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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.commons.lang3;
import java.util.BitSet;
import java.util.HashSet;
import java.util.concurrent.TimeUnit;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
/**
* Test to show whether using BitSet for removeAll() methods is faster than using HashSet.
*/
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Thread)
public class HashSetvBitSetTest extends AbstractLangTest {
private static final int numberOfElementsToCompute = 10;
@Benchmark
public int[] testHashSet() {
final HashSet<Integer> toRemove = new HashSet<>();
int found = 0;
for (int i = 0; i < numberOfElementsToCompute; i++) {
toRemove.add(found++);
}
return extractIndices(toRemove);
}
@Benchmark
public int[] testBitSet() {
final BitSet toRemove = new BitSet();
int found = 0;
for (int i = 0; i < numberOfElementsToCompute; i++) {
toRemove.set(found++);
}
return extractIndices(toRemove);
}
@Benchmark
public int[] timeBitSetRemoveAll() {
final BitSet toRemove = new BitSet();
final int[] array = new int[100];
toRemove.set(10, 20);
return (int[]) ArrayUtils.removeAll(array, toRemove);
}
@Benchmark
public int[] timeExtractRemoveAll() {
final BitSet toRemove = new BitSet();
final int[] array = new int[100];
toRemove.set(10, 20);
final int[] extractIndices = extractIndices(toRemove);
return (int[]) ArrayUtils.removeAll((Object) array, extractIndices);
}
// --- utility methods
private static int[] extractIndices(final HashSet<Integer> coll) {
final int[] result = new int[coll.size()];
int i = 0;
for (final Integer index : coll) {
result[i++] = index.intValue();
}
return result;
}
private static int[] extractIndices(final BitSet coll) {
final int[] result = new int[coll.cardinality()];
int i = 0;
int j=0;
while ((j=coll.nextSetBit(j)) != -1) {
result[i++] = j++;
}
return result;
}
}
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