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/*
 * 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
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package com.frameworkset.commons.pool2;

/**
 * An interface defining life-cycle methods for instances to be served by an
 * {@link ObjectPool}.
 * 

* By contract, when an {@link ObjectPool} delegates to a * {@link PooledObjectFactory}, *

*
    *
  1. * {@link #makeObject} is called whenever a new instance is needed. *
  2. *
  3. * {@link #activateObject} is invoked on every instance that has been * {@link #passivateObject passivated} before it is * {@link ObjectPool#borrowObject borrowed} from the pool. *
  4. *
  5. * {@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. *
  6. *
  7. * {@link #passivateObject} is invoked on every instance when it is returned * to the pool. *
  8. *
  9. * {@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. *
  10. *
* {@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 PoolableObjectFactory * at a time. *

* 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 Type of element managed in this factory. * * @see ObjectPool * * @since 2.0 */ public interface PooledObjectFactory { /** * Creates 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 makeObject() throws Exception; /** * Destroys an instance no longer needed by the pool. *

* It is important for implementations of this method to be aware that there * is no guarantee about what state obj will be in and the * implementation should be prepared to handle unexpected errors. *

*

* Also, an implementation must take in to consideration that instances lost * to the garbage collector may never be destroyed. *

* * @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 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 false if obj is not valid and should * be dropped from the pool, true otherwise. */ boolean validateObject(PooledObject p); /** * Reinitializes 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 obj, * this exception may be swallowed by the pool. * * @see #destroyObject */ void activateObject(PooledObject p) throws Exception; /** * Uninitializes 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 obj, * this exception may be swallowed by the pool. * * @see #destroyObject */ void passivateObject(PooledObject p) throws Exception; }




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