зеркало из https://github.com/mozilla/gecko-dev.git
Bug 1606706 - Part 1: Add new TaskController code to the tree. r=smaug,froydnj
Differential Revision: https://phabricator.services.mozilla.com/D74671
This commit is contained in:
Bas Schouten
Родитель
6653839518
Коммит
e79c5d94a5
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@ -0,0 +1,585 @@
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "TaskController.h"
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#include "nsIIdleRunnable.h"
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#include "nsIRunnable.h"
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#include "nsThreadUtils.h"
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#include <algorithm>
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#include <initializer_list>
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#include "mozilla/AbstractEventQueue.h"
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#include "mozilla/StaticMutex.h"
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#include "mozilla/ScopeExit.h"
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#include "mozilla/Unused.h"
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#include "nsIThreadInternal.h"
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#include "nsThread.h"
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namespace mozilla {
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std::unique_ptr<TaskController> TaskController::sSingleton;
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uint64_t Task::sCurrentTaskSeqNo = 0;
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bool TaskManager::
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UpdateCachesForCurrentIterationAndReportPriorityModifierChanged(
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const MutexAutoLock& aProofOfLock, IterationType aIterationType) {
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mCurrentSuspended = IsSuspended(aProofOfLock);
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if (aIterationType == IterationType::EVENT_LOOP_TURN) {
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int32_t oldModifier = mCurrentPriorityModifier;
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mCurrentPriorityModifier =
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GetPriorityModifierForEventLoopTurn(aProofOfLock);
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if (mCurrentPriorityModifier != oldModifier) {
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return true;
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}
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}
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return false;
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}
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Task* Task::GetHighestPriorityDependency() {
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Task* currentTask = this;
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while (!currentTask->mDependencies.empty()) {
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auto iter = currentTask->mDependencies.begin();
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while (iter != currentTask->mDependencies.end()) {
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if ((*iter)->mCompleted) {
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auto oldIter = iter;
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iter++;
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// Completed tasks are removed here to prevent needlessly keeping them
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// alive or iterating over them in the future.
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currentTask->mDependencies.erase(oldIter);
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continue;
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}
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currentTask = iter->get();
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break;
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}
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}
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return currentTask == this ? nullptr : currentTask;
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}
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TaskController* TaskController::Get() {
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MOZ_ASSERT(sSingleton.get());
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return sSingleton.get();
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}
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bool TaskController::Initialize() {
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MOZ_ASSERT(!sSingleton);
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sSingleton = std::make_unique<TaskController>();
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return sSingleton->InitializeInternal();
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}
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bool TaskController::InitializeInternal() {
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mMTProcessingRunnable = NS_NewRunnableFunction(
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"TaskController::ExecutePendingMTTasks()",
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[]() { TaskController::Get()->ProcessPendingMTTask(); });
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return true;
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}
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void TaskController::SetPerformanceCounterState(
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PerformanceCounterState* aPerformanceCounterState) {
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mPerformanceCounterState = aPerformanceCounterState;
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}
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/* static */
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void TaskController::Shutdown() {
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if (sSingleton) {
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sSingleton->ShutdownInternal();
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}
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MOZ_ASSERT(!sSingleton);
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}
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void TaskController::ShutdownInternal() { sSingleton = nullptr; }
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void TaskController::AddTask(already_AddRefed<Task>&& aTask) {
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MutexAutoLock lock(mGraphMutex);
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RefPtr<Task> task(aTask);
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if (TaskManager* manager = task->GetManager()) {
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if (manager->mTaskCount == 0) {
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mTaskManagers.insert(manager);
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}
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manager->DidQueueTask();
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// Set this here since if this manager's priority modifier doesn't change
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// we will not reprioritize when iterating over the queue.
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task->mPriorityModifier = manager->mCurrentPriorityModifier;
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}
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#ifdef DEBUG
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task->mIsInGraph = true;
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for (const RefPtr<Task>& otherTask : task->mDependencies) {
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MOZ_ASSERT(!otherTask->mTaskManager ||
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otherTask->mTaskManager == task->mTaskManager);
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}
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#endif
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auto insertion = mMainThreadTasks.insert(std::move(task));
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MOZ_ASSERT(insertion.second);
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(*insertion.first)->mIterator = insertion.first;
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MaybeInterruptTask(*insertion.first);
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}
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void TaskController::WaitForTaskOrMessage() {
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MutexAutoLock lock(mGraphMutex);
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while (!mMayHaveMainThreadTask) {
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mMainThreadCV.Wait();
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}
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}
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void TaskController::ExecuteNextTaskOnlyMainThread() {
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MOZ_ASSERT(NS_IsMainThread());
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MutexAutoLock lock(mGraphMutex);
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ExecuteNextTaskOnlyMainThreadInternal(lock);
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}
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void TaskController::ProcessPendingMTTask() {
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MOZ_ASSERT(NS_IsMainThread());
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MutexAutoLock lock(mGraphMutex);
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mHasScheduledMTRunnable = false;
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ExecuteNextTaskOnlyMainThreadInternal(lock);
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if (mMayHaveMainThreadTask) {
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EnsureMainThreadTasksScheduled();
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}
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}
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void TaskController::ReprioritizeTask(Task* aTask, uint32_t aPriority) {
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MutexAutoLock lock(mGraphMutex);
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std::set<RefPtr<Task>, Task::PriorityCompare>* queue = &mMainThreadTasks;
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MOZ_ASSERT(aTask->mIterator != queue->end());
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queue->erase(aTask->mIterator);
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aTask->mPriority = aPriority;
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auto insertion = queue->insert(aTask);
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MOZ_ASSERT(insertion.second);
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aTask->mIterator = insertion.first;
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MaybeInterruptTask(aTask);
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}
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// Code supporting runnable compatibility.
