tor-browser

prucv.c (17734B)

---

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#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) {
   PR_LOG(_pr_cvar_lm, PR_LOG_MIN, ("_PR_NotifyCondVar: cvar=%p", cvar));
   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;

 PR_ASSERT(_PR_MD_GET_INTSOFF() != 0);
 /* Figure out how much time elapsed since the last clock tick */
 now = PR_IntervalNow();
 elapsed = now - cpu->last_clock;
 cpu->last_clock = now;

 PR_LOG(_pr_clock_lm, PR_LOG_MAX, ("ExpireWaits: elapsed=%lld usec", elapsed));

 while (1) {
   _PR_SLEEPQ_LOCK(cpu);
   if (_PR_SLEEPQ(cpu).next == &_PR_SLEEPQ(cpu)) {
     _PR_SLEEPQ_UNLOCK(cpu);
     break;
   }

   thread = _PR_THREAD_PTR(_PR_SLEEPQ(cpu).next);
   PR_ASSERT(thread->cpu == cpu);

   if (elapsed < thread->sleep) {
     thread->sleep -= elapsed;
     _PR_SLEEPQMAX(thread->cpu) -= elapsed;
     _PR_SLEEPQ_UNLOCK(cpu);
     break;
   }
   _PR_SLEEPQ_UNLOCK(cpu);

   PR_ASSERT(!_PR_IS_NATIVE_THREAD(thread));

   _PR_THREAD_LOCK(thread);

   if (thread->cpu != cpu) {
     /*
     ** The thread was switched to another CPU
     ** between the time we unlocked the sleep
     ** queue and the time we acquired the thread
     ** lock, so it is none of our business now.
     */
     _PR_THREAD_UNLOCK(thread);
     continue;
   }

   /*
   ** Consume this sleeper's amount of elapsed time from the elapsed
   ** time value. The next remaining piece of elapsed time will be
   ** available for the next sleeping thread's timer.
   */
   _PR_SLEEPQ_LOCK(cpu);
   PR_ASSERT(!(thread->flags & _PR_ON_PAUSEQ));
   if (thread->flags & _PR_ON_SLEEPQ) {
     _PR_DEL_SLEEPQ(thread, PR_FALSE);
     elapsed -= thread->sleep;
     _PR_SLEEPQ_UNLOCK(cpu);
   } else {
     /* Thread was already handled; Go get another one */
     _PR_SLEEPQ_UNLOCK(cpu);
     _PR_THREAD_UNLOCK(thread);
     continue;
   }

   /* Notify the thread waiting on the condition variable */
   if (thread->flags & _PR_SUSPENDING) {
     PR_ASSERT((thread->state == _PR_IO_WAIT) ||
               (thread->state == _PR_COND_WAIT));
     /*
     ** Thread is suspended and its condition timeout
     ** expired. Transfer thread from sleepQ to suspendQ.
     */
     thread->wait.cvar = NULL;
     _PR_MISCQ_LOCK(cpu);
     thread->state = _PR_SUSPENDED;
     _PR_ADD_SUSPENDQ(thread, cpu);
     _PR_MISCQ_UNLOCK(cpu);
   } else {
     if (thread->wait.cvar) {
       PRThreadPriority pri;

       /* Do work very similar to what _PR_NotifyThread does */
       PR_ASSERT(!_PR_IS_NATIVE_THREAD(thread));

       /* Make thread runnable */
       pri = thread->priority;
       thread->state = _PR_RUNNABLE;
       PR_ASSERT(!(thread->flags & _PR_IDLE_THREAD));

       PR_ASSERT(thread->cpu == cpu);
       _PR_RUNQ_LOCK(cpu);
       _PR_ADD_RUNQ(thread, cpu, pri);
       _PR_RUNQ_UNLOCK(cpu);

       if (pri > me->priority) {
         _PR_SET_RESCHED_FLAG();
       }

       thread->wait.cvar = NULL;

       _PR_MD_WAKEUP_WAITER(thread);

     } else if (thread->io_pending == PR_TRUE) {
       /* Need to put IO sleeper back on runq */
       int pri = thread->priority;

       thread->io_suspended = PR_TRUE;
#ifdef WINNT
       /*
        * For NT, record the cpu on which I/O was issued
        * I/O cancellation is done on the same cpu
        */
       thread->md.thr_bound_cpu = cpu;
#endif

