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;
import java.util.function.ToIntFunction;

/**
 * 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;
    }

    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) 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 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 {
//         System.out.printf(
//             "iterations=%d size=%d, warmup=%1g, filter=\"%s\"%n",
//             iterations, size, warmupSeconds, nameFilter);

        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]);}}});
    }

    <T> Job iterateJob(String name, T x, ToIntFunction<T> sumFunction) {
        return new Job(name) {
            public void work() throws Throwable {
                for (int i = 0; i < iterations; i++) {
                    check.sum(sumFunction.applyAsInt(x));}}};
    }

    Stream<Job> listJobs(List<Integer> x) {
        final String klazz = goodClassName(x.getClass());
        final int[] sneakySum = new int[1];
        final Object sneakyAdder = sneakyAdder(sneakySum);

        return Stream.of(
            iterateJob(
                klazz + " indexOf", x,
                z -> {
                    sneakySum[0] = 0;
                    if (z.indexOf(sneakyAdder) != -1) throw new AssertionError();
                    return sneakySum[0]; }),
            iterateJob(
                klazz + " lastIndexOf", x,
                z -> {
                    sneakySum[0] = 0;
                    if (z.lastIndexOf(sneakyAdder) != -1) throw new AssertionError();
                    return sneakySum[0]; }));
    }
}
Revision:	1.37
Committed:	Sun Mar 25 19:00:09 2018 UTC (6 years, 2 months ago) by jsr166
Branch:	MAIN
Changes since 1.36:	+0 -58 lines
Log Message:	delete experimental subListJob code
#	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	1.36	import java.util.function.ToIntFunction;
62	jsr166	1.1
63			/**
64			* Usage: [iterations=N] [size=N] [filter=REGEXP] [warmup=SECONDS]
65			*
66			* To run this in micro-benchmark mode, simply run as a normal java program.
67			* Be patient; this program runs for a very long time.
68			* For faster runs, restrict execution using command line args.
69			*
70			* This is an interface based version of ArrayList/IteratorMicroBenchmark
71			*
72			* @author Martin Buchholz
73			*/
74			public class IteratorMicroBenchmark {
75			abstract static class Job {
76			private final String name;
77			public Job(String name) { this.name = name; }
78			public String name() { return name; }
79			public abstract void work() throws Throwable;
80			}
81
82	jsr166	1.11	final int iterations;
83			final int size; // number of elements in collections
84			final double warmupSeconds;
85			final long warmupNanos;
86	jsr166	1.31	final Pattern nameFilter; // select subset of Jobs to run
87	jsr166	1.11	final boolean reverse; // reverse order of Jobs
88			final boolean shuffle; // randomize order of Jobs
89
90			IteratorMicroBenchmark(String[] args) {
91			iterations = intArg(args, "iterations", 10_000);
92			size = intArg(args, "size", 1000);
93			warmupSeconds = doubleArg(args, "warmup", 7.0);
94	jsr166	1.31	nameFilter = patternArg(args, "filter");
95	jsr166	1.11	reverse = booleanArg(args, "reverse");
96			shuffle = booleanArg(args, "shuffle");
97
98			warmupNanos = (long) (warmupSeconds * (1000L * 1000L * 1000L));
99			}
100	jsr166	1.1
101			// --------------- GC finalization infrastructure ---------------
102
103			/** No guarantees, but effective in practice. */
104			static void forceFullGc() {
105			CountDownLatch finalizeDone = new CountDownLatch(1);
106			WeakReference<?> ref = new WeakReference<Object>(new Object() {
107	jsr166	1.36	@SuppressWarnings("deprecation")
108	jsr166	1.1	protected void finalize() { finalizeDone.countDown(); }});
109			try {
110			for (int i = 0; i < 10; i++) {
111			System.gc();
112			if (finalizeDone.await(1L, TimeUnit.SECONDS) && ref.get() == null) {
113			System.runFinalization(); // try to pick up stragglers
114			return;
115			}
116			}
117			} catch (InterruptedException unexpected) {
118			throw new AssertionError("unexpected InterruptedException");
119			}
120			throw new AssertionError("failed to do a \"full\" gc");
121			}
122
123			/**
124			* Runs each job for long enough that all the runtime compilers
125			* have had plenty of time to warm up, i.e. get around to
126			* compiling everything worth compiling.
127			* Returns array of average times per job per run.
