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1 // Copyright 2016 The Chromium Authors. All rights reserved. | 1 // Copyright 2016 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef NET_NQE_OBSERVATION_BUFFER_H_ | 5 #ifndef NET_NQE_OBSERVATION_BUFFER_H_ |
6 #define NET_NQE_OBSERVATION_BUFFER_H_ | 6 #define NET_NQE_OBSERVATION_BUFFER_H_ |
7 | 7 |
8 #include <float.h> | 8 #include <float.h> |
9 | 9 |
10 #include <algorithm> | 10 #include <algorithm> |
11 #include <deque> | 11 #include <deque> |
| 12 #include <memory> |
| 13 #include <utility> |
12 #include <vector> | 14 #include <vector> |
13 | 15 |
14 #include "base/gtest_prod_util.h" | |
15 #include "base/macros.h" | 16 #include "base/macros.h" |
| 17 #include "base/time/default_tick_clock.h" |
| 18 #include "base/time/tick_clock.h" |
16 #include "base/time/time.h" | 19 #include "base/time/time.h" |
17 #include "net/base/net_export.h" | 20 #include "net/base/net_export.h" |
| 21 #include "net/nqe/network_quality_observation.h" |
18 #include "net/nqe/network_quality_observation_source.h" | 22 #include "net/nqe/network_quality_observation_source.h" |
19 #include "net/nqe/weighted_observation.h" | 23 #include "net/nqe/weighted_observation.h" |
20 | 24 |
21 namespace net { | 25 namespace net { |
22 | 26 |
23 namespace nqe { | 27 namespace nqe { |
24 | 28 |
25 namespace internal { | 29 namespace internal { |
26 | 30 |
27 // Stores observations sorted by time. | 31 // Stores observations sorted by time. |
28 template <typename ValueType> | 32 template <typename ValueType> |
29 class NET_EXPORT_PRIVATE ObservationBuffer { | 33 class NET_EXPORT_PRIVATE ObservationBuffer { |
30 public: | 34 public: |
31 explicit ObservationBuffer(double weight_multiplier_per_second) | 35 explicit ObservationBuffer(double weight_multiplier_per_second) |
32 : weight_multiplier_per_second_(weight_multiplier_per_second) { | 36 : weight_multiplier_per_second_(weight_multiplier_per_second), |
| 37 tick_clock_(new base::DefaultTickClock()) { |
33 static_assert(kMaximumObservationsBufferSize > 0U, | 38 static_assert(kMaximumObservationsBufferSize > 0U, |
34 "Minimum size of observation buffer must be > 0"); | 39 "Minimum size of observation buffer must be > 0"); |
35 DCHECK_GE(weight_multiplier_per_second_, 0.0); | 40 DCHECK_GE(weight_multiplier_per_second_, 0.0); |
36 DCHECK_LE(weight_multiplier_per_second_, 1.0); | 41 DCHECK_LE(weight_multiplier_per_second_, 1.0); |
37 } | 42 } |
38 | 43 |
39 ~ObservationBuffer() {} | 44 ~ObservationBuffer() {} |
40 | 45 |
41 // Adds |observation| to the buffer. The oldest observation in the buffer | 46 // Adds |observation| to the buffer. The oldest observation in the buffer |
42 // will be evicted to make room if the buffer is already full. | 47 // will be evicted to make room if the buffer is already full. |
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63 // Clears the observations stored in this buffer. | 68 // Clears the observations stored in this buffer. |
64 void Clear() { observations_.clear(); } | 69 void Clear() { observations_.clear(); } |
65 | 70 |
66 // Returns true iff the |percentile| value of the observations in this | 71 // Returns true iff the |percentile| value of the observations in this |
67 // buffer is available. Sets |result| to the computed |percentile| | 72 // buffer is available. Sets |result| to the computed |percentile| |
68 // value among all observations since |begin_timestamp|. If the value is | 73 // value among all observations since |begin_timestamp|. If the value is |
69 // unavailable, false is returned and |result| is not modified. Percentile | 74 // unavailable, false is returned and |result| is not modified. Percentile |
70 // value is unavailable if all the values in observation buffer are older | 75 // value is unavailable if all the values in observation buffer are older |
71 // than |begin_timestamp|. | 76 // than |begin_timestamp|. |
72 // |result| must not be null. | 77 // |result| must not be null. |
| 78 // TODO(tbansal): Move out param |result| as the last param of the function. |
73 bool GetPercentile(const base::TimeTicks& begin_timestamp, | 79 bool GetPercentile(const base::TimeTicks& begin_timestamp, |
74 ValueType* result, | 80 ValueType* result, |
75 int percentile, | 81 int percentile, |
76 const std::vector<NetworkQualityObservationSource>& | 82 const std::vector<NetworkQualityObservationSource>& |
77 disallowed_observation_sources) const { | 83 disallowed_observation_sources) const { |
78 DCHECK(result); | 84 DCHECK(result); |
79 DCHECK_GE(Capacity(), Size()); | 85 DCHECK_GE(Capacity(), Size()); |
80 // Stores WeightedObservation in increasing order of value. | 86 // Stores WeightedObservation in increasing order of value. |
81 std::vector<WeightedObservation<ValueType>> weighted_observations; | 87 std::vector<WeightedObservation<ValueType>> weighted_observations; |
82 | 88 |
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109 | 115 |
110 // Computation may reach here due to floating point errors. This may happen | 116 // Computation may reach here due to floating point errors. This may happen |
111 // if |percentile| was 100 (or close to 100), and |desired_weight| was | 117 // if |percentile| was 100 (or close to 100), and |desired_weight| was |
