util/Collection/IteratorMicroBenchmark.java

/*
 * 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 IteratorMicroBenchmark iterations=1 size=8 warmup=0
 */

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

import java.lang.ref.WeakReference;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Deque;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import java.util.PriorityQueue;
import java.util.Spliterator;
import java.util.Vector;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ConcurrentLinkedDeque;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.LinkedTransferQueue;
import java.util.concurrent.PriorityBlockingQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.LongAdder;
import java.util.regex.Pattern;
import java.util.stream.Stream;

/**
 * Usage: [iterations=N] [size=N] [filter=REGEXP] [warmup=SECONDS]
 *
 * To run this in micro-benchmark mode, simply run as a normal java program.
 * Be patient; this program runs for a very long time.
 * For faster runs, restrict execution using command line args.
 *
 * This is an interface based version of ArrayList/IteratorMicroBenchmark
 *
 * @author Martin Buchholz
 */
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;
        public void run() {
            try { work(); }
            catch (Throwable ex) {
                // current job cannot always be deduced from stacktrace.
                throw new RuntimeException("Job failed: " + name(), ex);
            }
        }
    }

    final int iterations;
    final int size;             // number of elements in collections
    final double warmupSeconds;
    final long warmupNanos;
    final Pattern nameFilter;   // select subset of Jobs to run
    final boolean reverse;      // reverse order of Jobs
    final boolean shuffle;      // randomize order of Jobs

    IteratorMicroBenchmark(String[] args) {
        iterations    = intArg(args, "iterations", 10_000);
        size          = intArg(args, "size", 1000);
        warmupSeconds = doubleArg(args, "warmup", 7.0);
        nameFilter    = 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() {
            @SuppressWarnings("deprecation")
            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) {
        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.run(); 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 void deoptimize(int sum) {
        if (sum == 42)
            System.out.println("the answer");
    }

    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(); }};}};
    }

    // Checks for correctness *and* prevents loop optimizations
    static 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");
        }
    }
    volatile Check check = new Check();

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

    HashMap<Class<?>, String> goodClassName = new HashMap<>();

    String goodClassName(Class<?> klazz) {
        return goodClassName.computeIfAbsent(
            klazz,
            k -> {
                String simple = k.getSimpleName();
                return (simple.equals("SubList")) // too simple!
                    ? k.getName().replaceFirst(".*\\.", "")
                    : simple;
            });
    }

    static List<Integer> makeSubList(List<Integer> list) {
        final ThreadLocalRandom rnd = ThreadLocalRandom.current();
        int size = list.size();
        if (size <= 2) return list.subList(0, size);
        List<Integer> subList = list.subList(rnd.nextInt(0, 2),
                                             size - rnd.nextInt(0, 2));
        List<Integer> copy = new ArrayList<>(list);
        subList.clear();
        subList.addAll(copy);
        return subList;
    }

    void run() throws Throwable {
        final ArrayList<Integer> al = new ArrayList<>(size);

        // Populate collections with random data
        final ThreadLocalRandom rnd = ThreadLocalRandom.current();
        for (int i = 0; i < size; i++)
            al.add(rnd.nextInt(size));

        final ArrayDeque<Integer> ad = new ArrayDeque<>(al);
        final ArrayBlockingQueue<Integer> abq = new ArrayBlockingQueue<>(al.size());
        abq.addAll(al);

        // shuffle circular array elements so they wrap
        for (int i = 0, n = rnd.nextInt(size); i < n; i++) {
            ad.addLast(ad.removeFirst());
            abq.add(abq.remove());
        }

        ArrayList<Job> jobs = Stream.<Collection<Integer>>of(
                al, ad, abq,
                makeSubList(new ArrayList<>(al)),
                new LinkedList<>(al),
                makeSubList(new LinkedList<>(al)),
                new PriorityQueue<>(al),
                new Vector<>(al),
                makeSubList(new Vector<>(al)),
                new CopyOnWriteArrayList<>(al),
                makeSubList(new CopyOnWriteArrayList<>(al)),
                new ConcurrentLinkedQueue<>(al),
                new ConcurrentLinkedDeque<>(al),
                new LinkedBlockingQueue<>(al),
                new LinkedBlockingDeque<>(al),
                new LinkedTransferQueue<>(al),
                new PriorityBlockingQueue<>(al))
            .flatMap(x -> jobs(x))
            .filter(job ->
                nameFilter == null || nameFilter.matcher(job.name()).find())
            .collect(toCollection(ArrayList::new));

        if (reverse) Collections.reverse(jobs);
        if (shuffle) Collections.shuffle(jobs);

        time(jobs);
    }

    @SafeVarargs @SuppressWarnings("varargs")
    private <T> Stream<T> concatStreams(Stream<T> ... streams) {
        return Stream.of(streams).flatMap(s -> s);
    }

