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- // Copyright 2016 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #ifndef NET_NQE_OBSERVATION_BUFFER_H_
- #define NET_NQE_OBSERVATION_BUFFER_H_
- #include <stdint.h>
- #include <map>
- #include <memory>
- #include <set>
- #include <vector>
- #include "base/containers/circular_deque.h"
- #include "base/memory/raw_ptr.h"
- #include "base/time/tick_clock.h"
- #include "net/base/net_export.h"
- #include "net/nqe/network_quality_estimator_util.h"
- #include "net/nqe/network_quality_observation.h"
- #include "net/nqe/network_quality_observation_source.h"
- #include "third_party/abseil-cpp/absl/types/optional.h"
- namespace base {
- class TimeTicks;
- } // namespace base
- namespace net {
- class NetworkQualityEstimatorParams;
- namespace nqe::internal {
- struct WeightedObservation;
- // Stores observations sorted by time and provides utility functions for
- // computing weighted and non-weighted summary statistics.
- class NET_EXPORT_PRIVATE ObservationBuffer {
- public:
- ObservationBuffer(const NetworkQualityEstimatorParams* params,
- const base::TickClock* tick_clock,
- double weight_multiplier_per_second,
- double weight_multiplier_per_signal_level);
- // This constructor does not copy the |observations_| from |other| to |this|.
- // As such, this constructor should only be called before adding any
- // observations to |other|.
- ObservationBuffer(const ObservationBuffer& other);
- ObservationBuffer& operator=(const ObservationBuffer&) = delete;
- ~ObservationBuffer();
- // Adds |observation| to the buffer. The oldest observation in the buffer
- // will be evicted to make room if the buffer is already full.
- void AddObservation(const Observation& observation);
- // Returns the number of observations in this buffer.
- size_t Size() const { return static_cast<size_t>(observations_.size()); }
- // Returns the capacity of this buffer.
- size_t Capacity() const;
- // Clears the observations stored in this buffer.
- void Clear() { observations_.clear(); }
- // Returns true iff the |percentile| value of the observations in this
- // buffer is available. Sets |result| to the computed |percentile|
- // value of all observations made on or after |begin_timestamp|. If the
- // value is unavailable, false is returned and |result| is not modified.
- // Percentile value is unavailable if all the values in observation buffer are
- // older than |begin_timestamp|. |current_signal_strength| is the current
- // signal strength. |result| must not be null. If |observations_count| is not
- // null, then it is set to the number of observations that were available
- // in the observation buffer for computing the percentile.
- absl::optional<int32_t> GetPercentile(base::TimeTicks begin_timestamp,
- int32_t current_signal_strength,
- int percentile,
- size_t* observations_count) const;
- void SetTickClockForTesting(const base::TickClock* tick_clock) {
- tick_clock_ = tick_clock;
- }
- // Removes all observations from the buffer whose corresponding entry in
- // |deleted_observation_sources| is set to true. For example, if index 1 and
- // 3 in |deleted_observation_sources| are set to true, then all observations
- // in the buffer that have source set to either 1 or 3 would be removed.
- void RemoveObservationsWithSource(
- bool deleted_observation_sources[NETWORK_QUALITY_OBSERVATION_SOURCE_MAX]);
- private:
- // Computes the weighted observations and stores them in
- // |weighted_observations| sorted by ascending |WeightedObservation.value|.
- // Only the observations with timestamp later than |begin_timestamp| are
- // considered. |current_signal_strength| is the current signal strength
- // when the observation was taken. This method also sets |total_weight| to
- // the total weight of all observations. Should be called only when there is
- // at least one observation in the buffer.
- void ComputeWeightedObservations(
- const base::TimeTicks& begin_timestamp,
- int32_t current_signal_strength,
- std::vector<WeightedObservation>* weighted_observations,
- double* total_weight) const;
- raw_ptr<const NetworkQualityEstimatorParams> params_;
- // Holds observations sorted by time, with the oldest observation at the
- // front of the queue.
- base::circular_deque<Observation> observations_;
- // The factor by which the weight of an observation reduces every second.
- // For example, if an observation is 6 seconds old, its weight would be:
- // weight_multiplier_per_second_ ^ 6
- // Calculated from |kHalfLifeSeconds| by solving the following equation:
- // weight_multiplier_per_second_ ^ kHalfLifeSeconds = 0.5
- const double weight_multiplier_per_second_;
- // The factor by which the weight of an observation reduces for every unit
- // difference in the current signal strength, and the signal strength at
- // which the observation was taken.
- // For example, if the observation was taken at 1 unit, and current signal
- // strength is 4 units, the weight of the observation would be:
- // |weight_multiplier_per_signal_level_| ^ 3.
- const double weight_multiplier_per_signal_level_;
- raw_ptr<const base::TickClock> tick_clock_;
- };
- } // namespace nqe::internal
- } // namespace net
- #endif // NET_NQE_OBSERVATION_BUFFER_H_
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