/*

 * Copyright (c) 2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

/*

 * This is not a regression test, but a micro-benchmark.

 * To exercise swap, run with filter=LITTLE_ENDIAN on sparc,

 * filter=BIG_ENDIAN on x86.

 *

 * I have run this as follows:

 *

 * for f in -client -server; do mergeBench dolphin . jr -dsa -da $f SwapMicroBenchmark.java filter=LITTLE_ENDIAN; done

 *

 * @author Martin Buchholz

 */

import java.util.*;

import java.nio.*;

import java.util.concurrent.*;

import java.util.regex.Pattern;

public class SwapMicroBenchmark {

    abstract static class Job {

        private final String name;

        public Job(String name) { this.name = name; }

        public String name() { return name; }

        public abstract void work() throws Throwable;

    }

    private static void collectAllGarbage() {

        final java.util.concurrent.CountDownLatch drained

            = new java.util.concurrent.CountDownLatch(1);

        try {

            System.gc();        // enqueue finalizable objects

            new Object() { protected void finalize() {

                drained.countDown(); }};

            System.gc();        // enqueue detector

            drained.await();    // wait for finalizer queue to drain

            System.gc();        // cleanup finalized objects

        } catch (InterruptedException e) { throw new Error(e); }

    }

    /**

     * Runs each job for long enough that all the runtime compilers

     * have had plenty of time to warm up, i.e. get around to

     * compiling everything worth compiling.

     * Returns array of average times per job per run.

     */

    private static long[] time0(Job ... jobs) throws Throwable {

        final long warmupNanos = 10L * 1000L * 1000L * 1000L;

        long[] nanoss = new long[jobs.length];

        for (int i = 0; i < jobs.length; i++) {

            collectAllGarbage();

            long t0 = System.nanoTime();

            long t;

            int j = 0;

            do { jobs[i].work(); j++; }

            while ((t = System.nanoTime() - t0) < warmupNanos);

            nanoss[i] = t/j;

        }

        return nanoss;

    }

    private static void time(Job ... jobs) throws Throwable {

        long[] warmup = time0(jobs); // Warm up run

        long[] nanoss = time0(jobs); // Real timing run

        long[] milliss = new long[jobs.length];

        double[] ratios = new double[jobs.length];

        final String nameHeader   = "Method";

        final String millisHeader = "Millis";

        final String ratioHeader  = "Ratio";

        int nameWidth   = nameHeader.length();

        int millisWidth = millisHeader.length();

        int ratioWidth  = ratioHeader.length();

        for (int i = 0; i < jobs.length; i++) {

            nameWidth = Math.max(nameWidth, jobs[i].name().length());

            milliss[i] = nanoss[i]/(1000L * 1000L);

            millisWidth = Math.max(millisWidth,

                                   String.format("%d", milliss[i]).length());

            ratios[i] = (double) nanoss[i] / (double) nanoss[0];

            ratioWidth = Math.max(ratioWidth,

                                  String.format("%.3f", ratios[i]).length());

        }

        String format = String.format("%%-%ds %%%dd %%%d.3f%%n",

                                      nameWidth, millisWidth, ratioWidth);

        String headerFormat = String.format("%%-%ds %%%ds %%%ds%%n",

                                            nameWidth, millisWidth, ratioWidth);

        System.out.printf(headerFormat, "Method", "Millis", "Ratio");

        // Print out absolute and relative times, calibrated against first job

        for (int i = 0; i < jobs.length; i++)

            System.out.printf(format, jobs[i].name(), milliss[i], ratios[i]);

    }

    private static String keywordValue(String[] args, String keyword) {

        for (String arg : args)

            if (arg.startsWith(keyword))

                return arg.substring(keyword.length() + 1);

        return null;

    }

    private static int intArg(String[] args, String keyword, int defaultValue) {

        String val = keywordValue(args, keyword);

        return val == null ? defaultValue : Integer.parseInt(val);

    }

    private static Pattern patternArg(String[] args, String keyword) {

        String val = keywordValue(args, keyword);

        return val == null ? null : Pattern.compile(val);