       PR_ASSERT(!(thread->flags & _PR_IDLE_THREAD));
       PR_ASSERT(thread->cpu == cpu);
       thread->state = _PR_RUNNABLE;
       _PR_RUNQ_LOCK(cpu);
       _PR_ADD_RUNQ(thread, cpu, pri);
       _PR_RUNQ_UNLOCK(cpu);
     }
   }
   _PR_THREAD_UNLOCK(thread);
 }
}

/************************************************************************/

/*
** Create a new condition variable.
**  "lock" is the lock to use with the condition variable.
**
** Condition variables are synchronization objects that threads can use
** to wait for some condition to occur.
**
** This may fail if memory is tight or if some operating system resource
** is low.
*/
PR_IMPLEMENT(PRCondVar*) PR_NewCondVar(PRLock* lock) {
 PRCondVar* cvar;

 cvar = PR_NEWZAP(PRCondVar);
 if (cvar) {
   if (_PR_InitCondVar(cvar, lock) != PR_SUCCESS) {
     PR_DELETE(cvar);
     return NULL;
   }
 } else {
   PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
 }
 return cvar;
}

PRStatus _PR_InitCondVar(PRCondVar* cvar, PRLock* lock) {
 PR_ASSERT(lock != NULL);

#ifdef _PR_GLOBAL_THREADS_ONLY
 if (_PR_MD_NEW_CV(&cvar->md)) {
   PR_SetError(PR_INSUFFICIENT_RESOURCES_ERROR, 0);
   return PR_FAILURE;
 }
#endif
 if (_PR_MD_NEW_LOCK(&(cvar->ilock)) != PR_SUCCESS) {
   PR_SetError(PR_INSUFFICIENT_RESOURCES_ERROR, 0);
   return PR_FAILURE;
 }
 cvar->lock = lock;
 PR_INIT_CLIST(&cvar->condQ);
 return PR_SUCCESS;
}

/*
** Destroy a condition variable. There must be no thread
** waiting on the condvar. The caller is responsible for guaranteeing
** that the condvar is no longer in use.
**
*/
PR_IMPLEMENT(void) PR_DestroyCondVar(PRCondVar* cvar) {
 _PR_FreeCondVar(cvar);
 PR_DELETE(cvar);
}

void _PR_FreeCondVar(PRCondVar* cvar) {
 PR_ASSERT(cvar->condQ.next == &cvar->condQ);

#ifdef _PR_GLOBAL_THREADS_ONLY
 _PR_MD_FREE_CV(&cvar->md);
#endif
 _PR_MD_FREE_LOCK(&(cvar->ilock));
}

/*
** Wait for a notify on the condition variable. Sleep for "tiemout" amount
** of ticks (if "timeout" is zero then the sleep is indefinite). While
** the thread is waiting it unlocks lock. When the wait has
** finished the thread regains control of the condition variable after
** locking the associated lock.
**
** The thread waiting on the condvar will be resumed when the condvar is
** notified (assuming the thread is the next in line to receive the
** notify) or when the timeout elapses.
**
** Returns PR_FAILURE if the caller has not locked the lock associated
** with the condition variable or the thread has been interrupted.
*/
extern PRThread* suspendAllThread;
PR_IMPLEMENT(PRStatus) PR_WaitCondVar(PRCondVar* cvar, PRIntervalTime timeout) {
 PRThread* me = _PR_MD_CURRENT_THREAD();

 PR_ASSERT(cvar->lock->owner == me);
 PR_ASSERT(me != suspendAllThread);
 if (cvar->lock->owner != me) {
   return PR_FAILURE;
 }

 return _PR_WaitCondVar(me, cvar, cvar->lock, timeout);
}

/*
** Notify the highest priority thread waiting on the condition
** variable. If a thread is waiting on the condition variable (using
** PR_Wait) then it is awakened and begins waiting on the lock.
*/
PR_IMPLEMENT(PRStatus) PR_NotifyCondVar(PRCondVar* cvar) {
 PRThread* me = _PR_MD_CURRENT_THREAD();

 PR_ASSERT(cvar->lock->owner == me);
 PR_ASSERT(me != suspendAllThread);
 if (cvar->lock->owner != me) {
   return PR_FAILURE;
 }

