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      1 /*
      2  * Copyright (C) 2011 Google Inc.
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  * http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.google.caliper.worker;
     18 
     19 import static java.util.concurrent.TimeUnit.NANOSECONDS;
     20 
     21 import com.google.caliper.model.Measurement;
     22 import com.google.caliper.model.Value;
     23 import com.google.caliper.runner.InvalidBenchmarkException;
     24 import com.google.caliper.runner.Running.Benchmark;
     25 import com.google.caliper.runner.Running.BenchmarkMethod;
     26 import com.google.caliper.util.ShortDuration;
     27 import com.google.caliper.util.Util;
     28 import com.google.common.annotations.VisibleForTesting;
     29 import com.google.common.base.Ticker;
     30 import com.google.common.collect.ImmutableSet;
     31 
     32 import java.lang.reflect.Method;
     33 import java.util.Map;
     34 import java.util.Random;
     35 
     36 import javax.inject.Inject;
     37 
     38 /**
     39  * A {@link Worker} base class for micro and pico benchmarks.
     40  */
     41 public abstract class RuntimeWorker extends Worker {
     42   @VisibleForTesting static final int INITIAL_REPS = 100;
     43 
     44   protected final Random random;
     45   protected final Ticker ticker;
     46   protected final Options options;
     47   private long totalReps;
     48   private long totalNanos;
     49   private long nextReps;
     50 
     51   RuntimeWorker(Object benchmark,
     52       Method method, Random random, Ticker ticker,
     53       Map<String, String> workerOptions) {
     54     super(benchmark, method);
     55     this.random = random;
     56     // TODO(gak): investigate whether or not we can use Stopwatch
     57     this.ticker = ticker;
     58     this.options = new Options(workerOptions);
     59   }
     60 
     61   @Override public void bootstrap() throws Exception {
     62     totalReps = INITIAL_REPS;
     63     totalNanos = invokeTimeMethod(INITIAL_REPS);
     64   }
     65 
     66   @Override public void preMeasure(boolean inWarmup) throws Exception {
     67     nextReps = calculateTargetReps(totalReps, totalNanos, options.timingIntervalNanos,
     68         random.nextGaussian());
     69     if (options.gcBeforeEach && !inWarmup) {
     70       Util.forceGc();
     71     }
     72   }
     73 
     74   @Override public Iterable<Measurement> measure() throws Exception {
     75     long nanos = invokeTimeMethod(nextReps);
     76     Measurement measurement = new Measurement.Builder()
     77         .description("runtime")
     78         .value(Value.create(nanos, "ns"))
     79         .weight(nextReps)
     80         .build();
     81 
     82     totalReps += nextReps;
     83     totalNanos += nanos;
     84     return ImmutableSet.of(measurement);
     85   }
     86 
     87   abstract long invokeTimeMethod(long reps) throws Exception;
     88 
     89   /**
     90    * Returns a random number of reps based on a normal distribution around the estimated number of
     91    * reps for the timing interval. The distribution used has a standard deviation of one fifth of
     92    * the estimated number of reps.
     93    */
     94   @VisibleForTesting static long calculateTargetReps(long reps, long nanos, long targetNanos,
     95       double gaussian) {
     96     double targetReps = (((double) reps) / nanos) * targetNanos;
     97     return Math.max(1L, Math.round((gaussian * (targetReps / 5)) + targetReps));
     98   }
     99 
    100   /**
    101    * A {@link Worker} for micro benchmarks.
    102    */
    103   public static final class Micro extends RuntimeWorker {
    104     @Inject Micro(@Benchmark Object benchmark,
    105         @BenchmarkMethod Method method, Random random, Ticker ticker,
    106         @WorkerOptions Map<String, String> workerOptions) {
    107       super(benchmark, method, random, ticker, workerOptions);
    108     }
    109 
    110     @Override long invokeTimeMethod(long reps) throws Exception {
    111       int intReps = (int) reps;
    112       if (reps != intReps) {
    113         throw new InvalidBenchmarkException("%s.%s takes an int for reps, "
    114             + "but requires a greater number to fill the given timing interval (%s). "
    115             + "If this is expected (the benchmarked code is very fast), use a long parameter."
    116             + "Otherwise, check your benchmark for errors.",
    117                 benchmark.getClass(), benchmarkMethod.getName(),
    118                     ShortDuration.of(options.timingIntervalNanos, NANOSECONDS));
    119       }
    120       long before = ticker.read();
    121       benchmarkMethod.invoke(benchmark, intReps);
    122       return ticker.read() - before;
    123     }
    124   }
    125 
    126   /**
    127    * A {@link Worker} for pico benchmarks.
    128    */
    129   public static final class Pico extends RuntimeWorker {
    130     @Inject Pico(@Benchmark Object benchmark,
    131         @BenchmarkMethod Method method, Random random, Ticker ticker,
    132         @WorkerOptions Map<String, String> workerOptions) {
    133       super(benchmark, method, random, ticker, workerOptions);
    134     }
    135 
    136     @Override long invokeTimeMethod(long reps) throws Exception {
    137       long before = ticker.read();
    138       benchmarkMethod.invoke(benchmark, reps);
    139       return ticker.read() - before;
    140     }
    141   }
    142 
    143   private static final class Options {
    144     long timingIntervalNanos;
    145     boolean gcBeforeEach;
    146 
    147     Options(Map<String, String> optionMap) {
    148       this.timingIntervalNanos = Long.parseLong(optionMap.get("timingIntervalNanos"));
    149       this.gcBeforeEach = Boolean.parseBoolean(optionMap.get("gcBeforeEach"));
    150     }
    151   }
    152 }
    153