ARROW-5814: [Java] Implement a <Object, int> HashMap for DictionaryEncoder

java/performance/src/test/java/org/apache/arrow/vector/dictionary/DictionaryEncodeHashMapBenchmarks.java

@@ -0,0 +1,117 @@
+/*
+ * 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.arrow.vector.dictionary;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.Test;
+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.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.RunnerException;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+/**
+ * Benchmarks for {@link DictionaryEncodeHashMap}.
+ */
+@State(Scope.Benchmark)
+public class DictionaryEncodeHashMapBenchmarks {
+  private static final int SIZE = 1000;
+
+  private static final int KEY_LENGTH = 10;
+
+  private List<String> testData = new ArrayList<>();
+
+  private HashMap<String, Integer> hashMap =  new HashMap();
+  private DictionaryEncodeHashMap<String> dictionaryEncodeHashMap = new DictionaryEncodeHashMap();
+
+  /**
+   * Setup benchmarks.
+   */
+  @Setup
+  public void prepare() {
+    for (int i = 0; i < SIZE; i++) {
+      testData.add(getRandomString(KEY_LENGTH));
+    }
+  }
+
+  private String getRandomString(int length) {
+    String str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+    Random random = new Random();
+    StringBuffer sb = new StringBuffer();
+    for (int i = 0; i < length; i++) {
+      int number = random.nextInt(62);
+      sb.append(str.charAt(number));
+    }
+    return sb.toString();
+  }
+
+  /**
+   * Test set/get int values for {@link HashMap}.
+   * @return useless. To avoid DCE by JIT.
+   */
+  @Benchmark
+  @BenchmarkMode(Mode.AverageTime)
+  @OutputTimeUnit(TimeUnit.NANOSECONDS)
+  public int testHashMap() {
+    for (int i = 0; i < SIZE; i++) {
+      hashMap.put(testData.get(i), i);
+    }
+    for (int i = 0; i < SIZE; i++) {
+      hashMap.get(testData.get(i));
+    }
+    return 0;
+  }
+
+  /**
+   * Test set/get int values for {@link DictionaryEncodeHashMap}.
+   * @return useless. To avoid DCE by JIT.
+   */
+  @Benchmark
+  @BenchmarkMode(Mode.AverageTime)
+  @OutputTimeUnit(TimeUnit.NANOSECONDS)
+  public int testDictionaryEncodeHashMap() {
+    for (int i = 0; i < SIZE; i++) {
+      dictionaryEncodeHashMap.put(testData.get(i), i);
+    }
+    for (int i = 0; i < SIZE; i++) {
+      dictionaryEncodeHashMap.get(testData.get(i));
+    }
+    return 0;
+  }
+
+  @Test
+  public void evaluate() throws RunnerException {
+    Options opt = new OptionsBuilder()
+        .include(DictionaryEncodeHashMapBenchmarks.class.getSimpleName())
+        .forks(1)
+        .build();
+
+    new Runner(opt).run();
+  }
+}