/
BufferWriterPool.java
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/
BufferWriterPool.java
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/*
* Copyright 2015 the original author or authors.
*
* Licensed 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 net.kuujo.copycat.log.io;
import net.kuujo.copycat.log.io.util.ReferenceCounted;
import net.kuujo.copycat.log.io.util.ReferenceManager;
import java.util.ArrayDeque;
import java.util.Queue;
/**
* Buffer writer pool.
* <p>
* The writer pool reduces garbage produced by frequent reads by tracking references to existing writers and recycling
* writers once they're closed.
*
* @author <a href="http://github.com/kuujo">Jordan Halterman</a>
*/
public class BufferWriterPool<T extends Buffer & ReferenceCounted<? extends Buffer>> implements ReferenceManager<BufferWriter<T>> {
private final T buffer;
private final Queue<BufferWriter<T>> pool = new ArrayDeque<>(1024);
public BufferWriterPool(T buffer) {
if (buffer == null)
throw new NullPointerException("buffer cannot be null");
this.buffer = buffer;
}
/**
* Acquires a new multi buffer writer.
*/
public BufferWriter acquire() {
BufferWriter writer = pool.poll();
if (writer == null) {
synchronized (pool) {
writer = pool.poll();
if (writer == null) {
writer = new BufferWriter<>(buffer, 0, 0, this);
}
}
}
buffer.acquire();
return writer;
}
@Override
public void release(BufferWriter<T> reference) {
buffer.release();
pool.add(reference);
}
}