pjs/xpcom/threads/nsTimerImpl.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* 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 mozilla.org code.
*
* The Initial Developer of the Original Code is Netscape Communications
* Corporation. Portions created by the Initial Developer are
* Copyright (C) 2001 the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Stuart Parmenter <pavlov@netscape.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*/
#include "nsTimerImpl.h"
#include "TimerThread.h"
#include "nsAutoLock.h"
#include "nsVoidArray.h"
#include "nsIEventQueue.h"
static PRInt32 gGenerator = 0;
static TimerThread* gThread = nsnull;
static PRBool gFireOnIdle = PR_FALSE;
static nsTimerManager* gManager = nsnull;
#include "prmem.h"
#include "prinit.h"
#ifdef DEBUG_TIMERS
#include <math.h>
double nsTimerImpl::sDeltaSumSquared = 0;
double nsTimerImpl::sDeltaSum = 0;
double nsTimerImpl::sDeltaNum = 0;
static void
myNS_MeanAndStdDev(double n, double sumOfValues, double sumOfSquaredValues,
double *meanResult, double *stdDevResult)
{
double mean = 0.0, var = 0.0, stdDev = 0.0;
if (n > 0.0 && sumOfValues >= 0) {
mean = sumOfValues / n;
double temp = (n * sumOfSquaredValues) - (sumOfValues * sumOfValues);
if (temp < 0.0 || n <= 1)
var = 0.0;
else
var = temp / (n * (n - 1));
// for some reason, Windows says sqrt(0.0) is "-1.#J" (?!) so do this:
stdDev = var != 0.0 ? sqrt(var) : 0.0;
}
*meanResult = mean;
*stdDevResult = stdDev;
}
#endif
NS_IMPL_THREADSAFE_QUERY_INTERFACE2(nsTimerImpl, nsITimer, nsITimerInternal)
NS_IMPL_THREADSAFE_ADDREF(nsTimerImpl)
NS_IMETHODIMP_(nsrefcnt) nsTimerImpl::Release(void)
{
nsrefcnt count;
NS_PRECONDITION(0 != mRefCnt, "dup release");
count = PR_AtomicDecrement((PRInt32 *)&mRefCnt);
NS_LOG_RELEASE(this, count, "nsTimerImpl");
if (count == 0) {
mRefCnt = 1; /* stabilize */
/* enable this to find non-threadsafe destructors: */
/* NS_ASSERT_OWNINGTHREAD(nsTimerImpl); */
NS_DELETEXPCOM(this);
return 0;
}
// If only one reference remains, and mArmed is set, then the ref must be
// from the TimerThread::mTimers array, so we Cancel this timer to remove
// the mTimers element, and return 0 if Cancel in fact disarmed the timer.
//
// We use an inlined version of nsTimerImpl::Cancel here to check for the
// NS_ERROR_NOT_AVAILABLE code returned by gThread->RemoveTimer when this
// timer is not found in the mTimers array -- i.e., when the timer was not
// in fact armed once we acquired TimerThread::mLock, in spite of mArmed
// being true here. That can happen if the armed timer is being fired by
// TimerThread::Run as we race and test mArmed just before it is cleared by
// the timer thread. If the RemoveTimer call below doesn't find this timer
// in the mTimers array, then the last ref to this timer is held manually
// and temporarily by the TimerThread, so we should fall through to the
// final return and return 1, not 0.
//
// The original version of this thread-based timer code kept weak refs from
// TimerThread::mTimers, removing this timer's weak ref in the destructor,
// but that leads to double-destructions in the race described above, and
// adding mArmed doesn't help, because destructors can't be deferred, once
// begun. But by combining reference-counting and a specialized Release
// method with "is this timer still in the mTimers array once we acquire
// the TimerThread's lock" testing, we defer destruction until we're sure
// that only one thread has its hot little hands on this timer.
//
// Note that both approaches preclude a timer creator, and everyone else
// except the TimerThread who might have a strong ref, from dropping all
// their strong refs without implicitly canceling the timer. Timers need
// non-mTimers-element strong refs to stay alive.
