->cpu;
    PRIntervalTime elapsed, now;