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.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;
    }

    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() {
            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> 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(); }};}};
    }

    // 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();
    }

    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,
                new LinkedList<>(al),
                new PriorityQueue<>(al),
                new Vector<>(al),
                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.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());
    }

    Stream<Job> collectionJobs(Collection<Integer> x) {
        String klazz = x.getClass().getSimpleName();
        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 y = new Object() {
                        public boolean equals(Object z) {
                            sum[0] += (int) z; return false; }};
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        if (x.contains(y)) throw new AssertionError();
                        check.sum(sum[0]);}}},
            new Job(klazz + " remove(Object)") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    Object y = new Object() {
                        public boolean equals(Object z) {
                            sum[0] += (int) z; return false; }};
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        if (x.remove(y)) 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 = x.getClass().getSimpleName();
        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) {
        String klazz = x.getClass().getSimpleName();
        return Stream.of(
            new Job(klazz + " subList toArray()") {
                public void work() throws Throwable {
                    int size = x.size();
                    for (int i = 0; i < iterations; i++) {
                        int total = Stream.of(x.subList(0, size / 2),
                                              x.subList(size / 2, size))
                            .mapToInt(subList -> {
                                int sum = 0;
                                for (Object o : subList.toArray())
                                    sum += (Integer) o;
                                return sum; })
                            .sum();
                        check.sum(total);}}},
            new Job(klazz + " subList toArray(a)") {
                public void work() throws Throwable {
                    int size = x.size();
                    for (int i = 0; i < iterations; i++) {
                        int total = Stream.of(x.subList(0, size / 2),
                                              x.subList(size / 2, size))
                            .mapToInt(subList -> {
                                int sum = 0;
                                Integer[] a = new Integer[subList.size()];
                                for (Object o : subList.toArray(a))
                                    sum += (Integer) o;
                                return sum; })
                            .sum();
                        check.sum(total);}}},
            new Job(klazz + " subList toArray(empty)") {
                public void work() throws Throwable {
                    int size = x.size();
                    Integer[] empty = new Integer[0];
                    for (int i = 0; i < iterations; i++) {
                        int total = Stream.of(x.subList(0, size / 2),
                                              x.subList(size / 2, size))
                            .mapToInt(subList -> {
                                int sum = 0;
                                for (Object o : subList.toArray(empty))
                                    sum += (Integer) o;
                                return sum; })
                            .sum();
                        check.sum(total);}}});
    }
}
Revision:	1.32
Committed:	Sat Jan 27 20:27:09 2018 UTC (6 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.31:	+13 -9 lines
Log Message:	concatStreams
#	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			import java.util.Iterator;
40	jsr166	1.13	import java.util.LinkedList;
41	jsr166	1.1	import java.util.List;
42			import java.util.ListIterator;
43	jsr166	1.8	import java.util.PriorityQueue;
44	jsr166	1.1	import java.util.Spliterator;
45			import java.util.Vector;
46			import java.util.concurrent.ArrayBlockingQueue;
47			import java.util.concurrent.ConcurrentLinkedDeque;
48			import java.util.concurrent.ConcurrentLinkedQueue;
49	jsr166	1.30	import java.util.concurrent.CopyOnWriteArrayList;
50	jsr166	1.1	import java.util.concurrent.LinkedBlockingDeque;
51			import java.util.concurrent.LinkedBlockingQueue;
52			import java.util.concurrent.LinkedTransferQueue;
53	jsr166	1.8	import java.util.concurrent.PriorityBlockingQueue;
54	jsr166	1.1	import java.util.concurrent.CountDownLatch;
55			import java.util.concurrent.ThreadLocalRandom;
56			import java.util.concurrent.TimeUnit;
57	jsr166	1.19	import java.util.concurrent.atomic.LongAdder;
58	jsr166	1.1	import java.util.regex.Pattern;
59	jsr166	1.30	import java.util.stream.Stream;
60	jsr166	1.1
61			/**
62			* Usage: [iterations=N] [size=N] [filter=REGEXP] [warmup=SECONDS]
63			*
64			* To run this in micro-benchmark mode, simply run as a normal java program.
