gecko-dev/xpcom/threads/nsTimerImpl.cpp

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C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "nsTimerImpl.h"
#include "TimerThread.h"
#include "nsAutoPtr.h"
#include "nsThreadManager.h"
#include "nsThreadUtils.h"
#include "pratom.h"
#include "GeckoProfiler.h"
#include "mozilla/Atomics.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "mozilla/Logging.h"
#ifdef MOZ_NUWA_PROCESS
#include "ipc/Nuwa.h"
#endif
#ifdef MOZ_TASK_TRACER
#include "GeckoTaskTracerImpl.h"
using namespace mozilla::tasktracer;
#endif
#ifdef XP_WIN
#include <process.h>
#ifndef getpid
#define getpid _getpid
#endif
#else
#include <unistd.h>
#endif
using mozilla::Atomic;
using mozilla::LogLevel;
using mozilla::TimeDuration;
using mozilla::TimeStamp;
static Atomic<int32_t> gGenerator;
static TimerThread* gThread = nullptr;
// This module prints info about the precision of timers.
static mozilla::LazyLogModule sTimerLog("nsTimerImpl");
mozilla::LogModule*
GetTimerLog()
{
return sTimerLog;
}
// This module prints info about which timers are firing, which is useful for
// wakeups for the purposes of power profiling. Set the following environment
// variable before starting the browser.
//
// NSPR_LOG_MODULES=TimerFirings:4
//
// Then a line will be printed for every timer that fires. The name used for a
// |CallbackType::Function| timer depends on the circumstances.
//
// - If it was explicitly named (e.g. it was initialized with
// InitWithNamedFuncCallback()) then that explicit name will be shown.
//
// - Otherwise, if we are on a platform that supports function name lookup
// (Mac or Linux) then the looked-up name will be shown with a
// "[from dladdr]" annotation. On Mac the looked-up name will be immediately
// useful. On Linux it'll need post-processing with
// tools/rb/fix_linux_stack.py.
//
// - Otherwise, no name will be printed. If many timers hit this case then
// you'll need to re-run the workload on a Mac to find out which timers they
// are, and then give them explicit names.
//
// If you redirect this output to a file called "out", you can then
// post-process it with a command something like the following.
//
// cat out | grep timer | sort | uniq -c | sort -r -n
//
// This will show how often each unique line appears, with the most common ones
// first.
//
// More detailed docs are here:
// https://developer.mozilla.org/en-US/docs/Mozilla/Performance/TimerFirings_logging
//
static mozilla::LazyLogModule sTimerFiringsLog("TimerFirings");
mozilla::LogModule*
GetTimerFiringsLog()
{
return sTimerFiringsLog;
}
#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;
}
NS_IMPL_QUERY_INTERFACE(nsTimerImpl, nsITimer)
NS_IMPL_ADDREF(nsTimerImpl)
NS_IMETHODIMP_(MozExternalRefCountType)
nsTimerImpl::Release(void)
{
nsrefcnt count;
MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");
count = --mRefCnt;
NS_LOG_RELEASE(this, count, "nsTimerImpl");
if (count == 0) {
mRefCnt = 1; /* stabilize */
/* enable this to find non-threadsafe destructors: */
/* NS_ASSERT_OWNINGTHREAD(nsTimerImpl); */
delete 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 = true;
MOZ_ASSERT(gThread, "Armed timer exists after the thread timer stopped.");
if (NS_SUCCEEDED(gThread->RemoveTimer(this))) {
return 0;
}
}
return count;
}
nsTimerImpl::nsTimerImpl() :
mClosure(nullptr),
mName(nsTimerImpl::Nothing),
mCallbackType(CallbackType::Unknown),
mFiring(false),
mArmed(false),
mCanceled(false),
mGeneration(0),
mDelay(0)
{
// XXXbsmedberg: shouldn't this be in Init()?
