| /* |
| * 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.tomcat.dbcp.pool2; |
| |
| /** |
| * An interface defining life-cycle methods for instances to be served by an |
| * {@link ObjectPool}. |
| * <p> |
| * By contract, when an {@link ObjectPool} delegates to a |
| * {@link PooledObjectFactory}, |
| * <ol> |
| * <li> |
| * {@link #makeObject} is called whenever a new instance is needed. |
| * </li> |
| * <li> |
| * {@link #activateObject} is invoked on every instance that has been |
| * {@link #passivateObject passivated} before it is |
| * {@link ObjectPool#borrowObject borrowed} from the pool. |
| * </li> |
| * <li> |
| * {@link #validateObject} may be invoked on {@link #activateObject activated} |
| * instances to make sure they can be {@link ObjectPool#borrowObject borrowed} |
| * from the pool. {@link #validateObject} may also be used to |
| * test an instance being {@link ObjectPool#returnObject returned} to the pool |
| * before it is {@link #passivateObject passivated}. It will only be invoked |
| * on an activated instance. |
| * </li> |
| * <li> |
| * {@link #passivateObject} is invoked on every instance when it is returned |
| * to the pool. |
| * </li> |
| * <li> |
| * {@link #destroyObject} is invoked on every instance when it is being |
| * "dropped" from the pool (whether due to the response from |
| * {@link #validateObject}, or for reasons specific to the pool |
| * implementation.) There is no guarantee that the instance being destroyed |
| * will be considered active, passive or in a generally consistent state. |
| * </li> |
| * </ol> |
| * {@link PooledObjectFactory} must be thread-safe. The only promise |
| * an {@link ObjectPool} makes is that the same instance of an object will not |
| * be passed to more than one method of a <code>PoolableObjectFactory</code> |
| * at a time. |
| * <p> |
| * While clients of a {@link KeyedObjectPool} borrow and return instances of |
| * the underlying value type {@code V}, the factory methods act on instances of |
| * {@link PooledObject PooledObject<V>}. These are the object wrappers that |
| * pools use to track and maintain state information about the objects that |
| * they manage. |
| * |
| * @param <T> Type of element managed in this factory. |
| * |
| * @see ObjectPool |
| * |
| * @since 2.0 |
| */ |
| public interface PooledObjectFactory<T> { |
| /** |
| * Create an instance that can be served by the pool and wrap it in a |
| * {@link PooledObject} to be managed by the pool. |
| * |
| * @return a {@code PooledObject} wrapping an instance that can be served by the pool |
| * |
| * @throws Exception if there is a problem creating a new instance, |
| * this will be propagated to the code requesting an object. |
| */ |
| PooledObject<T> makeObject() throws Exception; |
| |
| /** |
| * Destroys an instance no longer needed by the pool. |
| * <p> |
| * It is important for implementations of this method to be aware that there |
| * is no guarantee about what state <code>obj</code> will be in and the |
| * implementation should be prepared to handle unexpected errors. |
| * <p> |
| * Also, an implementation must take in to consideration that instances lost |
| * to the garbage collector may never be destroyed. |
| * </p> |
| * |
| * @param p a {@code PooledObject} wrapping the instance to be destroyed |
| * |
| * @throws Exception should be avoided as it may be swallowed by |
| * the pool implementation. |
| * |
| * @see #validateObject |
| * @see ObjectPool#invalidateObject |
| */ |
| void destroyObject(PooledObject<T> p) throws Exception; |
| |
| /** |
| * Ensures that the instance is safe to be returned by the pool. |
| * |
| * @param p a {@code PooledObject} wrapping the instance to be validated |
| * |
| * @return <code>false</code> if <code>obj</code> is not valid and should |
| * be dropped from the pool, <code>true</code> otherwise. |
| */ |
| boolean validateObject(PooledObject<T> p); |
| |
| /** |
| * Reinitialize an instance to be returned by the pool. |
| * |
| * @param p a {@code PooledObject} wrapping the instance to be activated |
| * |
| * @throws Exception if there is a problem activating <code>obj</code>, |
| * this exception may be swallowed by the pool. |
| * |
| * @see #destroyObject |
| */ |
| void activateObject(PooledObject<T> p) throws Exception; |
| |
| /** |
| * Uninitialize an instance to be returned to the idle object pool. |
| * |
| * @param p a {@code PooledObject} wrapping the instance to be passivated |
| * |
| * @throws Exception if there is a problem passivating <code>obj</code>, |
| * this exception may be swallowed by the pool. |
| * |
| * @see #destroyObject |
| */ |
| void passivateObject(PooledObject<T> p) throws Exception; |
| } |