/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/**
* Abstract class that maps Class objects to lazily-computed values of
* type V. A concrete subclass must implement the computeValue method
* to determine how the values are computed.
*
* The keys are only weakly reachable through this map, so this map
* does not prevent a class (along with its class loader, etc.) from
* being garbage collected if it is not otherwise strongly reachable.
* The values are only softly reachable through this map, so that the
* computed values generally persist while not otherwise strongly
* reachable, but their storage may be reclaimed if necessary. Also,
* note that if a key is strongly reachable from a value, then the key
* is effectively softly reachable through this map, which may delay
* garbage collection of classes (see 4429536).
**/
public abstract class WeakClassHashMap<V> {
protected WeakClassHashMap() { }
/*
* Use a mutable cell (a one-element list) to hold the soft
* reference to a value, to allow the lazy value computation
* to be synchronized with entry-level granularity instead of
* by locking the whole table.
*/
synchronized (internalMap) {
}
}
synchronized (valueCell) {
}
}
return value;
}
}
private static class ValueCell<T> {
ValueCell() { }
}
}