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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
* The contents of this file are subject to the Netscape Public License
* Version 1.0 (the "NPL"); you may not use this file except in
* compliance with the NPL. You may obtain a copy of the NPL at
* http://www.mozilla.org/NPL/
*
* Software distributed under the NPL is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
* for the specific language governing rights and limitations under the
* NPL.
*
* The Initial Developer of this code under the NPL is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All Rights
* Reserved.
*/
#include "primpl.h"
/************************************************************************/
/*
** Create a new monitor.
*/
PR_IMPLEMENT(PRMonitor*) PR_NewMonitor()
{
PRMonitor *mon;
PRCondVar *cvar;
PRLock *lock;
mon = PR_NEWZAP(PRMonitor);
if (mon) {
lock = PR_NewLock();
if (!lock) {
PR_DELETE(mon);
return 0;
}
cvar = PR_NewCondVar(lock);
if (!cvar) {
PR_DestroyLock(lock);
PR_DELETE(mon);
return 0;
}
mon->cvar = cvar;
mon->name = NULL;
}
return mon;
}
PR_IMPLEMENT(PRMonitor*) PR_NewNamedMonitor(const char* name)
{
PRMonitor* mon = PR_NewMonitor();
mon->name = name;
return mon;
}
/*
** Destroy a monitor. There must be no thread waiting on the monitor's
** condition variable. The caller is responsible for guaranteeing that the
** monitor is no longer in use.
*/
PR_IMPLEMENT(void) PR_DestroyMonitor(PRMonitor *mon)
{
PR_DestroyLock(mon->cvar->lock);
PR_DestroyCondVar(mon->cvar);
PR_DELETE(mon);
}
/*
** Enter the lock associated with the monitor.
*/
PR_IMPLEMENT(void) PR_EnterMonitor(PRMonitor *mon)
{
if (mon->cvar->lock->owner == _PR_MD_CURRENT_THREAD()) {
mon->entryCount++;
} else {
PR_Lock(mon->cvar->lock);
mon->entryCount = 1;
}
}
/*
** Test and then enter the lock associated with the monitor if it's not
** already entered by some other thread. Return PR_FALSE if some other
** thread owned the lock at the time of the call.
*/
PR_IMPLEMENT(PRBool) PR_TestAndEnterMonitor(PRMonitor *mon)
{
if (mon->cvar->lock->owner == _PR_MD_CURRENT_THREAD()) {
mon->entryCount++;
return PR_TRUE;
} else {
if (PR_TestAndLock(mon->cvar->lock)) {
mon->entryCount = 1;
return PR_TRUE;
}
}
return PR_FALSE;
}
/*
** Exit the lock associated with the monitor once.
*/
PR_IMPLEMENT(PRStatus) PR_ExitMonitor(PRMonitor *mon)
{
if (mon->cvar->lock->owner != _PR_MD_CURRENT_THREAD()) {
return PR_FAILURE;
}
if (--mon->entryCount == 0) {
return PR_Unlock(mon->cvar->lock);
}
return PR_SUCCESS;
}
/*
** Return the number of times that the current thread has entered the
** lock. Returns zero if the current thread has not entered the lock.
*/
PR_IMPLEMENT(PRIntn) PR_GetMonitorEntryCount(PRMonitor *mon)
{
return (mon->cvar->lock->owner == _PR_MD_CURRENT_THREAD()) ?
mon->entryCount : 0;
}
/*
** Wait for a notify on the condition variable. Sleep for "ticks" amount
** of time (if "tick" is 0 then the sleep is indefinite). While
** the thread is waiting it exits the monitors lock (as if it called
** PR_ExitMonitor as many times as it had called PR_EnterMonitor). When
** the wait has finished the thread regains control of the monitors lock
** with the same entry count as before the wait began.
**
** The thread waiting on the monitor will be resumed when the monitor is
** notified (assuming the thread is the next in line to receive the
** notify) or when the "ticks" elapses.
**
** Returns PR_FAILURE if the caller has not locked the lock associated
** with the condition variable.
** This routine can return PR_PENDING_INTERRUPT if the waiting thread
** has been interrupted.
*/
PR_IMPLEMENT(PRStatus) PR_Wait(PRMonitor *mon, PRIntervalTime ticks)
{
PRUintn entryCount;
PRStatus status;
PRThread *me = _PR_MD_CURRENT_THREAD();
if (mon->cvar->lock->owner != me) return PR_FAILURE;
entryCount = mon->entryCount;
mon->entryCount = 0;
status = _PR_WaitCondVar(me, mon->cvar, mon->cvar->lock, ticks);
mon->entryCount = entryCount;
return status;
}
/*
** 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 monitor's lock.
*/
PR_IMPLEMENT(PRStatus) PR_Notify(PRMonitor *mon)
{
PRThread *me = _PR_MD_CURRENT_THREAD();
if (mon->cvar->lock->owner != me) return PR_FAILURE;
PR_NotifyCondVar(mon->cvar);
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 monitor first when the monitor is exited.
*/
PR_IMPLEMENT(PRStatus) PR_NotifyAll(PRMonitor *mon)
{
PRThread *me = _PR_MD_CURRENT_THREAD();
if (mon->cvar->lock->owner != me) return PR_FAILURE;
PR_NotifyAllCondVar(mon->cvar);
return PR_SUCCESS;
}
/************************************************************************/
PRUint32 _PR_MonitorToString(PRMonitor *mon, char *buf, PRUint32 buflen)
{
PRUint32 nb;
if (mon->cvar->lock->owner) {
nb = PR_snprintf(buf, buflen, "[%p] owner=%d[%p] count=%ld",
mon, mon->cvar->lock->owner->id,
mon->cvar->lock->owner, mon->entryCount);
} else {
nb = PR_snprintf(buf, buflen, "[%p]", mon);
}
return nb;
}
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