1/*
2 * libjingle
3 * Copyright 2004--2010, Google Inc.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 *  1. Redistributions of source code must retain the above copyright notice,
9 *     this list of conditions and the following disclaimer.
10 *  2. Redistributions in binary form must reproduce the above copyright notice,
11 *     this list of conditions and the following disclaimer in the documentation
12 *     and/or other materials provided with the distribution.
13 *  3. The name of the author may not be used to endorse or promote products
14 *     derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#include "talk/base/ratetracker.h"
29#include "talk/base/time.h"
30
31namespace talk_base {
32
33RateTracker::RateTracker()
34    : total_units_(0), units_second_(0),
35      last_units_second_time_(static_cast<uint32>(-1)),
36      last_units_second_calc_(0) {
37}
38
39size_t RateTracker::total_units() const {
40  return total_units_;
41}
42
43size_t RateTracker::units_second() {
44  // Snapshot units / second calculator. Determine how many seconds have
45  // elapsed since our last reference point. If over 1 second, establish
46  // a new reference point that is an integer number of seconds since the
47  // last one, and compute the units over that interval.
48  uint32 current_time = Time();
49  if (last_units_second_time_ != static_cast<uint32>(-1)) {
50    int delta = talk_base::TimeDiff(current_time, last_units_second_time_);
51    if (delta >= 1000) {
52      int fraction_time = delta % 1000;
53      int seconds = delta / 1000;
54      int fraction_units =
55          static_cast<int>(total_units_ - last_units_second_calc_) *
56              fraction_time / delta;
57      // Compute "units received during the interval" / "seconds in interval"
58      units_second_ =
59          (total_units_ - last_units_second_calc_ - fraction_units) / seconds;
60      last_units_second_time_ = current_time - fraction_time;
61      last_units_second_calc_ = total_units_ - fraction_units;
62    }
63  }
64  if (last_units_second_time_ == static_cast<uint32>(-1)) {
65    last_units_second_time_ = current_time;
66    last_units_second_calc_ = total_units_;
67  }
68
69  return units_second_;
70}
71
72void RateTracker::Update(size_t units) {
73  total_units_ += units;
74}
75
76uint32 RateTracker::Time() const {
77  return talk_base::Time();
78}
79
80}  // namespace talk_base
81