65			* Be patient; this program runs for a very long time.
66			* For faster runs, restrict execution using command line args.
67			*
68			* This is an interface based version of ArrayList/IteratorMicroBenchmark
69			*
70			* @author Martin Buchholz
71			*/
72			public class IteratorMicroBenchmark {
73			abstract static class Job {
74			private final String name;
75			public Job(String name) { this.name = name; }
76			public String name() { return name; }
77			public abstract void work() throws Throwable;
78			}
79
80	jsr166	1.11	final int iterations;
81			final int size; // number of elements in collections
82			final double warmupSeconds;
83			final long warmupNanos;
84	jsr166	1.31	final Pattern nameFilter; // select subset of Jobs to run
85	jsr166	1.11	final boolean reverse; // reverse order of Jobs
86			final boolean shuffle; // randomize order of Jobs
87
88			IteratorMicroBenchmark(String[] args) {
89			iterations = intArg(args, "iterations", 10_000);
90			size = intArg(args, "size", 1000);
91			warmupSeconds = doubleArg(args, "warmup", 7.0);
92	jsr166	1.31	nameFilter = patternArg(args, "filter");
93	jsr166	1.11	reverse = booleanArg(args, "reverse");
94			shuffle = booleanArg(args, "shuffle");
95
96			warmupNanos = (long) (warmupSeconds * (1000L * 1000L * 1000L));
97			}
98	jsr166	1.1
99			// --------------- GC finalization infrastructure ---------------
100
101			/** No guarantees, but effective in practice. */
102			static void forceFullGc() {
103			CountDownLatch finalizeDone = new CountDownLatch(1);
104			WeakReference<?> ref = new WeakReference<Object>(new Object() {
105			protected void finalize() { finalizeDone.countDown(); }});
106			try {
107			for (int i = 0; i < 10; i++) {
108			System.gc();
109			if (finalizeDone.await(1L, TimeUnit.SECONDS) && ref.get() == null) {
110			System.runFinalization(); // try to pick up stragglers
111			return;
112			}
113			}
114			} catch (InterruptedException unexpected) {
115			throw new AssertionError("unexpected InterruptedException");
116			}
117			throw new AssertionError("failed to do a \"full\" gc");
118			}
119
120			/**
121			* Runs each job for long enough that all the runtime compilers
122			* have had plenty of time to warm up, i.e. get around to
123			* compiling everything worth compiling.
124			* Returns array of average times per job per run.
125			*/
126			long[] time0(List<Job> jobs) throws Throwable {
127			final int size = jobs.size();
128			long[] nanoss = new long[size];
129			for (int i = 0; i < size; i++) {
130			if (warmupNanos > 0) forceFullGc();
131	jsr166	1.9	Job job = jobs.get(i);
132			long totalTime;
133			int runs = 0;
134			long startTime = System.nanoTime();
135			do { job.work(); runs++; }
136			while ((totalTime = System.nanoTime() - startTime) < warmupNanos);
137			nanoss[i] = totalTime/runs;
138	jsr166	1.1	}
139			return nanoss;
140			}
141
142			void time(List<Job> jobs) throws Throwable {
143	jsr166	1.9	if (warmupNanos > 0) time0(jobs); // Warm up run
144	jsr166	1.1	final int size = jobs.size();
145			final long[] nanoss = time0(jobs); // Real timing run
146			final long[] milliss = new long[size];
147			final double[] ratios = new double[size];
148
149			final String nameHeader = "Method";
150			final String millisHeader = "Millis";
151			final String ratioHeader = "Ratio";
152
153			int nameWidth = nameHeader.length();
154			int millisWidth = millisHeader.length();
