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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

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 * 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

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 */

/* @test

 * @bug 6907760 6929532

 * @summary Tests WatchService behavior when lots of events are pending

 * @library ..

 * @run main/timeout=180 LotsOfEvents

 */

import java.nio.file.*;

import static java.nio.file.StandardWatchEventKind.*;

import java.io.IOException;

import java.io.OutputStream;

import java.util.*;

import java.util.concurrent.TimeUnit;

public class LotsOfEvents {

    static final Random rand = new Random();

    public static void main(String[] args) throws Exception {

        Path dir = TestUtil.createTemporaryDirectory();

        try {

            testOverflowEvent(dir);

            testModifyEventsQueuing(dir);

        } finally {

            TestUtil.removeAll(dir);

        }

    }

    /**

     * Tests that OVERFLOW events are not retreived with other events.

     */

    static void testOverflowEvent(Path dir)

        throws IOException, InterruptedException

    {

        try (WatchService watcher = dir.getFileSystem().newWatchService()) {

            dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE);

            // create a lot of files

            int n = 1024;

            Path[] files = new Path[n];

            for (int i=0; i<n; i++) {

                files[i] = Files.createFile(dir.resolve("foo" + i));

            }

            // give time for events to accumulate (improve chance of overflow)

            Thread.sleep(1000);

            // check that we see the create events (or overflow)

            drainAndCheckOverflowEvents(watcher, ENTRY_CREATE, n);

            // delete the files

            for (int i=0; i<n; i++) {

                Files.delete(files[i]);

            }

            // give time for events to accumulate (improve chance of overflow)

            Thread.sleep(1000);

            // check that we see the delete events (or overflow)

            drainAndCheckOverflowEvents(watcher, ENTRY_DELETE, n);

        }

    }

    static void drainAndCheckOverflowEvents(WatchService watcher,

                                            WatchEvent.Kind<?> expectedKind,

                                            int count)

        throws IOException, InterruptedException

    {

        // wait for key to be signalled - the timeout is long to allow for

        // polling implementations

        WatchKey key = watcher.poll(15, TimeUnit.SECONDS);

        if (key != null && count == 0)

            throw new RuntimeException("Key was signalled (unexpected)");

        if (key == null && count > 0)

            throw new RuntimeException("Key not signalled (unexpected)");

        int nread = 0;

        boolean gotOverflow = false;

        while (key != null) {

            List<WatchEvent<?>> events = key.pollEvents();

            for (WatchEvent<?> event: events) {

                WatchEvent.Kind<?> kind = event.kind();

                if (kind == expectedKind) {

                    // expected event kind

                    if (++nread > count)

                        throw new RuntimeException("More events than expected!!");

                } else if (kind == OVERFLOW) {

                    // overflow event should not be retrieved with other events

                    if (events.size() > 1)

                        throw new RuntimeException("Overflow retrieved with other events");

                    gotOverflow = true;

                } else {

                    throw new RuntimeException("Unexpected event '" + kind + "'");

                }

            }

            if (!key.reset())

                throw new RuntimeException("Key is no longer valid");

            key = watcher.poll(2, TimeUnit.SECONDS);

        }

        // check that all expected events were received or there was an overflow

        if (nread < count && !gotOverflow)

            throw new RuntimeException("Insufficient events");

    }

    /**

     * Tests that check that ENTRY_MODIFY events are queued efficiently

     */

    static void testModifyEventsQueuing(Path dir)

        throws IOException, InterruptedException

    {

        // this test uses a random number of files

        final int nfiles = 5 + rand.nextInt(10);

        DirectoryEntry[] entries = new DirectoryEntry[nfiles];

        for (int i=0; i<nfiles; i++) {

            entries[i] = new DirectoryEntry(dir.resolve("foo" + i));

            // "some" of the files exist, some do not.

            entries[i].deleteIfExists();

            if (rand.nextBoolean())

                entries[i].create();

        }

        try (WatchService watcher = dir.getFileSystem().newWatchService()) {

            dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);

            // do several rounds of noise and test

            for (int round=0; round<10; round++) {

                // make some noise!!!

                for (int i=0; i<100; i++) {

                    DirectoryEntry entry = entries[rand.nextInt(nfiles)];

                    int action = rand.nextInt(10);

                    switch (action) {

                        case 0 : entry.create(); break;

                        case 1 : entry.deleteIfExists(); break;

                        default: entry.modifyIfExists();

                    }

                }

                // process events and ensure that we don't get repeated modify

                // events for the same file.

                WatchKey key = watcher.poll(15, TimeUnit.SECONDS);

                while (key != null) {

                    Set<Path> modified = new HashSet<>();

                    for (WatchEvent<?> event: key.pollEvents()) {

                        WatchEvent.Kind<?> kind = event.kind();

                        Path file = (kind == OVERFLOW) ? null : (Path)event.context();

                        if (kind == ENTRY_MODIFY) {

                            boolean added = modified.add(file);

                            if (!added) {

                                throw new RuntimeException(

                                    "ENTRY_MODIFY events not queued efficiently");

                            }

                        } else {

                            if (file != null) modified.remove(file);

                        }

                    }

                    if (!key.reset())

                        throw new RuntimeException("Key is no longer valid");

                    key = watcher.poll(2, TimeUnit.SECONDS);

                }

            }

        }

    }

    static class DirectoryEntry {

        private final Path file;

        DirectoryEntry(Path file) {

            this.file = file;

        }

        void create() throws IOException {

            if (Files.notExists(file))

                Files.createFile(file);

        }

        void deleteIfExists() throws IOException {

            Files.deleteIfExists(file);

        }

        void modifyIfExists() throws IOException {

            if (Files.exists(file)) {

                try (OutputStream out = Files.newOutputStream(file, StandardOpenOption.APPEND)) {

                    out.write("message".getBytes());

                }

            }

        }

    }

}