128			*/
129			long[] time0(List<Job> jobs) throws Throwable {
130			final int size = jobs.size();
131			long[] nanoss = new long[size];
132			for (int i = 0; i < size; i++) {
133			if (warmupNanos > 0) forceFullGc();
134	jsr166	1.9	Job job = jobs.get(i);
135			long totalTime;
136			int runs = 0;
137			long startTime = System.nanoTime();
138			do { job.work(); runs++; }
139			while ((totalTime = System.nanoTime() - startTime) < warmupNanos);
140			nanoss[i] = totalTime/runs;
141	jsr166	1.1	}
142			return nanoss;
143			}
144
145			void time(List<Job> jobs) throws Throwable {
146	jsr166	1.9	if (warmupNanos > 0) time0(jobs); // Warm up run
147	jsr166	1.1	final int size = jobs.size();
148			final long[] nanoss = time0(jobs); // Real timing run
149			final long[] milliss = new long[size];
150			final double[] ratios = new double[size];
151
152			final String nameHeader = "Method";
153			final String millisHeader = "Millis";
154			final String ratioHeader = "Ratio";
155
156			int nameWidth = nameHeader.length();
157			int millisWidth = millisHeader.length();
158			int ratioWidth = ratioHeader.length();
159
160			for (int i = 0; i < size; i++) {
161			nameWidth = Math.max(nameWidth, jobs.get(i).name().length());
162
163			milliss[i] = nanoss[i]/(1000L * 1000L);
164			millisWidth = Math.max(millisWidth,
165			String.format("%d", milliss[i]).length());
166
167			ratios[i] = (double) nanoss[i] / (double) nanoss[0];
168			ratioWidth = Math.max(ratioWidth,
169			String.format("%.3f", ratios[i]).length());
170			}
171
172			String format = String.format("%%-%ds %%%dd %%%d.3f%%n",
173			nameWidth, millisWidth, ratioWidth);
174			String headerFormat = String.format("%%-%ds %%%ds %%%ds%%n",
175			nameWidth, millisWidth, ratioWidth);
176			System.out.printf(headerFormat, "Method", "Millis", "Ratio");
177
178			// Print out absolute and relative times, calibrated against first job
179			for (int i = 0; i < size; i++)
180			System.out.printf(format, jobs.get(i).name(), milliss[i], ratios[i]);
181			}
182
183			private static String keywordValue(String[] args, String keyword) {
184			for (String arg : args)
185			if (arg.startsWith(keyword))
186			return arg.substring(keyword.length() + 1);
187			return null;
188			}
189
190			private static int intArg(String[] args, String keyword, int defaultValue) {
191			String val = keywordValue(args, keyword);
192			return (val == null) ? defaultValue : Integer.parseInt(val);
193			}
194
195			private static double doubleArg(String[] args, String keyword, double defaultValue) {
196			String val = keywordValue(args, keyword);
197			return (val == null) ? defaultValue : Double.parseDouble(val);
198			}
199
200			private static Pattern patternArg(String[] args, String keyword) {
201			String val = keywordValue(args, keyword);
202			return (val == null) ? null : Pattern.compile(val);
203			}
204
205	jsr166	1.10	private static boolean booleanArg(String[] args, String keyword) {
206			String val = keywordValue(args, keyword);
207			if (val == null \|\| val.equals("false")) return false;
208			if (val.equals("true")) return true;
209			throw new IllegalArgumentException(val);
210			}
211
212	jsr166	1.1	private static void deoptimize(int sum) {
213			if (sum == 42)
214			System.out.println("the answer");
215			}
216
217			private static <T> Iterable<T> backwards(final List<T> list) {
218			return new Iterable<T>() {
219			public Iterator<T> iterator() {
220			return new Iterator<T>() {
221			final ListIterator<T> it = list.listIterator(list.size());
222			public boolean hasNext() { return it.hasPrevious(); }
223			public T next() { return it.previous(); }
224			public void remove() { it.remove(); }};}};
225			}
226
227			// Checks for correctness and prevents loop optimizations
228	jsr166	1.25	static class Check {
229	jsr166	1.1	private int sum;
230			public void sum(int sum) {
231			if (this.sum == 0)
232			this.sum = sum;
233			if (this.sum != sum)
234			throw new AssertionError("Sum mismatch");
235			}
236			}
237	jsr166	1.2	volatile Check check = new Check();
238	jsr166	1.1
239			public static void main(String[] args) throws Throwable {
240	jsr166	1.11	new IteratorMicroBenchmark(args).run();
241	jsr166	1.1	}
242
243	jsr166	1.36	HashMap<Class<?>, String> goodClassName = new HashMap<>();
244
245			String goodClassName(Class<?> klazz) {
246			return goodClassName.computeIfAbsent(
247			klazz,
248			k -> {
249			String simple = k.getSimpleName();
250			return (simple.equals("SubList")) // too simple!
