/*

 * Copyright (c) 2014 Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * 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

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package org.openjdk.bench.java.util.stream.pipeline;

import org.openjdk.jmh.annotations.Benchmark;

import org.openjdk.jmh.annotations.BenchmarkMode;

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 java.util.Iterator;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.atomic.LongAdder;

import java.util.function.LongConsumer;

import java.util.stream.LongStream;

/**

 * Benchmark for forEach()/iterator()/into() operations;

 * Testing which one is faster for semantically-equvalent operations.

 */

@BenchmarkMode(Mode.Throughput)

@OutputTimeUnit(TimeUnit.SECONDS)

@State(Scope.Thread)

public class Terminal {

    /**

     * Implementation notes:

     *   - parallel version requires thread-safe sink, we use the same for sequential version for better comparison

     *   - operations are explicit inner classes to untangle unwanted lambda effects

     */

    @Param("100000")

    private int size;

    private LongAdder sink;

    private LongConsumer block;

    @Setup

    public void setup() {

        sink = new LongAdder();

        block = new LongConsumer() {

            @Override

            public void accept(long v) {

                sink.add(v);

            }

        };

    }

    @Benchmark

    public long baseline_prim_acc() {

        long s = 0;

        for (long l = 0L; l < size; l++) {

            s += l;

        }

        sink.add(s);

        return sink.sum();

    }

    @Benchmark

    public long baseline_prim_sink() {

        for (long l = 0L; l < size; l++) {

            sink.add(l);

        }

        return sink.sum();

    }

    @Benchmark

    public long baseline_iterator_acc() {

        long s = 0;

        for (Iterator<Long> iterator = LongStream.range(0, size).boxed().iterator(); iterator.hasNext(); ) {

            Long l = iterator.next();

            s += l;

        }

        sink.add(s);

        return sink.sum();

    }

    @Benchmark

    public long baseline_iterator_sink() {

        for (Iterator<Long> iterator = LongStream.range(0, size).boxed().iterator(); iterator.hasNext(); ) {

            sink.add(iterator.next());

        }

        return sink.sum();

    }

    @Benchmark

    public long seq_iterator() {

        Iterator<Long> i = LongStream.range(0, size).boxed().iterator();

        while (i.hasNext()) {

            sink.add(i.next());

        }

        return sink.sum();

    }

    @Benchmark

    public long par_iterator() {

        Iterator<Long> i = LongStream.range(0, size).parallel().boxed().iterator();

        while (i.hasNext()) {

            sink.add(i.next());

        }

        return sink.sum();

    }

    @Benchmark

    public long seq_forEach() {

        LongStream.range(1, size).forEach(block);

        return sink.sum();

    }

    @Benchmark

    public long par_forEach() {

        LongStream.range(1, size).parallel().forEach(block);

        return sink.sum();

    }

    @Benchmark

    public long seq_into() {

        return LongStream.range(1, size)

                .collect(LongAdder::new, LongAdder::add, (la1, la2) -> la1.add(la2.sum())).sum();

    }

    @Benchmark

    public long par_into() {

        return LongStream.range(1, size).parallel()

                .collect(LongAdder::new, LongAdder::add, (la1, la2) -> la1.add(la2.sum())).sum();

    }

}