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/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.server.wifi;
import android.net.wifi.WifiInfo;
/**
* Base class for connection scoring
*/
public abstract class ConnectedScore {
/** Maximum NetworkAgent score that should be generated by wifi */
public static final int WIFI_MAX_SCORE = 60;
/** Score at which wifi is considered poor enough to give up ant try something else */
public static final int WIFI_TRANSITION_SCORE = WIFI_MAX_SCORE - 10;
public static final int WIFI_MIN_SCORE = 0;
final Clock mClock;
/** This is a typical STD for the connected RSSI for a phone sitting still */
public double mDefaultRssiStandardDeviation = 2.0;
/**
*
* @param clock is the time source for getMillis()
*/
public ConnectedScore(Clock clock) {
mClock = clock;
}
/**
* Returns the current time in milliseconds
*
* This time is to be passed into the update methods.
* The scoring methods generally don't need a particular epoch, depending
* only on deltas. So a different time source may be used, as long as it is consistent.
*
* Note that when there are long intervals between updates, it is unlikely to matter much
* how large the interval is, so a time source that does not update while the processor is
* asleep could be just fine.
*
* @return millisecond-resolution time.
*/
public long getMillis() {
return mClock.getWallClockMillis();
}
/**
* Updates scoring state using RSSI alone
*
* @param rssi signal strength (dB).
* @param millis millisecond-resolution time.
*/
public void updateUsingRssi(int rssi, long millis) {
updateUsingRssi(rssi, millis, mDefaultRssiStandardDeviation);
}
/**
* Updates scoring state using RSSI and noise estimate
*
* This is useful if an RSSI comes from another source (e.g. scan results) and the
* expected noise varies by source.
*
* @param rssi signal strength (dB).
* @param millis millisecond-resolution time.
* @param standardDeviation of the RSSI.
*/
public abstract void updateUsingRssi(int rssi, long millis, double standardDeviation);
/**
* Updates the score using relevant parts of WifiInfo
*
* @param wifiInfo object holding relevant values.
* @param millis millisecond-resolution time.
*/
public void updateUsingWifiInfo(WifiInfo wifiInfo, long millis) {
updateUsingRssi(wifiInfo.getRssi(), millis);
}
/**
* Generates a score based on the current state
*
* @return network score - on NetworkAgent scale.
*/
public abstract int generateScore();
/**
* Clears out state associated with the connection
*/
public abstract void reset();
}
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