gecko-dev/xpcom/threads/LazyIdleThread.cpp

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14 KiB
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 "LazyIdleThread.h"
#include "nsIObserverService.h"
#include "GeckoProfiler.h"
#include "nsComponentManagerUtils.h"
#include "nsServiceManagerUtils.h"
#include "nsThreadUtils.h"
#include "mozilla/Services.h"
#ifdef DEBUG
#define ASSERT_OWNING_THREAD() \
PR_BEGIN_MACRO \
nsIThread* currentThread = NS_GetCurrentThread(); \
if (currentThread) { \
nsCOMPtr<nsISupports> current(do_QueryInterface(currentThread)); \
nsCOMPtr<nsISupports> test(do_QueryInterface(mOwningThread)); \
MOZ_ASSERT(current == test, "Wrong thread!"); \
} \
PR_END_MACRO
#else
#define ASSERT_OWNING_THREAD() /* nothing */
#endif
namespace mozilla {
LazyIdleThread::LazyIdleThread(uint32_t aIdleTimeoutMS,
const nsCSubstring& aName,
ShutdownMethod aShutdownMethod,
nsIObserver* aIdleObserver)
: mMutex("LazyIdleThread::mMutex")
, mOwningThread(NS_GetCurrentThread())
, mIdleObserver(aIdleObserver)
, mQueuedRunnables(nullptr)
, mIdleTimeoutMS(aIdleTimeoutMS)
, mPendingEventCount(0)
, mIdleNotificationCount(0)
, mShutdownMethod(aShutdownMethod)
, mShutdown(false)
, mThreadIsShuttingDown(false)
, mIdleTimeoutEnabled(true)
, mName(aName)
{
MOZ_ASSERT(mOwningThread, "Need owning thread!");
}
LazyIdleThread::~LazyIdleThread()
{
ASSERT_OWNING_THREAD();
Shutdown();
}
void
LazyIdleThread::SetWeakIdleObserver(nsIObserver* aObserver)
{
ASSERT_OWNING_THREAD();
if (mShutdown) {
NS_WARN_IF_FALSE(!aObserver,
"Setting an observer after Shutdown was called!");
return;
}
mIdleObserver = aObserver;
}
void
LazyIdleThread::DisableIdleTimeout()
{
ASSERT_OWNING_THREAD();
if (!mIdleTimeoutEnabled) {
return;
}
mIdleTimeoutEnabled = false;
if (mIdleTimer && NS_FAILED(mIdleTimer->Cancel())) {
NS_WARNING("Failed to cancel timer!");
}
MutexAutoLock lock(mMutex);
// Pretend we have a pending event to keep the idle timer from firing.
MOZ_ASSERT(mPendingEventCount < UINT32_MAX, "Way too many!");
mPendingEventCount++;
}
void
LazyIdleThread::EnableIdleTimeout()
{
ASSERT_OWNING_THREAD();
if (mIdleTimeoutEnabled) {
return;
}
mIdleTimeoutEnabled = true;
{
MutexAutoLock lock(mMutex);
MOZ_ASSERT(mPendingEventCount, "Mismatched calls to observer methods!");
--mPendingEventCount;
}
if (mThread) {
nsCOMPtr<nsIRunnable> runnable(new nsRunnable());
if (NS_FAILED(Dispatch(runnable, NS_DISPATCH_NORMAL))) {
NS_WARNING("Failed to dispatch!");
}
}
}
void
LazyIdleThread::PreDispatch()
{
MutexAutoLock lock(mMutex);
MOZ_ASSERT(mPendingEventCount < UINT32_MAX, "Way too many!");
mPendingEventCount++;
}
nsresult
LazyIdleThread::EnsureThread()
{
ASSERT_OWNING_THREAD();
if (mShutdown) {
return NS_ERROR_UNEXPECTED;
}
if (mThread) {
return NS_OK;
}
MOZ_ASSERT(!mPendingEventCount, "Shouldn't have events yet!");
MOZ_ASSERT(!mIdleNotificationCount, "Shouldn't have idle events yet!");