if (count == 1 && mArmed) {
mCanceled = PR_TRUE;
if (NS_SUCCEEDED(gThread->RemoveTimer(this)))
return 0;
}
return count;
}
PR_STATIC_CALLBACK(PRStatus) InitThread(void)
{
gThread = new TimerThread();
if (!gThread)
return PR_FAILURE;
NS_ADDREF(gThread);
nsresult rv = gThread->Init();
if (NS_FAILED(rv)) {
NS_RELEASE(gThread);
return PR_FAILURE;
}
return PR_SUCCESS;
}
nsTimerImpl::nsTimerImpl() :
mClosure(nsnull),
mCallbackType(CALLBACK_TYPE_UNKNOWN),
mIdle(PR_TRUE),
mFiring(PR_FALSE),
mArmed(PR_FALSE),
mCanceled(PR_FALSE),
mGeneration(0),
mDelay(0),
mTimeout(0)
{
nsIThread::GetCurrent(getter_AddRefs(mCallingThread));
static PRCallOnceType once;
PR_CallOnce(&once, InitThread);
mCallback.c = nsnull;
#ifdef DEBUG_TIMERS
mStart = 0;
mStart2 = 0;
#endif
}
nsTimerImpl::~nsTimerImpl()
{
ReleaseCallback();
}
void nsTimerImpl::Shutdown()
{
#ifdef DEBUG_TIMERS
if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
double mean = 0, stddev = 0;
myNS_MeanAndStdDev(sDeltaNum, sDeltaSum, sDeltaSumSquared, &mean, &stddev);
PR_LOG(gTimerLog, PR_LOG_DEBUG, ("sDeltaNum = %f, sDeltaSum = %f, sDeltaSumSquared = %f\n", sDeltaNum, sDeltaSum, sDeltaSumSquared));
PR_LOG(gTimerLog, PR_LOG_DEBUG, ("mean: %fms, stddev: %fms\n", mean, stddev));
}
#endif
if (!gThread)
return;
gThread->Shutdown();
NS_RELEASE(gThread);
gFireOnIdle = PR_FALSE;
}
nsresult nsTimerImpl::InitCommon(PRUint32 aType, PRUint32 aDelay)
{
/**
* In case of re-Init, both with and without a preceding Cancel, clear the
* mCanceled flag and assign a new mGeneration. But first, remove any armed
* timer from the timer thread's list.
*
* If we are racing with the timer thread to remove this timer and we lose,
* the RemoveTimer call made here will fail to find this timer in the timer
* thread's list, and will return false harmlessly. We test mArmed here to
* avoid the small overhead in RemoveTimer of locking the timer thread and
* checking its list for this timer. It's safe to test mArmed even though
* it might be cleared on another thread in the next cycle (or even already
* be cleared by another CPU whose store hasn't reached our CPU's cache),
* because RemoveTimer is idempotent.
*/
if (mArmed)
gThread->RemoveTimer(this);
mCanceled = PR_FALSE;
mGeneration = PR_AtomicIncrement(&gGenerator);
mType = (PRUint8)aType;
SetDelayInternal(aDelay);
return gThread->AddTimer(this);
}
NS_IMETHODIMP nsTimerImpl::InitWithFuncCallback(nsTimerCallbackFunc aFunc,
void *aClosure,
PRUint32 aDelay,
PRUint32 aType)
{
if (!gThread)
return NS_ERROR_FAILURE;
ReleaseCallback();
mCallbackType = CALLBACK_TYPE_FUNC;
mCallback.c = aFunc;
mClosure = aClosure;
return InitCommon(aType, aDelay);
}
NS_IMETHODIMP nsTimerImpl::InitWithCallback(nsITimerCallback *aCallback,
PRUint32 aDelay,
PRUint32 aType)
{
if (!gThread)
return NS_ERROR_FAILURE;
ReleaseCallback();
mCallbackType = CALLBACK_TYPE_INTERFACE;
mCallback.i = aCallback;
NS_ADDREF(mCallback.i);
return InitCommon(aType, aDelay);
}
NS_IMETHODIMP nsTimerImpl::Init(nsIObserver *aObserver,
PRUint32 aDelay,
PRUint32 aType)
{
if (!gThread)
return NS_ERROR_FAILURE;
ReleaseCallback();
mCallbackType = CALLBACK_TYPE_OBSERVER;
mCallback.o = aObserver;
NS_ADDREF(mCallback.o);
return InitCommon(aType, aDelay);
}
NS_IMETHODIMP nsTimerImpl::Cancel()
{
mCanceled = PR_TRUE;
if (gThread)
gThread->RemoveTimer(this);
return NS_OK;
}
NS_IMETHODIMP nsTimerImpl::SetDelay(PRUint32 aDelay)
{
// If we're already repeating precisely, update mTimeout now so that the
// new delay takes effect in the future.
if (mTimeout != 0 && mType == TYPE_REPEATING_PRECISE)
mTimeout = PR_IntervalNow();
SetDelayInternal(aDelay);
if (!mFiring && gThread)
gThread->TimerDelayChanged(this);
return NS_OK;
}
NS_IMETHODIMP nsTimerImpl::GetDelay(PRUint32* aDelay)
{
*aDelay = mDelay;
return NS_OK;
}
NS_IMETHODIMP nsTimerImpl::SetType(PRUint32 aType)
{
mType = (PRUint8)aType;
// XXX if this is called, we should change the actual type.. this could effect
// repeating timers. we need to ensure in Fire() that if mType has changed
// during the callback that we don't end up with the timer in the queue twice.
