/*
* 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
*
* https://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.tomcat.dbcp.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}.
* <p>
* This class is intended to be thread-safe.
* </p>
*
* @param <T> Type of element pooled in this pool.
*
* @since 2.0
*/
public abstract class BaseObjectPool<T> extends BaseObject implements ObjectPool<T> {
private volatile boolean closed;
/**
* Constructs a new instance.
*/
public BaseObjectPool() {
// empty
}
/**
* Not supported in this base implementation. Subclasses should override
* this behavior.
*
* @throws UnsupportedOperationException if the pool does not implement this
* method
*/
@Override
public void addObject() throws Exception {
throw new UnsupportedOperationException();
}
/**
* Throws an {@code 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");
}
}
@Override
public abstract T borrowObject() throws Exception;
/**
* Not supported in this base implementation.
*
* @throws UnsupportedOperationException if the pool does not implement this
* method
*/
@Override
public void clear() throws Exception {
throw new UnsupportedOperationException();
}
/**
* {@inheritDoc}
* <p>
* This affects the behavior of {@code isClosed} and
* {@code assertOpen}.
* </p>
*/
@Override
public void close() {
closed = true;
}
/**
* Not supported in this base implementation.
*
* @return a negative value.
*/
@Override
public int getNumActive() {
return -1;
}
/**
* Not supported in this base implementation.
*
* @return a negative value.
*/
@Override
public int getNumIdle() {
return -1;
}
@Override
public abstract void invalidateObject(T obj) throws Exception;
/**
* Has this pool instance been closed.
*
* @return {@code true} when this pool has been closed.
*/
public final boolean isClosed() {
return closed;
}
@Override
public abstract void returnObject(T obj) throws Exception;
@Override
protected void toStringAppendFields(final StringBuilder builder) {
builder.append("closed=");
builder.append(closed);
}
}