    Stream<Job> jobs(Collection<Integer> x) {
        return concatStreams(
            collectionJobs(x),

            (x instanceof Deque)
            ? dequeJobs((Deque<Integer>)x)
            : Stream.empty(),

            (x instanceof List)
            ? listJobs((List<Integer>)x)
            : Stream.empty());
    }

    Object sneakyAdder(int[] sneakySum) {
        return new Object() {
            public int hashCode() { throw new AssertionError(); }
            public boolean equals(Object z) {
                sneakySum[0] += (int) z; return false; }};
    }

    Stream<Job> collectionJobs(Collection<Integer> x) {
        final String klazz = goodClassName(x.getClass());
        return Stream.of(
            new Job(klazz + " iterate for loop") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        int sum = 0;
                        for (Integer n : x)
                            sum += n;
                        check.sum(sum);}}},
            new Job(klazz + " iterator().forEachRemaining()") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        x.iterator().forEachRemaining(n -> sum[0] += n);
                        check.sum(sum[0]);}}},
            new Job(klazz + " spliterator().tryAdvance()") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        Spliterator<Integer> spliterator = x.spliterator();
                        do {} while (spliterator.tryAdvance(n -> sum[0] += n));
                        check.sum(sum[0]);}}},
            new Job(klazz + " spliterator().forEachRemaining()") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        x.spliterator().forEachRemaining(n -> sum[0] += n);
                        check.sum(sum[0]);}}},
            new Job(klazz + " removeIf") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        if (x.removeIf(n -> { sum[0] += n; return false; }))
                            throw new AssertionError();
                        check.sum(sum[0]);}}},
            new Job(klazz + " contains") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    Object sneakyAdder = sneakyAdder(sum);
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        if (x.contains(sneakyAdder)) throw new AssertionError();
                        check.sum(sum[0]);}}},
            new Job(klazz + " remove(Object)") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    Object sneakyAdder = sneakyAdder(sum);
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        if (x.remove(sneakyAdder)) throw new AssertionError();
                        check.sum(sum[0]);}}},
            new Job(klazz + " forEach") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        x.forEach(n -> sum[0] += n);
                        check.sum(sum[0]);}}},
            new Job(klazz + " toArray()") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        for (Object o : x.toArray())
                            sum[0] += (Integer) o;
                        check.sum(sum[0]);}}},
            new Job(klazz + " toArray(a)") {
                public void work() throws Throwable {
                    Integer[] a = new Integer[x.size()];
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        x.toArray(a);
                        for (Object o : a)
                            sum[0] += (Integer) o;
                        check.sum(sum[0]);}}},
            new Job(klazz + " toArray(empty)") {
                public void work() throws Throwable {
                    Integer[] empty = new Integer[0];
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        for (Integer o : x.toArray(empty))
                            sum[0] += o;
                        check.sum(sum[0]);}}},
            new Job(klazz + " stream().forEach") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        x.stream().forEach(n -> sum[0] += n);
                        check.sum(sum[0]);}}},
            new Job(klazz + " stream().mapToInt") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        check.sum(x.stream().mapToInt(e -> e).sum());}}},
            new Job(klazz + " stream().collect") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        check.sum(x.stream()
                                  .collect(summingInt(e -> e)));}}},
            new Job(klazz + " stream()::iterator") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        for (Integer o : (Iterable<Integer>) x.stream()::iterator)
                            sum[0] += o;
                        check.sum(sum[0]);}}},
            new Job(klazz + " parallelStream().forEach") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        LongAdder sum = new LongAdder();
                        x.parallelStream().forEach(n -> sum.add(n));
                        check.sum((int) sum.sum());}}},
            new Job(klazz + " parallelStream().mapToInt") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        check.sum(x.parallelStream().mapToInt(e -> e).sum());}}},
            new Job(klazz + " parallelStream().collect") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        check.sum(x.parallelStream()
                                  .collect(summingInt(e -> e)));}}},
            new Job(klazz + " parallelStream()::iterator") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        for (Integer o : (Iterable<Integer>) x.parallelStream()::iterator)
                            sum[0] += o;
                        check.sum(sum[0]);}}});
    }