return NS_OK;
}
NS_IMETHODIMP nsTimerImpl::GetType(PRUint32* aType)
{
*aType = mType;
return NS_OK;
}
NS_IMETHODIMP nsTimerImpl::GetClosure(void** aClosure)
{
*aClosure = mClosure;
return NS_OK;
}
NS_IMETHODIMP nsTimerImpl::GetIdle(PRBool *aIdle)
{
*aIdle = mIdle;
return NS_OK;
}
NS_IMETHODIMP nsTimerImpl::SetIdle(PRBool aIdle)
{
mIdle = aIdle;
return NS_OK;
}
void nsTimerImpl::Fire()
{
if (mCanceled)
return;
PRIntervalTime now = PR_IntervalNow();
#ifdef DEBUG_TIMERS
if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
PRIntervalTime a = now - mStart; // actual delay in intervals
PRUint32 b = PR_MillisecondsToInterval(mDelay); // expected delay in intervals
PRUint32 d = PR_IntervalToMilliseconds((a > b) ? a - b : b - a); // delta in ms
sDeltaSum += d;
sDeltaSumSquared += double(d) * double(d);
sDeltaNum++;
PR_LOG(gTimerLog, PR_LOG_DEBUG, ("[this=%p] expected delay time %4dms\n", this, mDelay));
PR_LOG(gTimerLog, PR_LOG_DEBUG, ("[this=%p] actual delay time %4dms\n", this, PR_IntervalToMilliseconds(a)));
PR_LOG(gTimerLog, PR_LOG_DEBUG, ("[this=%p] (mType is %d) -------\n", this, mType));
PR_LOG(gTimerLog, PR_LOG_DEBUG, ("[this=%p] delta %4dms\n", this, (a > b) ? (PRInt32)d : -(PRInt32)d));
mStart = mStart2;
mStart2 = 0;
}
#endif
PRIntervalTime timeout = mTimeout;
if (mType == TYPE_REPEATING_PRECISE) {
// Precise repeating timers advance mTimeout by mDelay without fail before
// calling Fire().
timeout -= PR_MillisecondsToInterval(mDelay);
}
gThread->UpdateFilter(mDelay, timeout, now);
mFiring = PR_TRUE;
switch (mCallbackType) {
case CALLBACK_TYPE_FUNC:
mCallback.c(this, mClosure);
break;
case CALLBACK_TYPE_INTERFACE:
mCallback.i->Notify(this);
break;
case CALLBACK_TYPE_OBSERVER:
mCallback.o->Observe(NS_STATIC_CAST(nsITimer*,this),
NS_TIMER_CALLBACK_TOPIC,
nsnull);
break;
default:;
}
mFiring = PR_FALSE;
#ifdef DEBUG_TIMERS
if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
PR_LOG(gTimerLog, PR_LOG_DEBUG,
("[this=%p] Took %dms to fire timer callback\n",
this, PR_IntervalToMilliseconds(PR_IntervalNow() - now)));
}
#endif
if (mType == TYPE_REPEATING_SLACK) {
SetDelayInternal(mDelay); // force mTimeout to be recomputed.
if (gThread)
gThread->AddTimer(this);
}
}
struct TimerEventType : public PLEvent {
PRInt32 mGeneration;
#ifdef DEBUG_TIMERS
PRIntervalTime mInitTime;
#endif
};
void* handleTimerEvent(TimerEventType* event)
{
nsTimerImpl* timer = NS_STATIC_CAST(nsTimerImpl*, event->owner);
if (event->mGeneration != timer->GetGeneration())
return nsnull;
#ifdef DEBUG_TIMERS
if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
PRIntervalTime now = PR_IntervalNow();
PR_LOG(gTimerLog, PR_LOG_DEBUG,
("[this=%p] time between PostTimerEvent() and Fire(): %dms\n",
event->owner, PR_IntervalToMilliseconds(now - event->mInitTime)));
}
#endif
if (gFireOnIdle) {
PRBool idle = PR_FALSE;
timer->GetIdle(&idle);
if (idle) {
NS_ASSERTION(gManager, "Global Thread Manager is null!");
if (gManager)
gManager->AddIdleTimer(timer);
return nsnull;
}
}
timer->Fire();
return nsnull;
}
void destroyTimerEvent(TimerEventType* event)
{
nsTimerImpl *timer = NS_STATIC_CAST(nsTimerImpl*, event->owner);
NS_RELEASE(timer);
PR_DELETE(event);
}
void nsTimerImpl::PostTimerEvent()
{
// XXX we may want to reuse the PLEvent in the case of repeating timers.
TimerEventType* event;
// construct
event = PR_NEW(TimerEventType);
if (!event)
return;
// initialize
PL_InitEvent((PLEvent*)event, this,
(PLHandleEventProc)handleTimerEvent,
(PLDestroyEventProc)destroyTimerEvent);
// Since TimerThread addref'd 'this' for us, we don't need to addref here.