MOZ_ASSERT(!mIdleTimer, "Should have killed this long ago!");
MOZ_ASSERT(!mThreadIsShuttingDown, "Should have cleared that!");
nsresult rv;
if (mShutdownMethod == AutomaticShutdown && NS_IsMainThread()) {
nsCOMPtr<nsIObserverService> obs =
do_GetService(NS_OBSERVERSERVICE_CONTRACTID, &rv);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
rv = obs->AddObserver(this, "xpcom-shutdown-threads", false);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
}
mIdleTimer = do_CreateInstance(NS_TIMER_CONTRACTID, &rv);
if (NS_WARN_IF(!mIdleTimer)) {
return NS_ERROR_UNEXPECTED;
}
nsCOMPtr<nsIRunnable> runnable =
NS_NewRunnableMethod(this, &LazyIdleThread::InitThread);
if (NS_WARN_IF(!runnable)) {
return NS_ERROR_UNEXPECTED;
}
rv = NS_NewThread(getter_AddRefs(mThread), runnable);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
return NS_OK;
}
void
LazyIdleThread::InitThread()
{
#if !defined(MOZILLA_XPCOMRT_API)
char aLocal;
profiler_register_thread(mName.get(), &aLocal);
#endif // !defined(MOZILLA_XPCOMRT_API)
PR_SetCurrentThreadName(mName.get());
// Happens on mThread but mThread may not be set yet...
nsCOMPtr<nsIThreadInternal> thread(do_QueryInterface(NS_GetCurrentThread()));
MOZ_ASSERT(thread, "This should always succeed!");
if (NS_FAILED(thread->SetObserver(this))) {
NS_WARNING("Failed to set thread observer!");
}
}
void
LazyIdleThread::CleanupThread()
{
nsCOMPtr<nsIThreadInternal> thread(do_QueryInterface(NS_GetCurrentThread()));
MOZ_ASSERT(thread, "This should always succeed!");
if (NS_FAILED(thread->SetObserver(nullptr))) {
NS_WARNING("Failed to set thread observer!");
}
{
MutexAutoLock lock(mMutex);
MOZ_ASSERT(!mThreadIsShuttingDown, "Shouldn't be true ever!");
mThreadIsShuttingDown = true;
}
#if !defined(MOZILLA_XPCOMRT_API)
profiler_unregister_thread();
#endif // !defined(MOZILLA_XPCOMRT_API)
}
void
LazyIdleThread::ScheduleTimer()
{
ASSERT_OWNING_THREAD();
bool shouldSchedule;
{
MutexAutoLock lock(mMutex);
MOZ_ASSERT(mIdleNotificationCount, "Should have at least one!");
--mIdleNotificationCount;
shouldSchedule = !mIdleNotificationCount && !mPendingEventCount;
}
if (mIdleTimer) {
if (NS_FAILED(mIdleTimer->Cancel())) {
NS_WARNING("Failed to cancel timer!");
}
if (shouldSchedule &&
NS_FAILED(mIdleTimer->InitWithCallback(this, mIdleTimeoutMS,
nsITimer::TYPE_ONE_SHOT))) {
NS_WARNING("Failed to schedule timer!");
}
}
}
nsresult
LazyIdleThread::ShutdownThread()
{
ASSERT_OWNING_THREAD();
// Before calling Shutdown() on the real thread we need to put a queue in
// place in case a runnable is posted to the thread while it's in the
// process of shutting down. This will be our queue.
nsAutoTArray<nsCOMPtr<nsIRunnable>, 10> queuedRunnables;
nsresult rv;
// Make sure to cancel the shutdown timer before spinning the event loop
// during |mThread->Shutdown()| below. Otherwise the timer might fire and we
// could reenter here.