mEventTarget = static_cast<nsIEventTarget*>(NS_GetCurrentThread());
mCallback.c = nullptr;
}
nsTimerImpl::~nsTimerImpl()
{
ReleaseCallback();
}
//static
nsresult
nsTimerImpl::Startup()
{
nsresult rv;
gThread = new TimerThread();
NS_ADDREF(gThread);
rv = gThread->InitLocks();
if (NS_FAILED(rv)) {
NS_RELEASE(gThread);
}
return rv;
}
void
nsTimerImpl::Shutdown()
{
if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
double mean = 0, stddev = 0;
myNS_MeanAndStdDev(sDeltaNum, sDeltaSum, sDeltaSumSquared, &mean, &stddev);
MOZ_LOG(GetTimerLog(), LogLevel::Debug,
("sDeltaNum = %f, sDeltaSum = %f, sDeltaSumSquared = %f\n",
sDeltaNum, sDeltaSum, sDeltaSumSquared));
MOZ_LOG(GetTimerLog(), LogLevel::Debug,
("mean: %fms, stddev: %fms\n", mean, stddev));
}
if (!gThread) {
return;
}
gThread->Shutdown();
NS_RELEASE(gThread);
}
nsresult
nsTimerImpl::InitCommon(uint32_t aDelay, uint32_t aType)
{
nsresult rv;
if (NS_WARN_IF(!gThread)) {
return NS_ERROR_NOT_INITIALIZED;
}
if (!mEventTarget) {
NS_ERROR("mEventTarget is NULL");
return NS_ERROR_NOT_INITIALIZED;
}
rv = gThread->Init();
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
gThread->RemoveTimer(this);
mCanceled = false;
mTimeout = TimeStamp();
mGeneration = gGenerator++;
mType = (uint8_t)aType;
SetDelayInternal(aDelay);
return gThread->AddTimer(this);
}
nsresult
nsTimerImpl::InitWithFuncCallbackCommon(nsTimerCallbackFunc aFunc,
void* aClosure,
uint32_t aDelay,
uint32_t aType,
Name aName)
{
if (NS_WARN_IF(!aFunc)) {
return NS_ERROR_INVALID_ARG;
}
ReleaseCallback();
mCallbackType = CallbackType::Function;
mCallback.c = aFunc;
mClosure = aClosure;
mName = aName;
return InitCommon(aDelay, aType);
}
NS_IMETHODIMP
nsTimerImpl::InitWithFuncCallback(nsTimerCallbackFunc aFunc,
void* aClosure,
uint32_t aDelay,
uint32_t aType)
{
Name name(nsTimerImpl::Nothing);
return InitWithFuncCallbackCommon(aFunc, aClosure, aDelay, aType, name);
}
NS_IMETHODIMP
nsTimerImpl::InitWithNamedFuncCallback(nsTimerCallbackFunc aFunc,
void* aClosure,
uint32_t aDelay,
uint32_t aType,
const char* aNameString)
{
Name name(aNameString);
return InitWithFuncCallbackCommon(aFunc, aClosure, aDelay, aType, name);
}
NS_IMETHODIMP
nsTimerImpl::InitWithNameableFuncCallback(nsTimerCallbackFunc aFunc,
void* aClosure,
uint32_t aDelay,
uint32_t aType,
nsTimerNameCallbackFunc aNameFunc)
{
Name name(aNameFunc);
return InitWithFuncCallbackCommon(aFunc, aClosure, aDelay, aType, name);
}
NS_IMETHODIMP
nsTimerImpl::InitWithCallback(nsITimerCallback* aCallback,
uint32_t aDelay,
uint32_t aType)
{
if (NS_WARN_IF(!aCallback)) {
return NS_ERROR_INVALID_ARG;
}
ReleaseCallback();
mCallbackType = CallbackType::Interface;
mCallback.i = aCallback;
NS_ADDREF(mCallback.i);
return InitCommon(aDelay, aType);
}
NS_IMETHODIMP
nsTimerImpl::Init(nsIObserver* aObserver, uint32_t aDelay, uint32_t aType)
{
if (NS_WARN_IF(!aObserver)) {
return NS_ERROR_INVALID_ARG;
}
ReleaseCallback();
mCallbackType = CallbackType::Observer;
mCallback.o = aObserver;
NS_ADDREF(mCallback.o);
return InitCommon(aDelay, aType);
}
NS_IMETHODIMP
nsTimerImpl::Cancel()
{
mCanceled = true;
if (gThread) {
gThread->RemoveTimer(this);
}
ReleaseCallback();
return NS_OK;
}
NS_IMETHODIMP
nsTimerImpl::SetDelay(uint32_t aDelay)
{
if (mCallbackType == CallbackType::Unknown && mType == TYPE_ONE_SHOT) {
// This may happen if someone tries to re-use a one-shot timer
// by re-setting delay instead of reinitializing the timer.
