| /* |
| * 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. |
| */ |
| /* |
| * $Id: IteratorPool.java 475981 2006-11-16 23:35:53Z minchau $ |
| */ |
| package org.apache.xpath.axes; |
| |
| import java.util.ArrayList; |
| |
| import org.apache.xml.dtm.DTMIterator; |
| import org.apache.xml.utils.WrappedRuntimeException; |
| |
| /** |
| * Pool of object of a given type to pick from to help memory usage |
| * @xsl.usage internal |
| */ |
| public final class IteratorPool implements java.io.Serializable |
| { |
| static final long serialVersionUID = -460927331149566998L; |
| |
| /** |
| * Type of objects in this pool. |
| */ |
| private final DTMIterator m_orig; |
| |
| /** |
| * Stack of given objects this points to. |
| */ |
| private final ArrayList m_freeStack; |
| |
| /** |
| * Constructor IteratorPool |
| * |
| * @param original The original iterator from which all others will be cloned. |
| */ |
| public IteratorPool(DTMIterator original) |
| { |
| m_orig = original; |
| m_freeStack = new ArrayList(); |
| } |
| |
| /** |
| * Get an instance of the given object in this pool |
| * |
| * @return An instance of the given object |
| */ |
| public synchronized DTMIterator getInstanceOrThrow() |
| throws CloneNotSupportedException |
| { |
| // Check if the pool is empty. |
| if (m_freeStack.isEmpty()) |
| { |
| |
| // Create a new object if so. |
| return (DTMIterator)m_orig.clone(); |
| } |
| else |
| { |
| // Remove object from end of free pool. |
| DTMIterator result = (DTMIterator)m_freeStack.remove(m_freeStack.size() - 1); |
| return result; |
| } |
| } |
| |
| /** |
| * Get an instance of the given object in this pool |
| * |
| * @return An instance of the given object |
| */ |
| public synchronized DTMIterator getInstance() |
| { |
| // Check if the pool is empty. |
| if (m_freeStack.isEmpty()) |
| { |
| |
| // Create a new object if so. |
| try |
| { |
| return (DTMIterator)m_orig.clone(); |
| } |
| catch (Exception ex) |
| { |
| throw new WrappedRuntimeException(ex); |
| } |
| } |
| else |
| { |
| // Remove object from end of free pool. |
| DTMIterator result = (DTMIterator)m_freeStack.remove(m_freeStack.size() - 1); |
| return result; |
| } |
| } |
| |
| /** |
| * Add an instance of the given object to the pool |
| * |
| * |
| * @param obj Object to add. |
| */ |
| public synchronized void freeInstance(DTMIterator obj) |
| { |
| m_freeStack.add(obj); |
| } |
| } |