Coverage Report - org.apache.commons.pool.PoolableObjectFactory
 
Classes in this File Line Coverage Branch Coverage Complexity
PoolableObjectFactory
N/A
N/A
1
 
 1  
 /*
 2  
  * Licensed to the Apache Software Foundation (ASF) under one or more
 3  
  * contributor license agreements.  See the NOTICE file distributed with
 4  
  * this work for additional information regarding copyright ownership.
 5  
  * The ASF licenses this file to You under the Apache License, Version 2.0
 6  
  * (the "License"); you may not use this file except in compliance with
 7  
  * the License.  You may obtain a copy of the License at
 8  
  *
 9  
  *      http://www.apache.org/licenses/LICENSE-2.0
 10  
  *
 11  
  * Unless required by applicable law or agreed to in writing, software
 12  
  * distributed under the License is distributed on an "AS IS" BASIS,
 13  
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 14  
  * See the License for the specific language governing permissions and
 15  
  * limitations under the License.
 16  
  */
 17  
 
 18  
 package org.apache.commons.pool;
 19  
 
 20  
 /**
 21  
  * An interface defining life-cycle methods for
 22  
  * instances to be served by an {@link ObjectPool}.
 23  
  * <p>
 24  
  * By contract, when an {@link ObjectPool}
 25  
  * delegates to a {@link PoolableObjectFactory},
 26  
  * <ol>
 27  
  *  <li>
 28  
  *   {@link #makeObject makeObject}
 29  
  *   is called whenever a new instance is needed.
 30  
  *  </li>
 31  
  *  <li>
 32  
  *   {@link #activateObject activateObject}
 33  
  *   is invoked on every instance that has been
 34  
  *   {@link #passivateObject passivated} before it is
 35  
  *   {@link ObjectPool#borrowObject borrowed} from the pool.
 36  
  *  </li>
 37  
  *  <li>
 38  
  *   {@link #validateObject validateObject}
 39  
  *   is invoked on {@link #activateObject activated} instances to make sure
 40  
  *   they can be {@link ObjectPool#borrowObject borrowed} from the pool.
 41  
  *   <code>validateObject</code> <strong>may</strong> also be used to test an
 42  
  *   instance being {@link ObjectPool#returnObject returned} to the pool
 43  
  *   before it is {@link #passivateObject passivated}. It will only be invoked
 44  
  *   on an activated instance.
 45  
  *  </li>
 46  
  *  <li>
 47  
  *   {@link #passivateObject passivateObject}
 48  
  *   is invoked on every instance when it is returned to the pool.
 49  
  *  </li>
 50  
  *  <li>
 51  
  *   {@link #destroyObject destroyObject}
 52  
  *   is invoked on every instance when it is being "dropped" from the
 53  
  *   pool (whether due to the response from <code>validateObject</code>,
 54  
  *   or for reasons specific to the pool implementation.) There is no
 55  
  *   guarantee that the instance being destroyed will
 56  
  *   be considered active, passive or in a generally consistent state.
 57  
  *  </li>
 58  
  * </ol>
 59  
  * </p>
 60  
  * <p>
 61  
  * {@link PoolableObjectFactory} must be thread-safe. The only promise
 62  
  * an {@link ObjectPool} makes is that the same instance of an object will not
 63  
  * be passed to more than one method of a <code>PoolableObjectFactory</code>
 64  
  * at a time.
 65  
  * </p>
 66  
  *
 67  
  * @see ObjectPool
 68  
  *
 69  
  * @author Rodney Waldhoff
 70  
  * @author Sandy McArthur
 71  
  * @version $Revision: 777748 $ $Date: 2009-05-22 17:00:44 -0700 (Fri, 22 May 2009) $
 72  
  * @since Pool 1.0
 73  
  */
 74  
 public interface PoolableObjectFactory {
 75  
   /**
 76  
    * Creates an instance that can be served by the pool.
 77  
    * Instances returned from this method should be in the
 78  
    * same state as if they had been
 79  
    * {@link #activateObject activated}. They will not be
 80  
    * activated before being served by the pool.
 81  
    *
 82  
    * @return an instance that can be served by the pool.
 83  
    * @throws Exception if there is a problem creating a new instance,
 84  
    *    this will be propagated to the code requesting an object.
 85  
    */
 86  
   Object makeObject() throws Exception;
 87  
 
 88  
   /**
 89  
    * Destroys an instance no longer needed by the pool.
 90  
    * <p>
 91  
    * It is important for implementations of this method to be aware
 92  
    * that there is no guarantee about what state <code>obj</code>
 93  
    * will be in and the implementation should be prepared to handle
 94  
    * unexpected errors.
 95  
    * </p>
 96  
    * <p>
 97  
    * Also, an implementation must take in to consideration that
 98  
    * instances lost to the garbage collector may never be destroyed.
 99  
    * </p>
 100  
    *
 101  
    * @param obj the instance to be destroyed
 102  
    * @throws Exception should be avoided as it may be swallowed by
 103  
    *    the pool implementation.
 104  
    * @see #validateObject
 105  
    * @see ObjectPool#invalidateObject
 106  
    */
 107  
   void destroyObject(Object obj) throws Exception;
 108  
 
 109  
   /**
 110  
    * Ensures that the instance is safe to be returned by the pool.
 111  
    * Returns <code>false</code> if <code>obj</code> should be destroyed.
 112  
    *
 113  
    * @param obj the instance to be validated
 114  
    * @return <code>false</code> if <code>obj</code> is not valid and should
 115  
    *         be dropped from the pool, <code>true</code> otherwise.
 116  
    */
 117  
   boolean validateObject(Object obj);
 118  
 
 119  
   /**
 120  
    * Reinitialize an instance to be returned by the pool.
 121  
    *
 122  
    * @param obj the instance to be activated
 123  
    * @throws Exception if there is a problem activating <code>obj</code>,
 124  
    *    this exception may be swallowed by the pool.
 125  
    * @see #destroyObject
 126  
    */
 127  
   void activateObject(Object obj) throws Exception;
 128  
 
 129  
   /**
 130  
    * Uninitialize an instance to be returned to the idle object pool.
 131  
    *
 132  
    * @param obj the instance to be passivated
 133  
    * @throws Exception if there is a problem passivating <code>obj</code>,
 134  
    *    this exception may be swallowed by the pool.
 135  
    * @see #destroyObject
 136  
    */
 137  
   void passivateObject(Object obj) throws Exception;
 138  
 }