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// Copyright 2015 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_NETWORK_QUALITY_ESTIMATOR_H_
#define NET_NQE_NETWORK_QUALITY_ESTIMATOR_H_
#include <stdint.h>
#include <map>
#include <memory>
#include <string>
#include <vector>
#include "base/compiler_specific.h"
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "base/optional.h"
#include "base/threading/thread_checker.h"
#include "base/time/time.h"
#include "net/base/net_export.h"
#include "net/base/network_change_notifier.h"
#include "net/log/net_log_with_source.h"
#include "net/nqe/cached_network_quality.h"
#include "net/nqe/effective_connection_type.h"
#include "net/nqe/effective_connection_type_observer.h"
#include "net/nqe/event_creator.h"
#include "net/nqe/external_estimate_provider.h"
#include "net/nqe/network_id.h"
#include "net/nqe/network_quality.h"
#include "net/nqe/network_quality_estimator_params.h"
#include "net/nqe/network_quality_observation.h"
#include "net/nqe/network_quality_observation_source.h"
#include "net/nqe/network_quality_provider.h"
#include "net/nqe/network_quality_store.h"
#include "net/nqe/observation_buffer.h"
#include "net/nqe/rtt_throughput_estimates_observer.h"
#include "net/nqe/socket_watcher_factory.h"
namespace base {
class TickClock;
} // namespace base
namespace net {
class NetLog;
namespace nqe {
namespace internal {
class ThroughputAnalyzer;
}
}
class URLRequest;
// NetworkQualityEstimator provides network quality estimates (quality of the
// full paths to all origins that have been connected to).
// The estimates are based on the observed organic traffic.
// A NetworkQualityEstimator instance is attached to URLRequestContexts and
// observes the traffic of URLRequests spawned from the URLRequestContexts.
// A single instance of NQE can be attached to multiple URLRequestContexts,
// thereby increasing the single NQE instance's accuracy by providing more
// observed traffic characteristics.
class NET_EXPORT NetworkQualityEstimator
: public NetworkChangeNotifier::ConnectionTypeObserver,
public ExternalEstimateProvider::UpdatedEstimateDelegate,
public NetworkQualityProvider {
public:
// Observes measurements of round trip time.
class NET_EXPORT_PRIVATE RTTObserver {
public:
// Will be called when a new RTT observation is available. The round trip
// time is specified in milliseconds. The time when the observation was
// taken and the source of the observation are provided.
virtual void OnRTTObservation(int32_t rtt_ms,
const base::TimeTicks& timestamp,
NetworkQualityObservationSource source) = 0;
protected:
RTTObserver() {}
virtual ~RTTObserver() {}
private:
DISALLOW_COPY_AND_ASSIGN(RTTObserver);
};
// Observes measurements of throughput.
class NET_EXPORT_PRIVATE ThroughputObserver {
public:
// Will be called when a new throughput observation is available.
// Throughput is specified in kilobits per second.
virtual void OnThroughputObservation(
int32_t throughput_kbps,
const base::TimeTicks& timestamp,
NetworkQualityObservationSource source) = 0;
protected:
ThroughputObserver() {}
virtual ~ThroughputObserver() {}
private:
DISALLOW_COPY_AND_ASSIGN(ThroughputObserver);
};
// Creates a new NetworkQualityEstimator.
// |external_estimates_provider| may be NULL. |params| contains the
// configuration parameters relevant to network quality estimator. The caller
// must guarantee that |net_log| outlives |this|.
NetworkQualityEstimator(
std::unique_ptr<ExternalEstimateProvider> external_estimates_provider,
std::unique_ptr<NetworkQualityEstimatorParams> params,
NetLog* net_log);
~NetworkQualityEstimator() override;
// Returns the effective type of the current connection based on only the
// samples observed after |start_time|. This should only be used for
// recording the metrics. Virtualized for testing.
virtual EffectiveConnectionType GetRecentEffectiveConnectionType(
const base::TimeTicks& start_time) const;
// NetworkQualityProvider implementation:
// Must be called on the IO thread.
