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diff --git a/gnu/java/security/util/ExpirableObject.java b/gnu/java/security/util/ExpirableObject.java
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+/* ExpirableObject.java -- an object that is automatically destroyed.
+   Copyright (C) 2004, 2006 Free Software Foundation, Inc.
+
+This file is a part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or (at
+your option) any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; if not, write to the Free Software
+Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
+USA
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version.  */
+
+
+package gnu.java.security.util;
+
+import java.util.Timer;
+import java.util.TimerTask;
+
+import javax.security.auth.DestroyFailedException;
+import javax.security.auth.Destroyable;
+
+/**
+ * The base class for objects with sensitive data that are automatically
+ * destroyed after a timeout elapses. On creation, an object that extends
+ * this class will automatically be added to a {@link Timer} object that,
+ * once a timeout elapses, will automatically call the {@link
+ * Destroyable#destroy()} method.
+ *
+ * <p>Concrete subclasses must implement the {@link doDestroy()} method
+ * instead of {@link Destroyable#destroy()}; the behavior of that method
+ * should match exactly the behavior desired of <code>destroy()</code>.
+ *
+ * <p>Note that if a {@link DestroyFailedException} occurs when the timeout
+ * expires, it will not be reported.
+ *
+ * @see Destroyable
+ */
+public abstract class ExpirableObject implements Destroyable
+{
+
+  // Constants and fields.
+  // -------------------------------------------------------------------------
+
+  /**
+   * The default timeout, used in the default constructor.
+   */
+  public static final long DEFAULT_TIMEOUT = 3600000L;
+
+  /**
+   * The timer that expires instances.
+   */
+  private static final Timer EXPIRER = new Timer(true);
+
+  /**
+   * A reference to the task that will destroy this object when the timeout
+   * expires.
+   */
+  private final Destroyer destroyer;
+
+  // Constructors.
+  // -------------------------------------------------------------------------
+
+  /**
+   * Create a new expirable object that will expire after one hour.
+   */
+  protected ExpirableObject()
+  {
+    this(DEFAULT_TIMEOUT);
+  }
+
+  /**
+   * Create a new expirable object that will expire after the specified
+   * timeout.
+   *
+   * @param delay The delay before expiration.
+   * @throws IllegalArgumentException If <i>delay</i> is negative, or if
+   *  <code>delay + System.currentTimeMillis()</code> is negative.
+   */
+  protected ExpirableObject(final long delay)
+  {
+    destroyer = new Destroyer(this);
+    EXPIRER.schedule(destroyer, delay);
+  }
+
+  // Instance methods.
+  // -------------------------------------------------------------------------
+
+  /**
+   * Destroys this object. This method calls {@link doDestroy}, then, if
+   * no exception is thrown, cancels the task that would destroy this object
+   * when the timeout is reached.
+   *
+   * @throws DestroyFailedException If this operation fails.
+   */
+  public final void destroy() throws DestroyFailedException
+  {
+    doDestroy();
+    destroyer.cancel();
+  }
+
+  /**
+   * Subclasses must implement this method instead of the {@link
+   * Destroyable#destroy()} method.
+   *
+   * @throws DestroyFailedException If this operation fails.
+   */
+  protected abstract void doDestroy() throws DestroyFailedException;
+
+  // Inner classes.
+  // -------------------------------------------------------------------------
+
+  /**
+   * The task that destroys the target when the timeout elapses.
+   */
+  private final class Destroyer extends TimerTask
+  {
+
+    // Fields.
+    // -----------------------------------------------------------------------
+
+    private final ExpirableObject target;
+
+    // Constructor.
+    // -----------------------------------------------------------------------
+
+    Destroyer(final ExpirableObject target)
+    {
+      super();
+      this.target = target;
+    }
+
+    // Instance methods.
+    // -----------------------------------------------------------------------
+
+    public void run()
+    {
+      try
+        {
+          if (!target.isDestroyed())
+            target.doDestroy();
+        }
+      catch (DestroyFailedException dfe)
+        {
+        }
+    }
+  }
+}