8023139: java/nio/file/WatchService/SensitivityModifier.java failing intermittently (win8)

Reviewed-by: alanb
Contributed-by: yiming.wang@oracle.com

test/java/nio/file/WatchService/SensitivityModifier.java

@@ -54,7 +54,7 @@ public class SensitivityModifier {
     @SuppressWarnings("unchecked")
     static void doTest(Path top) throws Exception {
         FileSystem fs = top.getFileSystem();
-        WatchService watcher = fs.newWatchService();
+        try (WatchService watcher = fs.newWatchService()) {
 
             // create directories and files
             int nDirs = 5 + rand.nextInt(20);
@@ -84,30 +84,36 @@ public class SensitivityModifier {
                 try (OutputStream out = Files.newOutputStream(file)) {
                     out.write(new byte[100]);
                 }
-            System.out.println("Waiting for event...");
+
+                System.out.println("Waiting for event(s)...");
+                boolean eventReceived = false;
                 WatchKey key = watcher.take();
-            WatchEvent<?> event = key.pollEvents().iterator().next();
+                do {
+                    for (WatchEvent<?> event: key.pollEvents()) {
                         if (event.kind() != ENTRY_MODIFY)
                             throw new RuntimeException("Unexpected event: " + event);
                         Path name = ((WatchEvent<Path>)event).context();
-            if (!name.equals(file.getFileName()))
-                throw new RuntimeException("Unexpected context: " + name);
-            System.out.println("Event OK");
-
-            // drain events (to avoid interference)
-            do {
-                key.pollEvents();
+                        if (name.equals(file.getFileName())) {
+                            eventReceived = true;
+                            break;
+                        }
+                    }
                     key.reset();
                     key = watcher.poll(1, TimeUnit.SECONDS);
-            } while (key != null);
+                } while (key != null && !eventReceived);
+
+                // we should have received at least one ENTRY_MODIFY event
+                if (eventReceived) {
+                    System.out.println("Event OK");
+                } else {
+                    throw new RuntimeException("No ENTRY_MODIFY event received for " + file);
+                }
 
                 // re-register the directories to force changing their sensitivity
                 // level
                 register(dirs, watcher);
             }
-
-        // done
-        watcher.close();
+        }
     }
 
     public static void main(String[] args) throws Exception {