/*
 * Copyright (c) 2007, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @summary micro-benchmark correctness mode
 * @run main URLMicroBenchmark iterations=1 size=8 warmup=0
 */

import static java.util.stream.Collectors.summingInt;

import java.lang.ref.WeakReference;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;
import java.util.regex.Pattern;
import java.net.URL;


public class URLMicroBenchmark {
    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;
    }

    static String toExternalForm_jdk9(URL u) {
        // pre-compute length of StringBuffer
        int len = u.getProtocol().length() + 1;
        if (u.getAuthority() != null && u.getAuthority().length() > 0)
            len += 2 + u.getAuthority().length();
        if (u.getPath() != null) {
            len += u.getPath().length();
        }
        if (u.getQuery() != null) {
            len += 1 + u.getQuery().length();
        }
        if (u.getRef() != null)
            len += 1 + u.getRef().length();

        StringBuilder result = new StringBuilder(len);
        result.append(u.getProtocol());
        result.append(":");
        if (u.getAuthority() != null && u.getAuthority().length() > 0) {
            result.append("//");
            result.append(u.getAuthority());
        }
        if (u.getPath() != null) {
            result.append(u.getPath());
        }
        if (u.getQuery() != null) {
            result.append('?');
            result.append(u.getQuery());
        }
        if (u.getRef() != null) {
            result.append("#");
            result.append(u.getRef());
        }
        return result.toString();
    }

    static String toExternalForm_concat_chars(URL u) {
        String s;
        return u.getProtocol()
            + ':'
            + (((s = u.getAuthority()) != null && s.length() > 0)
               ? "//" + s : "")
            + (((s = u.getPath()) != null) ? s : "")
            + (((s = u.getQuery()) != null) ? '?' + s : "")
            + (((s = u.getRef()) != null) ? '#' + s : "");
    }

    static String toExternalForm_concat_string(URL u) {
        String s;
        return u.getProtocol()
            + ":"
            + (((s = u.getAuthority()) != null && s.length() > 0)
               ? "//" + s : "")
            + (((s = u.getPath()) != null) ? s : "")
            + (((s = u.getQuery()) != null) ? "?" + s : "")
            + (((s = u.getRef()) != null) ? "#" + s : "");
    }

    static String toExternalForm_concat_incremental_string(URL u) {
        String s;
        String r = u.getProtocol() + ":";
        if ((s = u.getAuthority()) != null && s.length() > 0)
            r += "//" + s;
        if ((s = u.getPath()) != null)
            r += s;
        if ((s = u.getQuery()) != null)
            r += "?" + s;
        if ((s = u.getRef()) != null)
            r += "#" + s;
        return r;
    }

    static String toExternalForm_concat_incremental_chars(URL u) {
        String s;
        String r = u.getProtocol() + ':';
        if ((s = u.getAuthority()) != null && s.length() > 0)
            r = r + "//" + s;
        if ((s = u.getPath()) != null)
            r = r + s;
        if ((s = u.getQuery()) != null)
            r = r +  '?' + s;
        if ((s = u.getRef()) != null)
            r = r + '#' + s;
        return r;
    }

    static String toExternalForm_StringBuilder_cache(URL u) {
        final String protocol, authority, path, query, ref;
        final int len = (protocol = u.getProtocol()).length() + 1
            + (((authority = u.getAuthority()) != null) ? 2 + authority.length() : 0)
            + (((path = u.getPath()) != null) ? path.length() : 0)
            + (((query = u.getQuery()) != null) ? 1 + query.length() : 0)
            + (((ref = u.getRef()) != null) ? 1 + ref.length() : 0);

        StringBuilder result = new StringBuilder(len);
        result.append(protocol).append(':');
        if (authority != null && authority.length() > 0)
            result.append('/').append('/').append(authority);
        if (path != null)
            result.append(path);
        if (query != null)
            result.append('?').append(query);
        if (ref != null)
            result.append('#').append(ref);
        return result.toString();
    }

    final int iterations;
    final double warmupSeconds;
    final long warmupNanos;
    final Pattern filter;       // select subset of Jobs to run
    final boolean reverse;      // reverse order of Jobs
    final boolean shuffle;      // randomize order of Jobs

    URLMicroBenchmark(String[] args) {
        iterations    = intArg(args, "iterations", 600_000);
        warmupSeconds = doubleArg(args, "warmup", 7.0);
        filter        = patternArg(args, "filter");
        reverse       = booleanArg(args, "reverse");
        shuffle       = booleanArg(args, "shuffle");

        warmupNanos = (long) (warmupSeconds * (1000L * 1000L * 1000L));
    }

    // --------------- GC finalization infrastructure ---------------

    /** No guarantees, but effective in practice. */
    static void forceFullGc() {
        CountDownLatch finalizeDone = new CountDownLatch(1);
        WeakReference<?> ref = new WeakReference<Object>(new Object() {
            protected void finalize() { finalizeDone.countDown(); }});
        try {
            for (int i = 0; i < 10; i++) {
                System.gc();
                if (finalizeDone.await(1L, TimeUnit.SECONDS) && ref.get() == null) {
                    System.runFinalization(); // try to pick up stragglers
                    return;
                }
            }
        } catch (InterruptedException unexpected) {
            throw new AssertionError("unexpected InterruptedException");
        }
        throw new AssertionError("failed to do a \"full\" gc");
    }

