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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.openjpa.lib.util;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.ref.Reference;
/**
* Map in which the key, value, or both may be weak/soft references.
*
* @author Abe White
* @nojavadoc
* @since 0.4.0
*/
public class ReferenceHashMap
extends org.apache.commons.collections.map.ReferenceMap
implements ReferenceMap, SizedMap {
private int _maxSize = Integer.MAX_VALUE;
public ReferenceHashMap(int keyType, int valueType) {
super(toReferenceConstant(keyType), toReferenceConstant(valueType));
}
public ReferenceHashMap(int keyType, int valueType, int capacity,
float loadFactor) {
super(toReferenceConstant(keyType), toReferenceConstant(valueType),
capacity, loadFactor);
}
/**
* Concver our reference constants to Apache's.
*/
private static int toReferenceConstant(int type) {
switch (type) {
case ReferenceMap.HARD:
return org.apache.commons.collections.map.ReferenceMap. HARD;
case ReferenceMap.SOFT:
return org.apache.commons.collections.map.ReferenceMap. SOFT;
default:
return org.apache.commons.collections.map.ReferenceMap. WEAK;
}
}
public int getMaxSize() {
return _maxSize;
}
public void setMaxSize(int maxSize) {
_maxSize = (maxSize < 0) ? Integer.MAX_VALUE : maxSize;
if (_maxSize != Integer.MAX_VALUE)
removeOverflow(_maxSize);
}
public boolean isFull() {
return size() >= _maxSize;
}
public void overflowRemoved(Object key, Object value) {
}
public void valueExpired(Object key) {
}
public void keyExpired(Object value) {
}
public void removeExpired() {
purge();
}
/**
* Remove any entries over max size.
*/
private void removeOverflow(int maxSize) {
Object key;
while (size() > maxSize) {
key = keySet().iterator().next();
overflowRemoved(key, remove(key));
}
}
protected void addMapping(int hashIndex, int hashCode, Object key,
Object value) {
if (_maxSize != Integer.MAX_VALUE)
removeOverflow(_maxSize - 1);
super.addMapping(hashIndex, hashCode, key, value);
}
protected HashEntry createEntry(HashEntry next, int hashCode, Object key,
Object value) {
return new AccessibleEntry(this, next, hashCode, key, value);
}
protected void purge(Reference ref) {
// the logic for this method is taken from the original purge method
// we're overriding, with added logic to track the expired key/value
int index = hashIndex(ref.hashCode(), data.length);
AccessibleEntry entry = (AccessibleEntry) data[index];
AccessibleEntry prev = null;
Object key = null, value = null;
while (entry != null) {
if (purge(entry, ref)) {
if (isHard(keyType))
key = entry.key();
else if (isHard(valueType))
value = entry.value();
if (prev == null)
data[index] = entry.nextEntry();
else
prev.setNextEntry(entry.nextEntry());
size--;
break;
}
prev = entry;
entry = entry.nextEntry();
}
if (key != null)
valueExpired(key);
else if (value != null)
keyExpired(value);
}
/**
* See the code for ReferenceMap.ReferenceEntry.purge.
*/
private boolean purge(AccessibleEntry entry, Reference ref) {
boolean match = (!isHard(keyType) && entry.key() == ref)
|| (!isHard(valueType) && entry.value() == ref);
if (match) {
if (!isHard(keyType))
((Reference) entry.key()).clear();
if (!isHard(valueType))
((Reference) entry.value()).clear();
else if (purgeValues)
entry.nullValue();
}
return match;
}
private static boolean isHard(int type) {
return type == org.apache.commons.collections.map. ReferenceMap.HARD;
}
protected void doWriteObject(ObjectOutputStream out) throws IOException {
out.writeInt(_maxSize);
super.doWriteObject(out);
}
protected void doReadObject(ObjectInputStream in)
throws ClassNotFoundException, IOException {
_maxSize = in.readInt();
super.doReadObject(in);
}
/**
* Extension of the base entry type that allows our outer class to access
* protected state.
*/
private static class AccessibleEntry extends ReferenceEntry {
public AccessibleEntry(org.apache.commons.collections.map.
AbstractReferenceMap map, HashEntry next,
int hashCode, Object key, Object value) {
super(map, next, hashCode, key, value);
}
public Object key() {
return key;
}
public Object value() {
return value;
}
public void nullValue() {
value = null;
}
public AccessibleEntry nextEntry() {
return (AccessibleEntry) next;
}
public void setNextEntry(AccessibleEntry next) {
this.next = next;
}
}
}
