task_runner.cc

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// 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.
 
#define FML_USED_ON_EMBEDDER
 
#include "flutter/fml/task_runner.h"
#include "flutter/fml/memory/task_runner_checker.h"
 
#include <utility>
 
#include "flutter/fml/logging.h"
#include "flutter/fml/message_loop.h"
#include "flutter/fml/message_loop_impl.h"
#include "flutter/fml/message_loop_task_queues.h"
 
namespace fml {
 
TaskRunner::TaskRunner(fml::RefPtr<MessageLoopImpl> loop)
    : loop_(std::move(loop)) {}
 
TaskRunner::~TaskRunner() = default;
 
void TaskRunner::PostTask(const fml::closure& task) {
  loop_->PostTask(task, fml::TimePoint::Now());
}
 
void TaskRunner::PostTaskForTime(const fml::closure& task,
                                 fml::TimePoint target_time) {
  loop_->PostTask(task, target_time);
}
 
void TaskRunner::PostDelayedTask(const fml::closure& task,
                                 fml::TimeDelta delay) {
  loop_->PostTask(task, fml::TimePoint::Now() + delay);
}
 
TaskQueueId TaskRunner::GetTaskQueueId() {
  FML_DCHECK(loop_);
  return loop_->GetTaskQueueId();
}
 
bool TaskRunner::RunsTasksOnCurrentThread() {
  if (!fml::MessageLoop::IsInitializedForCurrentThread()) {
    return false;
  }
 
  const auto current_queue_id = MessageLoop::GetCurrentTaskQueueId();
  const auto loop_queue_id = loop_->GetTaskQueueId();
 
  return TaskRunnerChecker::RunsOnTheSameThread(current_queue_id,
                                                loop_queue_id);
}
 
// static
void TaskRunner::RunNowOrPostTask(const fml::RefPtr<fml::TaskRunner>& runner,
                                  const fml::closure& task) {
  FML_DCHECK(runner);
  if (runner->RunsTasksOnCurrentThread()) {
    task();
  } else {
    runner->PostTask(task);
  }
}
 
// static
void TaskRunner::RunNowAndFlushMessages(
    const fml::RefPtr<fml::TaskRunner>& runner,
    const fml::closure& task) {
  FML_DCHECK(runner);
  if (runner->RunsTasksOnCurrentThread()) {
    task();
    // Post an empty task to make the UI message loop run its task observers.
    // The observers will execute any Dart microtasks queued by the platform
    // message handler.
    runner->PostTask([] {});
  } else {
    runner->PostTask(task);
  }
}
 
}  // namespace fml