    Stream<Job> dequeJobs(Deque<Integer> x) {
        String klazz = goodClassName(x.getClass());
        return Stream.of(
            new Job(klazz + " descendingIterator() loop") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        int sum = 0;
                        Iterator<Integer> it = x.descendingIterator();
                        while (it.hasNext())
                            sum += it.next();
                        check.sum(sum);}}},
            new Job(klazz + " descendingIterator().forEachRemaining()") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        x.descendingIterator().forEachRemaining(n -> sum[0] += n);
                        check.sum(sum[0]);}}});
    }

    Stream<Job> listJobs(List<Integer> x) {
        final String klazz = goodClassName(x.getClass());
        return Stream.of(
            new Job(klazz + " listIterator forward loop") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        int sum = 0;
                        ListIterator<Integer> it = x.listIterator();
                        while (it.hasNext())
                            sum += it.next();
                        check.sum(sum);}}},
            new Job(klazz + " listIterator backward loop") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        int sum = 0;
                        ListIterator<Integer> it = x.listIterator(x.size());
                        while (it.hasPrevious())
                            sum += it.previous();
                        check.sum(sum);}}},
            new Job(klazz + " indexOf") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    Object sneakyAdder = sneakyAdder(sum);
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        if (x.indexOf(sneakyAdder) != -1)
                            throw new AssertionError();
                        check.sum(sum[0]);}}},
            new Job(klazz + " lastIndexOf") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    Object sneakyAdder = sneakyAdder(sum);
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        if (x.lastIndexOf(sneakyAdder) != -1)
                            throw new AssertionError();
                        check.sum(sum[0]);}}});
    }
}
Revision:	1.41
Committed:	Tue Apr 3 19:07:36 2018 UTC (6 years, 2 months ago) by jsr166
Branch:	MAIN
Changes since 1.40:	+16 -0 lines
Log Message:	add listIterator Jobs
#	User	Rev	Content
1	jsr166	1.1	/*
2			* Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved.
3			* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4			*
5			* This code is free software; you can redistribute it and/or modify it
6			* under the terms of the GNU General Public License version 2 only, as
7			* published by the Free Software Foundation.
8			*
9			* This code is distributed in the hope that it will be useful, but WITHOUT
10			* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11			* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12			* version 2 for more details (a copy is included in the LICENSE file that
13			* accompanied this code).
14			*
15			* You should have received a copy of the GNU General Public License version
16			* 2 along with this work; if not, write to the Free Software Foundation,
17			* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18			*
19			* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20			* or visit www.oracle.com if you need additional information or have any
21			* questions.
22			*/
23
24			/*
25			* @test
26			* @summary micro-benchmark correctness mode
27			* @run main IteratorMicroBenchmark iterations=1 size=8 warmup=0
28			*/
29
30	jsr166	1.12	import static java.util.stream.Collectors.summingInt;
31	jsr166	1.31	import static java.util.stream.Collectors.toCollection;
32	jsr166	1.12
33	jsr166	1.1	import java.lang.ref.WeakReference;
34			import java.util.ArrayDeque;
35			import java.util.ArrayList;
36			import java.util.Collection;
