230 lines
8.3 KiB
Java
230 lines
8.3 KiB
Java
/*
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* Copyright (C) 2014 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 android.net;
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import android.annotation.NonNull;
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import android.annotation.Nullable;
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import android.annotation.SystemApi;
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import android.os.Parcel;
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import android.os.Parcelable;
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import java.util.Arrays;
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import java.util.Objects;
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/**
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* A curve defining the network score over a range of RSSI values.
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*
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* <p>For each RSSI bucket, the score may be any byte. Scores have no absolute meaning and are only
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* considered relative to other scores assigned by the same scorer. Networks with no score are
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* treated equivalently to a network with score {@link Byte#MIN_VALUE}, and will not be used.
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*
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* <p>For example, consider a curve starting at -110 dBm with a bucket width of 10 and the
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* following buckets: {@code [-20, -10, 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120]}.
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* This represents a linear curve between -110 dBm and 30 dBm. It scores progressively higher at
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* stronger signal strengths.
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*
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* <p>A network can be assigned a fixed score independent of RSSI by setting
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* {@link #rssiBuckets} to a one-byte array whose element is the fixed score. {@link #start}
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* should be set to the lowest RSSI value at which this fixed score should apply, and
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* {@link #bucketWidth} should be set such that {@code start + bucketWidth} is equal to the
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* highest RSSI value at which this fixed score should apply.
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*
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* <p>Note that RSSI values below -110 dBm or above 30 dBm are unlikely to cause any difference
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* in connectivity behavior from those endpoints. That is, the connectivity framework will treat
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* a network with a -120 dBm signal exactly as it would treat one with a -110 dBm signal.
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* Therefore, graphs which specify scores outside this range may be truncated to this range by
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* the system.
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*
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* @see ScoredNetwork
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* @deprecated as part of the {@link NetworkScoreManager} deprecation.
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* @hide
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*/
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@Deprecated
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@SystemApi
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public class RssiCurve implements Parcelable {
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private static final int DEFAULT_ACTIVE_NETWORK_RSSI_BOOST = 25;
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/** The starting dBm of the curve. */
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public final int start;
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/** The width of each RSSI bucket, in dBm. */
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public final int bucketWidth;
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/** The score for each RSSI bucket. */
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public final byte[] rssiBuckets;
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/**
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* The RSSI boost to give this network when active, in dBm.
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*
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* <p>When the system is connected to this network, it will pretend that the network has this
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* much higher of an RSSI. This is to avoid switching networks when another network has only a
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* slightly higher score.
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*/
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public final int activeNetworkRssiBoost;
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/**
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* Construct a new {@link RssiCurve}.
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*
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* @param start the starting dBm of the curve.
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* @param bucketWidth the width of each RSSI bucket, in dBm.
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* @param rssiBuckets the score for each RSSI bucket.
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*/
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public RssiCurve(int start, int bucketWidth, byte[] rssiBuckets) {
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this(start, bucketWidth, rssiBuckets, DEFAULT_ACTIVE_NETWORK_RSSI_BOOST);
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}
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/**
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* Construct a new {@link RssiCurve}.
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*
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* @param start the starting dBm of the curve.
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* @param bucketWidth the width of each RSSI bucket, in dBm.
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* @param rssiBuckets the score for each RSSI bucket.
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* @param activeNetworkRssiBoost the RSSI boost to apply when this network is active, in dBm.
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*/
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public RssiCurve(int start, int bucketWidth, byte[] rssiBuckets, int activeNetworkRssiBoost) {
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this.start = start;
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this.bucketWidth = bucketWidth;
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if (rssiBuckets == null || rssiBuckets.length == 0) {
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throw new IllegalArgumentException("rssiBuckets must be at least one element large.");
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}
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this.rssiBuckets = rssiBuckets;
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this.activeNetworkRssiBoost = activeNetworkRssiBoost;
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}
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private RssiCurve(Parcel in) {
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start = in.readInt();
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bucketWidth = in.readInt();
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int bucketCount = in.readInt();
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rssiBuckets = new byte[bucketCount];
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in.readByteArray(rssiBuckets);
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activeNetworkRssiBoost = in.readInt();
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}
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@Override
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public int describeContents() {
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return 0;
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}
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@Override
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public void writeToParcel(Parcel out, int flags) {
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out.writeInt(start);
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out.writeInt(bucketWidth);
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out.writeInt(rssiBuckets.length);
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out.writeByteArray(rssiBuckets);
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out.writeInt(activeNetworkRssiBoost);
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}
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/**
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* Lookup the score for a given RSSI value.
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*
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* @param rssi The RSSI to lookup. If the RSSI falls below the start of the curve, the score at
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* the start of the curve will be returned. If it falls after the end of the curve, the
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* score at the end of the curve will be returned.
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* @return the score for the given RSSI.
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*/
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public byte lookupScore(int rssi) {
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return lookupScore(rssi, false /* isActiveNetwork */);
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}
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/**
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* Lookup the score for a given RSSI value.
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*
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* @param rssi The RSSI to lookup. If the RSSI falls below the start of the curve, the score at
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* the start of the curve will be returned. If it falls after the end of the curve, the
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* score at the end of the curve will be returned.
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* @param isActiveNetwork Whether this network is currently active.
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* @return the score for the given RSSI.
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*/
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public byte lookupScore(int rssi, boolean isActiveNetwork) {
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if (isActiveNetwork) {
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rssi += activeNetworkRssiBoost;
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}
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int index = (rssi - start) / bucketWidth;
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// Snap the index to the closest bucket if it falls outside the curve.
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if (index < 0) {
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index = 0;
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} else if (index > rssiBuckets.length - 1) {
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index = rssiBuckets.length - 1;
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}
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return rssiBuckets[index];
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}
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/**
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* Determine if two RSSI curves are defined in the same way.
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*
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* <p>Note that two curves can be equivalent but defined differently, e.g. if one bucket in one
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* curve is split into two buckets in another. For the purpose of this method, these curves are
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* not considered equal to each other.
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*/
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@Override
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public boolean equals(@Nullable Object o) {
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if (this == o) return true;
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if (o == null || getClass() != o.getClass()) return false;
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RssiCurve rssiCurve = (RssiCurve) o;
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return start == rssiCurve.start &&
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bucketWidth == rssiCurve.bucketWidth &&
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Arrays.equals(rssiBuckets, rssiCurve.rssiBuckets) &&
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activeNetworkRssiBoost == rssiCurve.activeNetworkRssiBoost;
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}
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@Override
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public int hashCode() {
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return Objects.hash(start, bucketWidth, activeNetworkRssiBoost) ^ Arrays.hashCode(rssiBuckets);
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}
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@NonNull
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@Override
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public String toString() {
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StringBuilder sb = new StringBuilder();
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sb.append("RssiCurve[start=")
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.append(start)
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.append(",bucketWidth=")
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.append(bucketWidth)
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.append(",activeNetworkRssiBoost=")
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.append(activeNetworkRssiBoost);
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sb.append(",buckets=");
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for (int i = 0; i < rssiBuckets.length; i++) {
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sb.append(rssiBuckets[i]);
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if (i < rssiBuckets.length - 1) {
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sb.append(",");
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}
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}
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sb.append("]");
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return sb.toString();
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}
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public static final @android.annotation.NonNull Creator<RssiCurve> CREATOR =
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new Creator<RssiCurve>() {
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@Override
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public RssiCurve createFromParcel(Parcel in) {
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return new RssiCurve(in);
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}
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@Override
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public RssiCurve[] newArray(int size) {
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return new RssiCurve[size];
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}
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};
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}
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