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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
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 *
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package org.openjdk.bench.java.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.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;
import org.openjdk.jmh.infra.Blackhole;

import java.time.Duration;
import java.time.Instant;
import java.time.Year;
import java.time.ZonedDateTime;
import java.time.chrono.IsoChronology;
import java.time.temporal.ChronoUnit;
import java.util.GregorianCalendar;
import java.util.Random;
import java.util.concurrent.TimeUnit;
import java.util.stream.IntStream;

/**
 * Examine Year.leapYear-related operations
 */
@BenchmarkMode(Mode.Throughput)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
@Warmup(iterations = 5, time = 1)
@Measurement(iterations = 5, time = 1)
@Fork(3)
@State(Scope.Thread)
public class LeapYearBench {

    private long[] years;

    private GregorianCalendar calendar;

    @Setup
    public void createInstants() {
        // Large enough number of years to guarantee that the distribution of
        // leap years is reasonably realistic
        years = new long[2048];
        final Random random = new Random(0);
        for (int i = 0; i < years.length; i++) {
            years[i] = random.nextLong(2000) + 2000;
        }
        calendar = GregorianCalendar.from(ZonedDateTime.now());
    }

    @Benchmark
    public void isLeapYear(Blackhole bh) {
        for (long year : years) {
            bh.consume(Year.isLeap(year));
        }
    }

    @Benchmark
    public void isLeapYearChrono(Blackhole bh) {
        for (long year : years) {
            bh.consume(IsoChronology.INSTANCE.isLeapYear(year));
        }
    }

    @Benchmark
    public void isLeapYearGregorian(Blackhole bh) {
        for (long year : years) {
            bh.consume(calendar.isLeapYear((int)year));
        }
    }

    public static boolean isLeapNeriSchneider(long year) {
        int d = year % 100 != 0 ? 4 : 16;
        return (year & (d - 1)) == 0;
    }

    @Benchmark
    public void isLeapYearNS(Blackhole bh) {
        for (long year : years) {
            bh.consume(isLeapNeriSchneider(year));
        }
    }
}