/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.server.wifi;
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import android.net.NetworkAgent;
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import android.net.wifi.WifiInfo;
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/**
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* Base class for connection scoring
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*/
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public abstract class ConnectedScore {
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/** Maximum NetworkAgent score that should be generated by wifi */
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public static final int WIFI_MAX_SCORE = NetworkAgent.WIFI_BASE_SCORE;
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/** Score at which wifi is considered poor enough to give up ant try something else */
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public static final int WIFI_TRANSITION_SCORE = NetworkAgent.WIFI_BASE_SCORE - 10;
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public static final int WIFI_MIN_SCORE = 0;
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final Clock mClock;
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/** This is a typical STD for the connected RSSI for a phone sitting still */
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public double mDefaultRssiStandardDeviation = 2.0;
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/**
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*
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* @param clock is the time source for getMillis()
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*/
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public ConnectedScore(Clock clock) {
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mClock = clock;
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}
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/**
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* Returns the current time in milliseconds
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*
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* This time is to be passed into the update methods.
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* The scoring methods generally don't need a particular epoch, depending
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* only on deltas. So a different time source may be used, as long as it is consistent.
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*
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* Note that when there are long intervals between updates, it is unlikely to matter much
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* how large the interval is, so a time source that does not update while the processor is
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* asleep could be just fine.
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*
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* @return millisecond-resolution time.
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*/
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public long getMillis() {
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return mClock.getWallClockMillis();
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}
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/**
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* Updates scoring state using RSSI alone
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*
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* @param rssi signal strength (dB).
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* @param millis millisecond-resolution time.
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*/
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public void updateUsingRssi(int rssi, long millis) {
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updateUsingRssi(rssi, millis, mDefaultRssiStandardDeviation);
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}
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/**
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* Updates scoring state using RSSI and noise estimate
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*
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* This is useful if an RSSI comes from another source (e.g. scan results) and the
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* expected noise varies by source.
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*
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* @param rssi signal strength (dB).
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* @param millis millisecond-resolution time.
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* @param standardDeviation of the RSSI.
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*/
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public abstract void updateUsingRssi(int rssi, long millis, double standardDeviation);
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/**
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* Updates the score using relevant parts of WifiInfo
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*
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* @param wifiInfo object holding relevant values.
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* @param millis millisecond-resolution time.
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*/
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public void updateUsingWifiInfo(WifiInfo wifiInfo, long millis) {
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updateUsingRssi(wifiInfo.getRssi(), millis);
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}
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/**
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* Generates a score based on the current state
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*
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* @return network score - on NetworkAgent scale.
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*/
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public abstract int generateScore();
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/**
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* Clears out state associated with the connection
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*/
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public abstract void reset();
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}
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