155			int ratioWidth = ratioHeader.length();
156
157			for (int i = 0; i < size; i++) {
158			nameWidth = Math.max(nameWidth, jobs.get(i).name().length());
159
160			milliss[i] = nanoss[i]/(1000L * 1000L);
161			millisWidth = Math.max(millisWidth,
162			String.format("%d", milliss[i]).length());
163
164			ratios[i] = (double) nanoss[i] / (double) nanoss[0];
165			ratioWidth = Math.max(ratioWidth,
166			String.format("%.3f", ratios[i]).length());
167			}
168
169			String format = String.format("%%-%ds %%%dd %%%d.3f%%n",
170			nameWidth, millisWidth, ratioWidth);
171			String headerFormat = String.format("%%-%ds %%%ds %%%ds%%n",
172			nameWidth, millisWidth, ratioWidth);
173			System.out.printf(headerFormat, "Method", "Millis", "Ratio");
174
175			// Print out absolute and relative times, calibrated against first job
176			for (int i = 0; i < size; i++)
177			System.out.printf(format, jobs.get(i).name(), milliss[i], ratios[i]);
178			}
179
180			private static String keywordValue(String[] args, String keyword) {
181			for (String arg : args)
182			if (arg.startsWith(keyword))
183			return arg.substring(keyword.length() + 1);
184			return null;
185			}
186
187			private static int intArg(String[] args, String keyword, int defaultValue) {
188			String val = keywordValue(args, keyword);
189			return (val == null) ? defaultValue : Integer.parseInt(val);
190			}
191
192			private static double doubleArg(String[] args, String keyword, double defaultValue) {
193			String val = keywordValue(args, keyword);
194			return (val == null) ? defaultValue : Double.parseDouble(val);
195			}
196
197			private static Pattern patternArg(String[] args, String keyword) {
198			String val = keywordValue(args, keyword);
199			return (val == null) ? null : Pattern.compile(val);
200			}
201
202	jsr166	1.10	private static boolean booleanArg(String[] args, String keyword) {
203			String val = keywordValue(args, keyword);
204			if (val == null \|\| val.equals("false")) return false;
205			if (val.equals("true")) return true;
206			throw new IllegalArgumentException(val);
207			}
208
209	jsr166	1.1	private static void deoptimize(int sum) {
210			if (sum == 42)
211			System.out.println("the answer");
212			}
213
214			private static <T> List<T> asSubList(List<T> list) {
215			return list.subList(0, list.size());
216			}
217
218			private static <T> Iterable<T> backwards(final List<T> list) {
219			return new Iterable<T>() {
220			public Iterator<T> iterator() {
221			return new Iterator<T>() {
222			final ListIterator<T> it = list.listIterator(list.size());
223			public boolean hasNext() { return it.hasPrevious(); }
224			public T next() { return it.previous(); }
225			public void remove() { it.remove(); }};}};
226			}
227
228			// Checks for correctness and prevents loop optimizations
229	jsr166	1.25	static class Check {
230	jsr166	1.1	private int sum;
231			public void sum(int sum) {
232			if (this.sum == 0)
233			this.sum = sum;
234			if (this.sum != sum)
235			throw new AssertionError("Sum mismatch");
236			}
237			}
238	jsr166	1.2	volatile Check check = new Check();
239	jsr166	1.1
240			public static void main(String[] args) throws Throwable {
241	jsr166	1.11	new IteratorMicroBenchmark(args).run();
242	jsr166	1.1	}
243
244	jsr166	1.11	void run() throws Throwable {
245	jsr166	1.1	// System.out.printf(
246			// "iterations=%d size=%d, warmup=%1g, filter=\"%s\"%n",
