1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.server.wifi; 18 19 import android.net.NetworkAgent; 20 import android.net.wifi.WifiInfo; 21 22 /** 23 * Base class for connection scoring 24 */ 25 public abstract class ConnectedScore { 26 27 /** Maximum NetworkAgent score that should be generated by wifi */ 28 public static final int WIFI_MAX_SCORE = NetworkAgent.WIFI_BASE_SCORE; 29 30 /** Score at which wifi is considered poor enough to give up ant try something else */ 31 public static final int WIFI_TRANSITION_SCORE = NetworkAgent.WIFI_BASE_SCORE - 10; 32 33 public static final int WIFI_MIN_SCORE = 0; 34 35 final Clock mClock; 36 37 /** This is a typical STD for the connected RSSI for a phone sitting still */ 38 public double mDefaultRssiStandardDeviation = 2.0; 39 40 /** 41 * 42 * @param clock is the time source for getMillis() 43 */ 44 public ConnectedScore(Clock clock) { 45 mClock = clock; 46 } 47 48 /** 49 * Returns the current time in milliseconds 50 * 51 * This time is to be passed into the update methods. 52 * The scoring methods generally don't need a particular epoch, depending 53 * only on deltas. So a different time source may be used, as long as it is consistent. 54 * 55 * Note that when there are long intervals between updates, it is unlikely to matter much 56 * how large the interval is, so a time source that does not update while the processor is 57 * asleep could be just fine. 58 * 59 * @return millisecond-resolution time. 60 */ 61 public long getMillis() { 62 return mClock.getWallClockMillis(); 63 } 64 65 /** 66 * Updates scoring state using RSSI alone 67 * 68 * @param rssi signal strength (dB). 69 * @param millis millisecond-resolution time. 70 */ 71 public void updateUsingRssi(int rssi, long millis) { 72 updateUsingRssi(rssi, millis, mDefaultRssiStandardDeviation); 73 } 74 75 /** 76 * Updates scoring state using RSSI and noise estimate 77 * 78 * This is useful if an RSSI comes from another source (e.g. scan results) and the 79 * expected noise varies by source. 80 * 81 * @param rssi signal strength (dB). 82 * @param millis millisecond-resolution time. 83 * @param standardDeviation of the RSSI. 84 */ 85 public abstract void updateUsingRssi(int rssi, long millis, double standardDeviation); 86 87 /** 88 * Updates the score using relevant parts of WifiInfo 89 * 90 * @param wifiInfo object holding relevant values. 91 * @param millis millisecond-resolution time. 92 */ 93 public void updateUsingWifiInfo(WifiInfo wifiInfo, long millis) { 94 updateUsingRssi(wifiInfo.getRssi(), millis); 95 } 96 97 /** 98 * Generates a score based on the current state 99 * 100 * @return network score - on NetworkAgent scale. 101 */ 102 public abstract int generateScore(); 103 104 /** 105 * Clears out state associated with the connection 106 */ 107 public abstract void reset(); 108 } 109
