blob: 464afbc43827e8a8744b7fc88eacc4d66f2f0907 [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/shell/platform/windows/task_runner.h"
#include <atomic>
#include <utility>
namespace flutter {
TaskRunner::TaskRunner(CurrentTimeProc get_current_time,
const TaskExpiredCallback& on_task_expired)
: get_current_time_(get_current_time),
on_task_expired_(std::move(on_task_expired)) {}
std::chrono::nanoseconds TaskRunner::ProcessTasks() {
const TaskTimePoint now = GetCurrentTimeForTask();
std::vector<Task> expired_tasks;
// Process expired tasks.
{
std::lock_guard<std::mutex> lock(task_queue_mutex_);
while (!task_queue_.empty()) {
const auto& top = task_queue_.top();
// If this task (and all tasks after this) has not yet expired, there is
// nothing more to do. Quit iterating.
if (top.fire_time > now) {
break;
}
// Make a record of the expired task. Do NOT service the task here
// because we are still holding onto the task queue mutex. We don't want
// other threads to block on posting tasks onto this thread till we are
// done processing expired tasks.
expired_tasks.push_back(task_queue_.top());
// Remove the tasks from the delayed tasks queue.
task_queue_.pop();
}
}
// Fire expired tasks.
{
// Flushing tasks here without holing onto the task queue mutex.
for (const auto& task : expired_tasks) {
if (auto flutter_task = std::get_if<FlutterTask>(&task.variant)) {
on_task_expired_(flutter_task);
} else if (auto closure = std::get_if<TaskClosure>(&task.variant))
(*closure)();
}
}
// Calculate duration to sleep for on next iteration.
{
std::lock_guard<std::mutex> lock(task_queue_mutex_);
const auto next_wake = task_queue_.empty() ? TaskTimePoint::max()
: task_queue_.top().fire_time;
return std::min(next_wake - now, std::chrono::nanoseconds::max());
}
}
TaskRunner::TaskTimePoint TaskRunner::TimePointFromFlutterTime(
uint64_t flutter_target_time_nanos) const {
const auto now = GetCurrentTimeForTask();
const auto flutter_duration = flutter_target_time_nanos - get_current_time_();
return now + std::chrono::nanoseconds(flutter_duration);
}
void TaskRunner::PostFlutterTask(FlutterTask flutter_task,
uint64_t flutter_target_time_nanos) {
Task task;
task.fire_time = TimePointFromFlutterTime(flutter_target_time_nanos);
task.variant = flutter_task;
EnqueueTask(std::move(task));
}
void TaskRunner::PostTask(TaskClosure closure) {
Task task;
task.fire_time = GetCurrentTimeForTask();
task.variant = std::move(closure);
EnqueueTask(std::move(task));
}
void TaskRunner::EnqueueTask(Task task) {
static std::atomic_uint64_t sGlobalTaskOrder(0);
task.order = ++sGlobalTaskOrder;
{
std::lock_guard<std::mutex> lock(task_queue_mutex_);
task_queue_.push(task);
// Make sure the queue mutex is unlocked before waking up the loop. In case
// the wake causes this thread to be descheduled for the primary thread to
// process tasks, the acquisition of the lock on that thread while holding
// the lock here momentarily till the end of the scope is a pessimization.
}
WakeUp();
}
} // namespace flutter