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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
* limitations under the License.
*/
package org.apache.commons.pool2;
/**
* A simple base implementation of {@link ObjectPool}.
* Optional operations are implemented to either do nothing, return a value
* indicating it is unsupported or throw {@link UnsupportedOperationException}.
*
* This class is intended to be thread-safe.
*
* @param Type of element pooled in this pool.
*
* @version $Revision: 1333925 $
*
* @since 2.0
*/
public abstract class BaseObjectPool implements ObjectPool {
/**
* Obtains an instance from the pool.
*
* @return an instance from the pool
*
* @throws Exception if an instance cannot be obtained from the pool
*/
@Override
public abstract T borrowObject() throws Exception;
/**
* Returns an instance to the pool.
*
* @param obj instance to return to the pool
*/
@Override
public abstract void returnObject(T obj) throws Exception;
/**
* Invalidates an object from the pool.
*
* By contract, obj must have been obtained
* using {@link #borrowObject borrowObject}.
*
* This method should be used when an object that has been borrowed is
* determined (due to an exception or other problem) to be invalid.
*
* @param obj a {@link #borrowObject borrowed} instance to be disposed.
* @throws Exception
*/
@Override
public abstract void invalidateObject(T obj) throws Exception;
/**
* Not supported in this base implementation.
*
* @return a negative value.
*/
@Override
public int getNumIdle() {
return -1;
}
/**
* Not supported in this base implementation.
*
* @return a negative value.
*/
@Override
public int getNumActive() {
return -1;
}
/**
* Not supported in this base implementation.
*
* @throws UnsupportedOperationException
*/
@Override
public void clear() throws Exception, UnsupportedOperationException {
throw new UnsupportedOperationException();
}
/**
* Not supported in this base implementation.Always throws an
* {@link UnsupportedOperationException}, subclasses should override this
* behavior.
*
* @throws UnsupportedOperationException
*/
@Override
public void addObject() throws Exception, UnsupportedOperationException {
throw new UnsupportedOperationException();
}
/**
* Close this pool. This affects the behavior of isClosed and
* assertOpen.
*/
@Override
public void close() {
closed = true;
}
/**
* Has this pool instance been closed.
*
* @return true when this pool has been closed.
*/
public final boolean isClosed() {
return closed;
}
/**
* Throws an IllegalStateException when this pool has been
* closed.
*
* @throws IllegalStateException when this pool has been closed.
*
* @see #isClosed()
*/
protected final void assertOpen() throws IllegalStateException {
if (isClosed()) {
throw new IllegalStateException("Pool not open");
}
}
private volatile boolean closed = false;
}