EffectiveConnectionType GetEffectiveConnectionType() const override;
void AddEffectiveConnectionTypeObserver(
EffectiveConnectionTypeObserver* observer) override;
void RemoveEffectiveConnectionTypeObserver(
EffectiveConnectionTypeObserver* observer) override;
base::Optional<base::TimeDelta> GetHttpRTT() const override;
base::Optional<base::TimeDelta> GetTransportRTT() const override;
base::Optional<int32_t> GetDownstreamThroughputKbps() const override;
base::Optional<int32_t> GetBandwidthDelayProductKbits() const override;
void AddRTTAndThroughputEstimatesObserver(
RTTAndThroughputEstimatesObserver* observer) override;
void RemoveRTTAndThroughputEstimatesObserver(
RTTAndThroughputEstimatesObserver* observer) override;
// Notifies NetworkQualityEstimator that the response header of |request| has
// been received.
void NotifyHeadersReceived(const URLRequest& request);
// Notifies NetworkQualityEstimator that unfiltered bytes have been read for
// |request|.
void NotifyBytesRead(const URLRequest& request);
// Notifies NetworkQualityEstimator that the headers of |request| are about to
// be sent.
void NotifyStartTransaction(const URLRequest& request);
// Notifies NetworkQualityEstimator that the response body of |request| has
// been received.
void NotifyRequestCompleted(const URLRequest& request, int net_error);
// Notifies NetworkQualityEstimator that |request| will be destroyed.
void NotifyURLRequestDestroyed(const URLRequest& request);
// Adds |rtt_observer| to the list of round trip time observers. Must be
// called on the IO thread.
void AddRTTObserver(RTTObserver* rtt_observer);
// Removes |rtt_observer| from the list of round trip time observers if it
// is on the list of observers. Must be called on the IO thread.
void RemoveRTTObserver(RTTObserver* rtt_observer);
// Adds |throughput_observer| to the list of throughput observers. Must be
// called on the IO thread.
void AddThroughputObserver(ThroughputObserver* throughput_observer);
// Removes |throughput_observer| from the list of throughput observers if it
// is on the list of observers. Must be called on the IO thread.
void RemoveThroughputObserver(ThroughputObserver* throughput_observer);
SocketPerformanceWatcherFactory* GetSocketPerformanceWatcherFactory();
// |use_localhost_requests| should only be true when testing against local
// HTTP server and allows the requests to local host to be used for network
// quality estimation.
void SetUseLocalHostRequestsForTesting(bool use_localhost_requests);
// |use_small_responses| should only be true when testing.
// Allows the responses smaller than |kMinTransferSizeInBits| to be used for
// network quality estimation.
void SetUseSmallResponsesForTesting(bool use_small_responses);
// If |disable_offline_check| is set to true, then the device offline check is
// disabled when computing the effective connection type or when writing the
// prefs.
void DisableOfflineCheckForTesting(bool disable_offline_check);
// Reports |effective_connection_type| to all
// EffectiveConnectionTypeObservers.
void ReportEffectiveConnectionTypeForTesting(
EffectiveConnectionType effective_connection_type);
// Reports the RTTs and throughput to all RTTAndThroughputEstimatesObservers.
void ReportRTTsAndThroughputForTesting(base::TimeDelta http_rtt,
base::TimeDelta transport_rtt,
int32_t downstream_throughput_kbps);
// Adds and removes |observer| from the list of cache observers.
void AddNetworkQualitiesCacheObserver(
nqe::internal::NetworkQualityStore::NetworkQualitiesCacheObserver*
observer);
void RemoveNetworkQualitiesCacheObserver(
nqe::internal::NetworkQualityStore::NetworkQualitiesCacheObserver*
observer);
// Called when the persistent prefs have been read. |read_prefs| contains the
// parsed prefs as a map between NetworkIDs and CachedNetworkQualities.
void OnPrefsRead(
const std::map<nqe::internal::NetworkID,
nqe::internal::CachedNetworkQuality> read_prefs);
protected:
// Different experimental statistic algorithms that can be used for computing
// the predictions.
// TODO(tbansal): crbug.com/649887. Consider evaluating other statistical
// algorithms.
enum Statistic {
// Last statistic. Not to be used.
STATISTIC_LAST = 0
};
// NetworkChangeNotifier::ConnectionTypeObserver implementation:
void OnConnectionTypeChanged(
NetworkChangeNotifier::ConnectionType type) override;
// ExternalEstimateProvider::UpdatedEstimateObserver implementation.
void OnUpdatedEstimateAvailable(const base::TimeDelta& rtt,
int32_t downstream_throughput_kbps) override;
// Returns true if median RTT at the HTTP layer is available and sets |rtt|
// to the median of RTT observations since |start_time|.