if (mIdleTimer) {
rv = mIdleTimer->Cancel();
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
mIdleTimer = nullptr;
}
if (mThread) {
if (mShutdownMethod == AutomaticShutdown && NS_IsMainThread()) {
nsCOMPtr<nsIObserverService> obs =
mozilla::services::GetObserverService();
NS_WARN_IF_FALSE(obs, "Failed to get observer service!");
if (obs &&
NS_FAILED(obs->RemoveObserver(this, "xpcom-shutdown-threads"))) {
NS_WARNING("Failed to remove observer!");
}
}
if (mIdleObserver) {
mIdleObserver->Observe(static_cast<nsIThread*>(this), IDLE_THREAD_TOPIC,
nullptr);
}
#ifdef DEBUG
{
MutexAutoLock lock(mMutex);
MOZ_ASSERT(!mThreadIsShuttingDown, "Huh?!");
}
#endif
nsCOMPtr<nsIRunnable> runnable =
NS_NewRunnableMethod(this, &LazyIdleThread::CleanupThread);
if (NS_WARN_IF(!runnable)) {
return NS_ERROR_UNEXPECTED;
}
PreDispatch();
rv = mThread->Dispatch(runnable, NS_DISPATCH_NORMAL);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
// Put the temporary queue in place before calling Shutdown().
mQueuedRunnables = &queuedRunnables;
if (NS_FAILED(mThread->Shutdown())) {
NS_ERROR("Failed to shutdown the thread!");
}
// Now unset the queue.
mQueuedRunnables = nullptr;
mThread = nullptr;
{
MutexAutoLock lock(mMutex);
MOZ_ASSERT(!mPendingEventCount, "Huh?!");
MOZ_ASSERT(!mIdleNotificationCount, "Huh?!");
MOZ_ASSERT(mThreadIsShuttingDown, "Huh?!");
mThreadIsShuttingDown = false;
}
}
// If our temporary queue has any runnables then we need to dispatch them.
if (queuedRunnables.Length()) {
// If the thread manager has gone away then these runnables will never run.
if (mShutdown) {
NS_ERROR("Runnables dispatched to LazyIdleThread will never run!");
return NS_OK;
}
// Re-dispatch the queued runnables.
for (uint32_t index = 0; index < queuedRunnables.Length(); index++) {
nsCOMPtr<nsIRunnable> runnable;
runnable.swap(queuedRunnables[index]);
MOZ_ASSERT(runnable, "Null runnable?!");
if (NS_FAILED(Dispatch(runnable, NS_DISPATCH_NORMAL))) {
NS_ERROR("Failed to re-dispatch queued runnable!");
}
}
}
return NS_OK;
}
void
LazyIdleThread::SelfDestruct()
{
MOZ_ASSERT(mRefCnt == 1, "Bad refcount!");
delete this;
}
NS_IMPL_ADDREF(LazyIdleThread)
NS_IMETHODIMP_(MozExternalRefCountType)
LazyIdleThread::Release()
{
nsrefcnt count = --mRefCnt;
NS_LOG_RELEASE(this, count, "LazyIdleThread");
if (!count) {
// Stabilize refcount.
mRefCnt = 1;
nsCOMPtr<nsIRunnable> runnable =
NS_NewNonOwningRunnableMethod(this, &LazyIdleThread::SelfDestruct);
NS_WARN_IF_FALSE(runnable, "Couldn't make runnable!");
if (NS_FAILED(NS_DispatchToCurrentThread(runnable))) {
MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
// The only way this could fail is if we're in shutdown, and in that case
// threads should have been joined already. Deleting here isn't dangerous
// anymore because we won't spin the event loop waiting to join the
// thread.
SelfDestruct();
}
}
return count;
}
NS_IMPL_QUERY_INTERFACE(LazyIdleThread, nsIThread,
nsIEventTarget,
nsITimerCallback,
nsIThreadObserver,
nsIObserver)
NS_IMETHODIMP
LazyIdleThread::Dispatch(nsIRunnable* aEvent,
uint32_t aFlags)
{
ASSERT_OWNING_THREAD();
// LazyIdleThread can't always support synchronous dispatch currently.
if (NS_WARN_IF(aFlags != NS_DISPATCH_NORMAL)) {
return NS_ERROR_NOT_IMPLEMENTED;
}
if (NS_WARN_IF(mShutdown)) {
return NS_ERROR_UNEXPECTED;
}
// If our thread is shutting down then we can't actually dispatch right now.