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// Task that wraps a runnable.
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class RunnableTask : public Task {
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public:
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RunnableTask(already_AddRefed<nsIRunnable>&& aRunnable, int32_t aPriority,
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bool aMainThread = true)
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: Task(aMainThread, aPriority), mRunnable(aRunnable) {}
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virtual bool Run() override {
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mRunnable->Run();
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mRunnable = nullptr;
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return true;
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}
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void SetIdleDeadline(TimeStamp aDeadline) override {
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nsCOMPtr<nsIIdleRunnable> idleRunnable = do_QueryInterface(mRunnable);
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if (idleRunnable) {
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idleRunnable->SetDeadline(aDeadline);
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}
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}
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PerformanceCounter* GetPerformanceCounter() const override {
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return nsThread::GetPerformanceCounterBase(mRunnable);
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}
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private:
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RefPtr<nsIRunnable> mRunnable;
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};
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void TaskController::DispatchRunnable(already_AddRefed<nsIRunnable>&& aRunnable,
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uint32_t aPriority,
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TaskManager* aManager) {
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RefPtr<RunnableTask> task = new RunnableTask(std::move(aRunnable), aPriority);
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task->SetManager(aManager);
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TaskController::Get()->AddTask(task.forget());
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}
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nsIRunnable* TaskController::GetRunnableForMTTask(bool aReallyWait) {
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MutexAutoLock lock(mGraphMutex);
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while (mMainThreadTasks.empty()) {
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if (!aReallyWait) {
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return nullptr;
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}
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AUTO_PROFILER_LABEL("TaskController::GetRunnableForMTTask::Wait", IDLE);
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mMainThreadCV.Wait();
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}
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return mMTProcessingRunnable;
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}
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bool TaskController::HasMainThreadPendingTasks() {
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auto resetIdleState = MakeScopeExit([&idleManager = mIdleTaskManager] {
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if (idleManager) {
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idleManager->State().ClearCachedIdleDeadline();
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}
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});
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for (bool considerIdle : {false, true}) {
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if (considerIdle && !mIdleTaskManager) {
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continue;
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}
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MutexAutoLock lock(mGraphMutex);
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if (considerIdle) {
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mIdleTaskManager->State().ForgetPendingTaskGuarantee();
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// Temporarily unlock so we can peek our idle deadline.
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// XXX We could do this _before_ we take the lock if the API would let us.
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// We do want to do this before looking at mMainThreadTasks, in case
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// someone adds one while we're unlocked.
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{
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MutexAutoUnlock unlock(mGraphMutex);
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mIdleTaskManager->State().CachePeekedIdleDeadline(unlock);
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}
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}
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// Return early if there's no tasks at all.
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if (mMainThreadTasks.empty()) {
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return false;
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}
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// We can cheaply count how many tasks are suspended.
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uint64_t totalSuspended = 0;
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for (TaskManager* manager : mTaskManagers) {
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bool modifierChanged =
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manager
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->UpdateCachesForCurrentIterationAndReportPriorityModifierChanged(
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lock, TaskManager::IterationType::NOT_EVENT_LOOP_TURN);
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MOZ_ASSERT(!modifierChanged);
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// The idle manager should be suspended unless we're doing the idle pass.
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MOZ_ASSERT(manager != mIdleTaskManager || manager->mCurrentSuspended ||
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considerIdle,
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"Why are idle tasks not suspended here?");
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if (manager->mCurrentSuspended) {
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// XXX - If managers manage off-main-thread tasks this breaks! This
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// scenario is explicitly not supported.
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//
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// This is only incremented inside the lock -or- decremented on the main
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// thread so this is safe.
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totalSuspended += manager->mTaskCount;
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}
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}
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// Thi would break down if we have a non-suspended task depending on a
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// suspended task. This is why for the moment we do not allow tasks
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// to be dependent on tasks managed by another taskmanager.
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if (mMainThreadTasks.size() > totalSuspended) {
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// If mIdleTaskManager->mTaskCount is 0, we never updated the suspended
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// state of mIdleTaskManager above, hence shouldn't even check it here.
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// But in that case idle tasks are not contributing to our suspended task
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// count anyway.
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if (mIdleTaskManager && mIdleTaskManager->mTaskCount &&
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!mIdleTaskManager->mCurrentSuspended) {
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MOZ_ASSERT(considerIdle, "Why is mIdleTaskManager not suspended?");
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// Check whether the idle tasks were really needed to make our "we have
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// an unsuspended task" decision. If they were, we need to force-enable
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// idle tasks until we run our next task.
