| // Copyright (c) 2012 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 STORAGE_BROWSER_FILEAPI_TASK_RUNNER_BOUND_OBSERVER_LIST_H_ |
| #define STORAGE_BROWSER_FILEAPI_TASK_RUNNER_BOUND_OBSERVER_LIST_H_ |
| |
| #include <map> |
| #include <utility> |
| |
| #include "base/bind.h" |
| #include "base/location.h" |
| #include "base/memory/scoped_refptr.h" |
| #include "base/sequenced_task_runner.h" |
| #include "base/threading/thread.h" |
| |
| namespace storage { |
| |
| // An observer list helper to notify on a given task runner. |
| // Observer pointers must be kept alive until this list dispatches all the |
| // notifications. |
| // |
| // Unlike regular ObserverList or ObserverListThreadSafe internal observer |
| // list is immutable (though not declared const) and cannot be modified after |
| // constructed. |
| template <typename Observer> |
| class TaskRunnerBoundObserverList { |
| public: |
| using ObserversListMap = |
| std::map<Observer*, scoped_refptr<base::SequencedTaskRunner>>; |
| |
| // Creates an empty list. |
| TaskRunnerBoundObserverList() {} |
| |
| // Creates a new list with given |observers|. |
| explicit TaskRunnerBoundObserverList(const ObserversListMap& observers) |
| : observers_(observers) {} |
| |
| virtual ~TaskRunnerBoundObserverList() {} |
| |
| // Returns a new observer list with given observer. |
| // It is valid to give nullptr as |runner_to_notify|, and in that case |
| // notifications are dispatched on the current runner. |
| // Note that this is a const method and does NOT change 'this' observer |
| // list but returns a new list. |
| TaskRunnerBoundObserverList AddObserver( |
| Observer* observer, |
| base::SequencedTaskRunner* runner_to_notify) const { |
| ObserversListMap observers = observers_; |
| observers.insert(std::make_pair(observer, runner_to_notify)); |
| return TaskRunnerBoundObserverList(observers); |
| } |
| |
| // Notify on the task runner that is given to AddObserver. |
| // If we're already on the runner this just dispatches the method. |
| template <typename Method, typename... Params> |
| void Notify(Method method, Params&&... params) const { |
| for (auto& observer : observers_) { |
| if (!observer.second || observer.second->RunsTasksInCurrentSequence()) { |
| ((*observer.first).*method)(params...); |
| continue; |
| } |
| observer.second->PostTask( |
| FROM_HERE, |
| base::BindOnce(method, base::Unretained(observer.first), params...)); |
| } |
| } |
| |
| private: |
| ObserversListMap observers_; |
| }; |
| |
| class FileAccessObserver; |
| class FileChangeObserver; |
| class FileUpdateObserver; |
| |
| using AccessObserverList = TaskRunnerBoundObserverList<FileAccessObserver>; |
| using ChangeObserverList = TaskRunnerBoundObserverList<FileChangeObserver>; |
| using UpdateObserverList = TaskRunnerBoundObserverList<FileUpdateObserver>; |
| |
| } // namespace storage |
| |
| #endif // STORAGE_BROWSER_FILEAPI_TASK_RUNNER_BOUND_OBSERVER_LIST_H_ |