 _PR_NotifyCondVar(cvar, me);
 return PR_SUCCESS;
}

/*
** Notify all of the threads waiting on the condition variable. All of
** threads are notified in turn. The highest priority thread will
** probably acquire the lock.
*/
PR_IMPLEMENT(PRStatus) PR_NotifyAllCondVar(PRCondVar* cvar) {
 PRCList* q;
 PRIntn is;
 PRThread* me = _PR_MD_CURRENT_THREAD();

 PR_ASSERT(cvar->lock->owner == me);
 if (cvar->lock->owner != me) {
   return PR_FAILURE;
 }

#ifdef _PR_GLOBAL_THREADS_ONLY
 _PR_MD_NOTIFYALL_CV(&cvar->md, &cvar->lock->ilock);
 return PR_SUCCESS;
#else  /* _PR_GLOBAL_THREADS_ONLY */
 if (!_PR_IS_NATIVE_THREAD(me)) {
   _PR_INTSOFF(is);
 }
 _PR_CVAR_LOCK(cvar);
 q = cvar->condQ.next;
 while (q != &cvar->condQ) {
   PR_LOG(_pr_cvar_lm, PR_LOG_MIN, ("PR_NotifyAll: cvar=%p", cvar));
   _PR_NotifyThread(_PR_THREAD_CONDQ_PTR(q), me);
   q = q->next;
 }
 _PR_CVAR_UNLOCK(cvar);
 if (!_PR_IS_NATIVE_THREAD(me)) {
   _PR_INTSON(is);
 }

 return PR_SUCCESS;
#endif /* _PR_GLOBAL_THREADS_ONLY */
}

/*********************************************************************/
/*********************************************************************/
/********************ROUTINES FOR DCE EMULATION***********************/
/*********************************************************************/
/*********************************************************************/
#include "prpdce.h"

PR_IMPLEMENT(PRCondVar*) PRP_NewNakedCondVar(void) {
 PRCondVar* cvar = PR_NEWZAP(PRCondVar);
 if (NULL != cvar) {
   if (_PR_MD_NEW_LOCK(&(cvar->ilock)) == PR_FAILURE) {
     PR_DELETE(cvar);
     cvar = NULL;
   } else {
     PR_INIT_CLIST(&cvar->condQ);
     cvar->lock = _PR_NAKED_CV_LOCK;
   }
 }
 return cvar;
}

PR_IMPLEMENT(void) PRP_DestroyNakedCondVar(PRCondVar* cvar) {
 PR_ASSERT(cvar->condQ.next == &cvar->condQ);
 PR_ASSERT(_PR_NAKED_CV_LOCK == cvar->lock);

 _PR_MD_FREE_LOCK(&(cvar->ilock));

 PR_DELETE(cvar);
}

PR_IMPLEMENT(PRStatus)
PRP_NakedWait(PRCondVar* cvar, PRLock* lock, PRIntervalTime timeout) {
 PRThread* me = _PR_MD_CURRENT_THREAD();
 PR_ASSERT(_PR_NAKED_CV_LOCK == cvar->lock);
 return _PR_WaitCondVar(me, cvar, lock, timeout);
} /* PRP_NakedWait */

PR_IMPLEMENT(PRStatus) PRP_NakedNotify(PRCondVar* cvar) {
 PRThread* me = _PR_MD_CURRENT_THREAD();
 PR_ASSERT(_PR_NAKED_CV_LOCK == cvar->lock);

 _PR_NotifyCondVar(cvar, me);

 return PR_SUCCESS;
} /* PRP_NakedNotify */

PR_IMPLEMENT(PRStatus) PRP_NakedBroadcast(PRCondVar* cvar) {
 PRCList* q;
 PRIntn is;
 PRThread* me = _PR_MD_CURRENT_THREAD();
 PR_ASSERT(_PR_NAKED_CV_LOCK == cvar->lock);

 if (!_PR_IS_NATIVE_THREAD(me)) {
   _PR_INTSOFF(is);
 }
 _PR_MD_LOCK(&(cvar->ilock));
 q = cvar->condQ.next;
 while (q != &cvar->condQ) {
   PR_LOG(_pr_cvar_lm, PR_LOG_MIN, ("PR_NotifyAll: cvar=%p", cvar));
   _PR_NotifyThread(_PR_THREAD_CONDQ_PTR(q), me);
   q = q->next;
 }
 _PR_MD_UNLOCK(&(cvar->ilock));
 if (!_PR_IS_NATIVE_THREAD(me)) {
   _PR_INTSON(is);
 }

 return PR_SUCCESS;
} /* PRP_NakedBroadcast */