    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.pool2;
    018
    019import java.util.Objects;
    020
    021/**
    022 * A base implementation of {@code KeyedPooledObjectFactory}.
    023 * <p>
    024 * All operations defined here are essentially no-op's.
    025 * </p>
    026 * <p>
    027 * This class is immutable, and therefore thread-safe.
    028 * </p>
    029 *
    030 * @see KeyedPooledObjectFactory
    031 * @param <K> The type of keys managed by this factory.
    032 * @param <V> Type of element managed by this factory.
    033 * @since 2.0
    034 */
    035public abstract class BaseKeyedPooledObjectFactory<K, V> extends BaseObject implements KeyedPooledObjectFactory<K, V> {
    036
    037    /**
    038     * Reinitializes an instance to be returned by the pool.
    039     * <p>
    040     * The default implementation is a no-op.
    041     * </p>
    042     *
    043     * @param key the key used when selecting the object
    044     * @param p a {@code PooledObject} wrapping the instance to be activated
    045     */
    046    @Override
    047    public void activateObject(final K key, final PooledObject<V> p) throws Exception {
    048        // The default implementation is a no-op.
    049    }
    050
    051    /**
    052     * Creates an instance that can be served by the pool.
    053     *
    054     * @param key the key used when constructing the object
    055     * @return an instance that can be served by the pool
    056     * @throws Exception if there is a problem creating a new instance,
    057     *    this will be propagated to the code requesting an object.
    058     */
    059    public abstract V create(K key) throws Exception;
    060
    061    /**
    062     * Destroys an instance no longer needed by the pool.
    063     * <p>
    064     * The default implementation is a no-op.
    065     * </p>
    066     *
    067     * @param key the key used when selecting the instance
    068     * @param p a {@code PooledObject} wrapping the instance to be destroyed
    069     */
    070    @Override
    071    public void destroyObject(final K key, final PooledObject<V> p) throws Exception {
    072        // The default implementation is a no-op.
    073    }
    074
    075    @Override
    076    public PooledObject<V> makeObject(final K key) throws Exception {
    077        return wrap(
    078                Objects.requireNonNull(create(key), () -> String.format("BaseKeyedPooledObjectFactory(%s).create(key=%s) = null", getClass().getName(), key)));
    079    }
    080
    081    /**
    082     * Uninitializes an instance to be returned to the idle object pool.
    083     * <p>
    084     * The default implementation is a no-op.
    085     * </p>
    086     *
    087     * @param key the key used when selecting the object
    088     * @param p a {@code PooledObject} wrapping the instance to be passivated
    089     */
    090    @Override
    091    public void passivateObject(final K key, final PooledObject<V> p) throws Exception {
    092        // The default implementation is a no-op.
    093    }
    094
    095    /**
    096     * Ensures that the instance is safe to be returned by the pool.
    097     * <p>
    098     * The default implementation always returns {@code true}.
    099     * </p>
    100     *
    101     * @param key the key used when selecting the object
    102     * @param p a {@code PooledObject} wrapping the instance to be validated
    103     * @return always {@code true} in this default implementation
    104     */
    105    @Override
    106    public boolean validateObject(final K key, final PooledObject<V> p) {
    107        return true;
    108    }
    109
    110    /**
    111     * Wraps the provided instance with an implementation of
    112     * {@link PooledObject}.
    113     *
    114     * @param value the instance to wrap, should not be null.
    115     * @return The provided instance, wrapped by a {@link PooledObject}
    116     */
    117    public abstract PooledObject<V> wrap(V value);
    118}