NS_ERROR("nsITimer->SetDelay() called when the "
"one-shot timer is not set up.");
return NS_ERROR_NOT_INITIALIZED;
}
SetDelayInternal(aDelay);
if (!mFiring && gThread) {
gThread->TimerDelayChanged(this);
}
return NS_OK;
}
NS_IMETHODIMP
nsTimerImpl::GetDelay(uint32_t* aDelay)
{
*aDelay = mDelay;
return NS_OK;
}
NS_IMETHODIMP
nsTimerImpl::SetType(uint32_t aType)
{
mType = (uint8_t)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(uint32_t* aType)
{
*aType = mType;
return NS_OK;
}
NS_IMETHODIMP
nsTimerImpl::GetClosure(void** aClosure)
{
*aClosure = mClosure;
return NS_OK;
}
NS_IMETHODIMP
nsTimerImpl::GetCallback(nsITimerCallback** aCallback)
{
if (mCallbackType == CallbackType::Interface) {
NS_IF_ADDREF(*aCallback = mCallback.i);
} else if (mTimerCallbackWhileFiring) {
NS_ADDREF(*aCallback = mTimerCallbackWhileFiring);
} else {
*aCallback = nullptr;
}
return NS_OK;
}
NS_IMETHODIMP
nsTimerImpl::GetTarget(nsIEventTarget** aTarget)
{
NS_IF_ADDREF(*aTarget = mEventTarget);
return NS_OK;
}
NS_IMETHODIMP
nsTimerImpl::SetTarget(nsIEventTarget* aTarget)
{
if (NS_WARN_IF(mCallbackType != CallbackType::Unknown)) {
return NS_ERROR_ALREADY_INITIALIZED;
}
if (aTarget) {
mEventTarget = aTarget;
} else {
mEventTarget = static_cast<nsIEventTarget*>(NS_GetCurrentThread());
}
return NS_OK;
}
void
nsTimerImpl::Fire()
{
if (mCanceled) {
return;
}
PROFILER_LABEL("Timer", "Fire",
js::ProfileEntry::Category::OTHER);
TimeStamp now = TimeStamp::Now();
if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
TimeDuration a = now - mStart; // actual delay in intervals
TimeDuration b = TimeDuration::FromMilliseconds(mDelay); // expected delay in intervals
TimeDuration delta = (a > b) ? a - b : b - a;
uint32_t d = delta.ToMilliseconds(); // delta in ms
sDeltaSum += d;
sDeltaSumSquared += double(d) * double(d);
sDeltaNum++;
MOZ_LOG(GetTimerLog(), LogLevel::Debug,
("[this=%p] expected delay time %4ums\n", this, mDelay));
MOZ_LOG(GetTimerLog(), LogLevel::Debug,
("[this=%p] actual delay time %fms\n", this,
a.ToMilliseconds()));
MOZ_LOG(GetTimerLog(), LogLevel::Debug,
("[this=%p] (mType is %d) -------\n", this, mType));
MOZ_LOG(GetTimerLog(), LogLevel::Debug,
("[this=%p] delta %4dms\n",
this, (a > b) ? (int32_t)d : -(int32_t)d));
mStart = mStart2;
mStart2 = TimeStamp();
}
TimeStamp timeout = mTimeout;
if (IsRepeatingPrecisely()) {
// Precise repeating timers advance mTimeout by mDelay without fail before
// calling Fire().
timeout -= TimeDuration::FromMilliseconds(mDelay);
}
if (mCallbackType == CallbackType::Interface) {
mTimerCallbackWhileFiring = mCallback.i;
}
mFiring = true;
// Handle callbacks that re-init the timer, but avoid leaking.
// See bug 330128.
CallbackUnion callback = mCallback;
CallbackType callbackType = mCallbackType;
if (callbackType == CallbackType::Interface) {
NS_ADDREF(callback.i);
} else if (callbackType == CallbackType::Observer) {
NS_ADDREF(callback.o);
}
ReleaseCallback();
if (MOZ_LOG_TEST(GetTimerFiringsLog(), LogLevel::Debug)) {
LogFiring(callbackType, callback);
}
switch (callbackType) {
case CallbackType::Function:
callback.c(this, mClosure);
break;
case CallbackType::Interface:
callback.i->Notify(this);
break;
case CallbackType::Observer:
callback.o->Observe(static_cast<nsITimer*>(this),
NS_TIMER_CALLBACK_TOPIC,
nullptr);
break;
default:
;
}
// If the callback didn't re-init the timer, and it's not a one-shot timer,
// restore the callback state.
if (mCallbackType == CallbackType::Unknown &&
mType != TYPE_ONE_SHOT && !mCanceled) {
mCallback = callback;
mCallbackType = callbackType;
} else {
// The timer was a one-shot, or the callback was reinitialized.
if (callbackType == CallbackType::Interface) {
NS_RELEASE(callback.i);
} else if (callbackType == CallbackType::Observer) {
NS_RELEASE(callback.o);
}
}
mFiring = false;
mTimerCallbackWhileFiring = nullptr;
MOZ_LOG(GetTimerLog(), LogLevel::Debug,
("[this=%p] Took %fms to fire timer callback\n",
this, (TimeStamp::Now() - now).ToMilliseconds()));
// Reschedule repeating timers, but make sure that we aren't armed already
// (which can happen if the callback reinitialized the timer).
if (IsRepeating() && !mArmed) {
if (mType == TYPE_REPEATING_SLACK) {
SetDelayInternal(mDelay); // force mTimeout to be recomputed. For
}
// REPEATING_PRECISE_CAN_SKIP timers this has
// already happened.