// We will release in destroyMyEvent. We do need to copy the generation
// number from this timer into the event, so we can avoid firing a timer
// that was re-initialized after being canceled.
event->mGeneration = mGeneration;
#ifdef DEBUG_TIMERS
if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
event->mInitTime = PR_IntervalNow();
}
#endif
// If this is a repeating precise timer, we need to calculate the time for
// the next timer to fire before we make the callback.
if (mType == TYPE_REPEATING_PRECISE) {
SetDelayInternal(mDelay);
if (gThread)
gThread->AddTimer(this);
}
PRThread *thread;
nsresult rv = mCallingThread->GetPRThread(&thread);
if (NS_FAILED(rv)) {
NS_WARNING("Droping timer event because thread is dead");
return;
}
nsCOMPtr<nsIEventQueue> queue;
if (gThread)
gThread->mEventQueueService->GetThreadEventQueue(thread, getter_AddRefs(queue));
if (queue)
queue->PostEvent(event);
}
void nsTimerImpl::SetDelayInternal(PRUint32 aDelay)
{
PRIntervalTime delayInterval = PR_MillisecondsToInterval(aDelay);
if (delayInterval > DELAY_INTERVAL_MAX) {
delayInterval = DELAY_INTERVAL_MAX;
aDelay = PR_IntervalToMilliseconds(delayInterval);
}
mDelay = aDelay;
PRIntervalTime now = PR_IntervalNow();
if (mTimeout == 0 || mType != TYPE_REPEATING_PRECISE)
mTimeout = now;
mTimeout += delayInterval;
#ifdef DEBUG_TIMERS
if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
if (mStart == 0)
mStart = now;
else
mStart2 = now;
}
#endif
}
/**
* Timer Manager code
*/
NS_IMPL_THREADSAFE_ISUPPORTS1(nsTimerManager, nsITimerManager)
nsTimerManager::nsTimerManager()
{
mLock = PR_NewLock();
gManager = this;
}
nsTimerManager::~nsTimerManager()
{
gManager = nsnull;
PR_DestroyLock(mLock);
nsTimerImpl *theTimer;
PRInt32 count = mIdleTimers.Count();
for (PRInt32 i = 0; i < count; i++) {
theTimer = NS_STATIC_CAST(nsTimerImpl*, mIdleTimers[i]);
NS_IF_RELEASE(theTimer);
}
}
NS_IMETHODIMP nsTimerManager::SetUseIdleTimers(PRBool aUseIdleTimers)
{
if (aUseIdleTimers == PR_FALSE && gFireOnIdle == PR_TRUE)
return NS_ERROR_FAILURE;
gFireOnIdle = aUseIdleTimers;
return NS_OK;
}
NS_IMETHODIMP nsTimerManager::GetUseIdleTimers(PRBool *aUseIdleTimers)
{
*aUseIdleTimers = gFireOnIdle;
return NS_OK;
}
NS_IMETHODIMP nsTimerManager::HasIdleTimers(PRBool *aHasTimers)
{
nsAutoLock lock (mLock);
PRUint32 count = mIdleTimers.Count();
*aHasTimers = (count != 0);
return NS_OK;
}
nsresult nsTimerManager::AddIdleTimer(nsITimer* timer)
{
if (!timer)
return NS_ERROR_FAILURE;
nsAutoLock lock(mLock);
mIdleTimers.AppendElement(timer);
NS_ADDREF(timer);
return NS_OK;
}
NS_IMETHODIMP nsTimerManager::FireNextIdleTimer()
{
if (!gFireOnIdle || !nsIThread::IsMainThread()) {
return NS_OK;
}
nsTimerImpl *theTimer = nsnull;
{
nsAutoLock lock (mLock);
PRUint32 count = mIdleTimers.Count();
if (count == 0)
return NS_OK;
theTimer = NS_STATIC_CAST(nsTimerImpl*, mIdleTimers[0]);
mIdleTimers.RemoveElement(theTimer);
}
theTimer->Fire();
NS_RELEASE(theTimer);
return NS_OK;
}
// NOT FOR PUBLIC CONSUMPTION!
nsresult
NS_NewTimer(nsITimer* *aResult, nsTimerCallbackFunc aCallback, void *aClosure,
PRUint32 aDelay, PRUint32 aType)
{
nsTimerImpl* timer = new nsTimerImpl();
if (timer == nsnull)
return NS_ERROR_OUT_OF_MEMORY;
NS_ADDREF(timer);
nsresult rv = timer->InitWithFuncCallback(aCallback, aClosure,
aDelay, aType);
if (NS_FAILED(rv)) {
NS_RELEASE(timer);
return rv;
}
*aResult = timer;
return NS_OK;
}