37	jsr166	1.10	import java.util.Collections;
38	jsr166	1.1	import java.util.Deque;
39	jsr166	1.36	import java.util.HashMap;
40	jsr166	1.1	import java.util.Iterator;
41	jsr166	1.13	import java.util.LinkedList;
42	jsr166	1.1	import java.util.List;
43			import java.util.ListIterator;
44	jsr166	1.8	import java.util.PriorityQueue;
45	jsr166	1.1	import java.util.Spliterator;
46			import java.util.Vector;
47			import java.util.concurrent.ArrayBlockingQueue;
48			import java.util.concurrent.ConcurrentLinkedDeque;
49			import java.util.concurrent.ConcurrentLinkedQueue;
50	jsr166	1.30	import java.util.concurrent.CopyOnWriteArrayList;
51	jsr166	1.1	import java.util.concurrent.LinkedBlockingDeque;
52			import java.util.concurrent.LinkedBlockingQueue;
53			import java.util.concurrent.LinkedTransferQueue;
54	jsr166	1.8	import java.util.concurrent.PriorityBlockingQueue;
55	jsr166	1.1	import java.util.concurrent.CountDownLatch;
56			import java.util.concurrent.ThreadLocalRandom;
57			import java.util.concurrent.TimeUnit;
58	jsr166	1.19	import java.util.concurrent.atomic.LongAdder;
59	jsr166	1.1	import java.util.regex.Pattern;
60	jsr166	1.30	import java.util.stream.Stream;
61	jsr166	1.1
62			/**
63			* Usage: [iterations=N] [size=N] [filter=REGEXP] [warmup=SECONDS]
64			*
65			* To run this in micro-benchmark mode, simply run as a normal java program.
66			* Be patient; this program runs for a very long time.
67			* For faster runs, restrict execution using command line args.
68			*
69			* This is an interface based version of ArrayList/IteratorMicroBenchmark
70			*
71			* @author Martin Buchholz
72			*/
73			public class IteratorMicroBenchmark {
74			abstract static class Job {
75			private final String name;
76			public Job(String name) { this.name = name; }
77			public String name() { return name; }
78			public abstract void work() throws Throwable;
79	jsr166	1.38	public void run() {
80			try { work(); }
81			catch (Throwable ex) {
82			// current job cannot always be deduced from stacktrace.
83			throw new RuntimeException("Job failed: " + name(), ex);
84			}
85			}
86	jsr166	1.1	}
87
88	jsr166	1.11	final int iterations;
89			final int size; // number of elements in collections
90			final double warmupSeconds;
91			final long warmupNanos;
92	jsr166	1.31	final Pattern nameFilter; // select subset of Jobs to run
93	jsr166	1.11	final boolean reverse; // reverse order of Jobs
94			final boolean shuffle; // randomize order of Jobs
95
96			IteratorMicroBenchmark(String[] args) {
97			iterations = intArg(args, "iterations", 10_000);
98			size = intArg(args, "size", 1000);
99			warmupSeconds = doubleArg(args, "warmup", 7.0);
100	jsr166	1.31	nameFilter = patternArg(args, "filter");
101	jsr166	1.11	reverse = booleanArg(args, "reverse");
102			shuffle = booleanArg(args, "shuffle");
103
104			warmupNanos = (long) (warmupSeconds * (1000L * 1000L * 1000L));
105			}
106	jsr166	1.1
107			// --------------- GC finalization infrastructure ---------------
108
109			/** No guarantees, but effective in practice. */
110			static void forceFullGc() {
111			CountDownLatch finalizeDone = new CountDownLatch(1);
112			WeakReference<?> ref = new WeakReference<Object>(new Object() {
113	jsr166	1.36	@SuppressWarnings("deprecation")
114	jsr166	1.1	protected void finalize() { finalizeDone.countDown(); }});
115			try {
116			for (int i = 0; i < 10; i++) {
117			System.gc();
118			if (finalizeDone.await(1L, TimeUnit.SECONDS) && ref.get() == null) {
119			System.runFinalization(); // try to pick up stragglers
120			return;
121			}
122			}
123			} catch (InterruptedException unexpected) {
124			throw new AssertionError("unexpected InterruptedException");
125			}
126			throw new AssertionError("failed to do a \"full\" gc");
127			}
128
129			/**
130			* Runs each job for long enough that all the runtime compilers
131			* have had plenty of time to warm up, i.e. get around to
132			* compiling everything worth compiling.
