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1 /* | 1 /* |
2 * Copyright 2004 The WebRTC Project Authors. All rights reserved. | 2 * Copyright 2015 The WebRTC Project Authors. All rights reserved. |
3 * | 3 * |
4 * Use of this source code is governed by a BSD-style license | 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 | 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 | 6 * tree. An additional intellectual property rights grant can be found |
7 * in the file PATENTS. All contributing project authors may | 7 * in the file PATENTS. All contributing project authors may |
8 * be found in the AUTHORS file in the root of the source tree. | 8 * be found in the AUTHORS file in the root of the source tree. |
9 */ | 9 */ |
10 | 10 |
11 #include "webrtc/base/ratetracker.h" | 11 #include "webrtc/base/ratetracker.h" |
| 12 |
| 13 #include <stddef.h> |
| 14 |
| 15 #include <algorithm> |
| 16 |
| 17 #include "webrtc/base/checks.h" |
12 #include "webrtc/base/timeutils.h" | 18 #include "webrtc/base/timeutils.h" |
13 | 19 |
14 namespace rtc { | 20 namespace rtc { |
15 | 21 |
16 RateTracker::RateTracker() | 22 RateTracker::RateTracker( |
17 : total_units_(0), units_second_(0), | 23 uint32 bucket_milliseconds, size_t bucket_count) |
18 last_units_second_time_(~0u), | 24 : bucket_milliseconds_(bucket_milliseconds), |
19 last_units_second_calc_(0) { | 25 bucket_count_(bucket_count), |
| 26 sample_buckets_(new size_t[bucket_count + 1]), |
| 27 total_sample_count_(0u), |
| 28 bucket_start_time_milliseconds_(~0u) { |
| 29 CHECK(bucket_milliseconds > 0u); |
| 30 CHECK(bucket_count > 0u); |
20 } | 31 } |
21 | 32 |
22 size_t RateTracker::total_units() const { | 33 RateTracker::~RateTracker() { |
23 return total_units_; | 34 delete[] sample_buckets_; |
24 } | 35 } |
25 | 36 |
26 size_t RateTracker::units_second() { | 37 double RateTracker::ComputeRateForInterval( |
27 // Snapshot units / second calculator. Determine how many seconds have | 38 uint32 interval_milliseconds) const { |
28 // elapsed since our last reference point. If over 1 second, establish | 39 if (bucket_start_time_milliseconds_ == ~0u) { |
29 // a new reference point that is an integer number of seconds since the | 40 return 0.0; |
30 // last one, and compute the units over that interval. | 41 } |
31 uint32 current_time = Time(); | 42 uint32 current_time = Time(); |
32 if (last_units_second_time_ == ~0u) { | 43 // Calculate which buckets to sum up given the current time. If the time |
33 last_units_second_time_ = current_time; | 44 // has passed to a new bucket then we have to skip some of the oldest buckets. |
34 last_units_second_calc_ = total_units_; | 45 uint32 available_interval_milliseconds = std::min<uint32>( |
| 46 interval_milliseconds, |
| 47 bucket_milliseconds_ * static_cast<uint32>(bucket_count_)); |
| 48 // number of old buckets (i.e. after the current bucket in the ring buffer) |
| 49 // that are expired given our current time interval. |
| 50 size_t buckets_to_skip; |
| 51 // Number of milliseconds of the first bucket that are not a portion of the |
| 52 // current interval. |
| 53 uint32 milliseconds_to_skip; |
| 54 if (current_time > |
| 55 initialization_time_milliseconds_ + available_interval_milliseconds) { |
| 56 uint32 time_to_skip = current_time - bucket_start_time_milliseconds_ + |
| 57 static_cast<uint32>(bucket_count_) * bucket_milliseconds_ - |
| 58 available_interval_milliseconds; |
| 59 buckets_to_skip = time_to_skip / bucket_milliseconds_; |
| 60 milliseconds_to_skip = time_to_skip % bucket_milliseconds_; |
35 } else { | 61 } else { |
36 int delta = rtc::TimeDiff(current_time, last_units_second_time_); | 62 buckets_to_skip = bucket_count_ - current_bucket_; |
37 if (delta >= 1000) { | 63 milliseconds_to_skip = 0u; |
38 int fraction_time = delta % 1000; | 64 available_interval_milliseconds = |
39 int seconds = delta / 1000; | 65 TimeDiff(current_time, initialization_time_milliseconds_); |
40 int fraction_units = | |
41 static_cast<int>(total_units_ - last_units_second_calc_) * | |
42 fraction_time / delta; | |
