BasePooledObjectFactory.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.pool2;

import java.util.Objects;

/**
 * A base implementation of {@code PoolableObjectFactory}.
 * <p>
 * All operations defined here are essentially no-op's.
 * <p>
 * This class is immutable, and therefore thread-safe
 *
 * @param <T> Type of element managed in this factory.
 * @see PooledObjectFactory
 * @see BaseKeyedPooledObjectFactory
 * @since 2.0
 */
public abstract class BasePooledObjectFactory<T> extends BaseObject implements PooledObjectFactory<T> {

    /**
     * Constructs a new instance.
     */
    public BasePooledObjectFactory() {
        // empty
    }

    /**
     *  No-op.
     *
     *  @param p ignored
     */
    @Override
    public void activateObject(final PooledObject<T> p) throws Exception {
        // The default implementation is a no-op.
    }

    /**
     * Creates an object instance, to be wrapped in a {@link PooledObject}.
     * <p>This method <strong>must</strong> support concurrent, multi-threaded
     * invocation.</p>
     *
     * @return an instance to be served by the pool, not null.
     * @throws Exception if there is a problem creating a new instance,
     *    this will be propagated to the code requesting an object.
     */
    public abstract T create() throws Exception;

    /**
     *  No-op.
     *
     *  @param p ignored
     */
    @Override
    public void destroyObject(final PooledObject<T> p) throws Exception  {
        // The default implementation is a no-op.
    }

    @Override
    public PooledObject<T> makeObject() throws Exception {
        return wrap(Objects.requireNonNull(create(), () -> String.format("BasePooledObjectFactory(%s).create() = null", getClass().getName())));
    }

    /**
     *  No-op.
     *
     * @param p ignored
     */
    @Override
    public void passivateObject(final PooledObject<T> p) throws Exception {
        // The default implementation is a no-op.
    }

    /**
     * Always returns {@code true}.
     *
     * @param p ignored
     * @return {@code true}
     */
    @Override
    public boolean validateObject(final PooledObject<T> p) {
        return true;
    }

    /**
     * Wraps the provided instance with an implementation of
     * {@link PooledObject}.
     *
     * @param obj the instance to wrap, should not be null.
     * @return The provided instance, wrapped by a {@link PooledObject}
     */
    public abstract PooledObject<T> wrap(T obj);
}