1/*
2 *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
3 *
4 *  Use of this source code is governed by a BSD-style license
5 *  that can be found in the LICENSE file in the root of the source
6 *  tree. An additional intellectual property rights grant can be found
7 *  in the file PATENTS.  All contributing project authors may
8 *  be found in the AUTHORS file in the root of the source tree.
9 */
10
11#include "webrtc/base/ratetracker.h"
12#include "webrtc/base/timeutils.h"
13
14namespace rtc {
15
16RateTracker::RateTracker()
17    : total_units_(0), units_second_(0),
18      last_units_second_time_(static_cast<uint32>(-1)),
19      last_units_second_calc_(0) {
20}
21
22size_t RateTracker::total_units() const {
23  return total_units_;
24}
25
26size_t RateTracker::units_second() {
27  // Snapshot units / second calculator. Determine how many seconds have
28  // elapsed since our last reference point. If over 1 second, establish
29  // a new reference point that is an integer number of seconds since the
30  // last one, and compute the units over that interval.
31  uint32 current_time = Time();
32  if (last_units_second_time_ != static_cast<uint32>(-1)) {
33    int delta = rtc::TimeDiff(current_time, last_units_second_time_);
34    if (delta >= 1000) {
35      int fraction_time = delta % 1000;
36      int seconds = delta / 1000;
37      int fraction_units =
38          static_cast<int>(total_units_ - last_units_second_calc_) *
39              fraction_time / delta;
40      // Compute "units received during the interval" / "seconds in interval"
41      units_second_ =
42          (total_units_ - last_units_second_calc_ - fraction_units) / seconds;
43      last_units_second_time_ = current_time - fraction_time;
44      last_units_second_calc_ = total_units_ - fraction_units;
45    }
46  }
47  if (last_units_second_time_ == static_cast<uint32>(-1)) {
48    last_units_second_time_ = current_time;
49    last_units_second_calc_ = total_units_;
50  }
51
52  return units_second_;
53}
54
55void RateTracker::Update(size_t units) {
56  total_units_ += units;
57}
58
59uint32 RateTracker::Time() const {
60  return rtc::Time();
61}
62
63}  // namespace rtc
64