    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 *      https://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     * Constructs a new instance.
    039     */
    040    public BaseKeyedPooledObjectFactory() {
    041        // empty
    042    }
    043
    044    /**
    045     * Reinitializes an instance to be returned by the pool.
    046     * <p>
    047     * The default implementation is a no-op.
    048     * </p>
    049     *
    050     * @param key the key used when selecting the object
    051     * @param p a {@code PooledObject} wrapping the instance to be activated
    052     */
    053    @Override
    054    public void activateObject(final K key, final PooledObject<V> p) throws Exception {
    055        // The default implementation is a no-op.
    056    }
    057
    058    /**
    059     * Creates an instance that can be served by the pool.
    060     *
    061     * @param key the key used when constructing the object
    062     * @return an instance that can be served by the pool
    063     * @throws Exception if there is a problem creating a new instance,
    064     *    this will be propagated to the code requesting an object.
    065     */
    066    public abstract V create(K key) throws Exception;
    067
    068    /**
    069     * Destroys an instance no longer needed by the pool.
    070     * <p>
    071     * The default implementation is a no-op.
    072     * </p>
    073     *
    074     * @param key the key used when selecting the instance
    075     * @param p a {@code PooledObject} wrapping the instance to be destroyed
    076     */
    077    @Override
    078    public void destroyObject(final K key, final PooledObject<V> p) throws Exception {
    079        // The default implementation is a no-op.
    080    }
    081
    082    @Override
    083    public PooledObject<V> makeObject(final K key) throws Exception {
    084        return wrap(
    085                Objects.requireNonNull(create(key), () -> String.format("BaseKeyedPooledObjectFactory(%s).create(key=%s) = null", getClass().getName(), key)));
    086    }
    087
    088    /**
    089     * Uninitializes an instance to be returned to the idle object pool.
    090     * <p>
    091     * The default implementation is a no-op.
    092     * </p>
    093     *
    094     * @param key the key used when selecting the object
    095     * @param p a {@code PooledObject} wrapping the instance to be passivated
    096     */
    097    @Override
    098    public void passivateObject(final K key, final PooledObject<V> p) throws Exception {
    099        // The default implementation is a no-op.
    100    }
    101
    102    /**
    103     * Ensures that the instance is safe to be returned by the pool.
    104     * <p>
    105     * The default implementation always returns {@code true}.
    106     * </p>
    107     *
    108     * @param key the key used when selecting the object
    109     * @param p a {@code PooledObject} wrapping the instance to be validated
    110     * @return always {@code true} in this default implementation
    111     */
    112    @Override
    113    public boolean validateObject(final K key, final PooledObject<V> p) {
    114        return true;
    115    }
    116
    117    /**
    118     * Wraps the provided instance with an implementation of
    119     * {@link PooledObject}.
    120     *
    121     * @param value the instance to wrap, should not be null.
    122     * @return The provided instance, wrapped by a {@link PooledObject}
    123     */
    124    public abstract PooledObject<V> wrap(V value);
    125}