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 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 uint32_t[num_buckets_]()), 20 accumulated_count_(0), 21 oldest_time_(0), 22 oldest_index_(0), 23 scale_(scale / (num_buckets_ - 1)) { 24 } 25 26 RateStatistics::~RateStatistics() { 27 } 28 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 38 void RateStatistics::Update(uint32_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 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 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 uint32_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