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 == 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());
    }

    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:	1.34
Committed:	Sun Jan 28 07:02:19 2018 UTC (6 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.33:	+1 -1 lines
Log Message:	whitespace
#	Content
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	import static java.util.stream.Collectors.summingInt;
31	import static java.util.stream.Collectors.toCollection;
32
33	import java.lang.ref.WeakReference;
34	import java.util.ArrayDeque;
35	import java.util.ArrayList;
36	import java.util.Collection;
37	import java.util.Collections;
38	import java.util.Deque;
39	import java.util.Iterator;
40	import java.util.LinkedList;
41	import java.util.List;
42	import java.util.ListIterator;
43	import java.util.PriorityQueue;
44	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	import java.util.concurrent.CopyOnWriteArrayList;
50	import java.util.concurrent.LinkedBlockingDeque;
51	import java.util.concurrent.LinkedBlockingQueue;
52	import java.util.concurrent.LinkedTransferQueue;
53	import java.util.concurrent.PriorityBlockingQueue;
54	import java.util.concurrent.CountDownLatch;
55	import java.util.concurrent.ThreadLocalRandom;
56	import java.util.concurrent.TimeUnit;
57	import java.util.concurrent.atomic.LongAdder;
58	import java.util.regex.Pattern;
59	import java.util.stream.Stream;
60
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	final int iterations;
81	final int size; // number of elements in collections
82	final double warmupSeconds;
83	final long warmupNanos;
84	final Pattern nameFilter; // select subset of Jobs to run
85	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	nameFilter = patternArg(args, "filter");
93	reverse = booleanArg(args, "reverse");
94	shuffle = booleanArg(args, "shuffle");
95
96	warmupNanos = (long) (warmupSeconds * (1000L * 1000L * 1000L));
97	}
98
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	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	}
139	return nanoss;
140	}
141
142	void time(List<Job> jobs) throws Throwable {
143	if (warmupNanos > 0) time0(jobs); // Warm up run
144	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	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	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	static class Check {
230	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	volatile Check check = new Check();
239
240	public static void main(String[] args) throws Throwable {
241	new IteratorMicroBenchmark(args).run();
242	}
243
244	void run() throws Throwable {
245	// System.out.printf(
246	// "iterations=%d size=%d, warmup=%1g, filter=\"%s\"%n",
247	// iterations, size, warmupSeconds, nameFilter);
248
249	final ArrayList<Integer> al = new ArrayList<>(size);
250
251	// Populate collections with random data
252	final ThreadLocalRandom rnd = ThreadLocalRandom.current();
253	for (int i = 0; i < size; i++)
254	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	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 ->
280	nameFilter == null \|\| nameFilter.matcher(job.name()).find())
281	.collect(toCollection(ArrayList::new));
282
283	if (reverse) Collections.reverse(jobs);
284	if (shuffle) Collections.shuffle(jobs);
285
286	time(jobs);
287	}
288
289	@SafeVarargs @SuppressWarnings("varargs")
290	private <T> Stream<T> concatStreams(Stream<T> ... streams) {
291	return Stream.of(streams).flatMap(s -> s);
292	}
293
294	Stream<Job> jobs(Collection<Integer> x) {
295	return concatStreams(
296	collectionJobs(x),
297	(x instanceof Deque)
298	? dequeJobs((Deque<Integer>)x)
