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1 // Copyright (c) 2012 The Chromium 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 CHROME_COMMON_WORKER_THREAD_TICKER_H_ | |
6 #define CHROME_COMMON_WORKER_THREAD_TICKER_H_ | |
7 | |
8 #include <vector> | |
9 | |
10 #include "base/macros.h" | |
11 #include "base/synchronization/lock.h" | |
12 #include "base/threading/thread.h" | |
13 | |
14 // This class provides the following functionality: | |
15 // It invokes a set of registered handlers at periodic intervals in | |
16 // the context of an arbitrary worker thread. | |
17 // The timer runs on a separate thread, so it will run even if the current | |
18 // thread is hung. Similarly, the callbacks will be called on a separate | |
19 // thread so they won't block the main thread. | |
20 class WorkerThreadTicker { | |
21 public: | |
22 // This callback interface to be implemented by clients of this | |
23 // class | |
24 class Callback { | |
25 public: | |
26 // Gets invoked when the timer period is up | |
27 virtual void OnTick() = 0; | |
28 | |
29 protected: | |
30 virtual ~Callback() {} | |
31 }; | |
32 | |
33 // tick_interval is the periodic interval in which to invoke the | |
34 // registered handlers (in milliseconds) | |
35 explicit WorkerThreadTicker(int tick_interval); | |
36 | |
37 ~WorkerThreadTicker(); | |
38 | |
39 // Registers a callback handler interface | |
40 // tick_handler is the handler interface to register. The ownership of this | |
41 // object is not transferred to this class. | |
42 bool RegisterTickHandler(Callback *tick_handler); | |
43 | |
44 // Unregisters a callback handler interface | |
45 // tick_handler is the handler interface to unregister | |
46 bool UnregisterTickHandler(Callback *tick_handler); | |
47 | |
48 // Starts the ticker. Returns false if the ticker is already running | |
49 // or if the Start fails. | |
50 bool Start(); | |
51 // Stops the ticker and waits for all callbacks. to be done. This method | |
52 // does not provide a way to stop without waiting for the callbacks to be | |
53 // done because this is inherently risky. | |
54 // Returns false is the ticker is not running | |
55 bool Stop(); | |
56 bool IsRunning() const { | |
57 return is_running_; | |
58 } | |
59 | |
60 void set_tick_interval(int tick_interval) { | |
61 tick_interval_ = base::TimeDelta::FromMilliseconds(tick_interval); | |
62 } | |
63 | |
64 private: | |
65 void ScheduleTimerTask(); | |
66 | |
67 void TimerTask(); | |
68 | |
69 // A list type that holds all registered callback interfaces | |
70 typedef std::vector<Callback*> TickHandlerListType; | |
71 | |
72 // Lock to protect is_running_ and tick_handler_list_ | |
73 base::Lock lock_; | |
74 | |
75 base::Thread timer_thread_; | |
76 bool is_running_; | |
77 | |
78 // The interval at which the callbacks are to be invoked | |
79 base::TimeDelta tick_interval_; | |
80 | |
81 // A list that holds all registered callback interfaces | |
82 TickHandlerListType tick_handler_list_; | |
83 | |
84 DISALLOW_COPY_AND_ASSIGN(WorkerThreadTicker); | |
85 }; | |
86 | |
87 #endif // CHROME_COMMON_WORKER_THREAD_TICKER_H_ | |
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