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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.tuscany.sca.common.xml.dom;
import java.util.IdentityHashMap;
import java.util.Map;
public abstract class ParserPool<V> {
private int maxSize;
private Map<V, Boolean> objects;
public ParserPool() {
this(32, 0);
}
public ParserPool(int maxSize, int initialSize) {
super();
this.maxSize = maxSize;
this.objects = new IdentityHashMap<V, Boolean>(maxSize);
for (int i = 0; i < Math.min(initialSize, maxSize); i++) {
objects.put(newInstance(), Boolean.FALSE);
}
}
public synchronized V borrowFromPool() {
while (true) {
for (Map.Entry<V, Boolean> e : objects.entrySet()) {
if (Boolean.FALSE.equals(e.getValue())) {
// setValue fails on some Harmony based JDKs, see https://issues.apache.org/jira/browse/HARMONY-6419
//e.setValue(Boolean.TRUE); // in use
V key = e.getKey();
objects.put(key, Boolean.TRUE); // in use
return key;
}
}
if (objects.size() < maxSize) {
V obj = newInstance();
objects.put(obj, Boolean.TRUE);
return obj;
}
try {
wait();
} catch (InterruptedException e1) {
throw new IllegalStateException(e1);
}
}
}
public synchronized void returnToPool(V obj) {
resetInstance(obj);
objects.put(obj, Boolean.FALSE);
notifyAll();
}
public synchronized void clear() {
objects.clear();
}
public synchronized int inUse() {
int size = 0;
for (Map.Entry<V, Boolean> e : objects.entrySet()) {
if (Boolean.TRUE.equals(e.getValue())) {
size++;
}
}
return size;
}
/**
* Create a new instance
* @return
*/
protected abstract V newInstance();
/**
* Reset the instance before returning to the pool
* @param obj
*/
protected abstract void resetInstance(V obj);
// Expose it for testing purpose
public Map<V, Boolean> getObjects() {
return objects;
}
}
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