247	jsr166	1.31	// iterations, size, warmupSeconds, nameFilter);
248	jsr166	1.1
249	jsr166	1.17	final ArrayList<Integer> al = new ArrayList<>(size);
250	jsr166	1.1
251			// Populate collections with random data
252			final ThreadLocalRandom rnd = ThreadLocalRandom.current();
253	jsr166	1.3	for (int i = 0; i < size; i++)
254	jsr166	1.1	al.add(rnd.nextInt(size));
255
256			final ArrayDeque<Integer> ad = new ArrayDeque<>(al);
257			final ArrayBlockingQueue<Integer> abq = new ArrayBlockingQueue<>(al.size());
258			abq.addAll(al);
259
260			// shuffle circular array elements so they wrap
261			for (int i = 0, n = rnd.nextInt(size); i < n; i++) {
262			ad.addLast(ad.removeFirst());
263			abq.add(abq.remove());
264			}
265
266	jsr166	1.31	ArrayList<Job> jobs = Stream.<Collection<Integer>>of(
267			al, ad, abq,
268			new LinkedList<>(al),
269			new PriorityQueue<>(al),
270			new Vector<>(al),
271			new CopyOnWriteArrayList<>(al),
272			new ConcurrentLinkedQueue<>(al),
273			new ConcurrentLinkedDeque<>(al),
274			new LinkedBlockingQueue<>(al),
275			new LinkedBlockingDeque<>(al),
276			new LinkedTransferQueue<>(al),
277			new PriorityBlockingQueue<>(al))
278			.flatMap(x -> jobs(x))
279			.filter(job -> nameFilter.matcher(job.name()).find())
280			.collect(toCollection(ArrayList::new));
281	jsr166	1.1
282	jsr166	1.11	if (reverse) Collections.reverse(jobs);
283	jsr166	1.10	if (shuffle) Collections.shuffle(jobs);
284
285	jsr166	1.31	time(jobs);
286			}
287
288	jsr166	1.32	@SafeVarargs @SuppressWarnings("varargs")
289			private <T> Stream<T> concatStreams(Stream<T> ... streams) {
290			return Stream.of(streams).flatMap(s -> s);
291			}
292
293	jsr166	1.31	Stream<Job> jobs(Collection<Integer> x) {
294	jsr166	1.32	return concatStreams(
295			collectionJobs(x),
296			(x instanceof Deque)
297			? dequeJobs((Deque<Integer>)x)
298			: Stream.empty(),
299			(x instanceof List)
300			? listJobs((List<Integer>)x)
301			: Stream.empty());
302	jsr166	1.1	}
303
304	jsr166	1.31	Stream<Job> collectionJobs(Collection<Integer> x) {
305	jsr166	1.1	String klazz = x.getClass().getSimpleName();
306	jsr166	1.31	return Stream.of(
307	jsr166	1.5	new Job(klazz + " iterate for loop") {
308	jsr166	1.1	public void work() throws Throwable {
309			for (int i = 0; i < iterations; i++) {
310			int sum = 0;
311			for (Integer n : x)
312			sum += n;
313			check.sum(sum);}}},
314	jsr166	1.18	new Job(klazz + " iterator().forEachRemaining()") {
315	jsr166	1.1	public void work() throws Throwable {
316			int[] sum = new int[1];
317			for (int i = 0; i < iterations; i++) {
318			sum[0] = 0;
319			x.iterator().forEachRemaining(n -> sum[0] += n);
320			check.sum(sum[0]);}}},
321	jsr166	1.18	new Job(klazz + " spliterator().tryAdvance()") {
322	jsr166	1.1	public void work() throws Throwable {
323			int[] sum = new int[1];
324			for (int i = 0; i < iterations; i++) {
325			sum[0] = 0;
326			Spliterator<Integer> spliterator = x.spliterator();
327			do {} while (spliterator.tryAdvance(n -> sum[0] += n));
328			check.sum(sum[0]);}}},
329	jsr166	1.18	new Job(klazz + " spliterator().forEachRemaining()") {
330	jsr166	1.1	public void work() throws Throwable {
331			int[] sum = new int[1];
332			for (int i = 0; i < iterations; i++) {
333			sum[0] = 0;
334			x.spliterator().forEachRemaining(n -> sum[0] += n);
335			check.sum(sum[0]);}}},
336	jsr166	1.18	new Job(klazz + " removeIf") {
