src/org/apache/xalan/xsltc/dom/DocumentCache.java - xalan-java - Git at Google

 /*
  * 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.
  */
 /*
  * $Id$
  */

 package org.apache.xalan.xsltc.dom;

 import java.io.File;
 import java.io.PrintWriter;
 import java.net.URL;
 import java.net.URLConnection;
 import java.net.URLDecoder;
 import java.util.Date;
 import java.util.Hashtable;

 import javax.xml.parsers.ParserConfigurationException;
 import javax.xml.parsers.SAXParser;
 import javax.xml.parsers.SAXParserFactory;
 import javax.xml.transform.TransformerException;
 import javax.xml.transform.sax.SAXSource;

 import org.apache.xalan.xsltc.DOM;
 import org.apache.xalan.xsltc.DOMCache;
 import org.apache.xalan.xsltc.DOMEnhancedForDTM;
 import org.apache.xalan.xsltc.Translet;
 import org.apache.xalan.xsltc.runtime.AbstractTranslet;
 import org.apache.xalan.xsltc.runtime.BasisLibrary;
 import org.apache.xalan.xsltc.runtime.Constants;
 import org.apache.xml.utils.SystemIDResolver;

 import org.xml.sax.InputSource;
 import org.xml.sax.SAXException;
 import org.xml.sax.XMLReader;

 /**
  * @author Morten Jorgensen
  */
 public final class DocumentCache implements DOMCache {

     private int       _size;
     private Hashtable _references;
     private String[]  _URIs;
     private int       _count;
     private int       _current;
     private SAXParser _parser;
     private XMLReader _reader;
     private XSLTCDTMManager _dtmManager;

     private static final int REFRESH_INTERVAL = 1000;

     /*
      * Inner class containing a DOMImpl object and DTD handler
      */
     public final class CachedDocument {

 	// Statistics data
 	private long _firstReferenced;
 	private long _lastReferenced;
 	private long _accessCount;
 	private long _lastModified;
 	private long _lastChecked;
 	private long _buildTime;

 	// DOM and DTD handler references
 	private DOMEnhancedForDTM _dom = null;

 	/**
 	 * Constructor - load document and initialise statistics
 	 */
 	public CachedDocument(String uri) {
 	    // Initialise statistics variables
 	    final long stamp = System.currentTimeMillis();
 	    _firstReferenced = stamp;
 	    _lastReferenced  = stamp;
 	    _accessCount     = 0;
 	    loadDocument(uri);

 	    _buildTime = System.currentTimeMillis() - stamp;
 	}

 	/**
 	 * Loads the document and updates build-time (latency) statistics
 	 */
 	public void loadDocument(String uri) {

 	    try {
 		final long stamp = System.currentTimeMillis();
                 _dom = (DOMEnhancedForDTM)_dtmManager.getDTM(
                                  new SAXSource(_reader, new InputSource(uri)),
                                  false, null, true, false);
 		_dom.setDocumentURI(uri);

 		// The build time can be used for statistics for a better
 		// priority algorithm (currently round robin).
 		final long thisTime = System.currentTimeMillis() - stamp;
 		if (_buildTime > 0)
 		    _buildTime = (_buildTime + thisTime) >>> 1;
 		else
 		    _buildTime = thisTime;
 	    }
 	    catch (Exception e) {
 		_dom = null;
 	    }
 	}

 	public DOM getDocument()       { return(_dom); }

 	public long getFirstReferenced()   { return(_firstReferenced); }

 	public long getLastReferenced()    { return(_lastReferenced); }

 	public long getAccessCount()       { return(_accessCount); }

 	public void incAccessCount()       { _accessCount++; }

 	public long getLastModified()      { return(_lastModified); }

 	public void setLastModified(long t){ _lastModified = t; }

 	public long getLatency()           { return(_buildTime); }

 	public long getLastChecked()       { return(_lastChecked); }

 	public void setLastChecked(long t) { _lastChecked = t; }

 	public long getEstimatedSize() {
 	    if (_dom != null)
 		return(_dom.getSize() << 5); // ???
 	    else
 		return(0);
 	}

