--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/lang/ref/Finalizer.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,197 @@
+/*
+ * Copyright 1997-2004 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. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+
+package java.lang.ref;
+
+import java.security.PrivilegedAction;
+import java.security.AccessController;
+
+
+final class Finalizer extends FinalReference { /* Package-private; must be in
+ same package as the Reference
+ class */
+
+ /* A native method that invokes an arbitrary object's finalize method is
+ required since the finalize method is protected
+ */
+ static native void invokeFinalizeMethod(Object o) throws Throwable;
+
+ static private ReferenceQueue queue = new ReferenceQueue();
+ static private Finalizer unfinalized = null;
+ static private Object lock = new Object();
+
+ private Finalizer
+ next = null,
+ prev = null;
+
+ private boolean hasBeenFinalized() {
+ return (next == this);
+ }
+
+ private void add() {
+ synchronized (lock) {
+ if (unfinalized != null) {
+ this.next = unfinalized;
+ unfinalized.prev = this;
+ }
+ unfinalized = this;
+ }
+ }
+
+ private void remove() {
+ synchronized (lock) {
+ if (unfinalized == this) {
+ if (this.next != null) {
+ unfinalized = this.next;
+ } else {
+ unfinalized = this.prev;
+ }
+ }
+ if (this.next != null) {
+ this.next.prev = this.prev;
+ }
+ if (this.prev != null) {
+ this.prev.next = this.next;
+ }
+ this.next = this; /* Indicates that this has been finalized */
+ this.prev = this;
+ }
+ }
+
+ private Finalizer(Object finalizee) {
+ super(finalizee, queue);
+ add();
+ }
+
+ /* Invoked by VM */
+ static void register(Object finalizee) {
+ new Finalizer(finalizee);
+ }
+
+ private void runFinalizer() {
+ synchronized (this) {
+ if (hasBeenFinalized()) return;
+ remove();
+ }
+ try {
+ Object finalizee = this.get();
+ if (finalizee != null && !(finalizee instanceof java.lang.Enum)) {
+ invokeFinalizeMethod(finalizee);
+ /* Clear stack slot containing this variable, to decrease
+ the chances of false retention with a conservative GC */
+ finalizee = null;
+ }
+ } catch (Throwable x) { }
+ super.clear();
+ }
+
+ /* Create a privileged secondary finalizer thread in the system thread
+ group for the given Runnable, and wait for it to complete.
+
+ This method is used by both runFinalization and runFinalizersOnExit.
+ The former method invokes all pending finalizers, while the latter
+ invokes all uninvoked finalizers if on-exit finalization has been
+ enabled.
+
+ These two methods could have been implemented by offloading their work
+ to the regular finalizer thread and waiting for that thread to finish.
+ The advantage of creating a fresh thread, however, is that it insulates
+ invokers of these methods from a stalled or deadlocked finalizer thread.
+ */
+ private static void forkSecondaryFinalizer(final Runnable proc) {
+ PrivilegedAction pa = new PrivilegedAction() {
+ public Object run() {
+ ThreadGroup tg = Thread.currentThread().getThreadGroup();
+ for (ThreadGroup tgn = tg;
+ tgn != null;
+ tg = tgn, tgn = tg.getParent());
+ Thread sft = new Thread(tg, proc, "Secondary finalizer");
+ sft.start();
+ try {
+ sft.join();
+ } catch (InterruptedException x) {
+ /* Ignore */
+ }
+ return null;
+ }};
+ AccessController.doPrivileged(pa);
+ }
+
+ /* Called by Runtime.runFinalization() */
+ static void runFinalization() {
+ forkSecondaryFinalizer(new Runnable() {
+ public void run() {
+ for (;;) {
+ Finalizer f = (Finalizer)queue.poll();
+ if (f == null) break;
+ f.runFinalizer();
+ }
+ }
+ });
+ }
+
+ /* Invoked by java.lang.Shutdown */
+ static void runAllFinalizers() {
+ forkSecondaryFinalizer(new Runnable() {
+ public void run() {
+ for (;;) {
+ Finalizer f;
+ synchronized (lock) {
+ f = unfinalized;
+ if (f == null) break;
+ unfinalized = f.next;
+ }
+ f.runFinalizer();
+ }}});
+ }
+
+ private static class FinalizerThread extends Thread {
+ FinalizerThread(ThreadGroup g) {
+ super(g, "Finalizer");
+ }
+ public void run() {
+ for (;;) {
+ try {
+ Finalizer f = (Finalizer)queue.remove();
+ f.runFinalizer();
+ } catch (InterruptedException x) {
+ continue;
+ }
+ }
+ }
+ }
+
+ static {
+ ThreadGroup tg = Thread.currentThread().getThreadGroup();
+ for (ThreadGroup tgn = tg;
+ tgn != null;
+ tg = tgn, tgn = tg.getParent());
+ Thread finalizer = new FinalizerThread(tg);
+ finalizer.setPriority(Thread.MAX_PRIORITY - 2);
+ finalizer.setDaemon(true);
+ finalizer.start();
+ }
+
+}