org.elasticsearch.common.util.concurrent.SizeBlockingQueue Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of elasticsearch Show documentation
Show all versions of elasticsearch Show documentation
Elasticsearch subproject :server
/*
* 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.util.concurrent;
import java.util.AbstractQueue;
import java.util.Collection;
import java.util.Iterator;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
/**
* A size based queue wrapping another blocking queue to provide (somewhat relaxed) capacity checks.
* Mainly makes sense to use with blocking queues that are unbounded to provide the ability to do
* capacity verification.
*/
public class SizeBlockingQueue extends AbstractQueue implements BlockingQueue {
private final BlockingQueue queue;
private final int capacity;
private final AtomicInteger size = new AtomicInteger();
public SizeBlockingQueue(BlockingQueue queue, int capacity) {
assert capacity >= 0;
this.queue = queue;
this.capacity = capacity;
}
@Override
public int size() {
return size.get();
}
public int capacity() {
return this.capacity;
}
@Override
public Iterator iterator() {
final Iterator it = queue.iterator();
return new Iterator() {
E current;
@Override
public boolean hasNext() {
return it.hasNext();
}
@Override
public E next() {
current = it.next();
return current;
}
@Override
public void remove() {
// note, we can't call #remove on the iterator because we need to know
// if it was removed or not
if (queue.remove(current)) {
size.decrementAndGet();
}
}
};
}
@Override
public E peek() {
return queue.peek();
}
@Override
public E poll() {
E e = queue.poll();
if (e != null) {
size.decrementAndGet();
}
return e;
}
@Override
public E poll(long timeout, TimeUnit unit) throws InterruptedException {
E e = queue.poll(timeout, unit);
if (e != null) {
size.decrementAndGet();
}
return e;
}
@Override
public boolean remove(Object o) {
boolean v = queue.remove(o);
if (v) {
size.decrementAndGet();
}
return v;
}
/**
* Forces adding an element to the queue, without doing size checks.
*/
public void forcePut(E e) throws InterruptedException {
size.incrementAndGet();
try {
queue.put(e);
} catch (InterruptedException ie) {
size.decrementAndGet();
throw ie;
}
}
@Override
public boolean offer(E e) {
while (true) {
final int current = size.get();
if (current >= capacity()) {
return false;
}
if (size.compareAndSet(current, 1 + current)) {
break;
}
}
boolean offered = queue.offer(e);
if (!offered) {
size.decrementAndGet();
}
return offered;
}
@Override
public boolean offer(E e, long timeout, TimeUnit unit) throws InterruptedException {
// note, not used in ThreadPoolExecutor
throw new IllegalStateException("offer with timeout not allowed on size queue");
}
@Override
public void put(E e) throws InterruptedException {
// note, not used in ThreadPoolExecutor
throw new IllegalStateException("put not allowed on size queue");
}
@Override
public E take() throws InterruptedException {
E e;
try {
e = queue.take();
size.decrementAndGet();
} catch (InterruptedException ie) {
throw ie;
}
return e;
}
@Override
public int remainingCapacity() {
return capacity - size.get();
}
@Override
public int drainTo(Collection c) {
int v = queue.drainTo(c);
size.addAndGet(-v);
return v;
}
@Override
public int drainTo(Collection c, int maxElements) {
int v = queue.drainTo(c, maxElements);
size.addAndGet(-v);
return v;
}
@Override
public Object[] toArray() {
return queue.toArray();
}
@Override
public T[] toArray(T[] a) {
return (T[]) queue.toArray(a);
}
@Override
public boolean contains(Object o) {
return queue.contains(o);
}
@Override
public boolean containsAll(Collection c) {
return queue.containsAll(c);
}
}