001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.pool2; 018 019/** 020 * A simple base implementation of {@link ObjectPool}. 021 * Optional operations are implemented to either do nothing, return a value 022 * indicating it is unsupported or throw {@link UnsupportedOperationException}. 023 * <p> 024 * This class is intended to be thread-safe. 025 * 026 * @param <T> Type of element pooled in this pool. 027 * 028 * @version $Revision: 1566605 $ 029 * 030 * @since 2.0 031 */ 032public abstract class BaseObjectPool<T> implements ObjectPool<T> { 033 034 @Override 035 public abstract T borrowObject() throws Exception; 036 037 @Override 038 public abstract void returnObject(T obj) throws Exception; 039 040 @Override 041 public abstract void invalidateObject(T obj) throws Exception; 042 043 /** 044 * Not supported in this base implementation. 045 * 046 * @return a negative value. 047 */ 048 @Override 049 public int getNumIdle() { 050 return -1; 051 } 052 053 /** 054 * Not supported in this base implementation. 055 * 056 * @return a negative value. 057 */ 058 @Override 059 public int getNumActive() { 060 return -1; 061 } 062 063 /** 064 * Not supported in this base implementation. 065 * 066 * @throws UnsupportedOperationException if the pool does not implement this 067 * method 068 */ 069 @Override 070 public void clear() throws Exception, UnsupportedOperationException { 071 throw new UnsupportedOperationException(); 072 } 073 074 /** 075 * Not supported in this base implementation. Subclasses should override 076 * this behavior. 077 * 078 * @throws UnsupportedOperationException if the pool does not implement this 079 * method 080 */ 081 @Override 082 public void addObject() throws Exception, UnsupportedOperationException { 083 throw new UnsupportedOperationException(); 084 } 085 086 /** 087 * {@inheritDoc} 088 * <p> 089 * This affects the behavior of <code>isClosed</code> and 090 * <code>assertOpen</code>. 091 */ 092 @Override 093 public void close() { 094 closed = true; 095 } 096 097 /** 098 * Has this pool instance been closed. 099 * 100 * @return <code>true</code> when this pool has been closed. 101 */ 102 public final boolean isClosed() { 103 return closed; 104 } 105 106 /** 107 * Throws an <code>IllegalStateException</code> when this pool has been 108 * closed. 109 * 110 * @throws IllegalStateException when this pool has been closed. 111 * 112 * @see #isClosed() 113 */ 114 protected final void assertOpen() throws IllegalStateException { 115 if (isClosed()) { 116 throw new IllegalStateException("Pool not open"); 117 } 118 } 119 120 private volatile boolean closed = false; 121}