AddPaddingZeros.java

/*
 * Copyright (c) 2003, PostgreSQL Global Development Group
 * See the LICENSE file in the project root for more information.
 */

package org.postgresql.benchmark.time;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;
import org.openjdk.jmh.profile.GCProfiler;
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;

import java.sql.Timestamp;
import java.util.concurrent.TimeUnit;

@Fork(value = 0, jvmArgsPrepend = "-Xmx128m")
@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@State(Scope.Thread)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public class AddPaddingZeros {

  @Param({"1000", "1000000", "100000000"})
  int nanos;

  static final char[] ZEROS = "0000000000".toCharArray();

  Timestamp ts = new Timestamp(System.currentTimeMillis());

  StringBuffer sb = new StringBuffer();

  @Setup
  public void init() {
    ts.setNanos(nanos);
  }

  @Benchmark
  public void charArray() {
    sb.setLength(0);
    int nanos = ts.getNanos();
    char[] decimalStr = {'0', '0', '0', '0', '0', '0', '0', '0', '0'};
    char[] nanoStr = Integer.toString(nanos).toCharArray();
    System.arraycopy(nanoStr, 0, decimalStr, decimalStr.length - nanoStr.length, nanoStr.length);
    sb.append(decimalStr, 0, 6);
  }

  @Benchmark
  public void insert() {
    sb.setLength(0);
    int len = sb.length();
    int nanos = ts.getNanos();
    sb.append(nanos / 1000);
    int needZeros = 6 - (sb.length() - len);
    if (needZeros > 0) {
      sb.insert(len, ZEROS, 0, needZeros);
    }
  }

  public static void main(String[] args) throws RunnerException {
    Options opt = new OptionsBuilder()
        .include(AddPaddingZeros.class.getSimpleName())
        .addProfiler(GCProfiler.class)
        //.addProfiler(FlightRecorderProfiler.class)
        .detectJvmArgs()
        .build();

    new Runner(opt).run();
  }
}