/*

 * 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.io;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.RandomAccessFile;

import java.util.concurrent.TimeUnit;

import org.openjdk.jmh.annotations.Benchmark;

import org.openjdk.jmh.annotations.BenchmarkMode;

import org.openjdk.jmh.annotations.Level;

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.TearDown;

/**

 * Tests the overheads of I/O API.

 * This test is known to depend heavily on disk subsystem performance.

 */

@BenchmarkMode(Mode.Throughput)

@OutputTimeUnit(TimeUnit.MILLISECONDS)

@State(Scope.Thread)

public class RandomAccessRead {

    @Param("1000000")

    private int fileSize;

    private RandomAccessFile raf;

    private long offset;

    private int deltaIndex;

    private int[] deltas;

    private File f;

    @Setup(Level.Trial)

    public void beforeRun() throws IOException {

        f = File.createTempFile("RandomAccessBench", ".bin");

        try (FileOutputStream fos = new FileOutputStream(f)) {

            for (int i = 0; i < fileSize; i++) {

                fos.write((byte) i);

            }

        }

        deltas = new int[]{1, 2, 3, 5, 7, 11, 13, 17, 19, 23};

    }

    @TearDown(Level.Trial)

    public void afterRun() throws IOException {

        f.delete();

    }

    @Setup(Level.Iteration)

    public void beforeIteration() throws IOException {

        raf = new RandomAccessFile(f, "rw");

        offset = 0;

        deltaIndex = 0;

    }

    @TearDown(Level.Iteration)

    public void afterIteration() throws IOException {

        raf.close();

    }

    @Benchmark

    public int test() throws IOException {

        offset = offset + deltas[deltaIndex];

        if (offset >= fileSize) {

            offset = 0;

        }

        deltaIndex++;

        if (deltaIndex >= deltas.length) {

            deltaIndex = 0;

        }

        raf.seek(offset);

        return raf.read();

    }

}