133			* Returns array of average times per job per run.
134			*/
135	jsr166	1.38	long[] time0(List<Job> jobs) {
136	jsr166	1.1	final int size = jobs.size();
137			long[] nanoss = new long[size];
138			for (int i = 0; i < size; i++) {
139			if (warmupNanos > 0) forceFullGc();
140	jsr166	1.9	Job job = jobs.get(i);
141			long totalTime;
142			int runs = 0;
143			long startTime = System.nanoTime();
144	jsr166	1.38	do { job.run(); runs++; }
145	jsr166	1.9	while ((totalTime = System.nanoTime() - startTime) < warmupNanos);
146			nanoss[i] = totalTime/runs;
147	jsr166	1.1	}
148			return nanoss;
149			}
150
151			void time(List<Job> jobs) throws Throwable {
152	jsr166	1.9	if (warmupNanos > 0) time0(jobs); // Warm up run
153	jsr166	1.1	final int size = jobs.size();
154			final long[] nanoss = time0(jobs); // Real timing run
155			final long[] milliss = new long[size];
156			final double[] ratios = new double[size];
157
158			final String nameHeader = "Method";
159			final String millisHeader = "Millis";
160			final String ratioHeader = "Ratio";
161
162			int nameWidth = nameHeader.length();
163			int millisWidth = millisHeader.length();
164			int ratioWidth = ratioHeader.length();
165
166			for (int i = 0; i < size; i++) {
167			nameWidth = Math.max(nameWidth, jobs.get(i).name().length());
168
169			milliss[i] = nanoss[i]/(1000L * 1000L);
170			millisWidth = Math.max(millisWidth,
171			String.format("%d", milliss[i]).length());
172
173			ratios[i] = (double) nanoss[i] / (double) nanoss[0];
174			ratioWidth = Math.max(ratioWidth,
175			String.format("%.3f", ratios[i]).length());
176			}
177
178			String format = String.format("%%-%ds %%%dd %%%d.3f%%n",
179			nameWidth, millisWidth, ratioWidth);
180			String headerFormat = String.format("%%-%ds %%%ds %%%ds%%n",
181			nameWidth, millisWidth, ratioWidth);
182			System.out.printf(headerFormat, "Method", "Millis", "Ratio");
183
184			// Print out absolute and relative times, calibrated against first job
185			for (int i = 0; i < size; i++)
186			System.out.printf(format, jobs.get(i).name(), milliss[i], ratios[i]);
187			}
188
189			private static String keywordValue(String[] args, String keyword) {
190			for (String arg : args)
191			if (arg.startsWith(keyword))
192			return arg.substring(keyword.length() + 1);
193			return null;
194			}
195
196			private static int intArg(String[] args, String keyword, int defaultValue) {
197			String val = keywordValue(args, keyword);
198			return (val == null) ? defaultValue : Integer.parseInt(val);
199			}
200
201			private static double doubleArg(String[] args, String keyword, double defaultValue) {
202			String val = keywordValue(args, keyword);
203			return (val == null) ? defaultValue : Double.parseDouble(val);
204			}
205
206			private static Pattern patternArg(String[] args, String keyword) {
207			String val = keywordValue(args, keyword);
208			return (val == null) ? null : Pattern.compile(val);
209			}
210
211	jsr166	1.10	private static boolean booleanArg(String[] args, String keyword) {
212			String val = keywordValue(args, keyword);
213			if (val == null \|\| val.equals("false")) return false;
214			if (val.equals("true")) return true;
215			throw new IllegalArgumentException(val);
216			}
217
218	jsr166	1.1	private static void deoptimize(int sum) {
219			if (sum == 42)
220			System.out.println("the answer");
221			}
222
223			private static <T> Iterable<T> backwards(final List<T> list) {
224			return new Iterable<T>() {
225			public Iterator<T> iterator() {
226			return new Iterator<T>() {
227			final ListIterator<T> it = list.listIterator(list.size());
228			public boolean hasNext() { return it.hasPrevious(); }
229			public T next() { return it.previous(); }
230			public void remove() { it.remove(); }};}};
231			}
232
233			// Checks for correctness and prevents loop optimizations
234	jsr166	1.25	static class Check {
235	jsr166	1.1	private int sum;