// Virtualized for testing. |rtt| should not be null. The RTT at the HTTP
// layer measures the time from when the request was sent (this happens after
// the connection is established) to the time when the response headers were
// received.
// TODO(tbansal): Change it to return HTTP RTT as base::TimeDelta.
virtual bool GetRecentHttpRTT(const base::TimeTicks& start_time,
base::TimeDelta* rtt) const WARN_UNUSED_RESULT;
// Returns true if the median RTT at the transport layer is available and sets
// |rtt| to the median of transport layer RTT observations since
// |start_time|. |rtt| should not be null. Virtualized for testing.
// TODO(tbansal): Change it to return transport RTT as base::TimeDelta.
virtual bool GetRecentTransportRTT(const base::TimeTicks& start_time,
base::TimeDelta* rtt) const
WARN_UNUSED_RESULT;
// Returns true if median downstream throughput is available and sets |kbps|
// to the median of downstream throughput (in kilobits per second)
// observations since |start_time|. Virtualized for testing. |kbps|
// should not be null. Virtualized for testing.
// TODO(tbansal): Change it to return throughput as int32.
virtual bool GetRecentDownlinkThroughputKbps(
const base::TimeTicks& start_time,
int32_t* kbps) const WARN_UNUSED_RESULT;
// Returns the list of intervals at which the accuracy of network quality
// prediction should be recorded. Virtualized for testing.
virtual const std::vector<base::TimeDelta>& GetAccuracyRecordingIntervals()
const;
// Overrides the tick clock used by |this| for testing.
void SetTickClockForTesting(std::unique_ptr<base::TickClock> tick_clock);
// Returns a random double in the range [0.0, 1.0). Virtualized for testing.
virtual double RandDouble() const;
// Returns the effective type of the current connection based on only the
// observations received after |start_time|. |http_rtt|, |transport_rtt| and
// |downstream_throughput_kbps| must be non-null. |http_rtt|, |transport_rtt|
// and |downstream_throughput_kbps| are set to the expected HTTP RTT,
// transport RTT and downstream throughput (in kilobits per second) based on
// observations taken since |start_time|. Virtualized for testing.
virtual EffectiveConnectionType
GetRecentEffectiveConnectionTypeAndNetworkQuality(
const base::TimeTicks& start_time,
base::TimeDelta* http_rtt,
base::TimeDelta* transport_rtt,
int32_t* downstream_throughput_kbps) const;
// Notifies |this| of a new transport layer RTT. Called by socket watchers.
// Protected for testing.
void OnUpdatedTransportRTTAvailable(
SocketPerformanceWatcherFactory::Protocol protocol,
const base::TimeDelta& rtt,
const base::Optional<nqe::internal::IPHash>& host);
// Returns an estimate of network quality at the specified |percentile|.
// |disallowed_observation_sources| is the list of observation sources that
// should be excluded when computing the percentile.
// Only the observations later than |start_time| are taken into account.
// |percentile| must be between 0 and 100 (both inclusive) with higher
// percentiles indicating less performant networks. For example, if
// |percentile| is 90, then the network is expected to be faster than the
// returned estimate with 0.9 probability. Similarly, network is expected to
// be slower than the returned estimate with 0.1 probability. |statistic|
// is the statistic that should be used for computing the estimate. If unset,
// the default statistic is used. Virtualized for testing.
virtual base::TimeDelta GetRTTEstimateInternal(
const std::vector<NetworkQualityObservationSource>&
disallowed_observation_sources,
base::TimeTicks start_time,
const base::Optional<Statistic>& statistic,
int percentile) const;
int32_t GetDownlinkThroughputKbpsEstimateInternal(
const base::TimeTicks& start_time,
int percentile) const;
// Notifies the observers of RTT or throughput estimates computation.
virtual void NotifyObserversOfRTTOrThroughputComputed() const;
// Notifies |observer| of the current RTT and throughput if |observer| is
// still registered as an observer.
virtual void NotifyRTTAndThroughputEstimatesObserverIfPresent(
RTTAndThroughputEstimatesObserver* observer) const;
base::Optional<int32_t> ComputeIncreaseInTransportRTTForTests() {
return ComputeIncreaseInTransportRTT();
}
// Observer list for RTT or throughput estimates. Protected for testing.
base::ObserverList<RTTAndThroughputEstimatesObserver>
rtt_and_throughput_estimates_observer_list_;
// Observer list for changes in effective connection type.
