1 /*

     2  * Copyright (c) 2014, 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 /* @test

    25  * @bug 8029516

    26  * @summary Bash on WatchKey.cancel with a view to causing a crash when

    27  *    an outstanding I/O operation on directory completes after the

    28  *    directory has been closed

    29  */

    30 

    31 import java.nio.file.ClosedWatchServiceException;

    32 import java.nio.file.FileSystems;

    33 import java.nio.file.Files;

    34 import java.nio.file.Path;

    35 import java.nio.file.WatchKey;

    36 import java.nio.file.WatchService;

    37 import static java.nio.file.StandardWatchEventKinds.*;

    38 import java.util.concurrent.ExecutorService;

    39 import java.util.concurrent.Executors;

    40 import java.util.concurrent.TimeUnit;

    41 

    42 public class LotsOfCancels {

    43 

    44     // set to true for any exceptions

    45     static volatile boolean failed;

    46 

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

    48 

    49         // create a bunch of directories. Create two tasks for each directory,

    50         // one to bash on cancel, the other to poll the events

    51         ExecutorService pool = Executors.newCachedThreadPool();

    52         try {

    53             Path top = Files.createTempDirectory("work");

    54             top.toFile().deleteOnExit();

    55             for (int i=1; i<=16; i++) {

    56                 Path dir = Files.createDirectory(top.resolve("dir-" + i));

    57                 WatchService watcher = FileSystems.getDefault().newWatchService();

    58                 pool.submit(() -> handle(dir, watcher));

    59                 pool.submit(() -> poll(watcher));

    60             }

    61         } finally {

    62             pool.shutdown();

    63         }

    64 

    65         // give thread pool lots of time to terminate

    66         if (!pool.awaitTermination(5L, TimeUnit.MINUTES))

    67             throw new RuntimeException("Thread pool did not terminate");

    68 

    69         if (failed)

    70             throw new RuntimeException("Test failed, see log for details");

    71     }

    72 

    73     /**

    74      * Stress the given WatchService, specifically the cancel method, in

    75      * the given directory. Closes the WatchService when done.

    76      */

    77     static void handle(Path dir, WatchService watcher) {

    78         try {

    79             try {

    80                 Path file = dir.resolve("anyfile");

    81                 for (int i=0; i<2000; i++) {

    82                     WatchKey key = dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE);

    83                     Files.createFile(file);

    84                     Files.delete(file);

    85                     key.cancel();

    86                 }

    87             } finally {

    88                 watcher.close();

    89             }

    90         } catch (Exception e) {

    91             e.printStackTrace();

    92             failed = true;

    93         }

    94     }

    95 

    96     /**

    97      * Polls the given WatchService in a tight loop. This keeps the event

    98      * queue drained, it also hogs a CPU core which seems necessary to

    99      * tickle the original bug.

   100      */

   101     static void poll(WatchService watcher) {

   102         try {

   103             for (;;) {

   104                 WatchKey key = watcher.take();

   105                 if (key != null) {

   106                     key.pollEvents();

   107                     key.reset();

   108                 }

   109             }

   110         } catch (ClosedWatchServiceException expected) {

   111             // nothing to do

   112         } catch (Exception e) {

   113             e.printStackTrace();

   114             failed = true;

   115         }

   116     }

   117 

   118 }

   119