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1 // Copyright (c) 2013 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_BROWSER_POLICY_RATE_LIMITER_H_ | |
6 #define CHROME_BROWSER_POLICY_RATE_LIMITER_H_ | |
7 | |
8 #include <queue> | |
9 | |
10 #include "base/basictypes.h" | |
11 #include "base/callback.h" | |
12 #include "base/cancelable_callback.h" | |
13 #include "base/memory/ref_counted.h" | |
14 #include "base/memory/scoped_ptr.h" | |
15 #include "base/threading/non_thread_safe.h" | |
16 #include "base/time.h" | |
17 | |
18 namespace base { | |
19 class SequencedTaskRunner; | |
20 class TickClock; | |
21 } | |
22 | |
23 namespace policy { | |
24 | |
25 // A simple class to limit the rate at which a callback is invoked. | |
26 class RateLimiter : public base::NonThreadSafe { | |
27 public: | |
28 // Will limit invocations of |callback| to |max_requests| per |duration|. | |
29 // |task_runner| is used to post delayed tasks, and |clock| is used to | |
30 // measure elapsed time. | |
31 RateLimiter(size_t max_requests, | |
32 const base::TimeDelta& duration, | |
33 const base::Closure& callback, | |
34 scoped_refptr<base::SequencedTaskRunner> task_runner, | |
35 scoped_ptr<base::TickClock> clock); | |
36 ~RateLimiter(); | |
37 | |
38 // Posts a request to invoke |callback_|. It is invoked immediately if the | |
39 // rate in the preceding |duration_| period is within the limit, otherwise | |
40 // the callback will be invoked later, ensuring the allowed rate is not | |
41 // exceeded. | |
42 void PostRequest(); | |
43 | |
44 private: | |
45 const size_t max_requests_; | |
46 const base::TimeDelta duration_; | |
47 base::Closure callback_; | |
48 scoped_refptr<base::SequencedTaskRunner> task_runner_; | |
49 scoped_ptr<base::TickClock> clock_; | |
50 | |
51 std::queue<base::TimeTicks> invocation_times_; | |
52 base::CancelableClosure delayed_callback_; | |
53 | |
54 DISALLOW_COPY_AND_ASSIGN(RateLimiter); | |
55 }; | |
56 | |
57 } // namespace policy | |
58 | |
59 #endif // CHROME_BROWSER_POLICY_RATE_LIMITER_H_ | |
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