112 // slightly larger than |total_weight| (due to floating point errors). | 118 // slightly larger than |total_weight| (due to floating point errors). |
113 // In this case, we return the highest |value| among all observations. | 119 // In this case, we return the highest |value| among all observations. |
114 // This is same as value of the last observation in the sorted vector. | 120 // This is same as value of the last observation in the sorted vector. |
115 *result = weighted_observations.at(weighted_observations.size() - 1).value; | 121 *result = weighted_observations.at(weighted_observations.size() - 1).value; |
116 return true; | 122 return true; |
117 } | 123 } |
118 | 124 |
| 125 void SetTickClockForTesting(std::unique_ptr<base::TickClock> tick_clock) { |
| 126 tick_clock_ = std::move(tick_clock); |
| 127 } |
| 128 |
119 private: | 129 private: |
120 // Maximum number of observations that can be held in the ObservationBuffer. | 130 // Maximum number of observations that can be held in the ObservationBuffer. |
121 static const size_t kMaximumObservationsBufferSize = 300; | 131 static const size_t kMaximumObservationsBufferSize = 300; |
122 | 132 |
123 // Computes the weighted observations and stores them in | 133 // Computes the weighted observations and stores them in |
124 // |weighted_observations| sorted by ascending |WeightedObservation.value|. | 134 // |weighted_observations| sorted by ascending |WeightedObservation.value|. |
125 // Only the observations with timestamp later than |begin_timestamp| are | 135 // Only the observations with timestamp later than |begin_timestamp| are |
126 // considered. Also, sets |total_weight| to the total weight of all | 136 // considered. Also, sets |total_weight| to the total weight of all |
127 // observations. Should be called only when there is at least one | 137 // observations. Should be called only when there is at least one |
128 // observation in the buffer. | 138 // observation in the buffer. |
129 void ComputeWeightedObservations( | 139 void ComputeWeightedObservations( |
130 const base::TimeTicks& begin_timestamp, | 140 const base::TimeTicks& begin_timestamp, |
131 std::vector<WeightedObservation<ValueType>>& weighted_observations, | 141 std::vector<WeightedObservation<ValueType>>& weighted_observations, |
132 double* total_weight, | 142 double* total_weight, |
133 const std::vector<NetworkQualityObservationSource>& | 143 const std::vector<NetworkQualityObservationSource>& |
134 disallowed_observation_sources) const { | 144 disallowed_observation_sources) const { |
135 DCHECK_GE(Capacity(), Size()); | 145 DCHECK_GE(Capacity(), Size()); |
136 | 146 |
137 weighted_observations.clear(); | 147 weighted_observations.clear(); |
138 double total_weight_observations = 0.0; | 148 double total_weight_observations = 0.0; |
139 base::TimeTicks now = base::TimeTicks::Now(); | 149 base::TimeTicks now = tick_clock_->NowTicks(); |
140 | 150 |
141 for (const auto& observation : observations_) { | 151 for (const auto& observation : observations_) { |
142 if (observation.timestamp < begin_timestamp) | 152 if (observation.timestamp < begin_timestamp) |
143 continue; | 153 continue; |
144 bool disallowed = false; | 154 bool disallowed = false; |
145 for (const auto& disallowed_source : disallowed_observation_sources) { | 155 for (const auto& disallowed_source : disallowed_observation_sources) { |
146 if (disallowed_source == observation.source) | 156 if (disallowed_source == observation.source) |
147 disallowed = true; | 157 disallowed = true; |
148 } | 158 } |
149 if (disallowed) | 159 if (disallowed) |
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167 // front of the queue. | 177 // front of the queue. |
168 std::deque<Observation<ValueType>> observations_; | 178 std::deque<Observation<ValueType>> observations_; |
169 | 179 |
170 // The factor by which the weight of an observation reduces every second. | 180 // The factor by which the weight of an observation reduces every second. |
171 // For example, if an observation is 6 seconds old, its weight would be: | 181 // For example, if an observation is 6 seconds old, its weight would be: |
172 // weight_multiplier_per_second_ ^ 6 | 182 // weight_multiplier_per_second_ ^ 6 |
173 // Calculated from |kHalfLifeSeconds| by solving the following equation: | 183 // Calculated from |kHalfLifeSeconds| by solving the following equation: |
174 // weight_multiplier_per_second_ ^ kHalfLifeSeconds = 0.5 | 184 // weight_multiplier_per_second_ ^ kHalfLifeSeconds = 0.5 |
175 const double weight_multiplier_per_second_; | 185 const double weight_multiplier_per_second_; |
176 | 186 |
| 187 std::unique_ptr<base::TickClock> tick_clock_; |
| 188 |
177 DISALLOW_COPY_AND_ASSIGN(ObservationBuffer); | 189 DISALLOW_COPY_AND_ASSIGN(ObservationBuffer); |
178 }; | 190 }; |
179 | 191 |
180 } // namespace internal | 192 } // namespace internal |
181 | 193 |
182 } // namespace nqe | 194 } // namespace nqe |
183 | 195 |
184 } // namespace net | 196 } // namespace net |
185 | 197 |
186 #endif // NET_NQE_OBSERVATION_BUFFER_H_ | 198 #endif // NET_NQE_OBSERVATION_BUFFER_H_ |
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