/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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.apache.brooklyn.util.pool;

import java.io.Closeable;
import java.io.IOException;

import com.google.common.base.Function;

/**
 * See discussion at http://code.google.com/p/guava-libraries/issues/detail?id=683.
 * This API is inspired by that proposed by kevinb@google.com
 * 
 * There are two ways to use the pool.
 * 
 * Passive:
 * 
 * <pre>
 * {@code
 *   Pool<Expensive> pool = ...
 *   Lease<Expensive> lease = pool.leaseObject();
 *   try {
 *     Expensive o = lease.leasedObject();
 *     doSomethingWith(o);
 *   } finally {
 *     lease.close();
 *   }
 * }
 * </pre>
 *
 * Or active:
 * 
 * <pre>
 * {@code
 *   Pool<Expensive> pool = ...
 *   pool.exec(
 *       new Function<Expensive,Void>() {
 *         public Void apply(Expensive o) {
 *           doSomethingWith(o);
 *           return null;
 *         }
 *       });
 * }
 * </pre>
 * 
 * @see BasicPool
 * 
 * @author aled
 */
public interface Pool<T> extends Closeable {

    Lease<T> leaseObject();
    
    <R> R exec(Function<? super T,R> receiver);

    @Override
    void close() throws IOException;
}