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if (mMainThreadTasks.size() - mIdleTaskManager->mTaskCount <=
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totalSuspended) {
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mIdleTaskManager->State().EnforcePendingTaskGuarantee();
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}
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}
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return true;
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}
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}
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return false;
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}
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void TaskController::ExecuteNextTaskOnlyMainThreadInternal(
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const MutexAutoLock& aProofOfLock) {
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// Block to make it easier to jump to our cleanup.
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do {
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bool taskRan = DoExecuteNextTaskOnlyMainThreadInternal(aProofOfLock);
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if (taskRan) {
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break;
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}
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if (!mIdleTaskManager) {
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break;
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}
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if (mIdleTaskManager->mTaskCount) {
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// We have idle tasks that we may not have gotten above because
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// our idle state is not up to date. We need to update the idle state
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// and try again. We need to temporarily release the lock while we do
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// that.
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MutexAutoUnlock unlock(mGraphMutex);
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mIdleTaskManager->State().UpdateCachedIdleDeadline(unlock);
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} else {
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MutexAutoUnlock unlock(mGraphMutex);
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mIdleTaskManager->State().RanOutOfTasks(unlock);
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}
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// When we unlocked, someone may have queued a new task on us. So try to
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// see whether we can run things again.
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Unused << DoExecuteNextTaskOnlyMainThreadInternal(aProofOfLock);
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} while (false);
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if (mIdleTaskManager) {
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// The pending task guarantee is not needed anymore, since we just tried
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// running a task
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mIdleTaskManager->State().ForgetPendingTaskGuarantee();
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if (mMainThreadTasks.empty()) {
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// XXX the IdlePeriodState API demands we have a MutexAutoUnlock for it.
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// Otherwise we could perhaps just do this after we exit the locked block,
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// by pushing the lock down into this method. Though it's not clear that
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// we could check mMainThreadTasks.size() once we unlock, and whether we
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// could maybe substitute mMayHaveMainThreadTask for that check.
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MutexAutoUnlock unlock(mGraphMutex);
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mIdleTaskManager->State().RanOutOfTasks(unlock);
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}
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}
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}
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bool TaskController::DoExecuteNextTaskOnlyMainThreadInternal(
|
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const MutexAutoLock& aProofOfLock) {
|
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uint32_t totalSuspended = 0;
|
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for (TaskManager* manager : mTaskManagers) {
|
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bool modifierChanged =
|
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manager
|
||||
->UpdateCachesForCurrentIterationAndReportPriorityModifierChanged(
|
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aProofOfLock, TaskManager::IterationType::EVENT_LOOP_TURN);
|
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if (modifierChanged) {
|
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ProcessUpdatedPriorityModifier(manager);
|
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}
|
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if (manager->mCurrentSuspended) {
|
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totalSuspended += manager->mTaskCount;
|
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}
|
||||
}
|
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|
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MOZ_ASSERT(mMainThreadTasks.size() >= totalSuspended);
|
||||
|
||||
// This would break down if we have a non-suspended task depending on a
|
||||
// suspended task. This is why for the moment we do not allow tasks
|
||||
// to be dependent on tasks managed by another taskmanager.
|
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if (mMainThreadTasks.size() > totalSuspended) {
|
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for (auto iter = mMainThreadTasks.begin(); iter != mMainThreadTasks.end();
|
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iter++) {
|
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Task* task = iter->get();
|
||||
|
||||
if (task->mTaskManager && task->mTaskManager->mCurrentSuspended) {
|
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// Even though we may want to run some dependencies of this task, we
|
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// will run them at their own priority level and not the priority
|
||||
// level of their dependents.
|
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continue;
|
||||
}
|
||||
|
||||
task = GetFinalDependency(task);
|
||||
|
||||
if (!task->IsMainThreadOnly() || task->mInProgress ||
|
||||
(task->mTaskManager && task->mTaskManager->mCurrentSuspended)) {
|
||||
continue;
|
||||
}
|
||||
|
||||
mCurrentTasksMT.push(task);
|
||||
mMainThreadTasks.erase(task->mIterator);
|
||||
task->mIterator = mMainThreadTasks.end();
|
||||
task->mInProgress = true;
|
||||
TaskManager* manager = task->GetManager();
|
||||
bool result = false;
|
||||
|
||||
{
|
||||
MutexAutoUnlock unlock(mGraphMutex);
|
||||
if (manager) {
|
||||
manager->WillRunTask();
|
||||
if (manager != mIdleTaskManager) {
|
||||
// Notify the idle period state that we're running a non-idle task.
|
||||
// This needs to happen while our mutex is not locked!
|
||||
mIdleTaskManager->State().FlagNotIdle();
|
||||
} else {
|
||||
TimeStamp idleDeadline =
|
||||
mIdleTaskManager->State().GetCachedIdleDeadline();
|
||||
MOZ_ASSERT(
|
||||
idleDeadline,
|
||||
"How can we not have a deadline if our manager is enabled?");
|
||||
task->SetIdleDeadline(idleDeadline);
|
||||
}
|
||||
}
|
||||
if (mIdleTaskManager) {
|
||||
// We found a task to run; we can clear the idle deadline on our idle
|
||||
// task manager. This _must_ be done before we actually run the task,
|
||||
// because running the task could reenter via spinning the event loop
|
||||
// and we want to make sure there's no cached idle deadline at that
|
||||
// point. But we have to make sure we do it after out SetIdleDeadline
|
||||
// call above, in the case when the task is actually an idle task.
