remoting/base/rate_counter.cc

   1 // Copyright (c) 2011 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 "remoting/base/rate_counter.h"
   6
   7 #include "base/logging.h"
   8
   9 namespace remoting {
  10
  11 RateCounter::RateCounter(base::TimeDelta time_window)
  12     : time_window_(time_window),
  13       sum_(0) {
  14   DCHECK_GT(time_window.InMilliseconds(), 0);
  15 }
  16
  17 RateCounter::~RateCounter() {
  18 }
  19
  20 void RateCounter::Record(int64 value) {
  21   DCHECK(CalledOnValidThread());
  22
  23   base::Time current_time = CurrentTime();
  24   EvictOldDataPoints(current_time);
  25   sum_ += value;
  26   data_points_.push(std::make_pair(current_time, value));
  27 }
  28
  29 double RateCounter::Rate() {
  30   DCHECK(CalledOnValidThread());
  31
  32   EvictOldDataPoints(CurrentTime());
  33   return sum_ / time_window_.InSecondsF();
  34 }
  35
  36 void RateCounter::SetCurrentTimeForTest(base::Time current_time) {
  37   DCHECK(CalledOnValidThread());
  38   DCHECK(current_time >= current_time_for_test_);
  39
  40   current_time_for_test_ = current_time;
  41 }
  42
  43 void RateCounter::EvictOldDataPoints(base::Time current_time) {
  44   // Remove data points outside of the window.
  45   base::Time window_start = current_time - time_window_;
  46
  47   while (!data_points_.empty()) {
  48     if (data_points_.front().first > window_start)
  49       break;
  50
  51     sum_ -= data_points_.front().second;
  52     data_points_.pop();
  53   }
  54 }
  55
  56 base::Time RateCounter::CurrentTime() const {
  57   if (current_time_for_test_ == base::Time())
  58     return base::Time::Now();
  59   return current_time_for_test_;
  60 }
  61
  62 }  // namespace remoting