| // Copyright 2014 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef CONTENT_RENDERER_SCHEDULER_BASE_TASK_QUEUE_MANAGER_H_ |
| #define CONTENT_RENDERER_SCHEDULER_BASE_TASK_QUEUE_MANAGER_H_ |
| |
| #include <map> |
| |
| #include "base/atomic_sequence_num.h" |
| #include "base/debug/task_annotator.h" |
| #include "base/macros.h" |
| #include "base/memory/weak_ptr.h" |
| #include "base/message_loop/message_loop.h" |
| #include "base/pending_task.h" |
| #include "base/synchronization/lock.h" |
| #include "base/threading/thread_checker.h" |
| #include "components/scheduler/base/enqueue_order.h" |
| #include "components/scheduler/base/task_queue_impl.h" |
| #include "components/scheduler/base/task_queue_selector.h" |
| #include "components/scheduler/scheduler_export.h" |
| |
| namespace base { |
| class TickClock; |
| |
| namespace trace_event { |
| class ConvertableToTraceFormat; |
| class TracedValue; |
| } // namespace trace_event |
| } // namespace base |
| |
| namespace scheduler { |
| namespace internal { |
| class TaskQueueImpl; |
| } // namespace internal |
| |
| class LazyNow; |
| class RealTimeDomain; |
| class TimeDomain; |
| class TaskQueueManagerDelegate; |
| |
| // The task queue manager provides N task queues and a selector interface for |
| // choosing which task queue to service next. Each task queue consists of two |
| // sub queues: |
| // |
| // 1. Incoming task queue. Tasks that are posted get immediately appended here. |
| // When a task is appended into an empty incoming queue, the task manager |
| // work function (DoWork) is scheduled to run on the main task runner. |
| // |
| // 2. Work queue. If a work queue is empty when DoWork() is entered, tasks from |
| // the incoming task queue (if any) are moved here. The work queues are |
| // registered with the selector as input to the scheduling decision. |
| // |
| class SCHEDULER_EXPORT TaskQueueManager |
| : public internal::TaskQueueSelector::Observer { |
| public: |
| // Create a task queue manager where |delegate| identifies the thread |
| // on which where the tasks are eventually run. Category strings must have |
| // application lifetime (statics or literals). They may not include " chars. |
| TaskQueueManager(scoped_refptr<TaskQueueManagerDelegate> delegate, |
| const char* tracing_category, |
| const char* disabled_by_default_tracing_category, |
| const char* disabled_by_default_verbose_tracing_category); |
| ~TaskQueueManager() override; |
| |
| // Requests that a task to process work is posted on the main task runner. |
| // These tasks are de-duplicated in two buckets: main-thread and all other |
| // threads. This distinction is done to reduce the overehead from locks, we |
| // assume the main-thread path will be hot. |
| void MaybeScheduleImmediateWork(const tracked_objects::Location& from_here); |
| |
| // Requests that a delayed task to process work is posted on the main task |
| // runner. These delayed tasks are de-duplicated. Must be called on the thread |
| // this class was created on. |
| void MaybeScheduleDelayedWork(const tracked_objects::Location& from_here, |
| base::TimeTicks now, |
| base::TimeDelta delay); |
| |
| // Set the number of tasks executed in a single invocation of the task queue |
| // manager. Increasing the batch size can reduce the overhead of yielding |
| // back to the main message loop -- at the cost of potentially delaying other |
| // tasks posted to the main loop. The batch size is 1 by default. |
| void SetWorkBatchSize(int work_batch_size); |
| |
| // These functions can only be called on the same thread that the task queue |
| // manager executes its tasks on. |
| void AddTaskObserver(base::MessageLoop::TaskObserver* task_observer); |
| void RemoveTaskObserver(base::MessageLoop::TaskObserver* task_observer); |
| |
| // Returns true if any task from a monitored task queue was was run since the |
| // last call to GetAndClearSystemIsQuiescentBit. |
| bool GetAndClearSystemIsQuiescentBit(); |
| |
| // Creates a task queue with the given |spec|. Must be called on the thread |
| // this class was created on. |
| scoped_refptr<internal::TaskQueueImpl> NewTaskQueue( |
| const TaskQueue::Spec& spec); |
| |
| class SCHEDULER_EXPORT Observer { |
| public: |
| virtual ~Observer() {} |
| |
| // Called when |queue| is unregistered. |
| virtual void OnUnregisterTaskQueue( |
| const scoped_refptr<TaskQueue>& queue) = 0; |
| |
| // Called when the manager tried to execute a task from a disabled |
| // queue. See TaskQueue::Spec::SetShouldReportWhenExecutionBlocked. |
| virtual void OnTriedToExecuteBlockedTask(const TaskQueue& queue, |
| const base::PendingTask& task) = 0; |
| }; |
| |
| // Called once to set the Observer. This function is called on the main |
| // thread. If |observer| is null, then no callbacks will occur. |
| // Note |observer| is expected to outlive the SchedulerHelper. |
| void SetObserver(Observer* observer); |
| |
| // Returns the delegate used by the TaskQueueManager. |
| const scoped_refptr<TaskQueueManagerDelegate>& delegate() const; |
| |
| // Time domains must be registered for the task queues to get updated. |
| void RegisterTimeDomain(TimeDomain* time_domain); |
