| /* |
| * 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.calcite.util; |
| |
| import org.apache.calcite.linq4j.function.Function1; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.List; |
| |
| /** |
| * Helps to run benchmarks by running the same task repeatedly and averaging |
| * the running times. |
| */ |
| public class Benchmark { |
| /** |
| * Certain tests are enabled only if logging is enabled at debug level or |
| * higher. |
| */ |
| public static final Logger LOGGER = |
| LoggerFactory.getLogger(Benchmark.class); |
| |
| private final Function1<Statistician, Void> function; |
| private final int repeat; |
| private final Statistician statistician; |
| |
| public Benchmark(String description, Function1<Statistician, Void> function, |
| int repeat) { |
| this.function = function; |
| this.repeat = repeat; |
| this.statistician = new Statistician(description); |
| } |
| |
| /** |
| * Returns whether performance tests are enabled. |
| */ |
| public static boolean enabled() { |
| return LOGGER.isDebugEnabled(); |
| } |
| |
| static long printDuration(String desc, long t0) { |
| final long t1 = System.nanoTime(); |
| final long duration = t1 - t0; |
| LOGGER.debug("{} took {} nanos", desc, duration); |
| return duration; |
| } |
| |
| public void run() { |
| for (int i = 0; i < repeat; i++) { |
| function.apply(statistician); |
| } |
| statistician.printDurations(); |
| } |
| |
| /** |
| * Collects statistics for a test that is run multiple times. |
| */ |
| public static class Statistician { |
| private final String desc; |
| private final List<Long> durations = new ArrayList<>(); |
| |
| public Statistician(String desc) { |
| super(); |
| this.desc = desc; |
| } |
| |
| public void record(long start) { |
| durations.add( |
| printDuration( |
| desc + " iteration #" + (durations.size() + 1), start)); |
| } |
| |
| private void printDurations() { |
| if (!LOGGER.isDebugEnabled()) { |
| return; |
| } |
| |
| List<Long> coreDurations = durations; |
| String durationsString = durations.toString(); // save before sort |
| |
| // Ignore the first 3 readings. (JIT compilation takes a while to |
| // kick in.) |
| if (coreDurations.size() > 3) { |
| coreDurations = durations.subList(3, durations.size()); |
| } |
| Collections.sort(coreDurations); |
| // Further ignore the max and min. |
| List<Long> coreCoreDurations = coreDurations; |
| if (coreDurations.size() > 4) { |
| coreCoreDurations = |
| coreDurations.subList(1, coreDurations.size() - 1); |
| } |
| long sum = 0; |
| int count = coreCoreDurations.size(); |
| for (long duration : coreCoreDurations) { |
| sum += duration; |
| } |
| final double avg = ((double) sum) / count; |
| double y = 0; |
| for (long duration : coreCoreDurations) { |
| double x = duration - avg; |
| y += x * x; |
| } |
| final double stddev = Math.sqrt(y / count); |
| if (durations.size() == 0) { |
| LOGGER.debug("{}: {}", desc, "no runs"); |
| } else { |
| LOGGER.debug( |
| "{}: {} first; {} +- {}; {} min; {} max; {} nanos", |
| desc, |
| durations.get(0), avg, stddev, coreDurations.get(0), |
| Util.last(coreDurations), durationsString); |
| } |
| } |
| } |
| } |