|
||||
mIdleTaskManager->State().ClearCachedIdleDeadline();
|
||||
}
|
||||
|
||||
PerformanceCounterState::Snapshot snapshot =
|
||||
mPerformanceCounterState->RunnableWillRun(
|
||||
task->GetPerformanceCounter(), TimeStamp::Now(),
|
||||
manager == mIdleTaskManager);
|
||||
|
||||
result = task->Run();
|
||||
// Task itself should keep manager alive.
|
||||
if (manager) {
|
||||
manager->DidRunTask();
|
||||
}
|
||||
|
||||
mPerformanceCounterState->RunnableDidRun(std::move(snapshot));
|
||||
}
|
||||
|
||||
// Task itself should keep manager alive.
|
||||
if (manager && result && manager->mTaskCount == 0) {
|
||||
mTaskManagers.erase(manager);
|
||||
}
|
||||
|
||||
task->mInProgress = false;
|
||||
|
||||
if (!result) {
|
||||
// Presumably this task was interrupted, leave its dependencies
|
||||
// unresolved and reinsert into the queue.
|
||||
auto insertion =
|
||||
mMainThreadTasks.insert(std::move(mCurrentTasksMT.top()));
|
||||
MOZ_ASSERT(insertion.second);
|
||||
task->mIterator = insertion.first;
|
||||
manager->WillRunTask();
|
||||
} else {
|
||||
task->mCompleted = true;
|
||||
#ifdef DEBUG
|
||||
task->mIsInGraph = false;
|
||||
#endif
|
||||
// Clear dependencies to release references.
|
||||
task->mDependencies.clear();
|
||||
}
|
||||
|
||||
mCurrentTasksMT.pop();
|
||||
return true;
|
||||
}
|
||||
}
|
||||
|
||||
mMayHaveMainThreadTask = false;
|
||||
if (mIdleTaskManager) {
|
||||
// We did not find a task to run. We still need to clear the cached idle
|
||||
// deadline on our idle state, because that deadline was only relevant to
|
||||
// the execution of this function. Had we found a task, we would have
|
||||
// cleared the deadline before running that task.
|
||||
mIdleTaskManager->State().ClearCachedIdleDeadline();
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
Task* TaskController::GetFinalDependency(Task* aTask) {
|
||||
Task* nextTask;
|
||||
|
||||
while ((nextTask = aTask->GetHighestPriorityDependency())) {
|
||||
aTask = nextTask;
|
||||
}
|
||||
|
||||
return aTask;
|
||||
}
|
||||
|
||||
void TaskController::MaybeInterruptTask(Task* aTask) {
|
||||
mGraphMutex.AssertCurrentThreadOwns();
|
||||
|
||||
if (!aTask) {
|
||||
return;
|
||||
}
|
||||
|
||||
// This optimization prevents many slow lookups in long chains of similar
|
||||
// priority.
|
||||
if (!aTask->mDependencies.empty()) {
|
||||
Task* firstDependency = aTask->mDependencies.begin()->get();
|
||||
if (aTask->GetPriority() <= firstDependency->GetPriority() &&
|
||||
!firstDependency->mCompleted &&
|
||||
aTask->IsMainThreadOnly() == firstDependency->IsMainThreadOnly()) {
|
||||
// This task has the same or a higher priority as one of its dependencies,
|
||||
// never any need to interrupt.
|
||||
return;
|
||||
}
|
||||
}
|
||||
|
||||
Task* finalDependency = GetFinalDependency(aTask);
|
||||
|
||||
if (finalDependency->mInProgress) {
|
||||
// No need to wake anything, we can't schedule this task right now anyway.
|
||||
return;
|
||||
}
|
||||
|
||||
EnsureMainThreadTasksScheduled();
|
||||
|
||||
mMayHaveMainThreadTask = true;
|
||||
|
||||
if (mCurrentTasksMT.empty()) {
|
||||
return;
|
||||
}
|
||||
|
||||
// We could go through the steps above here and interrupt an off main
|
||||
// thread task in case it has a lower priority.
|
||||
if (!finalDependency->IsMainThreadOnly()) {
|
||||
return;
|
||||
}
|
||||
|
||||
if (mCurrentTasksMT.top()->GetPriority() < aTask->GetPriority()) {
|
||||
mCurrentTasksMT.top()->RequestInterrupt(aTask->GetPriority());
|
||||
}
|
||||
}
|
||||
|
||||
Task* TaskController::GetHighestPriorityMTTask() {
|
||||
mGraphMutex.AssertCurrentThreadOwns();
|
||||
|
||||
if (!mMainThreadTasks.empty()) {
|
||||
return mMainThreadTasks.begin()->get();
|
||||
}
|
||||
return nullptr;
|
||||
}
|
||||
|
||||
void TaskController::EnsureMainThreadTasksScheduled() {
|
||||
if (mObserver) {
|
||||
mObserver->OnDispatchedEvent();
|
||||
}
|
||||
if (mExternalCondVar) {
|
||||
mExternalCondVar->Notify();
|
||||
}
|
||||
mMainThreadCV.Notify();
|
||||
}
|
||||
|
||||
void TaskController::ProcessUpdatedPriorityModifier(TaskManager* aManager) {
|
||||
mGraphMutex.AssertCurrentThreadOwns();
|
||||
|
||||
MOZ_ASSERT(NS_IsMainThread());
|
||||
|
||||
int32_t modifier = aManager->mCurrentPriorityModifier;
|
||||
|
||||
std::vector<RefPtr<Task>> storedTasks;
|
||||
// Find all relevant tasks.
