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 *
032 * @param <K> The type of keys managed by this factory.
033 * @param <V> Type of element managed by this factory.
034 *
035 * @since 2.0
036 */
037public abstract class BaseKeyedPooledObjectFactory<K, V> extends BaseObject implements KeyedPooledObjectFactory<K, V> {
038
039    /**
040     * Reinitializes an instance to be returned by the pool.
041     * <p>
042     * The default implementation is a no-op.
043     * </p>
044     *
045     * @param key the key used when selecting the object
046     * @param p a {@code PooledObject} wrapping the instance to be activated
047     */
048    @Override
049    public void activateObject(final K key, final PooledObject<V> p) throws Exception {
050        // The default implementation is a no-op.
051    }
052
053    /**
054     * Creates an instance that can be served by the pool.
055     *
056     * @param key the key used when constructing the object
057     * @return an instance that can be served by the pool
058     *
059     * @throws Exception if there is a problem creating a new instance,
060     *    this will be propagated to the code requesting an object.
061     */
062    public abstract V create(K key) throws Exception;
063
064    /**
065     * Destroys an instance no longer needed by the pool.
066     * <p>
067     * The default implementation is a no-op.
068     * </p>
069     *
070     * @param key the key used when selecting the instance
071     * @param p a {@code PooledObject} wrapping the instance to be destroyed
072     */
073    @Override
074    public void destroyObject(final K key, final PooledObject<V> p) throws Exception {
075        // The default implementation is a no-op.
076    }
077
078    @Override
079    public PooledObject<V> makeObject(final K key) throws Exception {
080        return wrap(
081                Objects.requireNonNull(create(key), () -> String.format("BaseKeyedPooledObjectFactory(%s).create(key=%s) = null", getClass().getName(), key)));
082    }
083
084    /**
085     * Uninitializes an instance to be returned to the idle object pool.
086     * <p>
087     * The default implementation is a no-op.
088     * </p>
089     *
090     * @param key the key used when selecting the object
091     * @param p a {@code PooledObject} wrapping the instance to be passivated
092     */
093    @Override
094    public void passivateObject(final K key, final PooledObject<V> p) throws Exception {
095        // The default implementation is a no-op.
096    }
097
098    /**
099     * Ensures that the instance is safe to be returned by the pool.
100     * <p>
101     * The default implementation always returns {@code true}.
102     * </p>
103     *
104     * @param key the key used when selecting the object
105     * @param p a {@code PooledObject} wrapping the instance to be validated
106     * @return always {@code true} in this default implementation
107     */
108    @Override
109    public boolean validateObject(final K key, final PooledObject<V> p) {
110        return true;
111    }
112
113    /**
114     * Wraps the provided instance with an implementation of
115     * {@link PooledObject}.
116     *
117     * @param value the instance to wrap, should not be null.
118     * @return The provided instance, wrapped by a {@link PooledObject}
119     */
120    public abstract PooledObject<V> wrap(V value);
121}