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}