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
019/**
020 * A base implementation of {@code KeyedPooledObjectFactory}.
021 * <p>
022 * All operations defined here are essentially no-op's.
023 * </p>
024 * <p>
025 * This class is immutable, and therefore thread-safe.
026 * </p>
027 *
028 * @see KeyedPooledObjectFactory
029 *
030 * @param <K> The type of keys managed by this factory.
031 * @param <V> Type of element managed by this factory.
032 *
033 * @since 2.0
034 */
035public abstract class BaseKeyedPooledObjectFactory<K, V> extends BaseObject
036        implements KeyedPooledObjectFactory<K, V> {
037
038    /**
039     * Reinitialize an instance to be returned by the pool.
040     * <p>
041     * The default implementation is a no-op.
042     * </p>
043     *
044     * @param key the key used when selecting the object
045     * @param p a {@code PooledObject} wrapping the instance to be activated
046     */
047    @Override
048    public void activateObject(final K key, final PooledObject<V> p)
049        throws Exception {
050        // The default implementation is a no-op.
051    }
052
053    /**
054     * Create 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)
063        throws Exception;
064
065    /**
066     * Destroy an instance no longer needed by the pool.
067     * <p>
068     * The default implementation is a no-op.
069     * </p>
070     *
071     * @param key the key used when selecting the instance
072     * @param p a {@code PooledObject} wrapping the instance to be destroyed
073     */
074    @Override
075    public void destroyObject(final K key, final PooledObject<V> p)
076        throws Exception {
077        // The default implementation is a no-op.
078    }
079
080    @Override
081    public PooledObject<V> makeObject(final K key) throws Exception {
082        return wrap(create(key));
083    }
084
085    /**
086     * Uninitialize an instance to be returned to the idle object pool.
087     * <p>
088     * The default implementation is a no-op.
089     * </p>
090     *
091     * @param key the key used when selecting the object
092     * @param p a {@code PooledObject} wrapping the instance to be passivated
093     */
094    @Override
095    public void passivateObject(final K key, final PooledObject<V> p)
096        throws Exception {
097        // The default implementation is a no-op.
098    }
099
100    /**
101     * Ensures that the instance is safe to be returned by the pool.
102     * <p>
103     * The default implementation always returns {@code true}.
104     * </p>
105     *
106     * @param key the key used when selecting the object
107     * @param p a {@code PooledObject} wrapping the instance to be validated
108     * @return always {@code true} in the default implementation
109     */
110    @Override
111    public boolean validateObject(final K key, final PooledObject<V> p) {
112        return true;
113    }
114
115    /**
116     * Wrap the provided instance with an implementation of
117     * {@link PooledObject}.
118     *
119     * @param value the instance to wrap
120     *
121     * @return The provided instance, wrapped by a {@link PooledObject}
122     */
123    public abstract PooledObject<V> wrap(V value);
124}