|
||||
for (auto iter = mMainThreadTasks.begin(); iter != mMainThreadTasks.end();) {
|
||||
if ((*iter)->mTaskManager == aManager) {
|
||||
storedTasks.push_back(*iter);
|
||||
iter = mMainThreadTasks.erase(iter);
|
||||
} else {
|
||||
iter++;
|
||||
}
|
||||
}
|
||||
|
||||
// Reinsert found tasks with their new priorities.
|
||||
for (RefPtr<Task>& ref : storedTasks) {
|
||||
// Kept alive at first by the vector and then by mMainThreadTasks.
|
||||
Task* task = ref;
|
||||
task->mPriorityModifier = modifier;
|
||||
auto insertion = mMainThreadTasks.insert(std::move(ref));
|
||||
MOZ_ASSERT(insertion.second);
|
||||
task->mIterator = insertion.first;
|
||||
}
|
||||
}
|
||||
|
||||
} // namespace mozilla
|
||||
|
|
@ -0,0 +1,360 @@
|
|||
/* -*- 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/. */
|
||||
|
||||
#ifndef mozilla_TaskController_h
|
||||
#define mozilla_TaskController_h
|
||||
|
||||
#include "mozilla/CondVar.h"
|
||||
#include "mozilla/IdlePeriodState.h"
|
||||
#include "mozilla/RefPtr.h"
|
||||
#include "mozilla/Mutex.h"
|
||||
#include "mozilla/StaticMutex.h"
|
||||
#include "mozilla/TimeStamp.h"
|
||||
#include "mozilla/EventQueue.h"
|
||||
#include "nsISupportsImpl.h"
|
||||
#include "nsIEventTarget.h"
|
||||
|
||||
#include <thread>
|
||||
#include <memory>
|
||||
#include <vector>
|
||||
#include <set>
|
||||
#include <list>
|
||||
#include <stack>
|
||||
|
||||
class nsIRunnable;
|
||||
class nsIThreadObserver;
|
||||
|
||||
namespace mozilla {
|
||||
|
||||
class Task;
|
||||
class TaskController;
|
||||
class PerformanceCounter;
|
||||
class PerformanceCounterState;
|
||||
|
||||
const uint32_t kDefaultPriorityValue = uint32_t(EventQueuePriority::Normal);
|
||||
|
||||
// This file contains the core classes to access the Gecko scheduler. The
|
||||
// scheduler forms a graph of prioritize tasks, and is responsible for ensuring
|
||||
// the execution of tasks or their dependencies in order of inherited priority.
|
||||
//
|
||||
// The core class is the 'Task' class. The task class describes a single unit of
|
||||
// work. Users scheduling work implement this class and are required to
|
||||
// reimplement the 'Run' function in order to do work.
|
||||
//
|
||||
// The TaskManager class is reimplemented by users that require
|
||||
// the ability to reprioritize or suspend tasks.
|
||||
//
|
||||
// The TaskController is responsible for scheduling the work itself. The AddTask
|
||||
// function is used to schedule work. The ReprioritizeTask function may be used
|
||||
// to change the priority of a task already in the task graph, without
|
||||
// unscheduling it.
|
||||
|
||||
// The TaskManager is the baseclass used to atomically manage a large set of
|
||||
// tasks. API users reimplementing TaskManager may reimplement a number of
|
||||
// functions that they may use to indicate to the scheduler changes in the state
|
||||
// for any tasks they manage. They may be used to reprioritize or suspend tasks
|
||||
// under their control, and will also be notified before and after tasks under
|
||||
// their control are executed. Their methods will only be called once per event
|
||||
// loop turn, however they may still incur some performance overhead. In
|
||||
// addition to this frequent reprioritizations may incur a significant
|
||||
// performance overhead and are discouraged. A TaskManager may currently only be
|
||||
// used to manage tasks that are bound to the Gecko Main Thread.
|
||||
class TaskManager {
|
||||
public:
|
||||
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(TaskManager)
|
||||
|
||||
TaskManager() : mTaskCount(0) {}
|
||||
|
||||
// Subclasses implementing task manager will have this function called to
|
||||
// determine whether their associated tasks are currently suspended. This
|
||||
// will only be called once per iteration of the task queue, this means that
|
||||
// suspension of tasks managed by a single TaskManager may be assumed to
|
||||
// occur atomically.
|
||||
virtual bool IsSuspended(const MutexAutoLock& aProofOfLock) { return false; }
|
||||
|
||||
// Subclasses may implement this in order to supply a priority adjustment
|
||||
// to their managed tasks. This is called once per iteration of the task
|
||||
// queue, and may be assumed to occur atomically for all managed tasks.
