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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.common.recycler;
import java.util.Deque;
/**
* A {@link Recycler} implementation based on a {@link Deque}. This implementation is NOT thread-safe.
*/
public class DequeRecycler extends AbstractRecycler {
final Deque deque;
final int maxSize;
public DequeRecycler(C c, Deque queue, int maxSize) {
super(c);
this.deque = queue;
this.maxSize = maxSize;
}
@Override
public void close() {
// call destroy() for every cached object
for (T t : deque) {
c.destroy(t);
}
// finally get rid of all references
deque.clear();
}
@Override
public V obtain(int sizing) {
final T v = deque.pollFirst();
if (v == null) {
return new DV(c.newInstance(sizing), false);
}
return new DV(v, true);
}
/** Called before releasing an object, returns true if the object should be recycled and false otherwise. */
protected boolean beforeRelease() {
return deque.size() < maxSize;
}
/** Called after a release. */
protected void afterRelease(boolean recycled) {
// nothing to do
}
private class DV implements Recycler.V {
T value;
final boolean recycled;
DV(T value, boolean recycled) {
this.value = value;
this.recycled = recycled;
}
@Override
public T v() {
return value;
}
@Override
public boolean isRecycled() {
return recycled;
}
@Override
public void close() {
if (value == null) {
throw new IllegalStateException("recycler entry already released...");
}
final boolean recycle = beforeRelease();
if (recycle) {
c.recycle(value);
deque.addFirst(value);
}
else {
c.destroy(value);
}
value = null;
afterRelease(recycle);
}
}
}