Pool.java Source code

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Here is the source code for Pool.java

Source

/*
 * Copyright 2008-2010 the T2 Project ant the Others.
 *
 * 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 org.t2framework.commons.util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.CopyOnWriteArraySet;

public class Pool<T> {

    private static int DEFAULT_POOL_MAX = 10;

    private List<T> stock;

    private Set<T> havings;

    public static <T> Pool<T> create(T... stocks) {
        return new Pool<T>(Arrays.asList(stocks));
    }

    public static <T extends Cloneable> Pool<T> create(T origin) {
        return create(origin, DEFAULT_POOL_MAX);
    }

    public static <T extends Cloneable> Pool<T> create(T origin, int poolMax) {
        if (origin == null) {
            throw new IllegalArgumentException("origin: " + origin);
        }
        if (poolMax < 1) {
            throw new IllegalArgumentException("poolMax: " + poolMax);
        }
        List<T> copies = new ArrayList<T>();
        for (int i = 0; i < poolMax; i++) {
            try {
                @SuppressWarnings("unchecked")
                T copied = (T) origin.getClass().getMethod("clone").invoke(origin);
                copies.add(copied);
            } catch (Exception e) {
                throw new IllegalStateException(e);
            }
        }
        return new Pool<T>(copies);
    }

    private Pool(List<T> stocks) {
        if (stocks == null || stocks.size() == 0) {
            throw new IllegalArgumentException("stocks: " + stocks);
        }
        this.stock = new CopyOnWriteArrayList<T>();
        this.havings = new CopyOnWriteArraySet<T>();
        for (T stockItem : stocks) {
            stock.add(stockItem);
            havings.add(stockItem);
        }
    }

    public T borrowItem() {
        try {
            while (true) {
                if (0 < stock.size()) {
                    return stock.remove(0);
                }
                Thread.sleep(10);
            }
        } catch (InterruptedException e) {
            throw new IllegalStateException(e);
        }
    }

    public void returnItem(T item) {
        if (havings.contains(item) == false) {
            throw new IllegalStateException("item is not mine");
        }
        stock.add(item);
    }

}