| // Copyright (c) 2013 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef CHROME_BROWSER_POLICY_CLOUD_RATE_LIMITER_H_ |
| #define CHROME_BROWSER_POLICY_CLOUD_RATE_LIMITER_H_ |
| |
| #include <queue> |
| |
| #include "base/basictypes.h" |
| #include "base/callback.h" |
| #include "base/cancelable_callback.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/memory/scoped_ptr.h" |
| #include "base/threading/non_thread_safe.h" |
| #include "base/time/time.h" |
| |
| namespace base { |
| class SequencedTaskRunner; |
| class TickClock; |
| } |
| |
| namespace policy { |
| |
| // A simple class to limit the rate at which a callback is invoked. |
| class RateLimiter : public base::NonThreadSafe { |
| public: |
| // Will limit invocations of |callback| to |max_requests| per |duration|. |
| // |task_runner| is used to post delayed tasks, and |clock| is used to |
| // measure elapsed time. |
| RateLimiter(size_t max_requests, |
| const base::TimeDelta& duration, |
| const base::Closure& callback, |
| scoped_refptr<base::SequencedTaskRunner> task_runner, |
| scoped_ptr<base::TickClock> clock); |
| ~RateLimiter(); |
| |
| // Posts a request to invoke |callback_|. It is invoked immediately if the |
| // rate in the preceding |duration_| period is within the limit, otherwise |
| // the callback will be invoked later, ensuring the allowed rate is not |
| // exceeded. |
| void PostRequest(); |
| |
| private: |
| const size_t max_requests_; |
| const base::TimeDelta duration_; |
| base::Closure callback_; |
| scoped_refptr<base::SequencedTaskRunner> task_runner_; |
| scoped_ptr<base::TickClock> clock_; |
| |
| std::queue<base::TimeTicks> invocation_times_; |
| base::CancelableClosure delayed_callback_; |
| |
| DISALLOW_COPY_AND_ASSIGN(RateLimiter); |
| }; |
| |
| } // namespace policy |
| |
| #endif // CHROME_BROWSER_POLICY_CLOUD_RATE_LIMITER_H_ |