|
||||
virtual int32_t GetPriorityModifierForEventLoopTurn(
|
||||
const MutexAutoLock& aProofOfLock) {
|
||||
return 0;
|
||||
}
|
||||
|
||||
void DidQueueTask() { ++mTaskCount; }
|
||||
// This is called when a managed task is about to be executed by the
|
||||
// scheduler. Anyone reimplementing this should ensure to call the parent or
|
||||
// decrement mTaskCount.
|
||||
virtual void WillRunTask() { --mTaskCount; }
|
||||
// This is called when a managed task has finished being executed by the
|
||||
// scheduler.
|
||||
virtual void DidRunTask() {}
|
||||
uint32_t PendingTaskCount() { return mTaskCount; }
|
||||
|
||||
protected:
|
||||
virtual ~TaskManager() {}
|
||||
|
||||
private:
|
||||
friend class TaskController;
|
||||
|
||||
enum class IterationType { NOT_EVENT_LOOP_TURN, EVENT_LOOP_TURN };
|
||||
bool UpdateCachesForCurrentIterationAndReportPriorityModifierChanged(
|
||||
const MutexAutoLock& aProofOfLock, IterationType aIterationType);
|
||||
|
||||
bool mCurrentSuspended = false;
|
||||
int32_t mCurrentPriorityModifier = 0;
|
||||
|
||||
Atomic<uint32_t> mTaskCount;
|
||||
};
|
||||
|
||||
// A Task is the the base class for any unit of work that may be scheduled.
|
||||
// Subclasses may specify their priority and whether they should be bound to
|
||||
// the Gecko Main thread. When not bound to the main thread tasks may be
|
||||
// executed on any available thread (including the main thread), but they may
|
||||
// also be executed in parallel to any other task they do not have a dependency
|
||||
// relationship with. Tasks will be run in order of object creation.
|
||||
class Task {
|
||||
public:
|
||||
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(Task)
|
||||
|
||||
bool IsMainThreadOnly() { return mMainThreadOnly; }
|
||||
|
||||
// This returns the current task priority with its modifier applied.
|
||||
uint32_t GetPriority() { return mPriority + mPriorityModifier; }
|
||||
uint64_t GetSeqNo() { return mSeqNo; }
|
||||
|
||||
// Callee needs to assume this may be called on any thread.
|
||||
// aInterruptPriority passes the priority of the higher priority task that
|
||||
// is ready to be executed. The task may safely ignore this function, or
|
||||
// interrupt any work being done. It may return 'false' from its run function
|
||||
// in order to be run automatically in the future, or true if it will
|
||||
// reschedule incomplete work manually.
|
||||
virtual void RequestInterrupt(uint32_t aInterruptPriority) {}
|
||||
|
||||
// At the moment this -must- be called before the task is added to the
|
||||
// controller. Calling this after tasks have been added to the controller
|
||||
// results in undefined behavior!
|
||||
// At submission, tasks must depend only on tasks managed by the same, or
|
||||
// no idle manager.
|
||||
void AddDependency(Task* aTask) {
|
||||
MOZ_ASSERT(aTask);
|
||||
MOZ_ASSERT(!mIsInGraph);
|
||||
mDependencies.insert(aTask);
|
||||
}
|
||||
|
||||
// This sets the TaskManager for the current task. Calling this after the
|
||||
// task has been added to the TaskController results in undefined behavior.
|
||||
void SetManager(TaskManager* aManager) {
|
||||
MOZ_ASSERT(mMainThreadOnly);
|
||||
MOZ_ASSERT(!mIsInGraph);
|
||||
mTaskManager = aManager;
|
||||
}
|
||||
TaskManager* GetManager() { return mTaskManager; }
|
||||
|
||||
struct PriorityCompare {
|
||||
bool operator()(const RefPtr<Task>& aTaskA,
|
||||
const RefPtr<Task>& aTaskB) const {
|
||||
uint32_t prioA = aTaskA->GetPriority();
|
||||
uint32_t prioB = aTaskB->GetPriority();
|
||||
return (prioA > prioB) ||
|
||||
(prioA == prioB && (aTaskA->GetSeqNo() < aTaskB->GetSeqNo()));
|
||||
}
|
||||
};
|
||||
|
||||
// Tell the task about its idle deadline. Will only be called for
|
||||
// tasks managed by an IdleTaskManager, right before the task runs.
|
||||
virtual void SetIdleDeadline(TimeStamp aDeadline) {}
|
||||
|
||||
virtual PerformanceCounter* GetPerformanceCounter() const { return nullptr; }
|
||||
|
||||
protected:
|
||||
Task(bool aMainThreadOnly, uint32_t aPriority = kDefaultPriorityValue)
|
||||
: mMainThreadOnly(aMainThreadOnly),
|
||||
mSeqNo(sCurrentTaskSeqNo++),
|
||||
mPriority(aPriority) {}
|
||||
|
||||
virtual ~Task() {}
|
||||
|
||||
friend class TaskController;
|
||||
|
||||
// When this returns false, the task is considered incomplete and will be
|
||||
// rescheduled at the current 'mPriority' level.
