blob: 64e151d9482ec3e18fd92bb766f8c062c3a4875b [file] [log] [blame]
// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "flutter/fml/delayed_task.h"
#include "flutter/fml/task_queue_id.h"
#include "flutter/fml/task_source_grade.h"
namespace fml {
class MessageLoopTaskQueues;
* A Source of tasks for the `MessageLoopTaskQueues` task dispatcher. This is a
* wrapper around a primary and secondary task heap with the difference between
* them being that the secondary task heap can be paused and resumed by the task
* dispatcher. `TaskSourceGrade` determines what task heap the task is assigned
* to.
* Registering Tasks
* -----------------
* The task dispatcher associates a task source with each `TaskQueueID`. When
* the user of the task dispatcher registers a task, the task is in-turn
* registered with the `TaskSource` corresponding to the `TaskQueueID`.
* Processing Tasks
* ----------------
* Task dispatcher provides the event loop a way to acquire tasks to run via
* `GetNextTaskToRun`. Task dispatcher asks the underlying `TaskSource` for the
* next task.
class TaskSource {
struct TopTask {
TaskQueueId task_queue_id;
const DelayedTask& task;
/// Construts a TaskSource with the given `task_queue_id`.
explicit TaskSource(TaskQueueId task_queue_id);
/// Drops the pending tasks from both primary and secondary task heaps.
void ShutDown();
/// Adds a task to the corresponding task heap as dictated by the
/// `TaskSourceGrade` of the `DelayedTask`.
void RegisterTask(const DelayedTask& task);
/// Pops the task heap corresponding to the `TaskSourceGrade`.
void PopTask(TaskSourceGrade grade);
/// Returns the number of pending tasks. Excludes the tasks from the secondary
/// heap if it's paused.
size_t GetNumPendingTasks() const;
/// Returns true if `GetNumPendingTasks` is zero.
bool IsEmpty() const;
/// Returns the top task based on scheduled time, taking into account whether
/// the secondary heap has been paused or not.
TopTask Top() const;
/// Pause providing tasks from secondary task heap.
void PauseSecondary();
/// Resume providing tasks from secondary task heap.
void ResumeSecondary();
const fml::TaskQueueId task_queue_id_;
fml::DelayedTaskQueue primary_task_queue_;
fml::DelayedTaskQueue secondary_task_queue_;
int secondary_pause_requests_ = 0;
} // namespace fml