0N/A/*
2362N/A * Copyright (c) 2003, 2008, Oracle and/or its affiliates. All rights reserved.
0N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
0N/A *
0N/A * This code is free software; you can redistribute it and/or modify it
0N/A * under the terms of the GNU General Public License version 2 only, as
2362N/A * published by the Free Software Foundation. Oracle designates this
0N/A * particular file as subject to the "Classpath" exception as provided
2362N/A * by Oracle in the LICENSE file that accompanied this code.
0N/A *
0N/A * This code is distributed in the hope that it will be useful, but WITHOUT
0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
0N/A * version 2 for more details (a copy is included in the LICENSE file that
0N/A * accompanied this code).
0N/A *
0N/A * You should have received a copy of the GNU General Public License version
0N/A * 2 along with this work; if not, write to the Free Software Foundation,
0N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
0N/A *
2362N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
2362N/A * or visit www.oracle.com if you need additional information or have any
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0N/A */
0N/Apackage sun.rmi.server;
0N/A
0N/Aimport java.lang.ref.Reference;
0N/Aimport java.lang.ref.SoftReference;
0N/Aimport java.util.Map;
0N/Aimport java.util.WeakHashMap;
0N/A
0N/A/**
0N/A * Abstract class that maps Class objects to lazily-computed values of
0N/A * type V. A concrete subclass must implement the computeValue method
0N/A * to determine how the values are computed.
0N/A *
0N/A * The keys are only weakly reachable through this map, so this map
0N/A * does not prevent a class (along with its class loader, etc.) from
0N/A * being garbage collected if it is not otherwise strongly reachable.
0N/A * The values are only softly reachable through this map, so that the
0N/A * computed values generally persist while not otherwise strongly
0N/A * reachable, but their storage may be reclaimed if necessary. Also,
0N/A * note that if a key is strongly reachable from a value, then the key
0N/A * is effectively softly reachable through this map, which may delay
0N/A * garbage collection of classes (see 4429536).
0N/A **/
0N/Apublic abstract class WeakClassHashMap<V> {
0N/A
5559N/A private Map<Class<?>,ValueCell<V>> internalMap = new WeakHashMap<>();
0N/A
0N/A protected WeakClassHashMap() { }
0N/A
0N/A public V get(Class<?> remoteClass) {
0N/A /*
0N/A * Use a mutable cell (a one-element list) to hold the soft
0N/A * reference to a value, to allow the lazy value computation
0N/A * to be synchronized with entry-level granularity instead of
0N/A * by locking the whole table.
0N/A */
0N/A ValueCell<V> valueCell;
0N/A synchronized (internalMap) {
0N/A valueCell = internalMap.get(remoteClass);
0N/A if (valueCell == null) {
0N/A valueCell = new ValueCell<V>();
0N/A internalMap.put(remoteClass, valueCell);
0N/A }
0N/A }
0N/A synchronized (valueCell) {
0N/A V value = null;
0N/A if (valueCell.ref != null) {
28N/A value = valueCell.ref.get();
0N/A }
0N/A if (value == null) {
0N/A value = computeValue(remoteClass);
0N/A valueCell.ref = new SoftReference<V>(value);
0N/A }
0N/A return value;
0N/A }
0N/A }
0N/A
0N/A protected abstract V computeValue(Class<?> remoteClass);
0N/A
0N/A private static class ValueCell<T> {
0N/A Reference<T> ref = null;
0N/A ValueCell() { }
0N/A }
0N/A}