337	jsr166	1.1	public void work() throws Throwable {
338			int[] sum = new int[1];
339			for (int i = 0; i < iterations; i++) {
340			sum[0] = 0;
341	jsr166	1.16	if (x.removeIf(n -> { sum[0] += n; return false; }))
342			throw new AssertionError();
343	jsr166	1.1	check.sum(sum[0]);}}},
344	jsr166	1.18	new Job(klazz + " contains") {
345	jsr166	1.14	public void work() throws Throwable {
346			int[] sum = new int[1];
347	jsr166	1.15	Object y = new Object() {
348			public boolean equals(Object z) {
349			sum[0] += (int) z; return false; }};
350	jsr166	1.14	for (int i = 0; i < iterations; i++) {
351			sum[0] = 0;
352	jsr166	1.16	if (x.contains(y)) throw new AssertionError();
353			check.sum(sum[0]);}}},
354	jsr166	1.18	new Job(klazz + " remove(Object)") {
355	jsr166	1.16	public void work() throws Throwable {
356			int[] sum = new int[1];
357			Object y = new Object() {
358			public boolean equals(Object z) {
359			sum[0] += (int) z; return false; }};
360			for (int i = 0; i < iterations; i++) {
361			sum[0] = 0;
362			if (x.remove(y)) throw new AssertionError();
363	jsr166	1.14	check.sum(sum[0]);}}},
364	jsr166	1.18	new Job(klazz + " forEach") {
365	jsr166	1.1	public void work() throws Throwable {
366			int[] sum = new int[1];
367			for (int i = 0; i < iterations; i++) {
368			sum[0] = 0;
369			x.forEach(n -> sum[0] += n);
370	jsr166	1.6	check.sum(sum[0]);}}},
371	jsr166	1.18	new Job(klazz + " toArray()") {
372	jsr166	1.6	public void work() throws Throwable {
373			int[] sum = new int[1];
374			for (int i = 0; i < iterations; i++) {
375			sum[0] = 0;
376			for (Object o : x.toArray())
377			sum[0] += (Integer) o;
378			check.sum(sum[0]);}}},
379	jsr166	1.18	new Job(klazz + " toArray(a)") {
380	jsr166	1.6	public void work() throws Throwable {
381			Integer[] a = new Integer[x.size()];
382			int[] sum = new int[1];
383			for (int i = 0; i < iterations; i++) {
384			sum[0] = 0;
385			x.toArray(a);
386			for (Object o : a)
387			sum[0] += (Integer) o;
388	jsr166	1.7	check.sum(sum[0]);}}},
389	jsr166	1.18	new Job(klazz + " toArray(empty)") {
390	jsr166	1.7	public void work() throws Throwable {
391			Integer[] empty = new Integer[0];
392			int[] sum = new int[1];
393			for (int i = 0; i < iterations; i++) {
394			sum[0] = 0;
395			for (Integer o : x.toArray(empty))
396			sum[0] += o;
397	jsr166	1.12	check.sum(sum[0]);}}},
398	jsr166	1.19	new Job(klazz + " stream().forEach") {
399			public void work() throws Throwable {
400			int[] sum = new int[1];
401			for (int i = 0; i < iterations; i++) {
402			sum[0] = 0;
403			x.stream().forEach(n -> sum[0] += n);
404			check.sum(sum[0]);}}},
405			new Job(klazz + " stream().mapToInt") {
406			public void work() throws Throwable {
407			for (int i = 0; i < iterations; i++) {
408			check.sum(x.stream().mapToInt(e -> e).sum());}}},
409	jsr166	1.18	new Job(klazz + " stream().collect") {
410	jsr166	1.12	public void work() throws Throwable {
411			for (int i = 0; i < iterations; i++) {
412			check.sum(x.stream()
413			.collect(summingInt(e -> e)));}}},
414	jsr166	1.21	new Job(klazz + " stream()::iterator") {
415	jsr166	1.20	public void work() throws Throwable {
416			int[] sum = new int[1];
417			for (int i = 0; i < iterations; i++) {
418			sum[0] = 0;
419			for (Integer o : (Iterable<Integer>) x.stream()::iterator)
420			sum[0] += o;
421			check.sum(sum[0]);}}},
422	jsr166	1.19	new Job(klazz + " parallelStream().forEach") {