|
||||
virtual bool Run() = 0;
|
||||
|
||||
private:
|
||||
Task* GetHighestPriorityDependency();
|
||||
|
||||
// Iterator pointing to this task's position in
|
||||
// mThreadableTasks/mMainThreadTasks if, and only if this task is currently
|
||||
// scheduled to be executed. This allows fast access to the task's position
|
||||
// in the set, allowing for fast removal.
|
||||
// This is safe, and remains valid unless the task is removed from the set.
|
||||
// See also iterator invalidation in:
|
||||
// https://en.cppreference.com/w/cpp/container
|
||||
//
|
||||
// Or the spec:
|
||||
// "All Associative Containers: The insert and emplace members shall not
|
||||
// affect the validity of iterators and references to the container
|
||||
// [26.2.6/9]" "All Associative Containers: The erase members shall invalidate
|
||||
// only iterators and references to the erased elements [26.2.6/9]"
|
||||
std::set<RefPtr<Task>, PriorityCompare>::iterator mIterator;
|
||||
std::set<RefPtr<Task>, PriorityCompare> mDependencies;
|
||||
|
||||
RefPtr<TaskManager> mTaskManager;
|
||||
|
||||
// Access to these variables is protected by the GraphMutex.
|
||||
bool mMainThreadOnly;
|
||||
bool mCompleted = false;
|
||||
bool mInProgress = false;
|
||||
#ifdef DEBUG
|
||||
bool mIsInGraph = false;
|
||||
#endif
|
||||
|
||||
static uint64_t sCurrentTaskSeqNo;
|
||||
int64_t mSeqNo;
|
||||
uint32_t mPriority;
|
||||
// Modifier currently being applied to this task by its taskmanager.
|
||||
int32_t mPriorityModifier = 0;
|
||||
};
|
||||
|
||||
// A task manager implementation for priority levels that should only
|
||||
// run during idle periods.
|
||||
class IdleTaskManager : public TaskManager {
|
||||
public:
|
||||
explicit IdleTaskManager(already_AddRefed<nsIIdlePeriod>&& aIdlePeriod)
|
||||
: mIdlePeriodState(std::move(aIdlePeriod)) {}
|
||||
|
||||
IdlePeriodState& State() { return mIdlePeriodState; }
|
||||
|
||||
bool IsSuspended(const MutexAutoLock& aProofOfLock) override {
|
||||
TimeStamp idleDeadline = State().GetCachedIdleDeadline();
|
||||
return !idleDeadline;
|
||||
}
|
||||
|
||||
private:
|
||||
// Tracking of our idle state of various sorts.
|
||||
IdlePeriodState mIdlePeriodState;
|
||||
};
|
||||
|
||||
// The TaskController is the core class of the scheduler. It is used to
|
||||
// schedule tasks to be executed, as well as to reprioritize tasks that have
|
||||
// already been scheduled. The core functions to do this are AddTask and
|
||||
// ReprioritizeTask.
|
||||
class TaskController {
|
||||
public:
|
||||
TaskController()
|
||||
: mGraphMutex("TaskController::mGraphMutex"),
|
||||
mMainThreadCV(mGraphMutex, "TaskController::mMainThreadCV") {}
|
||||
|
||||
static TaskController* Get();
|
||||
|
||||
static bool Initialize();
|
||||
|
||||
void SetThreadObserver(nsIThreadObserver* aObserver) {
|
||||
mObserver = aObserver;
|
||||
}
|
||||
void SetConditionVariable(CondVar* aExternalCondVar) {
|
||||
mExternalCondVar = aExternalCondVar;
|
||||
}
|
||||
|
||||
void SetIdleTaskManager(IdleTaskManager* aIdleTaskManager) {
|
||||
mIdleTaskManager = aIdleTaskManager;
|
||||
}
|
||||
|
||||
// Initialization and shutdown code.
|
||||
bool InitializeInternal();
|
||||
void SetPerformanceCounterState(
|
||||
PerformanceCounterState* aPerformanceCounterState);
|
||||
|
||||
static void Shutdown();
|
||||
|
||||
// This adds a task to the TaskController graph.
|
||||
// This may be called on any thread.
|
||||
void AddTask(already_AddRefed<Task>&& aTask);
|
||||
|
||||
// This wait function is the theoretical function you would need if our main
|
||||
// thread needs to also process OS messages or something along those lines.
|
||||
void WaitForTaskOrMessage();
|
||||
|
||||
// This gets the next (highest priority) task that is only allowed to execute
|
||||
// on the main thread.
|
||||
void ExecuteNextTaskOnlyMainThread();
|
||||
|
||||
// Process all pending main thread tasks.
|
||||
void ProcessPendingMTTask();
|
||||
|
||||
// This allows reprioritization of a task already in the task graph.
|
||||
// This may be called on any thread.
|
||||
void ReprioritizeTask(Task* aTask, uint32_t aPriority);
|
||||
|
||||
void DispatchRunnable(already_AddRefed<nsIRunnable>&& aRunnable,
|
||||
uint32_t aPriority, TaskManager* aManager = nullptr);
|
||||
|
||||
nsIRunnable* GetRunnableForMTTask(bool aReallyWait);
|
||||
|
||||
bool HasMainThreadPendingTasks();
|
||||
|
||||
private:
|
||||
// This gets the next (highest priority) task that is only allowed to execute
|
||||
// on the main thread, if any, and executes it.
