127 lines
3.5 KiB
Java
127 lines
3.5 KiB
Java
/*
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* from: http://ashkrit.blogspot.com/2013/05/lock-less-java-object-pool.html
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* https://github.com/ashkrit/blog/tree/master/FastObjectPool
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* copyright ashkrit 2013
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Modified by dorkbox, llc
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*/
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package dorkbox.util.objectPool;
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import org.jctools.queues.MpmcArrayQueue;
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import org.jctools.util.Pow2;
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import java.util.concurrent.locks.Condition;
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import java.util.concurrent.locks.Lock;
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import java.util.concurrent.locks.ReentrantLock;
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class UnsafeObjectPool<T> implements ObjectPool<T> {
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public static final int FULL_RETRY_LIMIT = 200;
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private final MpmcArrayQueue<T> objects;
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private final Lock lock = new ReentrantLock();
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private final Condition empty = lock.newCondition();
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private final PoolableObject<T> poolableObject;
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UnsafeObjectPool(final PoolableObject<T> poolableObject, final int size) throws Throwable {
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this.poolableObject = poolableObject;
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int newSize = Pow2.roundToPowerOfTwo(size);
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objects = new MpmcArrayQueue<T>(newSize);
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for (int x = 0; x < newSize; x++) {
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T e = poolableObject.create();
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poolableObject.reset(e);
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objects.offer(e);
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}
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}
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@Override
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public
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T take() throws InterruptedException {
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T poll = objects.poll();
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if (poll == null) {
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lock.lock();
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try {
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while ((poll = objects.poll()) == null) {
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empty.await();
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}
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} finally {
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lock.unlock();
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}
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}
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return poll;
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}
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@Override
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public
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T takeUninterruptibly() {
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try {
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return take();
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} catch (InterruptedException e) {
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return null;
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}
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}
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@Override
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public
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void release(T object) {
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poolableObject.reset(object);
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boolean waiting = objects.peek() == null;
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// This could potentially happen due to optimistic calculations by the implementation queue.
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// From my observations, 1 retry was all that was needed.
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if (!objects.offer(object)) {
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int limit = FULL_RETRY_LIMIT;
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while (!objects.offer(object) && limit-- > 0) {
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Thread.yield();
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}
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if (limit <= 0) {
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throw new RuntimeException("Unable to insert item into object pool. Pool is full, and retry limit exceeded.");
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}
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}
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if (waiting) {
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lock.lock();
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try {
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if (objects.peek() == null) {
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// we only need to signal one, since the take/release calls must be symmetric
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empty.signal();
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}
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} finally {
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lock.unlock();
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}
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}
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}
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@Override
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public
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T newInstance() {
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return poolableObject.create();
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}
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/**
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* This is an optimistic calculation, and if being used by multiple threads, can be inaccurate.
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*/
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@Override
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public
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int size() {
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return objects.size();
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}
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}
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