236			public void sum(int sum) {
237			if (this.sum == 0)
238			this.sum = sum;
239			if (this.sum != sum)
240			throw new AssertionError("Sum mismatch");
241			}
242			}
243	jsr166	1.2	volatile Check check = new Check();
244	jsr166	1.1
245			public static void main(String[] args) throws Throwable {
246	jsr166	1.11	new IteratorMicroBenchmark(args).run();
247	jsr166	1.1	}
248
249	jsr166	1.36	HashMap<Class<?>, String> goodClassName = new HashMap<>();
250
251			String goodClassName(Class<?> klazz) {
252			return goodClassName.computeIfAbsent(
253			klazz,
254			k -> {
255			String simple = k.getSimpleName();
256			return (simple.equals("SubList")) // too simple!
257			? k.getName().replaceFirst(".*\\.", "")
258			: simple;
259			});
260			}
261
262			static List<Integer> makeSubList(List<Integer> list) {
263			final ThreadLocalRandom rnd = ThreadLocalRandom.current();
264			int size = list.size();
265			if (size <= 2) return list.subList(0, size);
266			List<Integer> subList = list.subList(rnd.nextInt(0, 2),
267			size - rnd.nextInt(0, 2));
268			List<Integer> copy = new ArrayList<>(list);
269			subList.clear();
270			subList.addAll(copy);
271			return subList;
272			}
273
274	jsr166	1.11	void run() throws Throwable {
275	jsr166	1.17	final ArrayList<Integer> al = new ArrayList<>(size);
276	jsr166	1.1
277			// Populate collections with random data
278			final ThreadLocalRandom rnd = ThreadLocalRandom.current();
279	jsr166	1.3	for (int i = 0; i < size; i++)
280	jsr166	1.1	al.add(rnd.nextInt(size));
281
282			final ArrayDeque<Integer> ad = new ArrayDeque<>(al);
283			final ArrayBlockingQueue<Integer> abq = new ArrayBlockingQueue<>(al.size());
284			abq.addAll(al);
285
286			// shuffle circular array elements so they wrap
287			for (int i = 0, n = rnd.nextInt(size); i < n; i++) {
288			ad.addLast(ad.removeFirst());
289			abq.add(abq.remove());
290			}
291
292	jsr166	1.31	ArrayList<Job> jobs = Stream.<Collection<Integer>>of(
293			al, ad, abq,
294	jsr166	1.36	makeSubList(new ArrayList<>(al)),
295	jsr166	1.31	new LinkedList<>(al),
296	jsr166	1.36	makeSubList(new LinkedList<>(al)),
297	jsr166	1.31	new PriorityQueue<>(al),
298			new Vector<>(al),
299	jsr166	1.36	makeSubList(new Vector<>(al)),
300	jsr166	1.31	new CopyOnWriteArrayList<>(al),
301	jsr166	1.36	makeSubList(new CopyOnWriteArrayList<>(al)),
302	jsr166	1.31	new ConcurrentLinkedQueue<>(al),
303			new ConcurrentLinkedDeque<>(al),
304			new LinkedBlockingQueue<>(al),
305			new LinkedBlockingDeque<>(al),
306			new LinkedTransferQueue<>(al),
307			new PriorityBlockingQueue<>(al))
308			.flatMap(x -> jobs(x))
309	jsr166	1.33	.filter(job ->
310			nameFilter == null \|\| nameFilter.matcher(job.name()).find())
311	jsr166	1.31	.collect(toCollection(ArrayList::new));
312	jsr166	1.1
313	jsr166	1.11	if (reverse) Collections.reverse(jobs);
314	jsr166	1.10	if (shuffle) Collections.shuffle(jobs);
315
316	jsr166	1.31	time(jobs);
317			}
318
319	jsr166	1.32	@SafeVarargs @SuppressWarnings("varargs")
320			private <T> Stream<T> concatStreams(Stream<T> ... streams) {
321			return Stream.of(streams).flatMap(s -> s);
322			}
323	jsr166	1.34
324	jsr166	1.31	Stream<Job> jobs(Collection<Integer> x) {
325	jsr166	1.32	return concatStreams(
326			collectionJobs(x),
327	jsr166	1.40
328	jsr166	1.32	(x instanceof Deque)
329			? dequeJobs((Deque<Integer>)x)
330			: Stream.empty(),
331	jsr166	1.40
332	jsr166	1.32	(x instanceof List)
333			? listJobs((List<Integer>)x)
334			: Stream.empty());
335	jsr166	1.1	}
336
337	jsr166	1.36	Object sneakyAdder(int[] sneakySum) {
338			return new Object() {
339			public int hashCode() { throw new AssertionError(); }
340			public boolean equals(Object z) {
341			sneakySum[0] += (int) z; return false; }};
342			}
343
344	jsr166	1.31	Stream<Job> collectionJobs(Collection<Integer> x) {
345	jsr166	1.36	final String klazz = goodClassName(x.getClass());
346	jsr166	1.31	return Stream.of(
347	jsr166	1.5	new Job(klazz + " iterate for loop") {