251			? k.getName().replaceFirst(".*\\.", "")
252			: simple;
253			});
254			}
255
256			static List<Integer> makeSubList(List<Integer> list) {
257			final ThreadLocalRandom rnd = ThreadLocalRandom.current();
258			int size = list.size();
259			if (size <= 2) return list.subList(0, size);
260			List<Integer> subList = list.subList(rnd.nextInt(0, 2),
261			size - rnd.nextInt(0, 2));
262			List<Integer> copy = new ArrayList<>(list);
263			subList.clear();
264			subList.addAll(copy);
265			return subList;
266			}
267
268	jsr166	1.11	void run() throws Throwable {
269	jsr166	1.1	// System.out.printf(
270			// "iterations=%d size=%d, warmup=%1g, filter=\"%s\"%n",
271	jsr166	1.31	// iterations, size, warmupSeconds, nameFilter);
272	jsr166	1.1
273	jsr166	1.17	final ArrayList<Integer> al = new ArrayList<>(size);
274	jsr166	1.1
275			// Populate collections with random data
276			final ThreadLocalRandom rnd = ThreadLocalRandom.current();
277	jsr166	1.3	for (int i = 0; i < size; i++)
278	jsr166	1.1	al.add(rnd.nextInt(size));
279
280			final ArrayDeque<Integer> ad = new ArrayDeque<>(al);
281			final ArrayBlockingQueue<Integer> abq = new ArrayBlockingQueue<>(al.size());
282			abq.addAll(al);
283
284			// shuffle circular array elements so they wrap
285			for (int i = 0, n = rnd.nextInt(size); i < n; i++) {
286			ad.addLast(ad.removeFirst());
287			abq.add(abq.remove());
288			}
289
290	jsr166	1.31	ArrayList<Job> jobs = Stream.<Collection<Integer>>of(
291			al, ad, abq,
292	jsr166	1.36	makeSubList(new ArrayList<>(al)),
293	jsr166	1.31	new LinkedList<>(al),
294	jsr166	1.36	makeSubList(new LinkedList<>(al)),
295	jsr166	1.31	new PriorityQueue<>(al),
296			new Vector<>(al),
297	jsr166	1.36	makeSubList(new Vector<>(al)),
298	jsr166	1.31	new CopyOnWriteArrayList<>(al),
299	jsr166	1.36	makeSubList(new CopyOnWriteArrayList<>(al)),
300	jsr166	1.31	new ConcurrentLinkedQueue<>(al),
301			new ConcurrentLinkedDeque<>(al),
302			new LinkedBlockingQueue<>(al),
303			new LinkedBlockingDeque<>(al),
304			new LinkedTransferQueue<>(al),
305			new PriorityBlockingQueue<>(al))
306			.flatMap(x -> jobs(x))
307	jsr166	1.33	.filter(job ->
308			nameFilter == null \|\| nameFilter.matcher(job.name()).find())
309	jsr166	1.31	.collect(toCollection(ArrayList::new));
310	jsr166	1.1
311	jsr166	1.11	if (reverse) Collections.reverse(jobs);
312	jsr166	1.10	if (shuffle) Collections.shuffle(jobs);
313
314	jsr166	1.31	time(jobs);
315			}
316
317	jsr166	1.32	@SafeVarargs @SuppressWarnings("varargs")
318			private <T> Stream<T> concatStreams(Stream<T> ... streams) {
319			return Stream.of(streams).flatMap(s -> s);
320			}
321	jsr166	1.34
322	jsr166	1.31	Stream<Job> jobs(Collection<Integer> x) {
323	jsr166	1.32	return concatStreams(
324			collectionJobs(x),
325			(x instanceof Deque)
326			? dequeJobs((Deque<Integer>)x)
327			: Stream.empty(),
328			(x instanceof List)
329			? listJobs((List<Integer>)x)
330			: Stream.empty());
331	jsr166	1.1	}
332
333	jsr166	1.36	Object sneakyAdder(int[] sneakySum) {
334			return new Object() {
335			public int hashCode() { throw new AssertionError(); }
336			public boolean equals(Object z) {
337			sneakySum[0] += (int) z; return false; }};
338			}
339
340	jsr166	1.31	Stream<Job> collectionJobs(Collection<Integer> x) {
341	jsr166	1.36	final String klazz = goodClassName(x.getClass());
342	jsr166	1.31	return Stream.of(
343	jsr166	1.5	new Job(klazz + " iterate for loop") {
344	jsr166	1.1	public void work() throws Throwable {
345			for (int i = 0; i < iterations; i++) {
346			int sum = 0;
347			for (Integer n : x)
348			sum += n;
