/*
 * 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.
 * Be patient; this runs for half an hour!
 *
 * I have run this as follows:
 *
 * for f in -client -server; do mergeBench dolphin . jr -dsa -da $f IteratorMicroBenchmark.java; done
 *
 * @version 1.1 07/06/11
 * @author Martin Buchholz
 */

import java.util.*;
import java.util.concurrent.*;
import java.util.regex.Pattern;

public class IteratorMicroBenchmark {
    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");
    }

    private static <T> List<T> asSubList(List<T> list) {
	return list.subList(0, list.size());
    }

    private static <T> Iterable<T> backwards(final List<T> list) {
	return new Iterable<T>() {
	    public Iterator<T> iterator() {
		return new Iterator<T>() {
		    final ListIterator<T> it = list.listIterator(list.size());
		    public boolean hasNext() { return it.hasPrevious(); }
		    public T next()          { return it.previous(); }
		    public void remove()     {        it.remove(); }};}};
    }

    /**
     * Usage: [iterations=N] [size=N] [filter=REGEXP]
     */
    public static void main(String[] args) throws Throwable {
	final int iterations = intArg(args, "iterations", 100000);
	final int size       = intArg(args, "size", 1000);
	final Pattern filter = patternArg(args, "filter");

	final ConcurrentSkipListMap<Integer,Integer> m
	    = new ConcurrentSkipListMap<Integer,Integer>();
	final Vector<Integer> v = new Vector<Integer>(size);
	final ArrayList<Integer> al = new ArrayList<Integer>(size);

	// Populate collections with random data
	final Random rnd = new Random();
	for (int i = 0; i < size; i++) {
	    m.put(rnd.nextInt(size), rnd.nextInt(size));
	    v.add(rnd.nextInt(size));
	}
	al.addAll(v);

	// Also test "short" collections
	final int shortSize = 5;
	final Vector<Integer> sv = new Vector<Integer>(v.subList(0, shortSize));
	final ArrayList<Integer> sal = new ArrayList<Integer>(sv);

	// Checks for correctness *and* prevents loop optimizations
	class Check {
	    private int sum;
	    public void sum(int sum) {
		if (this.sum == 0)
		    this.sum = sum;
		if (this.sum != sum)
		    throw new AssertionError("Sum mismatch");
	    }
	}
	final Check check      = new Check();
	final Check shortCheck = new Check();