348	jsr166	1.1	public void work() throws Throwable {
349			for (int i = 0; i < iterations; i++) {
350			int sum = 0;
351			for (Integer n : x)
352			sum += n;
353			check.sum(sum);}}},
354	jsr166	1.18	new Job(klazz + " iterator().forEachRemaining()") {
355	jsr166	1.1	public void work() throws Throwable {
356			int[] sum = new int[1];
357			for (int i = 0; i < iterations; i++) {
358			sum[0] = 0;
359			x.iterator().forEachRemaining(n -> sum[0] += n);
360			check.sum(sum[0]);}}},
361	jsr166	1.18	new Job(klazz + " spliterator().tryAdvance()") {
362	jsr166	1.1	public void work() throws Throwable {
363			int[] sum = new int[1];
364			for (int i = 0; i < iterations; i++) {
365			sum[0] = 0;
366			Spliterator<Integer> spliterator = x.spliterator();
367			do {} while (spliterator.tryAdvance(n -> sum[0] += n));
368			check.sum(sum[0]);}}},
369	jsr166	1.18	new Job(klazz + " spliterator().forEachRemaining()") {
370	jsr166	1.1	public void work() throws Throwable {
371			int[] sum = new int[1];
372			for (int i = 0; i < iterations; i++) {
373			sum[0] = 0;
374			x.spliterator().forEachRemaining(n -> sum[0] += n);
375			check.sum(sum[0]);}}},
376	jsr166	1.18	new Job(klazz + " removeIf") {
377	jsr166	1.1	public void work() throws Throwable {
378			int[] sum = new int[1];
379			for (int i = 0; i < iterations; i++) {
380			sum[0] = 0;
381	jsr166	1.16	if (x.removeIf(n -> { sum[0] += n; return false; }))
382			throw new AssertionError();
383	jsr166	1.1	check.sum(sum[0]);}}},
384	jsr166	1.18	new Job(klazz + " contains") {
385	jsr166	1.14	public void work() throws Throwable {
386			int[] sum = new int[1];
387	jsr166	1.36	Object sneakyAdder = sneakyAdder(sum);
388	jsr166	1.14	for (int i = 0; i < iterations; i++) {
389			sum[0] = 0;
390	jsr166	1.36	if (x.contains(sneakyAdder)) throw new AssertionError();
391	jsr166	1.16	check.sum(sum[0]);}}},
392	jsr166	1.18	new Job(klazz + " remove(Object)") {
393	jsr166	1.16	public void work() throws Throwable {
394			int[] sum = new int[1];
395	jsr166	1.36	Object sneakyAdder = sneakyAdder(sum);
396	jsr166	1.16	for (int i = 0; i < iterations; i++) {
397			sum[0] = 0;
398	jsr166	1.36	if (x.remove(sneakyAdder)) throw new AssertionError();
399	jsr166	1.14	check.sum(sum[0]);}}},
400	jsr166	1.18	new Job(klazz + " forEach") {
401	jsr166	1.1	public void work() throws Throwable {
402			int[] sum = new int[1];
403			for (int i = 0; i < iterations; i++) {
404			sum[0] = 0;
405			x.forEach(n -> sum[0] += n);
406	jsr166	1.6	check.sum(sum[0]);}}},
407	jsr166	1.18	new Job(klazz + " toArray()") {
408	jsr166	1.6	public void work() throws Throwable {
409			int[] sum = new int[1];
410			for (int i = 0; i < iterations; i++) {
411			sum[0] = 0;
412			for (Object o : x.toArray())
413			sum[0] += (Integer) o;
414			check.sum(sum[0]);}}},
415	jsr166	1.18	new Job(klazz + " toArray(a)") {
416	jsr166	1.6	public void work() throws Throwable {
417			Integer[] a = new Integer[x.size()];
418			int[] sum = new int[1];
419			for (int i = 0; i < iterations; i++) {
420			sum[0] = 0;
421			x.toArray(a);
422			for (Object o : a)
423			sum[0] += (Integer) o;
424	jsr166	1.7	check.sum(sum[0]);}}},
425	jsr166	1.18	new Job(klazz + " toArray(empty)") {
426	jsr166	1.7	public void work() throws Throwable {
427			Integer[] empty = new Integer[0];
428			int[] sum = new int[1];
429			for (int i = 0; i < iterations; i++) {
430			sum[0] = 0;
431			for (Integer o : x.toArray(empty))
432			sum[0] += o;
433	jsr166	1.12	check.sum(sum[0]);}}},
434	jsr166	1.19	new Job(klazz + " stream().forEach") {
435			public void work() throws Throwable {
436			int[] sum = new int[1];
437			for (int i = 0; i < iterations; i++) {
438			sum[0] = 0;
439			x.stream().forEach(n -> sum[0] += n);
440			check.sum(sum[0]);}}},
441			new Job(klazz + " stream().mapToInt") {
442			public void work() throws Throwable {
443			for (int i = 0; i < iterations; i++) {
444			check.sum(x.stream().mapToInt(e -> e).sum());}}},
