diff options
Diffstat (limited to 'src/main/java/com/c2kernel/utils/WeakCache.java')
| -rw-r--r-- | src/main/java/com/c2kernel/utils/WeakCache.java | 154 |
1 files changed, 0 insertions, 154 deletions
diff --git a/src/main/java/com/c2kernel/utils/WeakCache.java b/src/main/java/com/c2kernel/utils/WeakCache.java deleted file mode 100644 index 6b61474..0000000 --- a/src/main/java/com/c2kernel/utils/WeakCache.java +++ /dev/null @@ -1,154 +0,0 @@ -/**
- * This file is part of the CRISTAL-iSE kernel.
- * Copyright (c) 2001-2014 The CRISTAL Consortium. All rights reserved.
- *
- * This library is free software; you can redistribute it and/or modify it
- * under the terms of the GNU Lesser General Public License as published
- * by the Free Software Foundation; either version 3 of the License, or (at
- * your option) any later version.
- *
- * This library is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; with out even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
- * License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this library; if not, write to the Free Software Foundation,
- * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
- *
- * http://www.fsf.org/licensing/licenses/lgpl.html
- */
-package com.c2kernel.utils;
-
-import java.lang.ref.ReferenceQueue;
-import java.lang.ref.WeakReference;
-import java.util.AbstractMap;
-import java.util.HashMap;
-import java.util.LinkedList;
-import java.util.Map;
-import java.util.Set;
-
-/*******************************************************************************
- * WeakReferences are reaped if no strong references are left next time the gc has a chance.
- * The ClusterStorageManager caches can optionally use this one, for high volume imports etc
- *
- * $Revision: 1.5 $ $Date: 2004/10/29 13:29:09 $
- ******************************************************************************/
-public class WeakCache<K, V> extends AbstractMap<K, V> {
-
- private final Map<K, WeakValue<V>> hash = new HashMap<K, WeakValue<V>>();
- private final int minSize;
- private final LinkedList<V> hardCache = new LinkedList<V>();
- private final ReferenceQueue<V> queue = new ReferenceQueue<V>();
-
- public WeakCache() {
- this(0);
- }
-
- public WeakCache(int minSize) {
- this.minSize = minSize;
- }
-
- /* (non-Javadoc)
- * @see com.c2kernel.utils.NonStrongRefCache#get(java.lang.Object)
- */
- @Override
- public V get(Object key) {
- V result = null;
- WeakValue<V> weak_ref = hash.get(key);
- if (weak_ref != null) {
- result = weak_ref.get();
- if (result == null)
- hash.remove(key);
- else
- if (minSize > 0) { // add to hard cache so it's not reaped for a while
- hardCache.addFirst(result);
- if (hardCache.size() > minSize) // trim last one off
- hardCache.removeLast();
- }
- }
- return result;
- }
-
- /* (non-Javadoc)
- * @see com.c2kernel.utils.NonStrongRefCache#put(K, V)
- */
- @Override
- public V put(K key, V value) {
- processQueue();
- if (minSize > 0) {
- hardCache.addFirst(value);
- if (hardCache.size() > minSize)
- hardCache.removeLast();
- }
- hash.put(key, new WeakValue<V>(key, value, queue));
- return value;
- }
-
- /* (non-Javadoc)
- * @see com.c2kernel.utils.NonStrongRefCache#remove(java.lang.Object)
- */
- @Override
- public V remove(Object key) {
- processQueue();
- if (hash.containsKey(key)) return hash.remove(key).get();
- return null;
- }
-
- /* (non-Javadoc)
- * @see com.c2kernel.utils.NonStrongRefCache#clear()
- */
- @Override
- public void clear() {
- hardCache.clear();
- while(queue.poll()!=null);
- hash.clear();
- }
-
- /* (non-Javadoc)
- * @see com.c2kernel.utils.NonStrongRefCache#size()
- */
- @Override
- public int size() {
- processQueue();
- return hash.size();
- }
-
- /* (non-Javadoc)
- * @see com.c2kernel.utils.NonStrongRefCache#keySet()
- */
- @Override
- public Set<K> keySet() {
- processQueue();
- return hash.keySet();
- }
-
- /* (non-Javadoc)
- * @see com.c2kernel.utils.NonStrongRefCache#entrySet()
- */
- @Override
- public Set<Map.Entry<K, V>> entrySet() {
- // Would have to create another Map to do this - too expensive
- // Throwing runtime expensive is dangerous, but better than nulls
- throw new UnsupportedOperationException();
- }
-
- private static class WeakValue<V> extends WeakReference<V> {
- private final Object key;
- private WeakValue(Object key, V value, ReferenceQueue<V> q) {
- super(value, q);
- this.key = key;
- }
- }
-
- /**
- * Look for values that have been reaped, and remove their keys from the cache
- */
- private void processQueue() {
- WeakValue<V> sv;
- while ((sv = (WeakValue<V>) queue.poll()) != null) {
- hash.remove(sv.key);
- }
- }
-
-}
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