     }

     /**
      * DocumentCache constructor
      */
     public DocumentCache(int size) throws SAXException {
         this(size, null);
         try {
             _dtmManager = (XSLTCDTMManager)XSLTCDTMManager.getDTMManagerClass()
                                                           .newInstance();
         } catch (Exception e) {
             throw new SAXException(e);
         }
     }

     /**
      * DocumentCache constructor
      */
     public DocumentCache(int size, XSLTCDTMManager dtmManager) throws SAXException {
 	_dtmManager = dtmManager;
 	_count = 0;
 	_current = 0;
 	_size  = size;
 	_references = new Hashtable(_size+2);
 	_URIs = new String[_size];

 	try {
 	    // Create a SAX parser and get the XMLReader object it uses
 	    final SAXParserFactory factory = SAXParserFactory.newInstance();
 	    try {
 		factory.setFeature(Constants.NAMESPACE_FEATURE,true);
 	    }
 	    catch (Exception e) {
 		factory.setNamespaceAware(true);
 	    }
 	    _parser = factory.newSAXParser();
 	    _reader = _parser.getXMLReader();
 	}
 	catch (ParserConfigurationException e) {
 	    BasisLibrary.runTimeError(BasisLibrary.NAMESPACES_SUPPORT_ERR);
 	}
     }

     /**
      * Returns the time-stamp for a document's last update
      */
     private final long getLastModified(String uri) {
 	try {
 	    URL url = new URL(uri);
 	    URLConnection connection = url.openConnection();
 	    long timestamp = connection.getLastModified();
 	    // Check for a "file:" URI (courtesy of Brian Ewins)
 	    if (timestamp == 0){ // get 0 for local URI
 	        if ("file".equals(url.getProtocol())){
 	            File localfile = new File(URLDecoder.decode(url.getFile()));
 	            timestamp = localfile.lastModified();
 	        }
 	    }
 	    return(timestamp);
 	}
 	// Brutal handling of all exceptions
 	catch (Exception e) {
 	    return(System.currentTimeMillis());
 	}
     }

     /**
      *
      */
     private CachedDocument lookupDocument(String uri) {
 	return((CachedDocument)_references.get(uri));
     }

     /**
      *
      */
     private synchronized void insertDocument(String uri, CachedDocument doc) {
 	if (_count < _size) {
 	    // Insert out URI in circular buffer
 	    _URIs[_count++] = uri;
 	    _current = 0;
 	}
 	else {
 	    // Remove oldest URI from reference Hashtable
 	    _references.remove(_URIs[_current]);
 	    // Insert our URI in circular buffer
 	    _URIs[_current] = uri;
 	    if (++_current >= _size) _current = 0;
 	}
 	_references.put(uri, doc);
     }

     /**
      *
      */
     private synchronized void replaceDocument(String uri, CachedDocument doc) {
 	CachedDocument old = (CachedDocument)_references.get(uri);
 	if (doc == null)
 	    insertDocument(uri, doc);
 	else
 	    _references.put(uri, doc);
     }

     /**
      * Returns a document either by finding it in the cache or
      * downloading it and putting it in the cache.
      */
     public DOM retrieveDocument(String baseURI, String href, Translet trs) {
 	CachedDocument doc;

     String uri = href;
     if (baseURI != null && baseURI.length() != 0) {
         try {
             uri = SystemIDResolver.getAbsoluteURI(uri, baseURI);
         } catch (TransformerException te) {
             // ignore
         }
     }