445	jsr166	1.18	new Job(klazz + " stream().collect") {
446	jsr166	1.12	public void work() throws Throwable {
447			for (int i = 0; i < iterations; i++) {
448			check.sum(x.stream()
449			.collect(summingInt(e -> e)));}}},
450	jsr166	1.21	new Job(klazz + " stream()::iterator") {
451	jsr166	1.20	public void work() throws Throwable {
452			int[] sum = new int[1];
453			for (int i = 0; i < iterations; i++) {
454			sum[0] = 0;
455			for (Integer o : (Iterable<Integer>) x.stream()::iterator)
456			sum[0] += o;
457			check.sum(sum[0]);}}},
458	jsr166	1.19	new Job(klazz + " parallelStream().forEach") {
459			public void work() throws Throwable {
460			for (int i = 0; i < iterations; i++) {
461			LongAdder sum = new LongAdder();
462			x.parallelStream().forEach(n -> sum.add(n));
463			check.sum((int) sum.sum());}}},
464			new Job(klazz + " parallelStream().mapToInt") {
465			public void work() throws Throwable {
466			for (int i = 0; i < iterations; i++) {
467			check.sum(x.parallelStream().mapToInt(e -> e).sum());}}},
468	jsr166	1.18	new Job(klazz + " parallelStream().collect") {
469	jsr166	1.12	public void work() throws Throwable {
470			for (int i = 0; i < iterations; i++) {
471			check.sum(x.parallelStream()
472	jsr166	1.20	.collect(summingInt(e -> e)));}}},
473	jsr166	1.21	new Job(klazz + " parallelStream()::iterator") {
474	jsr166	1.20	public void work() throws Throwable {
475			int[] sum = new int[1];
476			for (int i = 0; i < iterations; i++) {
477			sum[0] = 0;
478			for (Integer o : (Iterable<Integer>) x.parallelStream()::iterator)
479			sum[0] += o;
480			check.sum(sum[0]);}}});
481	jsr166	1.1	}
482
483	jsr166	1.31	Stream<Job> dequeJobs(Deque<Integer> x) {
484	jsr166	1.36	String klazz = goodClassName(x.getClass());
485	jsr166	1.31	return Stream.of(
486	jsr166	1.18	new Job(klazz + " descendingIterator() loop") {
487	jsr166	1.1	public void work() throws Throwable {
488			for (int i = 0; i < iterations; i++) {
489			int sum = 0;
490			Iterator<Integer> it = x.descendingIterator();
491			while (it.hasNext())
492			sum += it.next();
493			check.sum(sum);}}},
494	jsr166	1.18	new Job(klazz + " descendingIterator().forEachRemaining()") {
495	jsr166	1.1	public void work() throws Throwable {
496			int[] sum = new int[1];
497			for (int i = 0; i < iterations; i++) {
498			sum[0] = 0;
499			x.descendingIterator().forEachRemaining(n -> sum[0] += n);
500			check.sum(sum[0]);}}});
501			}
502	jsr166	1.30
503	jsr166	1.31	Stream<Job> listJobs(List<Integer> x) {
504	jsr166	1.36	final String klazz = goodClassName(x.getClass());
505	jsr166	1.31	return Stream.of(
506	jsr166	1.41	new Job(klazz + " listIterator forward loop") {
507			public void work() throws Throwable {
508			for (int i = 0; i < iterations; i++) {
509			int sum = 0;
510			ListIterator<Integer> it = x.listIterator();
511			while (it.hasNext())
512			sum += it.next();
513			check.sum(sum);}}},
514			new Job(klazz + " listIterator backward loop") {
515			public void work() throws Throwable {
516			for (int i = 0; i < iterations; i++) {
517			int sum = 0;
518			ListIterator<Integer> it = x.listIterator(x.size());
519			while (it.hasPrevious())
520			sum += it.previous();
521			check.sum(sum);}}},
522	jsr166	1.39	new Job(klazz + " indexOf") {
523			public void work() throws Throwable {
524			int[] sum = new int[1];
525			Object sneakyAdder = sneakyAdder(sum);
526			for (int i = 0; i < iterations; i++) {
527			sum[0] = 0;
528			if (x.indexOf(sneakyAdder) != -1)
529			throw new AssertionError();
530			check.sum(sum[0]);}}},
531			new Job(klazz + " lastIndexOf") {
532			public void work() throws Throwable {
533			int[] sum = new int[1];
534			Object sneakyAdder = sneakyAdder(sum);
535			for (int i = 0; i < iterations; i++) {
536			sum[0] = 0;
537			if (x.lastIndexOf(sneakyAdder) != -1)
538			throw new AssertionError();
539			check.sum(sum[0]);}}});
540	jsr166	1.30	}
541	jsr166	1.1	}