/*
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* Copyright (C) 2019 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.util;
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import android.util.SparseIntArray;
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import com.android.server.wifi.nano.WifiMetricsProto.Int32Count;
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import java.lang.reflect.Array;
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import java.util.Iterator;
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/**
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* Utility class for counting occurrences of int keys using an int counter.
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* Note: this class can also be used for counting occurrences of enum values. Just define a new
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* Protobuf message, and call {@link #toProto(Class, ProtobufConverter)} with a
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* {@link ProtobufConverter} that populates your custom Protobuf message type.
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*/
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public class IntCounter extends SparseIntArray implements Iterable<IntCounter.KeyCount> {
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/**
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* A class to represent the number of occurrences for an int key.
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*/
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public static class KeyCount {
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public int key;
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public int count;
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public KeyCount(int key, int count) {
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this.key = key;
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this.count = count;
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}
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}
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/**
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* Calls to {@link #add(int, int)}/{@link #increment(int)} for all keys < keyLowerBound are
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* instead attributed to keyLowerBound.
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*/
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public final int keyLowerBound;
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/**
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* Calls to {@link #add(int, int)}/{@link #increment(int)} for all keys > keyUpperBound are
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* instead attributed to keyUpperBound.
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*/
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public final int keyUpperBound;
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public IntCounter() {
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this(Integer.MIN_VALUE, Integer.MAX_VALUE);
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}
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/**
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* Clamps keys to the range between keyLowerBound and keyUpperBound. See {@link #keyLowerBound}
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* and {@link #keyUpperBound}.
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*/
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public IntCounter(int keyLowerBound, int keyUpperBound) {
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this.keyLowerBound = keyLowerBound;
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this.keyUpperBound = keyUpperBound;
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}
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/**
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* Increments the count of a key by 1.
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*/
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public void increment(int key) {
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add(key, 1);
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}
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/**
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* Increments the count of a key by <code>count</code>.
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*/
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public void add(int key, int count) {
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key = Math.max(keyLowerBound, Math.min(key, keyUpperBound));
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int curCount = get(key); // returns 0 if key not found
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put(key, curCount + count);
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}
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/**
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* Iterates over all (key, count) pairs.
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*/
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@Override
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public Iterator<KeyCount> iterator() {
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return new Iterator<KeyCount>() {
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private int mIndex = 0;
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@Override
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public boolean hasNext() {
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return mIndex < size();
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}
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@Override
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public KeyCount next() {
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KeyCount kc = new KeyCount(keyAt(mIndex), valueAt(mIndex));
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mIndex++;
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return kc;
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}
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};
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}
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/**
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* Converter function that converts a single (key, count) pair to a Protobuf object.
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* @param <T> the type of the Protobuf output.
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*/
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public interface ProtobufConverter<T> {
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/**
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* Converter function that converts a single (key, count) pair to a Protobuf object.
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* @param key the key that we are counting occurrences for
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* @param count the number of occurrences for this key
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* @return the Protobuf output
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*/
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T convert(int key, int count);
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}
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/**
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* Converts this object to a custom Protobuf representation.
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* @param protoClass the class object for the Protobuf type.
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* @param converter a conversion function.
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* @param <T> the type of the Protobuf output.
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* @return an array of Protobuf representation of buckets generated by the converter function.
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*/
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public <T> T[] toProto(Class<T> protoClass, ProtobufConverter<T> converter) {
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@SuppressWarnings("unchecked")
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T[] output = (T[]) Array.newInstance(protoClass, size());
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int i = 0;
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for (KeyCount kc : this) {
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output[i] = converter.convert(kc.key, kc.count);
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i++;
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}
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return output;
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}
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/**
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* Converts this object to a standard Protobuf representation.
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*/
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public Int32Count[] toProto() {
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return toProto(Int32Count.class, (key, count) -> {
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Int32Count entry = new Int32Count();
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entry.key = key;
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entry.count = count;
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return entry;
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});
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}
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}
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