| void UnregisterTimeDomain(TimeDomain* time_domain); |
| |
| RealTimeDomain* real_time_domain() const { return real_time_domain_.get(); } |
| |
| LazyNow CreateLazyNow() const; |
| |
| TaskQueue* currently_executing_task_queue() const { |
| return currently_executing_task_queue_; |
| } |
| |
| private: |
| friend class LazyNow; |
| friend class internal::TaskQueueImpl; |
| friend class TaskQueueManagerTest; |
| |
| class DeletionSentinel : public base::RefCounted<DeletionSentinel> { |
| private: |
| friend class base::RefCounted<DeletionSentinel>; |
| ~DeletionSentinel() {} |
| }; |
| |
| // Unregisters a TaskQueue previously created by |NewTaskQueue()|. |
| // NOTE we have to flush the queue from |newly_updatable_| which means as a |
| // side effect MoveNewlyUpdatableQueuesIntoUpdatableQueueSet is called by this |
| // function. |
| void UnregisterTaskQueue(scoped_refptr<internal::TaskQueueImpl> task_queue); |
| |
| // TaskQueueSelector::Observer implementation: |
| void OnTaskQueueEnabled(internal::TaskQueueImpl* queue) override; |
| void OnTriedToSelectBlockedWorkQueue( |
| internal::WorkQueue* work_queue) override; |
| |
| // Called by the task queue to register a new pending task. |
| void DidQueueTask(const internal::TaskQueueImpl::Task& pending_task); |
| |
| // Use the selector to choose a pending task and run it. |
| void DoWork(base::TimeTicks run_time, bool from_main_thread); |
| |
| // Delayed Tasks with run_times <= Now() are enqueued onto the work queue. |
| // Reloads any empty work queues which have automatic pumping enabled and |
| // which are eligible to be auto pumped based on the |previous_task| which was |
| // run and |should_trigger_wakeup|. Call with an empty |previous_task| if no |
| // task was just run. |
| void UpdateWorkQueues(bool should_trigger_wakeup, |
| const internal::TaskQueueImpl::Task* previous_task); |
| |
| // Chooses the next work queue to service. Returns true if |out_queue| |
| // indicates the queue from which the next task should be run, false to |
| // avoid running any tasks. |
| bool SelectWorkQueueToService(internal::WorkQueue** out_work_queue); |
| |
| // Runs a single nestable task from the |queue|. On exit, |out_task| will |
| // contain the task which was executed. Non-nestable task are reposted on the |
| // run loop. The queue must not be empty. |
| enum class ProcessTaskResult { |
| DEFERRED, |
| EXECUTED, |
| TASK_QUEUE_MANAGER_DELETED |
| }; |
| ProcessTaskResult ProcessTaskFromWorkQueue( |
| internal::WorkQueue* work_queue, |
| internal::TaskQueueImpl::Task* out_previous_task); |
| |
| bool RunsTasksOnCurrentThread() const; |
| bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here, |
| const base::Closure& task, |
| base::TimeDelta delay); |
| |
| internal::EnqueueOrder GetNextSequenceNumber(); |
| |
| // Calls MaybeAdvanceTime on all time domains and returns true if one of them |
| // was able to advance. |
| bool TryAdvanceTimeDomains(); |
| |
| void MaybeRecordTaskDelayHistograms( |
| const internal::TaskQueueImpl::Task& pending_task, |
| const internal::TaskQueueImpl* queue); |
| |
| scoped_refptr<base::trace_event::ConvertableToTraceFormat> |
| AsValueWithSelectorResult(bool should_run, |
| internal::WorkQueue* selected_work_queue) const; |
| |
| std::set<TimeDomain*> time_domains_; |
| scoped_ptr<RealTimeDomain> real_time_domain_; |
| |
| std::set<scoped_refptr<internal::TaskQueueImpl>> queues_; |
| |
| // We have to be careful when deleting a queue because some of the code uses |
| // raw pointers and doesn't expect the rug to be pulled out from underneath. |
| std::set<scoped_refptr<internal::TaskQueueImpl>> queues_to_delete_; |
| |
| internal::EnqueueOrderGenerator enqueue_order_generator_; |
| base::debug::TaskAnnotator task_annotator_; |
| |
| base::ThreadChecker main_thread_checker_; |
| scoped_refptr<TaskQueueManagerDelegate> delegate_; |
| internal::TaskQueueSelector selector_; |
| |
| base::Closure from_main_thread_immediate_do_work_closure_; |
| base::Closure from_other_thread_immediate_do_work_closure_; |
| |
| bool task_was_run_on_quiescence_monitored_queue_; |
| |
| // To reduce locking overhead we track pending calls to DoWork seperatly for |
| // the main thread and other threads. |
| std::set<base::TimeTicks> main_thread_pending_wakeups_; |
| |
| // Protects |other_thread_pending_wakeups_|. |
| mutable base::Lock other_thread_lock_; |
| std::set<base::TimeTicks> other_thread_pending_wakeups_; |
| |
| int work_batch_size_; |
| size_t task_count_; |
| |
| base::ObserverList<base::MessageLoop::TaskObserver> task_observers_; |
| |
| const char* tracing_category_; |
| const char* disabled_by_default_tracing_category_; |
| const char* disabled_by_default_verbose_tracing_category_; |
| |
| internal::TaskQueueImpl* currently_executing_task_queue_; // NOT OWNED |
| |
| Observer* observer_; // NOT OWNED |
| scoped_refptr<DeletionSentinel> deletion_sentinel_; |
| base::WeakPtrFactory<TaskQueueManager> weak_factory_; |
| |
| DISALLOW_COPY_AND_ASSIGN(TaskQueueManager); |
| }; |
| |
| } // namespace scheduler |
| |
| #endif // CONTENT_RENDERER_SCHEDULER_BASE_TASK_QUEUE_MANAGER_H_ |