/*
* This file is part of NucleusFramework for Bukkit, licensed under the MIT License (MIT).
*
* Copyright (c) JCThePants (www.jcwhatever.com)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.jcwhatever.nucleus.utils.performance.pool;
import com.jcwhatever.nucleus.utils.ArrayUtils;
import java.util.Iterator;
import javax.annotation.Nullable;
/**
* A pool of objects that tracks elements that have been checked out of the pool.
*
* <p>The checked out elements can be retrieved by invoking {@link #getCheckedOut}
* and recycled by invoking the returned objects {@link CheckedOutElements#recycle}
* method. All checked out elements are recycled at once.</p>
*/
public class SimpleCheckoutPool<E> extends AbstractPool<E> {
private final CheckedOutElements<E> _checkedOut = new CheckedOutElements<>(this);
private final Object _sync = new Object();
/**
* Constructor.
*
* @param capacity The initial capacity of the pool.
*/
public SimpleCheckoutPool(int capacity) {
this(capacity, null, null);
}
/**
* Constructor.
*
* @param capacity The initial capacity of the pool.
* @param elementFactory The element factory used to create new elements when
* the pool is empty.
*/
public SimpleCheckoutPool(int capacity,
@Nullable IPoolElementFactory<E> elementFactory) {
this(capacity, elementFactory, null);
}
/**
* Constructor.
*
* @param capacity The initial capacity of the pool.
* @param elementFactory The element factory used to create new elements when
* the pool is empty.
* @param recycleHandler The handler to give a recycled element to for object teardown.
*/
public SimpleCheckoutPool(int capacity,
@Nullable IPoolElementFactory<E> elementFactory,
@Nullable IPoolRecycleHandler<E> recycleHandler) {
super(capacity, elementFactory, recycleHandler);
_checkedOut.array = new Object[capacity];
}
/**
* Checkout an element from the pool.
*
* <p>If the pool is empty, a new element is created if the pool has
* an element factory.</p>
*
* @return The element or null if the pool is empty and a pooled element
* factory is not being used.
*/
@Nullable
public E checkout() {
E element;
synchronized (_sync) {
element = super.retrieve();
if (element == null)
return null;
if (maxSize() > -1 && _checkedOut.size() >= maxSize())
return element;
if (_checkedOut.size() + 1 > _checkedOut.array.length)
_checkedOut.array = expand(_checkedOut.array, maxSize());
_checkedOut.arrayIndex++;
_checkedOut.array[_checkedOut.arrayIndex] = element;
}
return element;
}
/**
* Get the elements that have been checked out.
*/
public CheckedOutElements<E> getCheckedOut() {
return _checkedOut;
}
@Override
public int size() {
synchronized (_sync) {
return super.size();
}
}
@Override
public int maxSize() {
synchronized (_sync) {
return super.maxSize();
}
}
@Override
public void setMaxSize(int maxSize) {
synchronized (_sync) {
super.setMaxSize(maxSize);
}
}
@Override
public boolean contains(@Nullable Object element) {
synchronized (_sync) {
return super.contains(element);
}
}
@Override
public void clear() {
synchronized (_sync) {
super.clear();
}
}
@Override
public void fitToSize(int padding) {
synchronized (_sync) {
super.fitToSize(padding);
if (_checkedOut.size() <= pool().length) {
_checkedOut.array = resize(_checkedOut.array, pool().length, -1);
}
}
}
@Override
public boolean recycle(E element) {
boolean result = super.recycle(element);
_checkedOut.recycled(element);
return result;
}
/**
* Get the internal synchronization object.
*/
protected Object getSync() {
return _sync;
}
/**
* Elements that have been checked out of a checkout pool.
*
* <p>Iterable to iterate checked out elements. The iterator does not
* support the {@link Iterator#remove} method.</p>
*
* @param <E> The element type.
*/
public static class CheckedOutElements<E> implements Iterable<E> {
final SimpleCheckoutPool<E> parent;
Object[] array;
int arrayIndex = -1;
/**
* Constructor.
*
* @param pool The owning pool.
*/
CheckedOutElements(SimpleCheckoutPool<E> pool) {
this.parent = pool;
}
/**
* Get the owning pool.
*/
public SimpleCheckoutPool<E> getPool() {
return parent;
}
/**
* Get the number of checked out elements.
*/
public int size() {
synchronized (this) {
return arrayIndex + 1;
}
}
/**
* Recycle checked out elements back into the pool.
*/
public void recycle() {
int size = size();
if (size == 0)
return;
synchronized (this) {
synchronized (parent._sync) {
parent.recycleAll(array, 0, size);
clear();
}
}
}
/**
* Clear all checked out elements.
*
* <p>Does not put elements back into the pool.</p>
*/
public void clear() {
synchronized (this) {
ArrayUtils.reset(array);
arrayIndex = -1;
}
}
@Override
public Iterator<E> iterator() {
return new Iterator<E>() {
int index = -1;
@Override
public boolean hasNext() {
return index + 1 < size();
}
@Override
public E next() {
index++;
@SuppressWarnings("unchecked")
E element = (E)array[index];
return element;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
};
}
void recycled(E element) {
if (arrayIndex == -1)
return;
int i = 0;
// remove element from array
for (; i <= arrayIndex; i++) {
if (array[i].equals(element)) {
array[i] = null;
break;
}
}
// compact array
for (i++; i <= arrayIndex; i++) {
array[i - 1] = array[i];
}
array[arrayIndex] = null;
arrayIndex--;
}
}
}