|
||||
void ExecuteNextTaskOnlyMainThreadInternal(const MutexAutoLock& aProofOfLock);
|
||||
|
||||
// The guts of ExecuteNextTaskOnlyMainThreadInternal, which get idle handling
|
||||
// wrapped around them. Returns whether a task actually ran.
|
||||
bool DoExecuteNextTaskOnlyMainThreadInternal(
|
||||
const MutexAutoLock& aProofOfLock);
|
||||
|
||||
Task* GetFinalDependency(Task* aTask);
|
||||
void MaybeInterruptTask(Task* aTask);
|
||||
Task* GetHighestPriorityMTTask();
|
||||
|
||||
void EnsureMainThreadTasksScheduled();
|
||||
|
||||
void ProcessUpdatedPriorityModifier(TaskManager* aManager);
|
||||
|
||||
void ShutdownInternal();
|
||||
|
||||
static std::unique_ptr<TaskController> sSingleton;
|
||||
static StaticMutex sSingletonMutex;
|
||||
|
||||
// This protects access to the task graph.
|
||||
Mutex mGraphMutex;
|
||||
|
||||
CondVar mMainThreadCV;
|
||||
|
||||
// Variables below are protected by mGraphMutex.
|
||||
|
||||
std::stack<RefPtr<Task>> mCurrentTasksMT;
|
||||
|
||||
// A list of all tasks ordered by priority.
|
||||
std::set<RefPtr<Task>, Task::PriorityCompare> mMainThreadTasks;
|
||||
|
||||
// TaskManagers currently active.
|
||||
// We can use a raw pointer since tasks always hold on to their TaskManager.
|
||||
std::set<TaskManager*> mTaskManagers;
|
||||
|
||||
// This ensures we keep running the main thread if we processed a task there.
|
||||
bool mMayHaveMainThreadTask = true;
|
||||
|
||||
// Whether we have scheduled a runnable on the main thread event loop.
|
||||
// This is used for nsIRunnable compatibility.
|
||||
bool mHasScheduledMTRunnable = false;
|
||||
RefPtr<nsIRunnable> mMTProcessingRunnable;
|
||||
|
||||
// XXX - Thread observer to notify when a new event has been dispatched
|
||||
nsIThreadObserver* mObserver = nullptr;
|
||||
// XXX - External condvar to notify when we have received an event
|
||||
CondVar* mExternalCondVar = nullptr;
|
||||
// Idle task manager so we can properly do idle state stuff.
|
||||
RefPtr<IdleTaskManager> mIdleTaskManager;
|
||||
|
||||
// Our tracking of our performance counter and long task state,
|
||||
// shared with nsThread.
|
||||
PerformanceCounterState* mPerformanceCounterState = nullptr;
|
||||
};
|
||||
|
||||
} // namespace mozilla
|
||||
|
||||
#endif // mozilla_TaskController_h
|
||||
|
|
@ -69,6 +69,7 @@ EXPORTS.mozilla += [
|
|||
'SynchronizedEventQueue.h',
|
||||
'SyncRunnable.h',
|
||||
'TaskCategory.h',
|
||||
'TaskController.h',
|
||||
'TaskDispatcher.h',
|
||||
'TaskQueue.h',
|
||||
'ThreadBound.h',
|
||||
|
|
@ -106,6 +107,7 @@ UNIFIED_SOURCES += [
|
|||
'SchedulerGroup.cpp',
|
||||
'SharedThreadPool.cpp',
|
||||
'SynchronizedEventQueue.cpp',
|
||||
'TaskController.cpp',
|
||||
'TaskQueue.cpp',
|
||||
'ThreadEventQueue.cpp',
|
||||
'ThreadEventTarget.cpp',
|
||||
|
|
|
|||
|
|
@ -1008,6 +1008,12 @@ static bool GetLabeledRunnableName(nsIRunnable* aEvent, nsACString& aName,
|
|||
|
||||
mozilla::PerformanceCounter* nsThread::GetPerformanceCounter(
|
||||
nsIRunnable* aEvent) const {
|
||||
return GetPerformanceCounterBase(aEvent);
|
||||
}
|
||||
|
||||
// static
|
||||
mozilla::PerformanceCounter* nsThread::GetPerformanceCounterBase(
|
||||
nsIRunnable* aEvent) {
|
||||
RefPtr<SchedulerGroup::Runnable> docRunnable = do_QueryObject(aEvent);
|
||||
if (docRunnable) {
|
||||
mozilla::dom::DocGroup* docGroup = docRunnable->DocGroup();
|
||||
|
|
|
|||
|
|
@ -230,6 +230,9 @@ class nsThread : public nsIThreadInternal,
|
|||
virtual mozilla::PerformanceCounter* GetPerformanceCounter(
|
||||
nsIRunnable* aEvent) const;
|
||||
|
||||
static mozilla::PerformanceCounter* GetPerformanceCounterBase(
|
||||
nsIRunnable* aEvent);
|
||||
|
||||
size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
|
||||
|
||||
// Returns the size of this object, its PRThread, and its shutdown contexts,
|
||||
|
|
|
|||
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