task_observers.h

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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.
 
#ifndef FLUTTER_FML_PLATFORM_FUCHSIA_TASK_OBSERVERS_H_
#define FLUTTER_FML_PLATFORM_FUCHSIA_TASK_OBSERVERS_H_
 
#include <lib/fit/function.h>
 
#include "flutter/fml/task_queue_id.h"
 
namespace fml {
 
// Executes all closures that were registered via
// `CurrentMessageLoopAddAfterTaskObserver` on this thread.
//
// WARNING(fxbug.dev/77957): These task observers are distinct from the task
// observers that can be specified via `fml::MessageLoop::AddTaskObserver` and
// they behave differently!
//
// Task observers registered via `fml::MessageLoop::AddTaskObserver` only fire
// after work that was posted via the `fml::MessageLoop`'s `TaskRunner`
// completes. Work that is posted directly to the Fuchsia message loop (e.g.
// using `async::PostTask(async_get_default_dispatcher(), ...)`) is invisible to
// `fml::MessageLoop`, so the `fml::MessageLoop`'s task observers don't fire.
//
// The task observers registered with `CurrentMessageLoopAddAfterTaskObserver`,
// however, fire after _every_ work item is completed, regardless of whether it
// was posted to the Fuchsia message loop directly or via `fml::MessageLoop`.
//
// These two mechanisms are redundant and confusing, so we should fix it
// somehow.
void ExecuteAfterTaskObservers();
 
fml::TaskQueueId CurrentMessageLoopAddAfterTaskObserver(intptr_t key,
                                                        fit::closure observer);
 
void CurrentMessageLoopRemoveAfterTaskObserver(fml::TaskQueueId queue_id,
                                               intptr_t key);
 
}  // namespace fml
 
#endif  // FLUTTER_FML_PLATFORM_FUCHSIA_TASK_OBSERVERS_H_