base::ObserverList<EffectiveConnectionTypeObserver>
effective_connection_type_observer_list_;
private:
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
AdaptiveRecomputationEffectiveConnectionType);
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, StoreObservations);
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestAddObservation);
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
DefaultObservationsOverridden);
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, ComputedPercentiles);
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestGetMetricsSince);
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
TestExternalEstimateProviderMergeEstimates);
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
UnknownEffectiveConnectionType);
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
TypicalNetworkQualities);
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
OnPrefsReadWithReadingDisabled);
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
ForceEffectiveConnectionTypeThroughFieldTrial);
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestBDPComputation);
FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
TestComputeIncreaseInTransportRTTFullHostsOverlap);
FRIEND_TEST_ALL_PREFIXES(
NetworkQualityEstimatorTest,
TestComputeIncreaseInTransportRTTPartialHostsOverlap);
typedef nqe::internal::Observation Observation;
typedef nqe::internal::ObservationBuffer ObservationBuffer;
// Defines how a metric (e.g, transport RTT) should be used when computing
// the effective connection type.
enum class MetricUsage {
// The metric should not be used when computing the effective connection
// type.
DO_NOT_USE = 0,
// If the metric is available, then it should be used when computing the
// effective connection type.
USE_IF_AVAILABLE,
// The metric is required when computing the effective connection type.
// If the value of the metric is unavailable, effective connection type
// should be set to |EFFECTIVE_CONNECTION_TYPE_UNKNOWN|.
MUST_BE_USED,
};
// Returns the RTT value to be used when the valid RTT is unavailable. Readers
// should discard RTT if it is set to the value returned by |InvalidRTT()|.
static const base::TimeDelta InvalidRTT();
// Queries external estimate provider for network quality. When the network
// quality is available, OnUpdatedEstimateAvailable() is called.
void MaybeQueryExternalEstimateProvider() const;
// Records UMA when there is a change in connection type.
void RecordMetricsOnConnectionTypeChanged() const;
// Records UMA on whether the NetworkID was available or not. Called right
// after a network change event.
void RecordNetworkIDAvailability() const;
// Records UMA on main frame requests.
void RecordMetricsOnMainFrameRequest() const;
// Records a downstream throughput observation to the observation buffer if
// a valid observation is available. |downstream_kbps| is the downstream
// throughput in kilobits per second.
void OnNewThroughputObservationAvailable(int32_t downstream_kbps);
// Adds the default median RTT and downstream throughput estimate for the
// current connection type to the observation buffer.
void AddDefaultEstimates();
// Returns the current network ID checking by calling the platform APIs.
// Virtualized for testing.
virtual nqe::internal::NetworkID GetCurrentNetworkID() const;
// Adds |observation| to the buffer of RTT observations, and notifies RTT
// observers of |observation|. May also trigger recomputation of effective
// connection type.
void AddAndNotifyObserversOfRTT(const Observation& observation);
// Adds |observation| to the buffer of throughput observations, and notifies
// throughput observers of |observation|. May also trigger recomputation of
// effective connection type.
void AddAndNotifyObserversOfThroughput(const Observation& observation);
// Returns true only if the |request| can be used for RTT estimation.
bool RequestProvidesRTTObservation(const URLRequest& request) const;
// Recomputes effective connection type, if it was computed more than the
// specified duration ago, or if there has been a connection change recently.
void MaybeComputeEffectiveConnectionType();
// Notifies observers of a change in effective connection type.
void NotifyObserversOfEffectiveConnectionTypeChanged();
// Notifies |observer| of the current effective connection type if |observer|
// is still registered as an observer.
void NotifyEffectiveConnectionTypeObserverIfPresent(
EffectiveConnectionTypeObserver* observer) const;
// Records NQE accuracy metrics. |measuring_duration| should belong to the
// vector returned by AccuracyRecordingIntervals().
// RecordAccuracyAfterMainFrame should be called |measuring_duration| after a
// main frame request is observed.
void RecordAccuracyAfterMainFrame(base::TimeDelta measuring_duration) const;
// Obtains the current cellular signal strength value and updates
// |min_signal_strength_since_connection_change_| and
// |max_signal_strength_since_connection_change_|.
void UpdateSignalStrength();
// Returns the effective type of the current connection based on only the
// samples observed after |start_time|. May use HTTP RTT, transport RTT and
// downstream throughput to compute the effective connection type based on
// |http_rtt_metric|, |transport_rtt_metric| and
// |downstream_throughput_kbps_metric|, respectively. |http_rtt|,
// |transport_rtt| and |downstream_throughput_kbps| must be non-null.
