Update URL Resource Loader to Implement Timeout
-----------------------------------------------
Key: VELOCITY-585
URL: https://issues.apache.org/jira/browse/VELOCITY-585
Project: Velocity
Issue Type: Improvement
Components: Engine
Affects Versions: 1.5
Reporter: Tim White
Priority: Minor
Since sometimes URLs can be down, or take forever to load, it's important to be
able to implement a timeout for them, to avoid threads hanging forever.
I've hacked the URLResourceLoader, as below, to implement this timeout. I
think it would be wise to add a config param to adjust the timeout for the
final version.
package com.qwest.velocity.runtime.resource.loader;
/*
* 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
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
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*/
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.HashMap;
import org.apache.commons.collections.ExtendedProperties;
import org.apache.commons.lang.StringUtils;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.runtime.resource.Resource;
import org.apache.velocity.runtime.resource.loader.ResourceLoader;
/**
* This is a simple URL-based loader.
*
* @author <a href="mailto:[EMAIL PROTECTED]">Geir Magnusson Jr.</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Nathan Bubna</a>
* @version $Id: URLResourceLoader.java 191743 2005-06-21 23:22:20Z dlr $
*/
public class PortalURLResourceLoader extends ResourceLoader {
private String[] roots = null;
protected HashMap templateRoots = null;
/**
* @see
org.apache.velocity.runtime.resource.loader.ResourceLoader#init(org.apache.commons.collections.ExtendedProperties)
*/
public void init(ExtendedProperties configuration) {
rsvc.getLog().debug("URLResourceLoader : initialization
starting.");
roots = configuration.getStringArray("root");
for (int i = 0; i < roots.length; i++) {
rsvc.getLog().info("URLResourceLoader : adding root '"
+ roots[i] + "'");
}
// init the template paths map
templateRoots = new HashMap();
rsvc.getLog().debug("URLResourceLoader : initialization
complete.");
}
/**
* Get an InputStream so that the Runtime can build a template with it.
*
* @param name
* name of template to fetch bytestream of
* @return InputStream containing the template
* @throws ResourceNotFoundException
* if template not found in the file template path.
*/
public synchronized InputStream getResourceStream(String name) throws
ResourceNotFoundException {
if (StringUtils.isEmpty(name)) {
throw new ResourceNotFoundException("URLResourceLoader
: No template name provided");
}
InputStream inputStream = null;
Exception exception = null;
for (int i = 0; i < roots.length; i++) {
try {
URL u = new URL(roots[i] + name);
URLConnection conn = u.openConnection();
conn.setConnectTimeout(10000);
conn.setReadTimeout(10000);
inputStream = conn.getInputStream();
if (inputStream != null) {
if (rsvc.getLog().isDebugEnabled()) {
rsvc.getLog().debug("URLResourceLoader: Found '" + name + "' at '" + roots[i] +
"'");
}
// save this root for later re-use
templateRoots.put(name, roots[i]);
break;
}
} catch (Exception e) {
rsvc.getLog().error("URLResourceLoader:
Exception when looking for '" + name + "' at '" + roots[i] + "'");
rsvc.getLog().error(e);
// only save the first one for later throwing
if (exception == null) {
exception = e;
}
}
}
// if we never found the template
if (inputStream == null) {
String msg;
if (exception == null) {
msg = "URLResourceLoader : Resource '" + name +
"' not found.";
} else {
msg = exception.getMessage();
}
// convert to a general Velocity
ResourceNotFoundException
throw new ResourceNotFoundException(msg);
}
return inputStream;
}
/**
* Checks to see if a resource has been deleted, moved or modified.
*
* @param resource
* Resource The resource to check for modification
* @return boolean True if the resource has been modified, moved, or
unreachable
*/
public boolean isSourceModified(Resource resource) {
long fileLastModified = getLastModified(resource);
// if the file is unreachable or otherwise changed
if (fileLastModified == 0 || fileLastModified !=
resource.getLastModified()) {
return true;
}
return false;
}
/**
* Checks to see when a resource was last modified
*
* @param resource
* Resource the resource to check
* @return long The time when the resource was last modified or 0 if
the file can't be reached
*/
public long getLastModified(Resource resource) {
// get the previously used root
String name = resource.getName();
String root = (String) templateRoots.get(name);
try {
// get a connection to the URL
URL u = new URL(root + name);
URLConnection conn = u.openConnection();
conn.setConnectTimeout(10000);
conn.setReadTimeout(10000);
return conn.getLastModified();
} catch (IOException ioe) {
// the file is not reachable at its previous address
rsvc.getLog().error("URLResourceLoader: '" + name + "'
is no longer reachable at '" + root + "'");
rsvc.getLog().error(ioe);
return 0;
}
}
}
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