6929532: (file) WatchService should avoid queuing new modify events when lots of files are changing
authoralanb
Sat, 27 Feb 2010 18:18:33 +0000
changeset 4979 9043b4b40b30
parent 4978 6bee79de5db6
child 4980 bbfb5ddd9e58
6929532: (file) WatchService should avoid queuing new modify events when lots of files are changing Reviewed-by: alanb Contributed-by: sebastian.sickelmann@gmx.de
jdk/src/share/classes/sun/nio/fs/AbstractWatchKey.java
jdk/test/java/nio/file/WatchService/LotsOfEvents.java
jdk/test/java/nio/file/WatchService/OverflowEventIsLoner.java
--- a/jdk/src/share/classes/sun/nio/fs/AbstractWatchKey.java	Thu Feb 25 13:32:40 2010 +0800
+++ b/jdk/src/share/classes/sun/nio/fs/AbstractWatchKey.java	Sat Feb 27 18:18:33 2010 +0000
@@ -59,10 +59,15 @@
     // pending events
     private List<WatchEvent<?>> events;
 
+    // maps a context to the last event for the context (iff the last queued
+    // event for the context is an ENTRY_MODIFY event).
+    private Map<Object,WatchEvent<?>> lastModifyEvents;
+
     protected AbstractWatchKey(AbstractWatchService watcher) {
         this.watcher = watcher;
         this.state = State.READY;
         this.events = new ArrayList<WatchEvent<?>>();
+        this.lastModifyEvents = new HashMap<Object,WatchEvent<?>>();
     }
 
     final AbstractWatchService watcher() {
@@ -86,6 +91,7 @@
      */
     @SuppressWarnings("unchecked")
     final void signalEvent(WatchEvent.Kind<?> kind, Object context) {
+        boolean isModify = (kind == StandardWatchEventKind.ENTRY_MODIFY);
         synchronized (this) {
             int size = events.size();
             if (size > 0) {
@@ -100,17 +106,43 @@
                     return;
                 }
 
+                // if this is a modify event and the last entry for the context
+                // is a modify event then we simply increment the count
+                if (!lastModifyEvents.isEmpty()) {
+                    if (isModify) {
+                        WatchEvent<?> ev = lastModifyEvents.get(context);
+                        if (ev != null) {
+                            assert ev.kind() == StandardWatchEventKind.ENTRY_MODIFY;
+                            ((Event<?>)ev).increment();
+                            return;
+                        }
+                    } else {
+                        // not a modify event so remove from the map as the
+                        // last event will no longer be a modify event.
+                        lastModifyEvents.remove(context);
+                    }
+                }
+
                 // if the list has reached the limit then drop pending events
                 // and queue an OVERFLOW event
                 if (size >= MAX_EVENT_LIST_SIZE) {
-                    events.clear();
                     kind = StandardWatchEventKind.OVERFLOW;
+                    isModify = false;
                     context = null;
                 }
             }
 
             // non-repeated event
-            events.add(new Event<Object>((WatchEvent.Kind<Object>)kind, context));
+            Event<Object> ev =
+                new Event<Object>((WatchEvent.Kind<Object>)kind, context);
+            if (isModify) {
+                lastModifyEvents.put(context, ev);
+            } else if (kind == StandardWatchEventKind.OVERFLOW) {
+                // drop all pending events
+                events.clear();
+                lastModifyEvents.clear();
+            }
+            events.add(ev);
             signal();
         }
     }
@@ -120,6 +152,7 @@
         synchronized (this) {
             List<WatchEvent<?>> result = events;
             events = new ArrayList<WatchEvent<?>>();
+            lastModifyEvents.clear();
             return result;
         }
     }
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/nio/file/WatchService/LotsOfEvents.java	Sat Feb 27 18:18:33 2010 +0000
@@ -0,0 +1,222 @@
+/*
+ * Copyright 2010 Sun Microsystems, Inc.  All Rights Reserved.
+ * 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.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/* @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
+    {
+        WatchService watcher = dir.getFileSystem().newWatchService();
+        try {
+            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] = dir.resolve("foo" + i).createFile();
+            }
+
+            // 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[i].delete();
+            }
+
+            // 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);
+        } finally {
+            watcher.close();
+        }
+    }
+
+    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;
+        do {
+            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);
+        } while (key != null);
+
+        // 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();
+        }
+
+        WatchService watcher = dir.getFileSystem().newWatchService();
+        try {
+            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);
+                do {
+                    Set<Path> modified = new HashSet<Path>();
+                    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);
+                } while (key != null);
+            }
+
+        } finally {
+            watcher.close();
+        }
+    }
+
+    static class DirectoryEntry {
+        private final Path file;
+        DirectoryEntry(Path file) {
+            this.file = file;
+        }
+        void create() throws IOException {
+            if (file.notExists())
+                file.createFile();
+
+        }
+        void deleteIfExists() throws IOException {
+            file.deleteIfExists();
+        }
+        void modifyIfExists() throws IOException {
+            if (file.exists()) {
+                OutputStream out = file.newOutputStream(StandardOpenOption.APPEND);
+                try {
+                    out.write("message".getBytes());
+                } finally {
+                    out.close();
+                }
+            }
+        }
+    }
+
+}
--- a/jdk/test/java/nio/file/WatchService/OverflowEventIsLoner.java	Thu Feb 25 13:32:40 2010 +0800
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,122 +0,0 @@
-/*
- * Copyright 2010 Sun Microsystems, Inc.  All Rights Reserved.
- * 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.
- *
- * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
- * CA 95054 USA or visit www.sun.com if you need additional information or
- * have any questions.
- */
-
-/* @test
- * @bug 6907760
- * @summary Check that the OVERFLOW event is not retrieved with other events
- * @library ..
- */
-
-import java.nio.file.*;
-import static java.nio.file.StandardWatchEventKind.*;
-import java.io.IOException;
-import java.util.List;
-import java.util.concurrent.TimeUnit;
-
-public class OverflowEventIsLoner {
-
-    static void drainEvents(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;
-        do {
-            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);
-        } while (key != null);
-
-        // check that all expected events were received or there was an overflow
-        if (nread < count && !gotOverflow)
-            throw new RuntimeException("Insufficient events");
-    }
-
-
-    static void test(Path dir) throws IOException, InterruptedException {
-        WatchService watcher = dir.getFileSystem().newWatchService();
-        try {
-            WatchKey key = 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] = dir.resolve("foo" + i).createFile();
-            }
-
-            // give time for events to accumulate (improve chance of overflow)
-            Thread.sleep(1000);
-
-            // check that we see the create events (or overflow)
-            drainEvents(watcher, ENTRY_CREATE, n);
-
-            // delete the files
-            for (int i=0; i<n; i++) {
-                files[i].delete();
-            }
-
-            // give time for events to accumulate (improve chance of overflow)
-            Thread.sleep(1000);
-
-            // check that we see the delete events (or overflow)
-            drainEvents(watcher, ENTRY_DELETE, n);
-        } finally {
-            watcher.close();
-        }
-    }
-
-    public static void main(String[] args) throws Exception {
-        Path dir = TestUtil.createTemporaryDirectory();
-        try {
-            test(dir);
-        } finally {
-            TestUtil.removeAll(dir);
-        }
-    }
-}