 	// Try to get the document from the cache first
 	if ((doc = lookupDocument(uri)) == null) {
 	    doc = new CachedDocument(uri);
 	    if (doc == null) return null; // better error handling needed!!!
 	    doc.setLastModified(getLastModified(uri));
 	    insertDocument(uri, doc);
 	}
 	// If the document is in the cache we must check if it is still valid
 	else {
 	    long now = System.currentTimeMillis();
 	    long chk = doc.getLastChecked();
 	    doc.setLastChecked(now);
 	    // Has the modification time for this file been checked lately?
 	    if (now > (chk + REFRESH_INTERVAL)) {
 		doc.setLastChecked(now);
 		long last = getLastModified(uri);
 		// Reload document if it has been modified since last download
 		if (last > doc.getLastModified()) {
 		    doc = new CachedDocument(uri);
 		    if (doc == null) return null;
 		    doc.setLastModified(getLastModified(uri));
 		    replaceDocument(uri, doc);
 		}
 	    }

 	}

 	// Get the references to the actual DOM and DTD handler
 	final DOM dom = doc.getDocument();

 	// The dom reference may be null if the URL pointed to a
 	// non-existing document
 	if (dom == null) return null;

 	doc.incAccessCount(); // For statistics

 	final AbstractTranslet translet = (AbstractTranslet)trs;

 	// Give the translet an early opportunity to extract any
         // information from the DOM object that it would like.
 	translet.prepassDocument(dom);

 	return(doc.getDocument());
     }

     /**
      * Outputs the cache statistics
      */
     public void getStatistics(PrintWriter out) {
 	out.println("<h2>DOM cache statistics</h2><center><table border=\"2\">"+
 		    "<tr><td><b>Document URI</b></td>"+
 		    "<td><center><b>Build time</b></center></td>"+
 		    "<td><center><b>Access count</b></center></td>"+
 		    "<td><center><b>Last accessed</b></center></td>"+
 		    "<td><center><b>Last modified</b></center></td></tr>");

 	for (int i=0; i<_count; i++) {
 	    CachedDocument doc = (CachedDocument)_references.get(_URIs[i]);
 	    out.print("<tr><td><a href=\""+_URIs[i]+"\">"+
 		      "<font size=-1>"+_URIs[i]+"</font></a></td>");
 	    out.print("<td><center>"+doc.getLatency()+"ms</center></td>");
 	    out.print("<td><center>"+doc.getAccessCount()+"</center></td>");
 	    out.print("<td><center>"+(new Date(doc.getLastReferenced()))+
 		      "</center></td>");
 	    out.print("<td><center>"+(new Date(doc.getLastModified()))+
 		      "</center></td>");
 	    out.println("</tr>");
 	}

 	out.println("</table></center>");
     }
 }
	/*
	* 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.
	*/
	/*
	* $Id$
	*/

	package org.apache.xalan.xsltc.dom;

	import java.io.File;
	import java.io.PrintWriter;
	import java.net.URL;
	import java.net.URLConnection;
	import java.net.URLDecoder;
	import java.util.Date;
	import java.util.Hashtable;

	import javax.xml.parsers.ParserConfigurationException;
	import javax.xml.parsers.SAXParser;
	import javax.xml.parsers.SAXParserFactory;
	import javax.xml.transform.TransformerException;
	import javax.xml.transform.sax.SAXSource;

	import org.apache.xalan.xsltc.DOM;
	import org.apache.xalan.xsltc.DOMCache;
	import org.apache.xalan.xsltc.DOMEnhancedForDTM;
	import org.apache.xalan.xsltc.Translet;
	import org.apache.xalan.xsltc.runtime.AbstractTranslet;
	import org.apache.xalan.xsltc.runtime.BasisLibrary;
	import org.apache.xalan.xsltc.runtime.Constants;
	import org.apache.xml.utils.SystemIDResolver;

	import org.xml.sax.InputSource;
	import org.xml.sax.SAXException;
	import org.xml.sax.XMLReader;

	/**
	* @author Morten Jorgensen
	*/
	public final class DocumentCache implements DOMCache {

	private int _size;
	private Hashtable _references;
	private String[] _URIs;
	private int _count;
	private int _current;
	private SAXParser _parser;
	private XMLReader _reader;
	private XSLTCDTMManager _dtmManager;

	private static final int REFRESH_INTERVAL = 1000;

