svn commit: r929844 - in /ofbiz/trunk/framework/base/src/org/ofbiz/base/util: ReferenceCleaner.java test/ReferenceCleanerTests.java

[doogie-3]

Author: doogie
Date: Thu Apr  1 04:50:21 2010
New Revision: 929844

URL: http://svn.apache.org/viewvc?rev=929844&view=rev
Log:
Helper class to poll a ReferenceQueue with a background thread.

Added:
    ofbiz/trunk/framework/base/src/org/ofbiz/base/util/ReferenceCleaner.java
    ofbiz/trunk/framework/base/src/org/ofbiz/base/util/test/ReferenceCleanerTests.java

Added: ofbiz/trunk/framework/base/src/org/ofbiz/base/util/ReferenceCleaner.java
URL: http://svn.apache.org/viewvc/ofbiz/trunk/framework/base/src/org/ofbiz/base/util/ReferenceCleaner.java?rev=929844&view=auto
==============================================================================
--- ofbiz/trunk/framework/base/src/org/ofbiz/base/util/ReferenceCleaner.java (added)
+++ ofbiz/trunk/framework/base/src/org/ofbiz/base/util/ReferenceCleaner.java Thu Apr  1 04:50:21 2010
@@ -0,0 +1,89 @@
+/*******************************************************************************
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *******************************************************************************/
+package org.ofbiz.base.util;
+
+import java.lang.ref.Reference;
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.PhantomReference;
+import java.lang.ref.SoftReference;
+import java.lang.ref.WeakReference;
+
+public final class ReferenceCleaner {
+    public static final String module = ReferenceCleaner.class.getName();
+
+    private static final class CleanerThread extends Thread {
+        private boolean keepRunning = true;
+
+        protected CleanerThread() {
+            setDaemon(true);
+            setName("ReferenceCleaner");
+        }
+
+        protected void stopRunning() {
+            keepRunning = false;
+        }
+
+        public void run() {
+            while (keepRunning) {
+                try {
+                    ((Removable) QUEUE.remove()).remove();
+                } catch (Throwable t) {
+                    // ignore
+                }
+                if (interrupted()) {
+                    stopRunning();
+                    cleanerThread = new CleanerThread();
+                    cleanerThread.start();
+                }
+            }
+        }
+    }
+    private static CleanerThread cleanerThread = new CleanerThread();
+
+    static {
+        cleanerThread.start();
+    }
+
+    private ReferenceCleaner() {
+    }
+
+    private static final ReferenceQueue<Object> QUEUE = new ReferenceQueue<Object>();
+
+    public interface Removable {
+        void remove() throws Exception;
+    }
+
+    public abstract static class Soft<V> extends SoftReference<V> implements Removable {
+        public Soft(V value) {
+            super(value, QUEUE);
+        }
+    }
+
+    public abstract static class Phantom<V> extends PhantomReference<V> implements Removable {
+        public Phantom(V value) {
+            super(value, QUEUE);
+        }
+    }
+
+    public abstract static class Weak<V> extends WeakReference<V> implements Removable {
+        public Weak(V value) {
+            super(value, QUEUE);
+        }
+    }
+}

Added: ofbiz/trunk/framework/base/src/org/ofbiz/base/util/test/ReferenceCleanerTests.java
URL: http://svn.apache.org/viewvc/ofbiz/trunk/framework/base/src/org/ofbiz/base/util/test/ReferenceCleanerTests.java?rev=929844&view=auto
==============================================================================
--- ofbiz/trunk/framework/base/src/org/ofbiz/base/util/test/ReferenceCleanerTests.java (added)
+++ ofbiz/trunk/framework/base/src/org/ofbiz/base/util/test/ReferenceCleanerTests.java Thu Apr  1 04:50:21 2010
@@ -0,0 +1,82 @@
+/*******************************************************************************
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *******************************************************************************/
+package org.ofbiz.base.util.test;
+
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Exchanger;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.SynchronousQueue;
+
+import org.ofbiz.base.util.ReferenceCleaner;
+import org.ofbiz.base.lang.SourceMonitored;
+import org.ofbiz.base.test.GenericTestCaseBase;
+
+@SourceMonitored
+public class ReferenceCleanerTests extends GenericTestCaseBase {
+    public ReferenceCleanerTests(String name) {
+        super(name);
+    }
+
+    public void testReferenceCleaner() throws Exception {
+        assertStaticHelperClass(ReferenceCleaner.class);
+        final SynchronousQueue<String> queue = new SynchronousQueue<String>();
+        Object obj = new Object();
+        final CountDownLatch softLatch = new CountDownLatch(1);
+        ReferenceCleaner.Soft<Object> soft = new ReferenceCleaner.Soft<Object>(obj) {
+            public void remove() throws Exception {
+                queue.put("soft");
+                Thread.currentThread().interrupt();
+            }
+        };
+        final CountDownLatch weakLatch = new CountDownLatch(1);
+        ReferenceCleaner.Weak<Object> weak = new ReferenceCleaner.Weak<Object>(obj) {
+            public void remove() throws Exception {
+                queue.put("weak");
+                throw new RuntimeException();
+            }
+        };
+        final CountDownLatch phantomLatch = new CountDownLatch(1);
+        ReferenceCleaner.Phantom<Object> phantom = new ReferenceCleaner.Phantom<Object>(obj) {
+            public void remove() throws Exception {
+                queue.put("phantom");
+            }
+        };
+        HashSet<String> foundEvents = new HashSet<String>();
+        useAllMemory();
+        assertSame("still-soft", obj, soft.get());
+        assertSame("still-weak", obj, weak.get());
+        assertNull("no event", queue.poll(100, TimeUnit.MILLISECONDS));
+        obj = null;
+        useAllMemory();
+        foundEvents.add(queue.poll(100, TimeUnit.MILLISECONDS));
+        foundEvents.add(queue.poll(100, TimeUnit.MILLISECONDS));
+        foundEvents.add(queue.poll(100, TimeUnit.MILLISECONDS));
+        useAllMemory();
+        foundEvents.add(queue.poll(100, TimeUnit.MILLISECONDS));
+        foundEvents.remove(null);
+        assertFalse("no null", foundEvents.contains(null));
+        assertNull("no-soft", soft.get());
+        assertNull("no-weak", weak.get());
+        assertTrue("soft event", foundEvents.contains("soft"));
+        assertTrue("weak event", foundEvents.contains("weak"));
+        assertTrue("phantom event", foundEvents.contains("phantom"));
+    }
+}