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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright 2014 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef WEBKIT_BROWSER_FILEAPI_TASK_RUNNER_BOUND_OBSERVER_LIST_H_ | 5 #include "storage/browser/fileapi/task_runner_bound_observer_list.h" |
6 #define WEBKIT_BROWSER_FILEAPI_TASK_RUNNER_BOUND_OBSERVER_LIST_H_ | |
7 | |
8 #include <map> | |
9 | |
10 #include "base/basictypes.h" | |
11 #include "base/bind.h" | |
12 #include "base/memory/ref_counted.h" | |
13 #include "base/sequenced_task_runner.h" | |
14 #include "base/threading/thread.h" | |
15 | |
16 namespace storage { | |
17 | |
18 // A wrapper for dispatching method. | |
19 template <class T, class Method, class Params> | |
20 void NotifyWrapper(T obj, Method m, const Params& p) { | |
21 DispatchToMethod(base::internal::UnwrapTraits<T>::Unwrap(obj), m, p); | |
22 } | |
23 | |
24 // An observer list helper to notify on a given task runner. | |
25 // Observer pointers (stored as ObserverStoreType) must be kept alive | |
26 // until this list dispatches all the notifications. | |
27 // | |
28 // Unlike regular ObserverList or ObserverListThreadSafe internal observer | |
29 // list is immutable (though not declared const) and cannot be modified after | |
30 // constructed. | |
31 // | |
32 // It is ok to specify scoped_refptr<Observer> as ObserverStoreType to | |
33 // explicitly keep references if necessary. | |
34 template <class Observer, class ObserverStoreType = Observer*> | |
35 class TaskRunnerBoundObserverList { | |
36 public: | |
37 typedef scoped_refptr<base::SequencedTaskRunner> TaskRunnerPtr; | |
38 typedef std::map<ObserverStoreType, TaskRunnerPtr> ObserversListMap; | |
39 | |
40 // Creates an empty list. | |
41 TaskRunnerBoundObserverList<Observer, ObserverStoreType>() {} | |
42 | |
43 // Creates a new list with given |observers|. | |
44 explicit TaskRunnerBoundObserverList<Observer, ObserverStoreType>( | |
45 const ObserversListMap& observers) | |
46 : observers_(observers) {} | |
47 | |
48 virtual ~TaskRunnerBoundObserverList<Observer, ObserverStoreType>() {} | |
49 | |
50 // Returns a new observer list with given observer. | |
51 // It is valid to give NULL as |runner_to_notify|, and in that case | |
52 // notifications are dispatched on the current runner. | |
53 // Note that this is a const method and does NOT change 'this' observer | |
54 // list but returns a new list. | |
55 TaskRunnerBoundObserverList<Observer, ObserverStoreType> AddObserver( | |
56 Observer* observer, | |
57 base::SequencedTaskRunner* runner_to_notify) const { | |
58 ObserversListMap observers = observers_; | |
59 observers.insert(std::make_pair(observer, runner_to_notify)); | |
60 return TaskRunnerBoundObserverList<Observer, ObserverStoreType>(observers); | |
61 } | |
62 | |
63 // Notify on the task runner that is given to AddObserver. | |
64 // If we're already on the runner this just dispatches the method. | |
65 template <class Method, class Params> | |
66 void Notify(Method method, const Params& params) const { | |
67 COMPILE_ASSERT( | |
68 (base::internal::ParamsUseScopedRefptrCorrectly<Params>::value), | |
69 badunboundmethodparams); | |
70 for (typename ObserversListMap::const_iterator it = observers_.begin(); | |
71 it != observers_.end(); ++it) { | |
72 if (!it->second.get() || it->second->RunsTasksOnCurrentThread()) { | |
73 DispatchToMethod(UnwrapTraits::Unwrap(it->first), method, params); | |
74 continue; | |
75 } | |
76 it->second->PostTask( | |
77 FROM_HERE, | |
78 base::Bind(&NotifyWrapper<ObserverStoreType, Method, Params>, | |
79 it->first, method, params)); | |
80 } | |
81 } | |
82 | |
83 private: | |
84 typedef base::internal::UnwrapTraits<ObserverStoreType> UnwrapTraits; | |
85 | |
86 ObserversListMap observers_; | |
87 }; | |
88 | |
89 class FileAccessObserver; | |
90 class FileChangeObserver; | |
91 class FileUpdateObserver; | |
92 | |
93 typedef TaskRunnerBoundObserverList<FileAccessObserver> AccessObserverList; | |
94 typedef TaskRunnerBoundObserverList<FileChangeObserver> ChangeObserverList; | |
95 typedef TaskRunnerBoundObserverList<FileUpdateObserver> UpdateObserverList; | |
96 | |
97 } // namespace storage | |
98 | |
99 #endif // WEBKIT_BROWSER_FILEAPI_TASK_RUNNER_BOUND_OBSERVER_LIST_H_ | |
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