    }

    private static Job[] filter(Pattern filter, Job[] jobs) {

        if (filter == null) return jobs;

        Job[] newJobs = new Job[jobs.length];

        int n = 0;

        for (Job job : jobs)

            if (filter.matcher(job.name()).find())

                newJobs[n++] = job;

        // Arrays.copyOf not available in JDK 5

        Job[] ret = new Job[n];

        System.arraycopy(newJobs, 0, ret, 0, n);

        return ret;

    }

    private static void deoptimize(int sum) {

        if (sum == 42)

            System.out.println("the answer");

    }

    /**

     * Usage: [iterations=N] [size=N] [filter=REGEXP]

     */

    public static void main(String[] args) throws Throwable {

        final int iterations = intArg(args, "iterations", 10000);

        final int size       = intArg(args, "size", 1024);

        final Pattern filter = patternArg(args, "filter");

        final Random rnd = new Random();

        final ByteBuffer b = ByteBuffer.allocateDirect(8*size);

        for (int i = 0; i < b.limit(); i++)

            b.put(i, (byte) rnd.nextInt());

        Job[] jobs = {

            new Job("swap char BIG_ENDIAN") {

                public void work() throws Throwable {

                    b.order(ByteOrder.BIG_ENDIAN);

                    CharBuffer x = b.asCharBuffer();

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

                        int sum = 0;

                        for (int j = 0, end = x.limit(); j < end; j++)

                            sum += x.get(j);

                        deoptimize(sum);}}},

            new Job("swap char LITTLE_ENDIAN") {

                public void work() throws Throwable {

                    b.order(ByteOrder.LITTLE_ENDIAN);

                    CharBuffer x = b.asCharBuffer();

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

                        int sum = 0;

                        for (int j = 0, end = x.limit(); j < end; j++)

                            sum += x.get(j);

                        deoptimize(sum);}}},

            new Job("swap short BIG_ENDIAN") {

                public void work() throws Throwable {

                    b.order(ByteOrder.BIG_ENDIAN);

                    ShortBuffer x = b.asShortBuffer();

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

                        int sum = 0;

                        for (int j = 0, end = x.limit(); j < end; j++)

                            sum += x.get(j);

                        deoptimize(sum);}}},

            new Job("swap short LITTLE_ENDIAN") {

                public void work() throws Throwable {

                    b.order(ByteOrder.LITTLE_ENDIAN);

                    ShortBuffer x = b.asShortBuffer();

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

                        int sum = 0;

                        for (int j = 0, end = x.limit(); j < end; j++)

                            sum += x.get(j);

                        deoptimize(sum);}}},

            new Job("swap int BIG_ENDIAN") {

                public void work() throws Throwable {

                    b.order(ByteOrder.BIG_ENDIAN);

                    IntBuffer x = b.asIntBuffer();

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

                        int sum = 0;

                        for (int j = 0, end = x.limit(); j < end; j++)

                            sum += x.get(j);

                        deoptimize(sum);}}},

            new Job("swap int LITTLE_ENDIAN") {

                public void work() throws Throwable {

                    b.order(ByteOrder.LITTLE_ENDIAN);

                    IntBuffer x = b.asIntBuffer();

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

                        int sum = 0;

                        for (int j = 0, end = x.limit(); j < end; j++)

                            sum += x.get(j);

                        deoptimize(sum);}}},

            new Job("swap long BIG_ENDIAN") {

                public void work() throws Throwable {

                    b.order(ByteOrder.BIG_ENDIAN);

                    LongBuffer x = b.asLongBuffer();

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

                        int sum = 0;

                        for (int j = 0, end = x.limit(); j < end; j++)

                            sum += x.get(j);

                        deoptimize(sum);}}},

            new Job("swap long LITTLE_ENDIAN") {

                public void work() throws Throwable {

                    b.order(ByteOrder.LITTLE_ENDIAN);

                    LongBuffer x = b.asLongBuffer();

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

                        int sum = 0;

                        for (int j = 0, end = x.limit(); j < end; j++)

                            sum += x.get(j);

                        deoptimize(sum);}}}

        };

        time(filter(filter, jobs));

    }

}