43 // Compute "units received during the interval" / "seconds in interval" | |
44 units_second_ = | |
45 (total_units_ - last_units_second_calc_ - fraction_units) / seconds; | |
46 last_units_second_time_ = current_time - fraction_time; | |
47 last_units_second_calc_ = total_units_ - fraction_units; | |
48 } | |
49 } | 66 } |
50 | 67 // If we're skipping all buckets that means that there have been no samples |
51 return units_second_; | 68 // within the sampling interval so report 0. |
| 69 if (buckets_to_skip > bucket_count_ || |
| 70 available_interval_milliseconds == 0u) { |
| 71 return 0.0; |
| 72 } |
| 73 size_t start_bucket = NextBucketIndex(current_bucket_ + buckets_to_skip); |
| 74 // Only count a portion of the first bucket according to how much of the |
| 75 // first bucket is within the current interval. |
| 76 size_t total_samples = sample_buckets_[start_bucket] * |
| 77 (bucket_milliseconds_ - milliseconds_to_skip) / |
| 78 bucket_milliseconds_; |
| 79 // All other buckets in the interval are counted in their entirety. |
| 80 for (size_t i = NextBucketIndex(start_bucket); |
| 81 i != NextBucketIndex(current_bucket_); |
| 82 i = NextBucketIndex(i)) { |
| 83 total_samples += sample_buckets_[i]; |
| 84 } |
| 85 // Convert to samples per second. |
| 86 return static_cast<double>(total_samples * 1000u) / |
| 87 static_cast<double>(available_interval_milliseconds); |
52 } | 88 } |
53 | 89 |
54 void RateTracker::Update(size_t units) { | 90 double RateTracker::ComputeTotalRate() const { |
55 if (last_units_second_time_ == ~0u) | 91 if (bucket_start_time_milliseconds_ == ~0u) { |
56 last_units_second_time_ = Time(); | 92 return 0.0; |
57 total_units_ += units; | 93 } |
| 94 uint32 current_time = Time(); |
| 95 if (TimeIsLaterOrEqual(current_time, initialization_time_milliseconds_)) { |
| 96 return 0.0; |
| 97 } |
| 98 return static_cast<double>(total_sample_count_ * 1000u) / |
| 99 static_cast<double>( |
| 100 TimeDiff(current_time, initialization_time_milliseconds_)); |
| 101 } |
| 102 |
| 103 size_t RateTracker::TotalSampleCount() const { |
| 104 return total_sample_count_; |
| 105 } |
| 106 |
| 107 void RateTracker::AddSamples(size_t sample_count) { |
| 108 EnsureInitialized(); |
| 109 uint32 current_time = Time(); |
| 110 // Advance the current bucket as needed for the current time, and reset |
| 111 // bucket counts as we advance. |
| 112 for (size_t i = 0u; i <= bucket_count_ && |
| 113 current_time >= bucket_start_time_milliseconds_ + bucket_milliseconds_; |
| 114 ++i) { |
| 115 bucket_start_time_milliseconds_ += bucket_milliseconds_; |
| 116 current_bucket_ = NextBucketIndex(current_bucket_); |
| 117 sample_buckets_[current_bucket_] = 0u; |
| 118 } |
| 119 // Ensure that bucket_start_time_milliseconds_ is updated appropriately if |
| 120 // the entire buffer of samples has been expired. |
| 121 bucket_start_time_milliseconds_ += bucket_milliseconds_ * |
| 122 ((current_time - bucket_start_time_milliseconds_) / bucket_milliseconds_); |
| 123 // Add all samples in the bucket that includes the current time. |
| 124 sample_buckets_[current_bucket_] += sample_count; |
| 125 total_sample_count_ += sample_count; |
58 } | 126 } |
59 | 127 |
60 uint32 RateTracker::Time() const { | 128 uint32 RateTracker::Time() const { |
61 return rtc::Time(); | 129 return rtc::Time(); |
62 } | 130 } |
63 | 131 |
| 132 void RateTracker::EnsureInitialized() { |
| 133 if (bucket_start_time_milliseconds_ == ~0u) { |
| 134 initialization_time_milliseconds_ = Time(); |
| 135 bucket_start_time_milliseconds_ = initialization_time_milliseconds_; |
| 136 current_bucket_ = 0u; |
| 137 // We only need to initialize the first bucket because we reset buckets when |
| 138 // current_bucket_ increments. |
| 139 sample_buckets_[current_bucket_] = 0u; |
| 140 } |
| 141 } |
| 142 |
| 143 size_t RateTracker::NextBucketIndex(size_t bucket_index) const { |
| 144 return (bucket_index + 1u) % (bucket_count_ + 1u); |
| 145 } |
| 146 |
64 } // namespace rtc | 147 } // namespace rtc |
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