if (gThread) {
gThread->AddTimer(this);
}
}
}
#if defined(HAVE_DLADDR) && defined(HAVE___CXA_DEMANGLE)
#define USE_DLADDR 1
#endif
#ifdef USE_DLADDR
#include <cxxabi.h>
#include <dlfcn.h>
#endif
// See the big comment above GetTimerFiringsLog() to understand this code.
void
nsTimerImpl::LogFiring(CallbackType aCallbackType, CallbackUnion aCallback)
{
const char* typeStr;
switch (mType) {
case TYPE_ONE_SHOT: typeStr = "ONE_SHOT"; break;
case TYPE_REPEATING_SLACK: typeStr = "SLACK "; break;
case TYPE_REPEATING_PRECISE: /* fall through */
case TYPE_REPEATING_PRECISE_CAN_SKIP: typeStr = "PRECISE "; break;
default: MOZ_CRASH("bad type");
}
switch (aCallbackType) {
case CallbackType::Function: {
bool needToFreeName = false;
const char* annotation = "";
const char* name;
static const size_t buflen = 1024;
char buf[buflen];
if (mName.is<NameString>()) {
name = mName.as<NameString>();
} else if (mName.is<NameFunc>()) {
mName.as<NameFunc>()(this, mClosure, buf, buflen);
name = buf;
} else {
MOZ_ASSERT(mName.is<NameNothing>());
#ifdef USE_DLADDR
annotation = "[from dladdr] ";
Dl_info info;
void* addr = reinterpret_cast<void*>(aCallback.c);
if (dladdr(addr, &info) == 0) {
name = "???[dladdr: failed]";
} else if (info.dli_sname) {
int status;
name = abi::__cxa_demangle(info.dli_sname, nullptr, nullptr, &status);
if (status == 0) {
// Success. Because we didn't pass in a buffer to __cxa_demangle it
// allocates its own one with malloc() which we must free() later.
MOZ_ASSERT(name);
needToFreeName = true;
} else if (status == -1) {
name = "???[__cxa_demangle: OOM]";
} else if (status == -2) {
name = "???[__cxa_demangle: invalid mangled name]";
} else if (status == -3) {
name = "???[__cxa_demangle: invalid argument]";
} else {
name = "???[__cxa_demangle: unexpected status value]";
}
} else if (info.dli_fname) {
// The "#0: " prefix is necessary for fix_linux_stack.py to interpret
// this string as something to convert.
snprintf(buf, buflen, "#0: ???[%s +0x%" PRIxPTR "]\n",
info.dli_fname, uintptr_t(addr) - uintptr_t(info.dli_fbase));
name = buf;
} else {
name = "???[dladdr: no symbol or shared object obtained]";
}
#else
name = "???[dladdr is unimplemented or doesn't work well on this OS]";
#endif
}
MOZ_LOG(GetTimerFiringsLog(), LogLevel::Debug,
("[%d] fn timer (%s %5d ms): %s%s\n",
getpid(), typeStr, mDelay, annotation, name));
if (needToFreeName) {
free(const_cast<char*>(name));
}
break;
}
case CallbackType::Interface: {
MOZ_LOG(GetTimerFiringsLog(), LogLevel::Debug,
("[%d] iface timer (%s %5d ms): %p\n",
getpid(), typeStr, mDelay, aCallback.i));
break;
}
case CallbackType::Observer: {
MOZ_LOG(GetTimerFiringsLog(), LogLevel::Debug,
("[%d] obs timer (%s %5d ms): %p\n",
getpid(), typeStr, mDelay, aCallback.o));
break;
}
case CallbackType::Unknown:
default: {
MOZ_LOG(GetTimerFiringsLog(), LogLevel::Debug,
("[%d] ??? timer (%s, %5d ms)\n",
getpid(), typeStr, mDelay));
break;
}
}
}
void
nsTimerImpl::SetDelayInternal(uint32_t aDelay)
{
TimeDuration delayInterval = TimeDuration::FromMilliseconds(aDelay);
mDelay = aDelay;
TimeStamp now = TimeStamp::Now();
mTimeout = now;
mTimeout += delayInterval;
if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
if (mStart.IsNull()) {
mStart = now;
} else {
mStart2 = now;
}
}
}
size_t
nsTimerImpl::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
{
return aMallocSizeOf(this);
}
/* static */ const nsTimerImpl::NameNothing nsTimerImpl::Nothing = 0;
#ifdef MOZ_TASK_TRACER
void
nsTimerImpl::GetTLSTraceInfo()
{
mTracedTask.GetTLSTraceInfo();
}
TracedTaskCommon
nsTimerImpl::GetTracedTask()
{
return mTracedTask;
}
#endif