src/chrome/browser/policy/cloud/rate_limiter.cc

   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 #include "chrome/browser/policy/cloud/rate_limiter.h"
   6
   7 #include "base/bind.h"
   8 #include "base/bind_helpers.h"
   9 #include "base/location.h"
  10 #include "base/logging.h"
  11 #include "base/sequenced_task_runner.h"
  12 #include "base/time/tick_clock.h"
  13
  14 namespace policy {
  15
  16 RateLimiter::RateLimiter(size_t max_requests,
  17                          const base::TimeDelta& duration,
  18                          const base::Closure& callback,
  19                          scoped_refptr<base::SequencedTaskRunner> task_runner,
  20                          scoped_ptr<base::TickClock> clock)
  21     : max_requests_(max_requests),
  22       duration_(duration),
  23       callback_(callback),
  24       task_runner_(task_runner),
  25       clock_(clock.Pass()) {
  26   DCHECK_GT(max_requests_, 0u);
  27 }
  28
  29 RateLimiter::~RateLimiter() {}
  30
  31 void RateLimiter::PostRequest() {
  32   DCHECK(CalledOnValidThread());
  33
  34   const base::TimeTicks now = clock_->NowTicks();
  35   const base::TimeTicks period_start = now - duration_;
  36   while (!invocation_times_.empty() &&
  37          invocation_times_.front() <= period_start) {
  38     invocation_times_.pop();
  39   }
  40
  41   delayed_callback_.Cancel();
  42
  43   if (invocation_times_.size() < max_requests_) {
  44     invocation_times_.push(now);
  45     callback_.Run();
  46   } else {
  47     // From the while() loop above we have front() > period_start,
  48     // so time_until_next_callback > 0.
  49     const base::TimeDelta time_until_next_callback =
  50         invocation_times_.front() - period_start;
  51     delayed_callback_.Reset(
  52         base::Bind(&RateLimiter::PostRequest, base::Unretained(this)));
  53     task_runner_->PostDelayedTask(
  54         FROM_HERE, delayed_callback_.callback(), time_until_next_callback);
  55   }
  56 }
  57
  58 }  // namespace policy