| package org.apache.xpath.axes; |
| |
| import java.util.*; |
| import org.apache.xml.dtm.DTMIterator; |
| import org.apache.xml.utils.WrappedRuntimeException; |
| |
| /** |
| * <meta name="usage" content="internal"/> |
| * Pool of object of a given type to pick from to help memory usage |
| */ |
| public class IteratorPool implements java.io.Serializable |
| { |
| |
| /** Type of objects in this pool. |
| * @serial */ |
| private final DTMIterator m_orig; |
| |
| /** Vector of given objects this points to. |
| * @serial */ |
| private final Vector 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 Vector(); |
| } |
| |
| /** |
| * 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.lastElement(); |
| |
| m_freeStack.setSize(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.addElement(obj); |
| } |
| } |