423			public void work() throws Throwable {
424			for (int i = 0; i < iterations; i++) {
425			LongAdder sum = new LongAdder();
426			x.parallelStream().forEach(n -> sum.add(n));
427			check.sum((int) sum.sum());}}},
428			new Job(klazz + " parallelStream().mapToInt") {
429			public void work() throws Throwable {
430			for (int i = 0; i < iterations; i++) {
431			check.sum(x.parallelStream().mapToInt(e -> e).sum());}}},
432	jsr166	1.18	new Job(klazz + " parallelStream().collect") {
433	jsr166	1.12	public void work() throws Throwable {
434			for (int i = 0; i < iterations; i++) {
435			check.sum(x.parallelStream()
436	jsr166	1.20	.collect(summingInt(e -> e)));}}},
437	jsr166	1.21	new Job(klazz + " parallelStream()::iterator") {
438	jsr166	1.20	public void work() throws Throwable {
439			int[] sum = new int[1];
440			for (int i = 0; i < iterations; i++) {
441			sum[0] = 0;
442			for (Integer o : (Iterable<Integer>) x.parallelStream()::iterator)
443			sum[0] += o;
444			check.sum(sum[0]);}}});
445	jsr166	1.1	}
446
447	jsr166	1.31	Stream<Job> dequeJobs(Deque<Integer> x) {
448	jsr166	1.1	String klazz = x.getClass().getSimpleName();
449	jsr166	1.31	return Stream.of(
450	jsr166	1.18	new Job(klazz + " descendingIterator() loop") {
451	jsr166	1.1	public void work() throws Throwable {
452			for (int i = 0; i < iterations; i++) {
453			int sum = 0;
454			Iterator<Integer> it = x.descendingIterator();
455			while (it.hasNext())
456			sum += it.next();
457			check.sum(sum);}}},
458	jsr166	1.18	new Job(klazz + " descendingIterator().forEachRemaining()") {
459	jsr166	1.1	public void work() throws Throwable {
460			int[] sum = new int[1];
461			for (int i = 0; i < iterations; i++) {
462			sum[0] = 0;
463			x.descendingIterator().forEachRemaining(n -> sum[0] += n);
464			check.sum(sum[0]);}}});
465			}
466	jsr166	1.30
467	jsr166	1.31	Stream<Job> listJobs(List<Integer> x) {
468	jsr166	1.30	String klazz = x.getClass().getSimpleName();
469	jsr166	1.31	return Stream.of(
470	jsr166	1.30	new Job(klazz + " subList toArray()") {
471			public void work() throws Throwable {
472			int size = x.size();
473			for (int i = 0; i < iterations; i++) {
474			int total = Stream.of(x.subList(0, size / 2),
475			x.subList(size / 2, size))
476			.mapToInt(subList -> {
477			int sum = 0;
478			for (Object o : subList.toArray())
479			sum += (Integer) o;
480			return sum; })
481			.sum();
482			check.sum(total);}}},
483			new Job(klazz + " subList toArray(a)") {
484			public void work() throws Throwable {
485			int size = x.size();
486			for (int i = 0; i < iterations; i++) {
487			int total = Stream.of(x.subList(0, size / 2),
488			x.subList(size / 2, size))
489			.mapToInt(subList -> {
490			int sum = 0;
491			Integer[] a = new Integer[subList.size()];
492			for (Object o : subList.toArray(a))
493			sum += (Integer) o;
494			return sum; })
495			.sum();
496			check.sum(total);}}},
497			new Job(klazz + " subList toArray(empty)") {
498			public void work() throws Throwable {
499			int size = x.size();
500			Integer[] empty = new Integer[0];
501			for (int i = 0; i < iterations; i++) {
502			int total = Stream.of(x.subList(0, size / 2),
503			x.subList(size / 2, size))
504			.mapToInt(subList -> {
505			int sum = 0;
506			for (Object o : subList.toArray(empty))
507			sum += (Integer) o;
508			return sum; })
509			.sum();
510			check.sum(total);}}});
511			}
512	jsr166	1.1	}