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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/gnu/java/security/util/ExpirableObject.java | |
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Diffstat (limited to 'libjava/classpath/gnu/java/security/util/ExpirableObject.java')
-rw-r--r-- | libjava/classpath/gnu/java/security/util/ExpirableObject.java | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/java/security/util/ExpirableObject.java b/libjava/classpath/gnu/java/security/util/ExpirableObject.java new file mode 100644 index 000000000..e24af249a --- /dev/null +++ b/libjava/classpath/gnu/java/security/util/ExpirableObject.java @@ -0,0 +1,150 @@ +/* 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 +{ + /** + * 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; + + /** + * 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); + } + + /** + * 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; + + /** + * The task that destroys the target when the timeout elapses. + */ + private final class Destroyer + extends TimerTask + { + private final ExpirableObject target; + + Destroyer(final ExpirableObject target) + { + super(); + this.target = target; + } + + public void run() + { + try + { + if (! target.isDestroyed()) + target.doDestroy(); + } + catch (DestroyFailedException dfe) + { + } + } + } +} |