// |http_rtt|, |transport_rtt| and |downstream_throughput_kbps| are
// set to the expected HTTP RTT, transport RTT and downstream throughput (in
// kilobits per second) based on observations taken since |start_time|.
EffectiveConnectionType GetRecentEffectiveConnectionTypeUsingMetrics(
const base::TimeTicks& start_time,
MetricUsage http_rtt_metric,
MetricUsage transport_rtt_metric,
MetricUsage downstream_throughput_kbps_metric,
base::TimeDelta* http_rtt,
base::TimeDelta* transport_rtt,
int32_t* downstream_throughput_kbps) const;
// Values of external estimate provider status. This enum must remain
// synchronized with the enum of the same name in
// metrics/histograms/histograms.xml.
enum NQEExternalEstimateProviderStatus {
EXTERNAL_ESTIMATE_PROVIDER_STATUS_NOT_AVAILABLE,
EXTERNAL_ESTIMATE_PROVIDER_STATUS_AVAILABLE,
EXTERNAL_ESTIMATE_PROVIDER_STATUS_QUERIED,
EXTERNAL_ESTIMATE_PROVIDER_STATUS_QUERY_SUCCESSFUL,
EXTERNAL_ESTIMATE_PROVIDER_STATUS_CALLBACK,
EXTERNAL_ESTIMATE_PROVIDER_STATUS_RTT_AVAILABLE,
EXTERNAL_ESTIMATE_PROVIDER_STATUS_DOWNLINK_BANDWIDTH_AVAILABLE,
EXTERNAL_ESTIMATE_PROVIDER_STATUS_BOUNDARY
};
// Records the metrics related to external estimate provider.
void RecordExternalEstimateProviderMetrics(
NQEExternalEstimateProviderStatus status) const;
// Returns true if the cached network quality estimate was successfully read.
bool ReadCachedNetworkQualityEstimate();
// Records a correlation metric that can be used for computing the correlation
// between HTTP-layer RTT, transport-layer RTT, throughput and the time
// taken to complete |request|.
void RecordCorrelationMetric(const URLRequest& request, int net_error) const;
// Returns true if transport RTT should be used for computing the effective
// connection type.
bool UseTransportRTT() const;
// Computes the bandwidth delay product in kilobits. The computed value is
// stored in |bandwidth_delay_product_kbits_| and can be accessed using
// |GetBandwidthDelayProductKbits|.
void ComputeBandwidthDelayProduct();
// Computes the current increase in transport RTT in milliseconds over the
// baseline transport RTT due to congestion. This value can be interpreted as
// the additional delay caused due to an increase in queue length in the last
// mile. The baseline is computed using the transport RTT observations in the
// past 60 seconds. The current RTT is computed using the observations in the
// past 5 seconds. Returns an empty optional when there was no recent data.
base::Optional<int32_t> ComputeIncreaseInTransportRTT() const;
// Periodically updates |increase_in_transport_rtt_| by posting delayed tasks.
void IncreaseInTransportRTTUpdater();
// Forces computation of effective connection type, and notifies observers
// if there is a change in its value.
void ComputeEffectiveConnectionType();
// May update the network quality of the current network if |network_id|
// matches the ID of the current network. |cached_network_quality| is the
// cached network quality of the network with id |network_id|.
void MaybeUpdateNetworkQualityFromCache(
const nqe::internal::NetworkID& network_id,
const nqe::internal::CachedNetworkQuality& cached_network_quality);
const char* GetNameForStatistic(int i) const;
// Gathers metrics for the next connection type. Called when there is a change
// in the connection type.
void GatherEstimatesForNextConnectionType();
// Params to configure the network quality estimator.
const std::unique_ptr<NetworkQualityEstimatorParams> params_;
// Determines if the requests to local host can be used in estimating the
// network quality. Set to true only for tests.
bool use_localhost_requests_;
// When set to true, the device offline check is disabled when computing the
// effective connection type or when writing the prefs. Set to true only for
// testing.
bool disable_offline_check_;
// Tick clock used by the network quality estimator.
std::unique_ptr<base::TickClock> tick_clock_;
// Intervals after the main frame request arrives at which accuracy of network
// quality prediction is recorded.
std::vector<base::TimeDelta> accuracy_recording_intervals_;
// Time when last connection change was observed.
base::TimeTicks last_connection_change_;
// ID of the current network.
nqe::internal::NetworkID current_network_id_;
// Buffer that holds throughput observations (in kilobits per second) sorted
// by timestamp.
