GH-3451. Add a JMH benchmark for variants

parquet-benchmarks/pom.xml

@@ -52,6 +52,11 @@
       <artifactId>parquet-common</artifactId>
       <version>${project.version}</version>
     </dependency>
+    <dependency>
+      <groupId>org.apache.parquet</groupId>
+      <artifactId>parquet-variant</artifactId>
+      <version>${project.version}</version>
+    </dependency>
     <dependency>
       <groupId>org.apache.hadoop</groupId>
       <artifactId>hadoop-client</artifactId>

parquet-benchmarks/run.sh

@@ -43,6 +43,7 @@ read        | Reading files with different compression, page and block sizes.
 write       | Writing files.
 checksum    | Reading and writing with and without CRC checksums.
 filter      | Filtering column indexes
+variant     | Variant performance
 
 Examples:
 
@@ -100,6 +101,9 @@ else
   "filter")
     BENCHMARK_REGEX="org.apache.parquet.benchmarks.FilteringBenchmarks"
     ;;
+  "variant")
+    BENCHMARK_REGEX="org.apache.parquet.variant.Variant*"
+    ;;
   esac
 
   echo JMH command: java -jar ${SCRIPT_PATH}/target/parquet-benchmarks.jar $BENCHMARK_REGEX $JMH_OPTIONS

parquet-benchmarks/src/main/java/org/apache/parquet/variant/VariantBenchmarkMeasurementSettings.java

@@ -0,0 +1,36 @@
+/*
+ * 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.parquet.variant;
+
+/**
+ * Common measurement settings.
+ */
+class VariantBenchmarkMeasurementSettings {
+
+  /**
+   * How long to warm up. Goal: JIT compiler has done its work.
+   * If flamegraphs show compilation: increase.
+   */
+  static final int SMALL_BENCHMARK_WARMUP = 500;
+
+  /**
+   * Meaurement for the small benchmarks.
+   */
+  static final int SMALL_BENCHMARK_MEASUREMENTS = 500;
+}