1 /*
2 * Copyright (c) 2013 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/modules/remote_bitrate_estimator/rate_statistics.h"
12
13 #include <assert.h>
14
15 namespace webrtc {
16
RateStatistics(uint32_t window_size_ms,float scale)17 RateStatistics::RateStatistics(uint32_t window_size_ms, float scale)
18 : num_buckets_(window_size_ms + 1), // N ms in (N+1) buckets.
19 buckets_(new size_t[num_buckets_]()),
20 accumulated_count_(0),
21 oldest_time_(0),
22 oldest_index_(0),
23 scale_(scale / (num_buckets_ - 1)) {
24 }
25
~RateStatistics()26 RateStatistics::~RateStatistics() {
27 }
28
Reset()29 void RateStatistics::Reset() {
30 accumulated_count_ = 0;
31 oldest_time_ = 0;
32 oldest_index_ = 0;
33 for (int i = 0; i < num_buckets_; i++) {
34 buckets_[i] = 0;
35 }
36 }
37
Update(size_t count,int64_t now_ms)38 void RateStatistics::Update(size_t count, int64_t now_ms) {
39 if (now_ms < oldest_time_) {
40 // Too old data is ignored.
41 return;
42 }
43
44 EraseOld(now_ms);
45
46 int now_offset = static_cast<int>(now_ms - oldest_time_);
47 assert(now_offset < num_buckets_);
48 int index = oldest_index_ + now_offset;
49 if (index >= num_buckets_) {
50 index -= num_buckets_;
51 }
52 buckets_[index] += count;
53 accumulated_count_ += count;
54 }
55
Rate(int64_t now_ms)56 uint32_t RateStatistics::Rate(int64_t now_ms) {
57 EraseOld(now_ms);
58 return static_cast<uint32_t>(accumulated_count_ * scale_ + 0.5f);
59 }
60
EraseOld(int64_t now_ms)61 void RateStatistics::EraseOld(int64_t now_ms) {
62 int64_t new_oldest_time = now_ms - num_buckets_ + 1;
63 if (new_oldest_time <= oldest_time_) {
64 return;
65 }
66
67 while (oldest_time_ < new_oldest_time) {
68 size_t count_in_oldest_bucket = buckets_[oldest_index_];
69 assert(accumulated_count_ >= count_in_oldest_bucket);
70 accumulated_count_ -= count_in_oldest_bucket;
71 buckets_[oldest_index_] = 0;
72 if (++oldest_index_ >= num_buckets_) {
73 oldest_index_ = 0;
74 }
75 ++oldest_time_;
76 if (accumulated_count_ == 0) {
77 // This guarantees we go through all the buckets at most once, even if
78 // |new_oldest_time| is far greater than |oldest_time_|.
79 break;
80 }
81 }
82 oldest_time_ = new_oldest_time;
83 }
84
85 } // namespace webrtc
86