349			check.sum(sum);}}},
350	jsr166	1.18	new Job(klazz + " iterator().forEachRemaining()") {
351	jsr166	1.1	public void work() throws Throwable {
352			int[] sum = new int[1];
353			for (int i = 0; i < iterations; i++) {
354			sum[0] = 0;
355			x.iterator().forEachRemaining(n -> sum[0] += n);
356			check.sum(sum[0]);}}},
357	jsr166	1.18	new Job(klazz + " spliterator().tryAdvance()") {
358	jsr166	1.1	public void work() throws Throwable {
359			int[] sum = new int[1];
360			for (int i = 0; i < iterations; i++) {
361			sum[0] = 0;
362			Spliterator<Integer> spliterator = x.spliterator();
363			do {} while (spliterator.tryAdvance(n -> sum[0] += n));
364			check.sum(sum[0]);}}},
365	jsr166	1.18	new Job(klazz + " spliterator().forEachRemaining()") {
366	jsr166	1.1	public void work() throws Throwable {
367			int[] sum = new int[1];
368			for (int i = 0; i < iterations; i++) {
369			sum[0] = 0;
370			x.spliterator().forEachRemaining(n -> sum[0] += n);
371			check.sum(sum[0]);}}},
372	jsr166	1.18	new Job(klazz + " removeIf") {
373	jsr166	1.1	public void work() throws Throwable {
374			int[] sum = new int[1];
375			for (int i = 0; i < iterations; i++) {
376			sum[0] = 0;
377	jsr166	1.16	if (x.removeIf(n -> { sum[0] += n; return false; }))
378			throw new AssertionError();
379	jsr166	1.1	check.sum(sum[0]);}}},
380	jsr166	1.18	new Job(klazz + " contains") {
381	jsr166	1.14	public void work() throws Throwable {
382			int[] sum = new int[1];
383	jsr166	1.36	Object sneakyAdder = sneakyAdder(sum);
384	jsr166	1.14	for (int i = 0; i < iterations; i++) {
385			sum[0] = 0;
386	jsr166	1.36	if (x.contains(sneakyAdder)) throw new AssertionError();
387	jsr166	1.16	check.sum(sum[0]);}}},
388	jsr166	1.18	new Job(klazz + " remove(Object)") {
389	jsr166	1.16	public void work() throws Throwable {
390			int[] sum = new int[1];
391	jsr166	1.36	Object sneakyAdder = sneakyAdder(sum);
392	jsr166	1.16	for (int i = 0; i < iterations; i++) {
393			sum[0] = 0;
394	jsr166	1.36	if (x.remove(sneakyAdder)) throw new AssertionError();
395	jsr166	1.14	check.sum(sum[0]);}}},
396	jsr166	1.18	new Job(klazz + " forEach") {
397	jsr166	1.1	public void work() throws Throwable {
398			int[] sum = new int[1];
399			for (int i = 0; i < iterations; i++) {
400			sum[0] = 0;
401			x.forEach(n -> sum[0] += n);
402	jsr166	1.6	check.sum(sum[0]);}}},
403	jsr166	1.18	new Job(klazz + " toArray()") {
404	jsr166	1.6	public void work() throws Throwable {
405			int[] sum = new int[1];
406			for (int i = 0; i < iterations; i++) {
407			sum[0] = 0;
408			for (Object o : x.toArray())
409			sum[0] += (Integer) o;
410			check.sum(sum[0]);}}},
411	jsr166	1.18	new Job(klazz + " toArray(a)") {
412	jsr166	1.6	public void work() throws Throwable {
413			Integer[] a = new Integer[x.size()];
414			int[] sum = new int[1];
415			for (int i = 0; i < iterations; i++) {
416			sum[0] = 0;
417			x.toArray(a);
418			for (Object o : a)
419			sum[0] += (Integer) o;
420	jsr166	1.7	check.sum(sum[0]);}}},
421	jsr166	1.18	new Job(klazz + " toArray(empty)") {
422	jsr166	1.7	public void work() throws Throwable {
423			Integer[] empty = new Integer[0];
424			int[] sum = new int[1];
425			for (int i = 0; i < iterations; i++) {
426			sum[0] = 0;
427			for (Integer o : x.toArray(empty))
428			sum[0] += o;
429	jsr166	1.12	check.sum(sum[0]);}}},
430	jsr166	1.19	new Job(klazz + " stream().forEach") {
431			public void work() throws Throwable {
432			int[] sum = new int[1];
433			for (int i = 0; i < iterations; i++) {
434			sum[0] = 0;
435			x.stream().forEach(n -> sum[0] += n);
436			check.sum(sum[0]);}}},