    /**
     * 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.
     */
    long[] time0(List<Job> jobs) throws Throwable {
        final int size = jobs.size();
        long[] nanoss = new long[size];
        for (int i = 0; i < size; i++) {
            if (warmupNanos > 0) forceFullGc();
            Job job = jobs.get(i);
            long totalTime;
            int runs = 0;
            long startTime = System.nanoTime();
            do { job.work(); runs++; }
            while ((totalTime = System.nanoTime() - startTime) < warmupNanos);
            nanoss[i] = totalTime/runs;
        }
        return nanoss;
    }

    void time(List<Job> jobs) throws Throwable {
        if (warmupNanos > 0) time0(jobs); // Warm up run
        final int size = jobs.size();
        final long[] nanoss = time0(jobs); // Real timing run
        final long[] milliss = new long[size];
        final double[] ratios = new double[size];

        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 < size; i++) {
            nameWidth = Math.max(nameWidth, jobs.get(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 < size; i++)
            System.out.printf(format, jobs.get(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 double doubleArg(String[] args, String keyword, double defaultValue) {
        String val = keywordValue(args, keyword);
        return (val == null) ? defaultValue : Double.parseDouble(val);
    }

    private static Pattern patternArg(String[] args, String keyword) {
        String val = keywordValue(args, keyword);
        return (val == null) ? null : Pattern.compile(val);
    }

    private static boolean booleanArg(String[] args, String keyword) {
        String val = keywordValue(args, keyword);
        if (val == null || val.equals("false")) return false;
        if (val.equals("true")) return true;
        throw new IllegalArgumentException(val);
    }

    private static List<Job> filter(Pattern filter, List<Job> jobs) {
        if (filter == null) return jobs;
        ArrayList<Job> newJobs = new ArrayList<>();
        for (Job job : jobs)
            if (filter.matcher(job.name()).find())
                newJobs.add(job);
        return newJobs;
    }

    public static void main(String[] args) throws Throwable {
        new URLMicroBenchmark(args).run();
    }

    void run() throws Throwable {
        time(filter(filter, jobs()));
    }
    List<Job> jobs() throws Throwable {
        final String[] urlStrings = new String[] {
            "https://docs.oracle.com/javase/9/docs/api/java/net/URL.html",
            "https://docs.oracle.com/javase/9/docs/api/java/net/URL.html#URL-java.lang.String-java.lang.String-int-java.lang.String-java.net.URLStreamHandler-",
        };
        final URL[] urls = Arrays.stream(urlStrings)
            .map(s -> { try { return new URL(s); }
                     catch (Throwable t) { throw new Error(t); }})
            .toArray(URL[]::new);
        final String[] externalForms = new String[urls.length];
        return List.of(
            new Job("StringBuilder jdk9") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++)
                        for (int j = 0; j < urls.length; j++)
                            externalForms[j] = toExternalForm_jdk9(urls[j]);
                    if (!Arrays.equals(urlStrings, externalForms)) throw new Error();
                }},
            new Job("concat_chars") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++)
                        for (int j = 0; j < urls.length; j++)
                            externalForms[j] = toExternalForm_concat_chars(urls[j]);
                    if (!Arrays.equals(urlStrings, externalForms)) throw new Error();
                }},
            new Job("concat_string") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++)
                        for (int j = 0; j < urls.length; j++)
                            externalForms[j] = toExternalForm_concat_string(urls[j]);
                    if (!Arrays.equals(urlStrings, externalForms)) throw new Error();
                }},
            new Job("concat_incremental_string") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++)
                        for (int j = 0; j < urls.length; j++)
                            externalForms[j] = toExternalForm_concat_incremental_string(urls[j]);
                    if (!Arrays.equals(urlStrings, externalForms)) throw new Error();
                }},
            new Job("concat_incremental_chars") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++)
                        for (int j = 0; j < urls.length; j++)
                            externalForms[j] = toExternalForm_concat_incremental_chars(urls[j]);
                    if (!Arrays.equals(urlStrings, externalForms)) throw new Error();
                }},
            new Job("StringBuilder_cache") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++)
                        for (int j = 0; j < urls.length; j++)
                            externalForms[j] = toExternalForm_StringBuilder_cache(urls[j]);
                    if (!Arrays.equals(urlStrings, externalForms)) throw new Error();
                }});
    }
}