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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 a {@link KeyedObjectPool}.
 * 

* By contract, when an {@link KeyedObjectPool} * delegates to a {@link KeyedPooledObjectFactory}, *

*
    *
  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 KeyedObjectPool#borrowObject borrowed} from the pool. *
  4. *
  5. * {@link #validateObject} may be invoked on {@link #activateObject activated} * instances to make sure they can be * {@link KeyedObjectPool#borrowObject borrowed} from the pool. * validateObject may also be used to test an * instance being {@link KeyedObjectPool#returnObject returned} to the pool * before it is {@link #passivateObject passivated}. It will only be invoked * on an activated instance. *
  6. *
  7. * {@link #passivateObject passivateObject} * is invoked on every instance when it is returned to the pool. *
  8. *
  9. * {@link #destroyObject destroyObject} * is invoked on every instance when it is being "dropped" from the * pool (whether due to the response from 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 KeyedPooledObjectFactory} must be thread-safe. The only promise * an {@link KeyedObjectPool} makes is that the same instance of an object will * not be passed to more than one method of a * KeyedPoolableObjectFactory at a time. *

* While clients of a {@link KeyedObjectPool} borrow and return instances of * the underlying value type 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 informations about the objects that * they manage. *

* * @see KeyedObjectPool * @see BaseKeyedPooledObjectFactory * * @param The type of keys managed by this factory. * @param Type of element managed by this factory. * * @since 2.0 */ public interface KeyedPooledObjectFactory { /** * Create an instance that can be served by the pool and * wrap it in a {@link PooledObject} to be managed by the pool. * * @param key the key used when constructing the object * * @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(K key) throws Exception; /** * Destroy 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 key the key used when selecting the instance * @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 KeyedObjectPool#invalidateObject */ void destroyObject(K key, PooledObject p) throws Exception; /** * Ensures that the instance is safe to be returned by the pool. * * @param key the key used when selecting the object * @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(K key, PooledObject p); /** * Reinitialize an instance to be returned by the pool. * * @param key the key used when selecting the object * @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(K key, PooledObject p) throws Exception; /** * Uninitialize an instance to be returned to the idle object pool. * * @param key the key used when selecting the object * @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(K key, PooledObject p) throws Exception; }




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