ObservationBuffer downstream_throughput_kbps_observations_;
// Buffer that holds RTT observations (in milliseconds) sorted by timestamp.
ObservationBuffer rtt_ms_observations_;
// Time when the transaction for the last main frame request was started.
base::TimeTicks last_main_frame_request_;
// Estimated network quality when the transaction for the last main frame
// request was started.
nqe::internal::NetworkQuality estimated_quality_at_last_main_frame_;
EffectiveConnectionType effective_connection_type_at_last_main_frame_;
// Estimated network quality obtained from external estimate provider when the
// external estimate provider was last queried.
nqe::internal::NetworkQuality external_estimate_provider_quality_;
// ExternalEstimateProvider that provides network quality using operating
// system APIs. May be NULL.
const std::unique_ptr<ExternalEstimateProvider> external_estimate_provider_;
// Observer lists for round trip times and throughput measurements.
base::ObserverList<RTTObserver> rtt_observer_list_;
base::ObserverList<ThroughputObserver> throughput_observer_list_;
std::unique_ptr<nqe::internal::SocketWatcherFactory> watcher_factory_;
// Takes throughput measurements, and passes them back to |this| through the
// provided callback. |this| stores the throughput observations in
// |downstream_throughput_kbps_observations_|, which are later used for
// estimating the throughput.
std::unique_ptr<nqe::internal::ThroughputAnalyzer> throughput_analyzer_;
// Minimum duration between two consecutive computations of effective
// connection type. Set to non-zero value as a performance optimization.
const base::TimeDelta effective_connection_type_recomputation_interval_;
// Time when the effective connection type was last computed.
base::TimeTicks last_effective_connection_type_computation_;
// Number of RTT and bandwidth samples available when effective connection
// type was last recomputed.
size_t rtt_observations_size_at_last_ect_computation_;
size_t throughput_observations_size_at_last_ect_computation_;
// Current estimate of the network quality.
nqe::internal::NetworkQuality network_quality_;
// Current estimate of the bandwidth delay product (BDP) in kilobits.
base::Optional<int32_t> bandwidth_delay_product_kbits_;
// Current estimate of the increase in the transport RTT due to congestion.
base::Optional<int32_t> increase_in_transport_rtt_;
// This is true if there is a task posted for |IncreaseInTransportRTTUpdater|.
bool increase_in_transport_rtt_updater_posted_;
// Current effective connection type. It is updated on connection change
// events. It is also updated every time there is network traffic (provided
// the last computation was more than
// |effective_connection_type_recomputation_interval_| ago).
EffectiveConnectionType effective_connection_type_;
// Last known value of the wireless signal strength level. If the signal
// strength level is available, the value is set to between 0 and 4, both
// inclusive. If the value is unavailable, |signal_strength_| has null value.
base::Optional<int32_t> signal_strength_;
// Minimum and maximum signal strength level observed since last connection
// change. Updated on connection change and main frame requests.
base::Optional<int32_t> min_signal_strength_since_connection_change_;
base::Optional<int32_t> max_signal_strength_since_connection_change_;
// Stores the qualities of different networks.
std::unique_ptr<nqe::internal::NetworkQualityStore> network_quality_store_;
base::ThreadChecker thread_checker_;
NetLogWithSource net_log_;
// Manages the writing of events to the net log.
nqe::internal::EventCreator event_creator_;
// Vector that contains observation sources that should not be used when
// computing the estimate at HTTP layer.
const std::vector<NetworkQualityObservationSource>
disallowed_observation_sources_for_http_;
// Vector that contains observation sources that should not be used when
// computing the estimate at transport layer.
const std::vector<NetworkQualityObservationSource>
disallowed_observation_sources_for_transport_;
base::WeakPtrFactory<NetworkQualityEstimator> weak_ptr_factory_;
DISALLOW_COPY_AND_ASSIGN(NetworkQualityEstimator);
};
} // namespace net
#endif // NET_NQE_NETWORK_QUALITY_ESTIMATOR_H_