	/*
	* Inner class containing a DOMImpl object and DTD handler
	*/
	public final class CachedDocument {

	// Statistics data
	private long _firstReferenced;
	private long _lastReferenced;
	private long _accessCount;
	private long _lastModified;
	private long _lastChecked;
	private long _buildTime;

	// DOM and DTD handler references
	private DOMEnhancedForDTM _dom = null;

	/**
	* Constructor - load document and initialise statistics
	*/
	public CachedDocument(String uri) {
	// Initialise statistics variables
	final long stamp = System.currentTimeMillis();
	_firstReferenced = stamp;
	_lastReferenced = stamp;
	_accessCount = 0;
	loadDocument(uri);

	_buildTime = System.currentTimeMillis() - stamp;
	}

	/**
	* Loads the document and updates build-time (latency) statistics
	*/
	public void loadDocument(String uri) {

	try {
	final long stamp = System.currentTimeMillis();
	_dom = (DOMEnhancedForDTM)_dtmManager.getDTM(
	new SAXSource(_reader, new InputSource(uri)),
	false, null, true, false);
	_dom.setDocumentURI(uri);

	// The build time can be used for statistics for a better
	// priority algorithm (currently round robin).
	final long thisTime = System.currentTimeMillis() - stamp;
	if (_buildTime > 0)
	_buildTime = (_buildTime + thisTime) >>> 1;
	else
	_buildTime = thisTime;
	}
	catch (Exception e) {
	_dom = null;
	}
	}

	public DOM getDocument() { return(_dom); }

	public long getFirstReferenced() { return(_firstReferenced); }

	public long getLastReferenced() { return(_lastReferenced); }

	public long getAccessCount() { return(_accessCount); }

	public void incAccessCount() { _accessCount++; }

	public long getLastModified() { return(_lastModified); }

	public void setLastModified(long t){ _lastModified = t; }

	public long getLatency() { return(_buildTime); }

	public long getLastChecked() { return(_lastChecked); }

	public void setLastChecked(long t) { _lastChecked = t; }

	public long getEstimatedSize() {
	if (_dom != null)
	return(_dom.getSize() << 5); // ???
	else
	return(0);
	}

	}

	/**
	* DocumentCache constructor
	*/
	public DocumentCache(int size) throws SAXException {
	this(size, null);
	try {
	_dtmManager = (XSLTCDTMManager)XSLTCDTMManager.getDTMManagerClass()
	.newInstance();
	} catch (Exception e) {
	throw new SAXException(e);
	}
	}

	/**
	* DocumentCache constructor
	*/
	public DocumentCache(int size, XSLTCDTMManager dtmManager) throws SAXException {
	_dtmManager = dtmManager;
	_count = 0;
	_current = 0;
	_size = size;
	_references = new Hashtable(_size+2);
	_URIs = new String[_size];

	try {
	// Create a SAX parser and get the XMLReader object it uses
	final SAXParserFactory factory = SAXParserFactory.newInstance();
	try {
	factory.setFeature(Constants.NAMESPACE_FEATURE,true);
	}
	catch (Exception e) {
	factory.setNamespaceAware(true);
	}
	_parser = factory.newSAXParser();
	_reader = _parser.getXMLReader();
	}
	catch (ParserConfigurationException e) {
	BasisLibrary.runTimeError(BasisLibrary.NAMESPACES_SUPPORT_ERR);
	}
	}

	/**
	* Returns the time-stamp for a document's last update
	*/
	private final long getLastModified(String uri) {
	try {
	URL url = new URL(uri);
	URLConnection connection = url.openConnection();
	long timestamp = connection.getLastModified();
	// Check for a "file:" URI (courtesy of Brian Ewins)
	if (timestamp == 0){ // get 0 for local URI
	if ("file".equals(url.getProtocol())){
	File localfile = new File(URLDecoder.decode(url.getFile()));
	timestamp = localfile.lastModified();
	}
	}
	return(timestamp);
	}
	// Brutal handling of all exceptions
	catch (Exception e) {
	return(System.currentTimeMillis());
	}
	}