	Job[] jobs = {
// 	    new Job("Vector iterate desugared") {
// 		public void work() throws Throwable {
// 		    for (int i = 0; i < iterations; i++) {
// 			int sum = 0;
// 			for (Iterator<Integer> it = v.iterator(); it.hasNext();)
// 			    sum += it.next();
// 			check.sum(sum);}}},
	    new Job("array loop") {
		public void work() throws Throwable {
		    Integer[] a = al.toArray(new Integer[0]);
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
                        int size = a.length;
                        for (int j = 0; j < size; ++j)
                            sum += a[j];
			check.sum(sum);}}},
	    new Job("Vector get loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
                        int size = v.size();
                        for (int j = 0; j < size; ++j)
                            sum += v.get(j);
			check.sum(sum);}}},
	    new Job("Vector iterate for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			for (Integer n : v)
			    sum += n;
			check.sum(sum);}}},
	    new Job("Vector descending listIterator loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			ListIterator<Integer> it = v.listIterator(al.size());
			while (it.hasPrevious())
			    sum += it.previous();
			check.sum(sum);}}},
	    new Job("Vector Enumeration loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			Enumeration<Integer> it = v.elements();
			while (it.hasMoreElements())
			    sum += it.nextElement();
			check.sum(sum);}}},
	    new Job("Vector subList iterate for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			for (Integer n : asSubList(v))
			    sum += n;
			check.sum(sum);}}},
	    new Job("Vector subList subList subList iterate for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			for (Integer n : asSubList(asSubList(asSubList(v))))
			    sum += n;
			check.sum(sum);}}},
	    new Job("Vector backwards wrapper ListIterator for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			for (Integer n : backwards(v))
			    sum += n;
			check.sum(sum);}}},
	    new Job("Vector backwards wrapper subList ListIterator for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			for (Integer n : backwards(asSubList(v)))
			    sum += n;
			check.sum(sum);}}},
// 	    new Job("Vector iterate for loop invokeinterface") {
// 		public void work() throws Throwable {
// 		    final List<Integer> l = v;
// 		    for (int i = 0; i < iterations; i++) {
// 			int sum = 0;
// 			for (Integer n : l)
// 			    sum += n;
// 			check.sum(sum);}}},
// 	    new Job("Vector subList iterate for loop invokeinterface") {
// 		public void work() throws Throwable {
// 		    final List<Integer> l = v;
// 		    for (int i = 0; i < iterations; i++) {
// 			int sum = 0;
// 			for (Integer n : asSubList(l))
// 			    sum += n;
// 			check.sum(sum);}}},
	    new Job("Short Vector get loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < (iterations * size / shortSize); i++) {
			int sum = 0;
                        int size = sv.size();
                        for (int j = 0; j < size; ++j)
                            sum += sv.get(j);
			shortCheck.sum(sum);}}},
	    new Job("Short Vector iterate for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < (iterations * size / shortSize); i++) {
			int sum = 0;
			for (Integer n : sv)
			    sum += n;
			shortCheck.sum(sum);}}},
	    new Job("Short Vector sublist iterate for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < (iterations * size / shortSize); i++) {
			int sum = 0;
			for (Integer n : asSubList(sv))
			    sum += n;
			shortCheck.sum(sum);}}},
	    new Job("ArrayList get loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
                        int size = al.size();
                        for (int j = 0; j < size; ++j)
                            sum += al.get(j);
			check.sum(sum);}}},
	    new Job("ArrayList iterate for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			for (Integer n : al)
			    sum += n;
			check.sum(sum);}}},
	    new Job("ArrayList descending listIterator loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			ListIterator<Integer> it = al.listIterator(al.size());
			while (it.hasPrevious())
			    sum += it.previous();
			check.sum(sum);}}},
	    new Job("ArrayList listIterator loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			ListIterator<Integer> it = al.listIterator();
			while (it.hasNext())
			    sum += it.next();
			check.sum(sum);}}},
	    new Job("ArrayList subList get loop") {
		public void work() throws Throwable {
		    List<Integer> sl = asSubList(al);
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
                        int size = sl.size();
                        for (int j = 0; j < size; ++j)
                            sum += sl.get(j);
			check.sum(sum);}}},
	    new Job("ArrayList subList iterate for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			for (Integer n : asSubList(al))
			    sum += n;
			check.sum(sum);}}},
	    new Job("ArrayList subList subList subList iterate for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			for (Integer n : asSubList(asSubList(asSubList(al))))
			    sum += n;
			check.sum(sum);}}},
	    new Job("ArrayList backwards wrapper ListIterator for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			for (Integer n : backwards(al))
			    sum += n;
			check.sum(sum);}}},
	    new Job("ArrayList backwards wrapper subList ListIterator for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			for (Integer n : backwards(asSubList(al)))
			    sum += n;
			check.sum(sum);}}},
// 	    new Job("ArrayList iterate desugared") {
// 		public void work() throws Throwable {
// 		    for (int i = 0; i < iterations; i++) {
// 			int sum = 0;
// 			for (Iterator<Integer> it = al.iterator(); it.hasNext();)
// 			    sum += it.next();
// 			check.sum(sum);}}},
	    new Job("Short ArrayList get loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < (iterations * size / shortSize); i++) {
			int sum = 0;
                        int size = sal.size();
                        for (int j = 0; j < size; ++j)
                            sum += sal.get(j);
			shortCheck.sum(sum);}}},
	    new Job("Short ArrayList iterate for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < (iterations * size / shortSize); i++) {
			int sum = 0;
			for (Integer n : sal)
			    sum += n;
			shortCheck.sum(sum);}}},
	    new Job("Short ArrayList sublist iterate for loop") {
		public void work() throws Throwable {
		    for (int i = 0; i < (iterations * size / shortSize); i++) {
			int sum = 0;
			for (Integer n : asSubList(sal))
			    sum += n;
			shortCheck.sum(sum);}}},
	    new Job("Vector ArrayList alternating iteration") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			Iterator<Integer> it1 = v.iterator();
			Iterator<Integer> it2 = al.iterator();
			while (it1.hasNext())
			    sum += it1.next() + it2.next();
			check.sum(sum/2);}}},
	    new Job("Vector ArrayList alternating invokeVirtual iteration") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			List<Iterator<Integer>> its
			    = new ArrayList<Iterator<Integer>>(2);
			its.add(v.iterator());
			its.add(al.iterator());
			for (int k = 0; its.get(k).hasNext(); k = (k == 0) ? 1 : 0)
			    sum += its.get(k).next();
			check.sum(sum/2);}}},
	    new Job("ConcurrentSkipListMap entrySet iterate") {
		public void work() throws Throwable {
		    for (int i = 0; i < iterations; i++) {
			int sum = 0;
			for (Map.Entry<Integer,Integer> e : m.entrySet())
			    sum += e.getKey();
			deoptimize(sum);}}}
	};

	time(filter(filter, jobs));
    }
}