299	: Stream.empty(),
300	(x instanceof List)
301	? listJobs((List<Integer>)x)
302	: Stream.empty());
303	}
304
305	Stream<Job> collectionJobs(Collection<Integer> x) {
306	String klazz = x.getClass().getSimpleName();
307	return Stream.of(
308	new Job(klazz + " iterate for loop") {
309	public void work() throws Throwable {
310	for (int i = 0; i < iterations; i++) {
311	int sum = 0;
312	for (Integer n : x)
313	sum += n;
314	check.sum(sum);}}},
315	new Job(klazz + " iterator().forEachRemaining()") {
316	public void work() throws Throwable {
317	int[] sum = new int[1];
318	for (int i = 0; i < iterations; i++) {
319	sum[0] = 0;
320	x.iterator().forEachRemaining(n -> sum[0] += n);
321	check.sum(sum[0]);}}},
322	new Job(klazz + " spliterator().tryAdvance()") {
323	public void work() throws Throwable {
324	int[] sum = new int[1];
325	for (int i = 0; i < iterations; i++) {
326	sum[0] = 0;
327	Spliterator<Integer> spliterator = x.spliterator();
328	do {} while (spliterator.tryAdvance(n -> sum[0] += n));
329	check.sum(sum[0]);}}},
330	new Job(klazz + " spliterator().forEachRemaining()") {
331	public void work() throws Throwable {
332	int[] sum = new int[1];
333	for (int i = 0; i < iterations; i++) {
334	sum[0] = 0;
335	x.spliterator().forEachRemaining(n -> sum[0] += n);
336	check.sum(sum[0]);}}},
337	new Job(klazz + " removeIf") {
338	public void work() throws Throwable {
339	int[] sum = new int[1];
340	for (int i = 0; i < iterations; i++) {
341	sum[0] = 0;
342	if (x.removeIf(n -> { sum[0] += n; return false; }))
343	throw new AssertionError();
344	check.sum(sum[0]);}}},
345	new Job(klazz + " contains") {
346	public void work() throws Throwable {
347	int[] sum = new int[1];
348	Object y = new Object() {
349	public boolean equals(Object z) {
350	sum[0] += (int) z; return false; }};
351	for (int i = 0; i < iterations; i++) {
352	sum[0] = 0;
353	if (x.contains(y)) throw new AssertionError();
354	check.sum(sum[0]);}}},
355	new Job(klazz + " remove(Object)") {
356	public void work() throws Throwable {
357	int[] sum = new int[1];
358	Object y = new Object() {
359	public boolean equals(Object z) {
360	sum[0] += (int) z; return false; }};
361	for (int i = 0; i < iterations; i++) {
362	sum[0] = 0;
363	if (x.remove(y)) throw new AssertionError();
364	check.sum(sum[0]);}}},
365	new Job(klazz + " forEach") {
366	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.forEach(n -> sum[0] += n);
371	check.sum(sum[0]);}}},
372	new Job(klazz + " toArray()") {
373	public void work() throws Throwable {
374	int[] sum = new int[1];
375	for (int i = 0; i < iterations; i++) {
376	sum[0] = 0;
377	for (Object o : x.toArray())
378	sum[0] += (Integer) o;
379	check.sum(sum[0]);}}},
380	new Job(klazz + " toArray(a)") {
381	public void work() throws Throwable {
382	Integer[] a = new Integer[x.size()];
383	int[] sum = new int[1];
384	for (int i = 0; i < iterations; i++) {
385	sum[0] = 0;
386	x.toArray(a);
387	for (Object o : a)
388	sum[0] += (Integer) o;
389	check.sum(sum[0]);}}},
390	new Job(klazz + " toArray(empty)") {
391	public void work() throws Throwable {
392	Integer[] empty = new Integer[0];
393	int[] sum = new int[1];
394	for (int i = 0; i < iterations; i++) {
395	sum[0] = 0;
396	for (Integer o : x.toArray(empty))
397	sum[0] += o;
398	check.sum(sum[0]);}}},
399	new Job(klazz + " stream().forEach") {
400	public void work() throws Throwable {
401	int[] sum = new int[1];
402	for (int i = 0; i < iterations; i++) {
403	sum[0] = 0;
404	x.stream().forEach(n -> sum[0] += n);
405	check.sum(sum[0]);}}},
406	new Job(klazz + " stream().mapToInt") {
407	public void work() throws Throwable {