	/**
	*
	*/
	private CachedDocument lookupDocument(String uri) {
	return((CachedDocument)_references.get(uri));
	}

	/**
	*
	*/
	private synchronized void insertDocument(String uri, CachedDocument doc) {
	if (_count < _size) {
	// Insert out URI in circular buffer
	_URIs[_count++] = uri;
	_current = 0;
	}
	else {
	// Remove oldest URI from reference Hashtable
	_references.remove(_URIs[_current]);
	// Insert our URI in circular buffer
	_URIs[_current] = uri;
	if (++_current >= _size) _current = 0;
	}
	_references.put(uri, doc);
	}

	/**
	*
	*/
	private synchronized void replaceDocument(String uri, CachedDocument doc) {
	CachedDocument old = (CachedDocument)_references.get(uri);
	if (doc == null)
	insertDocument(uri, doc);
	else
	_references.put(uri, doc);
	}

	/**
	* Returns a document either by finding it in the cache or
	* downloading it and putting it in the cache.
	*/
	public DOM retrieveDocument(String baseURI, String href, Translet trs) {
	CachedDocument doc;

	String uri = href;
	if (baseURI != null && baseURI.length() != 0) {
	try {
	uri = SystemIDResolver.getAbsoluteURI(uri, baseURI);
	} catch (TransformerException te) {
	// ignore
	}
	}

	// Try to get the document from the cache first
	if ((doc = lookupDocument(uri)) == null) {
	doc = new CachedDocument(uri);
	if (doc == null) return null; // better error handling needed!!!
	doc.setLastModified(getLastModified(uri));
	insertDocument(uri, doc);
	}
	// If the document is in the cache we must check if it is still valid
	else {
	long now = System.currentTimeMillis();
	long chk = doc.getLastChecked();
	doc.setLastChecked(now);
	// Has the modification time for this file been checked lately?
	if (now > (chk + REFRESH_INTERVAL)) {
	doc.setLastChecked(now);
	long last = getLastModified(uri);
	// Reload document if it has been modified since last download
	if (last > doc.getLastModified()) {
	doc = new CachedDocument(uri);
	if (doc == null) return null;
	doc.setLastModified(getLastModified(uri));
	replaceDocument(uri, doc);
	}
	}

	}

	// Get the references to the actual DOM and DTD handler
	final DOM dom = doc.getDocument();

	// The dom reference may be null if the URL pointed to a
	// non-existing document
	if (dom == null) return null;

	doc.incAccessCount(); // For statistics

	final AbstractTranslet translet = (AbstractTranslet)trs;

	// Give the translet an early opportunity to extract any
	// information from the DOM object that it would like.
	translet.prepassDocument(dom);

	return(doc.getDocument());
	}

	/**
	* Outputs the cache statistics
	*/
	public void getStatistics(PrintWriter out) {
	out.println("<h2>DOM cache statistics</h2><center><table border=\"2\">"+
	"<tr><td><b>Document URI</b></td>"+
	"<td><center><b>Build time</b></center></td>"+
	"<td><center><b>Access count</b></center></td>"+
	"<td><center><b>Last accessed</b></center></td>"+
	"<td><center><b>Last modified</b></center></td></tr>");

	for (int i=0; i<_count; i++) {
	CachedDocument doc = (CachedDocument)_references.get(_URIs[i]);
	out.print("<tr><td><a href=\""+_URIs[i]+"\">"+
	"<font size=-1>"+_URIs[i]+"</font></a></td>");
	out.print("<td><center>"+doc.getLatency()+"ms</center></td>");
	out.print("<td><center>"+doc.getAccessCount()+"</center></td>");
	out.print("<td><center>"+(new Date(doc.getLastReferenced()))+
	"</center></td>");
	out.print("<td><center>"+(new Date(doc.getLastModified()))+
	"</center></td>");
	out.println("</tr>");
	}

	out.println("</table></center>");
	}
	}