1 files changed, 96 insertions, 0 deletions
diff --git a/src/test/java/org/apache/commons/lang3/HashSetvBitSetTest.java b/src/test/java/org/apache/commons/lang3/HashSetvBitSetTest.java
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index 000000000..a5ba1085c
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+++ b/src/test/java/org/apache/commons/lang3/HashSetvBitSetTest.java
@@ -0,0 +1,96 @@
+/*
+ * 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;
+    }
+}