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