437			new Job(klazz + " stream().mapToInt") {
438			public void work() throws Throwable {
439			for (int i = 0; i < iterations; i++) {
440			check.sum(x.stream().mapToInt(e -> e).sum());}}},
441	jsr166	1.18	new Job(klazz + " stream().collect") {
442	jsr166	1.12	public void work() throws Throwable {
443			for (int i = 0; i < iterations; i++) {
444			check.sum(x.stream()
445			.collect(summingInt(e -> e)));}}},
446	jsr166	1.21	new Job(klazz + " stream()::iterator") {
447	jsr166	1.20	public void work() throws Throwable {
448			int[] sum = new int[1];
449			for (int i = 0; i < iterations; i++) {
450			sum[0] = 0;
451			for (Integer o : (Iterable<Integer>) x.stream()::iterator)
452			sum[0] += o;
453			check.sum(sum[0]);}}},
454	jsr166	1.19	new Job(klazz + " parallelStream().forEach") {
455			public void work() throws Throwable {
456			for (int i = 0; i < iterations; i++) {
457			LongAdder sum = new LongAdder();
458			x.parallelStream().forEach(n -> sum.add(n));
459			check.sum((int) sum.sum());}}},
460			new Job(klazz + " parallelStream().mapToInt") {
461			public void work() throws Throwable {
462			for (int i = 0; i < iterations; i++) {
463			check.sum(x.parallelStream().mapToInt(e -> e).sum());}}},
464	jsr166	1.18	new Job(klazz + " parallelStream().collect") {
465	jsr166	1.12	public void work() throws Throwable {
466			for (int i = 0; i < iterations; i++) {
467			check.sum(x.parallelStream()
468	jsr166	1.20	.collect(summingInt(e -> e)));}}},
469	jsr166	1.21	new Job(klazz + " parallelStream()::iterator") {
470	jsr166	1.20	public void work() throws Throwable {
471			int[] sum = new int[1];
472			for (int i = 0; i < iterations; i++) {
473			sum[0] = 0;
474			for (Integer o : (Iterable<Integer>) x.parallelStream()::iterator)
475			sum[0] += o;
476			check.sum(sum[0]);}}});
477	jsr166	1.1	}
478
479	jsr166	1.31	Stream<Job> dequeJobs(Deque<Integer> x) {
480	jsr166	1.36	String klazz = goodClassName(x.getClass());
481	jsr166	1.31	return Stream.of(
482	jsr166	1.18	new Job(klazz + " descendingIterator() loop") {
483	jsr166	1.1	public void work() throws Throwable {
484			for (int i = 0; i < iterations; i++) {
485			int sum = 0;
486			Iterator<Integer> it = x.descendingIterator();
487			while (it.hasNext())
488			sum += it.next();
489			check.sum(sum);}}},
490	jsr166	1.18	new Job(klazz + " descendingIterator().forEachRemaining()") {
491	jsr166	1.1	public void work() throws Throwable {
492			int[] sum = new int[1];
493			for (int i = 0; i < iterations; i++) {
494			sum[0] = 0;
495			x.descendingIterator().forEachRemaining(n -> sum[0] += n);
496			check.sum(sum[0]);}}});
497			}
498	jsr166	1.30
499	jsr166	1.36	<T> Job iterateJob(String name, T x, ToIntFunction<T> sumFunction) {
500			return new Job(name) {
501			public void work() throws Throwable {
502			for (int i = 0; i < iterations; i++) {
503			check.sum(sumFunction.applyAsInt(x));}}};
504			}
505
506	jsr166	1.31	Stream<Job> listJobs(List<Integer> x) {
507	jsr166	1.36	final String klazz = goodClassName(x.getClass());
508			final int[] sneakySum = new int[1];
509			final Object sneakyAdder = sneakyAdder(sneakySum);
510
511	jsr166	1.31	return Stream.of(
512	jsr166	1.36	iterateJob(
513			klazz + " indexOf", x,
514			z -> {
515			sneakySum[0] = 0;
516			if (z.indexOf(sneakyAdder) != -1) throw new AssertionError();
517			return sneakySum[0]; }),
518			iterateJob(
519			klazz + " lastIndexOf", x,
520			z -> {
521			sneakySum[0] = 0;
522			if (z.lastIndexOf(sneakyAdder) != -1) throw new AssertionError();
523			return sneakySum[0]; }));
524	jsr166	1.30	}
525	jsr166	1.1	}