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