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// 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_
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