// Queue this runnable for later.
if (UseRunnableQueue()) {
mQueuedRunnables->AppendElement(aEvent);
return NS_OK;
}
nsresult rv = EnsureThread();
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
PreDispatch();
return mThread->Dispatch(aEvent, aFlags);
}
NS_IMETHODIMP
LazyIdleThread::IsOnCurrentThread(bool* aIsOnCurrentThread)
{
if (mThread) {
return mThread->IsOnCurrentThread(aIsOnCurrentThread);
}
*aIsOnCurrentThread = false;
return NS_OK;
}
NS_IMETHODIMP
LazyIdleThread::GetPRThread(PRThread** aPRThread)
{
if (mThread) {
return mThread->GetPRThread(aPRThread);
}
*aPRThread = nullptr;
return NS_ERROR_NOT_AVAILABLE;
}
NS_IMETHODIMP
LazyIdleThread::Shutdown()
{
ASSERT_OWNING_THREAD();
mShutdown = true;
nsresult rv = ShutdownThread();
MOZ_ASSERT(!mThread, "Should have destroyed this by now!");
mIdleObserver = nullptr;
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
return NS_OK;
}
NS_IMETHODIMP
LazyIdleThread::HasPendingEvents(bool* aHasPendingEvents)
{
// This is only supposed to be called from the thread itself so it's not
// implemented here.
NS_NOTREACHED("Shouldn't ever call this!");
return NS_ERROR_UNEXPECTED;
}
NS_IMETHODIMP
LazyIdleThread::ProcessNextEvent(bool aMayWait,
bool* aEventWasProcessed)
{
// This is only supposed to be called from the thread itself so it's not
// implemented here.
NS_NOTREACHED("Shouldn't ever call this!");
return NS_ERROR_UNEXPECTED;
}
NS_IMETHODIMP
LazyIdleThread::Notify(nsITimer* aTimer)
{
ASSERT_OWNING_THREAD();
{
MutexAutoLock lock(mMutex);
if (mPendingEventCount || mIdleNotificationCount) {
// Another event was scheduled since this timer was set. Don't do
// anything and wait for the timer to fire again.
return NS_OK;
}
}
nsresult rv = ShutdownThread();
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
return NS_OK;
}
NS_IMETHODIMP
LazyIdleThread::OnDispatchedEvent(nsIThreadInternal* /*aThread */)
{
MOZ_ASSERT(NS_GetCurrentThread() == mOwningThread, "Wrong thread!");
return NS_OK;
}
NS_IMETHODIMP
LazyIdleThread::OnProcessNextEvent(nsIThreadInternal* /* aThread */,
bool /* aMayWait */,
uint32_t /* aRecursionDepth */)
{
return NS_OK;
}
NS_IMETHODIMP
LazyIdleThread::AfterProcessNextEvent(nsIThreadInternal* /* aThread */,
uint32_t /* aRecursionDepth */,
bool aEventWasProcessed)
{
bool shouldNotifyIdle;
{
MutexAutoLock lock(mMutex);
if (aEventWasProcessed) {
MOZ_ASSERT(mPendingEventCount, "Mismatched calls to observer methods!");
--mPendingEventCount;
}
if (mThreadIsShuttingDown) {
// We're shutting down, no need to fire any timer.
return NS_OK;
}
shouldNotifyIdle = !mPendingEventCount;
if (shouldNotifyIdle) {
MOZ_ASSERT(mIdleNotificationCount < UINT32_MAX, "Way too many!");
mIdleNotificationCount++;
}
}
if (shouldNotifyIdle) {
nsCOMPtr<nsIRunnable> runnable =
NS_NewRunnableMethod(this, &LazyIdleThread::ScheduleTimer);
if (NS_WARN_IF(!runnable)) {
return NS_ERROR_UNEXPECTED;
}
nsresult rv = mOwningThread->Dispatch(runnable, NS_DISPATCH_NORMAL);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
}
return NS_OK;
}
NS_IMETHODIMP
LazyIdleThread::Observe(nsISupports* /* aSubject */,
const char* aTopic,
const char16_t* /* aData */)
{
MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
MOZ_ASSERT(mShutdownMethod == AutomaticShutdown,
"Should not receive notifications if not AutomaticShutdown!");
MOZ_ASSERT(!strcmp("xpcom-shutdown-threads", aTopic), "Bad topic!");
Shutdown();
return NS_OK;
}
} // namespace mozilla