1 | // Copyright 2013 The Flutter Authors. All rights reserved. |
2 | // Use of this source code is governed by a BSD-style license that can be |
3 | // found in the LICENSE file. |
4 | |
5 | #ifndef FLUTTER_FML_SYNCHRONIZATION_SYNC_SWITCH_H_ |
6 | #define FLUTTER_FML_SYNCHRONIZATION_SYNC_SWITCH_H_ |
7 | |
8 | #include <forward_list> |
9 | #include <functional> |
10 | #include <mutex> |
11 | |
12 | #include "flutter/fml/macros.h" |
13 | |
14 | namespace fml { |
15 | |
16 | /// A threadsafe structure that allows you to switch between 2 different |
17 | /// execution paths. |
18 | /// |
19 | /// Execution and setting the switch is exclusive, i.e. only one will happen |
20 | /// at a time. |
21 | class SyncSwitch { |
22 | public: |
23 | /// Represents the 2 code paths available when calling |SyncSwitch::Execute|. |
24 | struct Handlers { |
25 | /// Sets the handler that will be executed if the |SyncSwitch| is true. |
26 | Handlers& SetIfTrue(const std::function<void()>& handler); |
27 | |
28 | /// Sets the handler that will be executed if the |SyncSwitch| is false. |
29 | Handlers& SetIfFalse(const std::function<void()>& handler); |
30 | |
31 | std::function<void()> true_handler = [] {}; |
32 | std::function<void()> false_handler = [] {}; |
33 | }; |
34 | |
35 | /// Create a |SyncSwitch| with the false value. |
36 | SyncSwitch(); |
37 | |
38 | /// Create a |SyncSwitch| with the specified value. |
39 | /// |
40 | /// @param[in] value Default value for the |SyncSwitch|. |
41 | SyncSwitch(bool value); |
42 | |
43 | /// Diverge execution between true and false values of the SyncSwitch. |
44 | /// |
45 | /// This can be called on any thread. Note that attempting to call |
46 | /// |SetSwitch| inside of the handlers will result in a self deadlock. |
47 | /// |
48 | /// @param[in] handlers Called for the correct value of the |SyncSwitch|. |
49 | void Execute(const Handlers& handlers); |
50 | |
51 | /// Set the value of the SyncSwitch. |
52 | /// |
53 | /// This can be called on any thread. |
54 | /// |
55 | /// @param[in] value New value for the |SyncSwitch|. |
56 | void SetSwitch(bool value); |
57 | |
58 | private: |
59 | std::mutex mutex_; |
60 | bool value_; |
61 | |
62 | FML_DISALLOW_COPY_AND_ASSIGN(SyncSwitch); |
63 | }; |
64 | |
65 | } // namespace fml |
66 | |
67 | #endif // FLUTTER_FML_SYNCHRONIZATION_SYNC_SWITCH_H_ |
68 | |