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 "components/policy/core/common/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
RateLimiter(size_t max_requests,const base::TimeDelta & duration,const base::Closure & callback,scoped_refptr<base::SequencedTaskRunner> task_runner,scoped_ptr<base::TickClock> clock)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
~RateLimiter()29 RateLimiter::~RateLimiter() {}
30
PostRequest()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
59