org.apache.hadoop.hive.metastore.tools.MicroBenchmark.java Source code

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Here is the source code for org.apache.hadoop.hive.metastore.tools.MicroBenchmark.java

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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.hadoop.hive.metastore.tools;

import org.apache.commons.math3.stat.descriptive.DescriptiveStatistics;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

/**
 * Micro-benchmark some piece of code.<p>
 *
 * Every benchmark has three parts:
 * <ul>
 *   <li>Optional pre-test</li>
 *   <li>Mandatory test</lI>
 *   <li>Optional post-test</li>
 * </ul>
 * Measurement consists of the warm-up phase and measurement phase.
 * Consumer can specify number of times the warmup and measurement is repeated.<p>
 * All time is measured in nanoseconds.
 */
class MicroBenchmark {
    // Specify defaults
    private static final int WARMUP_DEFAULT = 15;
    private static final int ITERATIONS_DEFAULT = 100;
    private static final int SCALE_DEFAULT = 1;

    private final int warmup;
    private final int iterations;
    private final int scaleFactor;

    /**
     * Create default micro benchmark measurer
     */
    public MicroBenchmark() {
        this(WARMUP_DEFAULT, ITERATIONS_DEFAULT, SCALE_DEFAULT);
    }

    /**
     * Create micro benchmark measurer.
     * @param warmup number of test calls for warmup
     * @param iterations number of test calls for measurement
     */
    MicroBenchmark(int warmup, int iterations) {
        this(warmup, iterations, SCALE_DEFAULT);
    }

    /**
     * Create micro benchmark measurer.
     *
     * @param warmup number of test calls for warmup
     * @param iterations number of test calls for measurement
     * @param scaleFactor Every delta is divided by scale factor
     */
    private MicroBenchmark(int warmup, int iterations, int scaleFactor) {
        this.warmup = warmup;
        this.iterations = iterations;
        this.scaleFactor = scaleFactor;
    }

    /**
     * Run the benchmark and measure run-time statistics in nanoseconds.<p>
     * Before the run the warm-up phase is executed.
     * @param pre Optional pre-test setup
     * @param test Mandatory test
     * @param post Optional post-test cleanup
     * @return Statistics describing the results. All times are in nanoseconds.
     */
    public DescriptiveStatistics measure(@Nullable Runnable pre, @NotNull Runnable test, @Nullable Runnable post) {
        // Warmup phase
        for (int i = 0; i < warmup; i++) {
            if (pre != null) {
                pre.run();
            }
            test.run();
            if (post != null) {
                post.run();
            }
        }
        // Run the benchmark
        DescriptiveStatistics stats = new DescriptiveStatistics();
        for (int i = 0; i < iterations; i++) {
            if (pre != null) {
                pre.run();
            }
            long start = System.nanoTime();
            test.run();
            long end = System.nanoTime();
            stats.addValue((double) (end - start) / scaleFactor);
            if (post != null) {
                post.run();
            }
        }
        return stats;
    }

    /**
     * Run the benchmark and measure run-time statistics in nanoseconds.<p>
     * Before the run the warm-up phase is executed. No pre or post operations are executed.
     * @param test test to measure
     * @return Statistics describing the results. All times are in nanoseconds.
     */
    public DescriptiveStatistics measure(@NotNull Runnable test) {
        return measure(null, test, null);
    }
}