408	for (int i = 0; i < iterations; i++) {
409	check.sum(x.stream().mapToInt(e -> e).sum());}}},
410	new Job(klazz + " stream().collect") {
411	public void work() throws Throwable {
412	for (int i = 0; i < iterations; i++) {
413	check.sum(x.stream()
414	.collect(summingInt(e -> e)));}}},
415	new Job(klazz + " stream()::iterator") {
416	public void work() throws Throwable {
417	int[] sum = new int[1];
418	for (int i = 0; i < iterations; i++) {
419	sum[0] = 0;
420	for (Integer o : (Iterable<Integer>) x.stream()::iterator)
421	sum[0] += o;
422	check.sum(sum[0]);}}},
423	new Job(klazz + " parallelStream().forEach") {
424	public void work() throws Throwable {
425	for (int i = 0; i < iterations; i++) {
426	LongAdder sum = new LongAdder();
427	x.parallelStream().forEach(n -> sum.add(n));
428	check.sum((int) sum.sum());}}},
429	new Job(klazz + " parallelStream().mapToInt") {
430	public void work() throws Throwable {
431	for (int i = 0; i < iterations; i++) {
432	check.sum(x.parallelStream().mapToInt(e -> e).sum());}}},
433	new Job(klazz + " parallelStream().collect") {
434	public void work() throws Throwable {
435	for (int i = 0; i < iterations; i++) {
436	check.sum(x.parallelStream()
437	.collect(summingInt(e -> e)));}}},
438	new Job(klazz + " parallelStream()::iterator") {
439	public void work() throws Throwable {
440	int[] sum = new int[1];
441	for (int i = 0; i < iterations; i++) {
442	sum[0] = 0;
443	for (Integer o : (Iterable<Integer>) x.parallelStream()::iterator)
444	sum[0] += o;
445	check.sum(sum[0]);}}});
446	}
447
448	Stream<Job> dequeJobs(Deque<Integer> x) {
449	String klazz = x.getClass().getSimpleName();
450	return Stream.of(
451	new Job(klazz + " descendingIterator() loop") {
452	public void work() throws Throwable {
453	for (int i = 0; i < iterations; i++) {
454	int sum = 0;
455	Iterator<Integer> it = x.descendingIterator();
456	while (it.hasNext())
457	sum += it.next();
458	check.sum(sum);}}},
459	new Job(klazz + " descendingIterator().forEachRemaining()") {
460	public void work() throws Throwable {
461	int[] sum = new int[1];
462	for (int i = 0; i < iterations; i++) {
463	sum[0] = 0;
464	x.descendingIterator().forEachRemaining(n -> sum[0] += n);
465	check.sum(sum[0]);}}});
466	}
467
468	Stream<Job> listJobs(List<Integer> x) {
469	String klazz = x.getClass().getSimpleName();
470	return Stream.of(
471	new Job(klazz + " subList toArray()") {
472	public void work() throws Throwable {
473	int size = x.size();
474	for (int i = 0; i < iterations; i++) {
475	int total = Stream.of(x.subList(0, size / 2),
476	x.subList(size / 2, size))
477	.mapToInt(subList -> {
478	int sum = 0;
479	for (Object o : subList.toArray())
480	sum += (Integer) o;
481	return sum; })
482	.sum();
483	check.sum(total);}}},
484	new Job(klazz + " subList toArray(a)") {
485	public void work() throws Throwable {
486	int size = x.size();
487	for (int i = 0; i < iterations; i++) {
488	int total = Stream.of(x.subList(0, size / 2),
489	x.subList(size / 2, size))
490	.mapToInt(subList -> {
491	int sum = 0;
492	Integer[] a = new Integer[subList.size()];
493	for (Object o : subList.toArray(a))
494	sum += (Integer) o;
495	return sum; })
496	.sum();
497	check.sum(total);}}},
498	new Job(klazz + " subList toArray(empty)") {
499	public void work() throws Throwable {
500	int size = x.size();
501	Integer[] empty = new Integer[0];
502	for (int i = 0; i < iterations; i++) {
503	int total = Stream.of(x.subList(0, size / 2),
504	x.subList(size / 2, size))
505	.mapToInt(subList -> {
506	int sum = 0;
507	for (Object o : subList.toArray(empty))
508	sum += (Integer) o;
509	return sum; })
510	.sum();
511	check.sum(total);}}});
512	}
513	}