8153925: (fs) WatchService hangs on GetOverlappedResult and locks directory (win)

Co-authored-by: Thomas Mader <tmader@redhat.com>
Reviewed-by: alanb

jdk/src/java.base/windows/classes/sun/nio/fs/WindowsWatchService.java

@@ -113,6 +113,10 @@ class WindowsWatchService
         // completion key (used to map I/O completion to WatchKey)
         private int completionKey;
 
+        // flag indicates that ReadDirectoryChangesW failed
+        // and overlapped I/O operation wasn't started
+        private boolean errorStartingOverlapped;
+
         WindowsWatchKey(Path dir,
                         AbstractWatchService watcher,
                         FileKey fileKey)
@@ -175,6 +179,14 @@ class WindowsWatchService
             return completionKey;
         }
 
+        void setErrorStartingOverlapped(boolean value) {
+            errorStartingOverlapped = value;
+        }
+
+        boolean isErrorStartingOverlapped() {
+            return errorStartingOverlapped;
+        }
+
         // Invalidate the key, assumes that resources have been released
         void invalidate() {
             ((WindowsWatchService)watcher()).poller.releaseResources(this);
@@ -182,6 +194,7 @@ class WindowsWatchService
             buffer = null;
             countAddress = 0;
             overlappedAddress = 0;
+            errorStartingOverlapped = false;
         }
 
         @Override
@@ -455,12 +468,14 @@ class WindowsWatchService
          * resources.
          */
         private void releaseResources(WindowsWatchKey key) {
+            if (!key.isErrorStartingOverlapped()) {
                 try {
                     CancelIo(key.handle());
                     GetOverlappedResult(key.handle(), key.overlappedAddress());
                 } catch (WindowsException expected) {
                     // expected as I/O operation has been cancelled
                 }
+            }
             CloseHandle(key.handle());
             closeAttachedEvent(key.overlappedAddress());
             key.buffer().free();
@@ -628,6 +643,7 @@ class WindowsWatchService
                     } catch (WindowsException x) {
                         // no choice but to cancel key
                         criticalError = true;
+                        key.setErrorStartingOverlapped(true);
                     }
                 }
                 if (criticalError) {

jdk/test/java/nio/file/WatchService/DeleteInterference.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2016, Red Hat, Inc. and/or its affiliates.
+ * 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.
+ */
+
+/**
+ * @test
+ * @bug 8153925
+ * @summary Tests potential interference between a thread creating and closing
+ *     a WatchService with another thread that is deleting and re-creating the
+ *     directory at around the same time. This scenario tickled a timing bug
+ *     in the Windows implementation.
+ */
+
+import java.io.IOException;
+import java.nio.file.DirectoryStream;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.WatchService;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+import static java.nio.file.StandardWatchEventKinds.*;
+
+public class DeleteInterference {
+
+    private static final int ITERATIONS_COUNT = 1024;
+
+    /**
+     * Execute two tasks in a thread pool. One task loops on creating and
+     * closing a WatchService, the other task deletes and re-creates the
+     * directory.
+     */
+    public static void main(String[] args) throws Exception {
+        Path dir = Files.createTempDirectory("work");
+        ExecutorService pool = Executors.newCachedThreadPool();
+        try {
+            Future<?> task1 = pool.submit(() -> openAndCloseWatcher(dir));
+            Future<?> task2 = pool.submit(() -> deleteAndRecreateDirectory(dir));
+            task1.get();
+            task2.get();
+        } finally {
+            pool.shutdown();
+            deleteFileTree(dir);
+        }
+    }
+
+    private static void openAndCloseWatcher(Path dir) {
+        FileSystem fs = FileSystems.getDefault();
+        for (int i = 0; i < ITERATIONS_COUNT; i++) {
+            try (WatchService watcher = fs.newWatchService()) {
+                dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
+            } catch (IOException ioe) {
+                // ignore
+            }
+        }
+    }
+
+    private static void deleteAndRecreateDirectory(Path dir) {
+        for (int i = 0; i < ITERATIONS_COUNT; i++) {
+            try {
+                deleteFileTree(dir);
+                Path subdir = Files.createDirectories(dir.resolve("subdir"));
+                Files.createFile(subdir.resolve("test"));
+            } catch (IOException ioe) {
+                // ignore
+            }
+        }
+    }
+
+    private static void deleteFileTree(Path file) {
+        try {
+            if (Files.isDirectory(file)) {
+                try (DirectoryStream<Path> stream = Files.newDirectoryStream(file)) {
+                    for (Path pa : stream) {
+                        deleteFileTree(pa);
+                    }
+                }
+            }
+            Files.delete(file);
+        } catch (IOException ioe) {
+            // ignore
+        }
+    }
+}