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package org.apache.velocity.runtime.parser;
/*
* 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.
*/
import org.apache.velocity.runtime.parser.node.SimpleNode;
import org.apache.velocity.util.introspection.Info;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.MDC;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
/**
* <p>Track location in template files during rendering by populating the slf4j MDC tags <code>file</code>, <code>line</code> and <code>column</code>.</p>
* <p>An MDC-aware logger can then use this info to display the template location in the message</p>
* <p>For instance with webapp-slf4j-logger, it's enough to use <code>%file</code>, <code>%line</code> and <code>%column</code> in the logger format string.</p>
* <p>Since this feature can have a performance impact, it has to be enabled in <code>velocity.properties</code> using:</p>
* <pre><code>runtime.log.track_location = true</code></pre>
* <p>(typically in a development environment)</p>
*
* @author Claude Brisson
* @version $Id:$
* @since 2.2
*/
public class LogContext
{
protected static Logger logger = LoggerFactory.getLogger("rendering");
public static final String MDC_FILE = "file";
public static final String MDC_LINE = "line";
public static final String MDC_COLUMN = "column";
private boolean trackLocation;
public LogContext(boolean trackLocation)
{
this.trackLocation = trackLocation;
}
private static ThreadLocal<Deque<StackElement>> contextStack = new ThreadLocal<Deque<StackElement>>()
{
@Override
public Deque<StackElement> initialValue()
{
return new ArrayDeque<StackElement>();
}
};
private static class StackElement
{
protected StackElement(SimpleNode src, Info info)
{
this.src = src;
this.info = info;
}
protected SimpleNode src;
protected int count = 1;
protected Info info;
}
public void pushLogContext(SimpleNode src, Info info)
{
if (!trackLocation)
{
return;
}
Deque<StackElement> stack = contextStack.get();
StackElement last = stack.peek();
if (last != null && last.src == src)
{
++last.count;
}
else
{
stack.push(new StackElement(src, info));
setLogContext(info);
}
}
public void popLogContext()
{
if (!trackLocation)
{
return;
}
Deque<StackElement> stack = contextStack.get();
StackElement last = stack.peek();
if (last == null)
{
logger.error("log context is already empty");
return;
}
if (--last.count == 0)
{
stack.pop();
last = stack.peek();
if (last == null)
{
clearLogContext();
}
else
{
setLogContext(last.info);
}
}
}
private void setLogContext(Info info)
{
MDC.put(MDC_FILE, info.getTemplateName());
MDC.put(MDC_LINE, String.valueOf(info.getLine()));
MDC.put(MDC_COLUMN, String.valueOf(info.getColumn()));
}
private void clearLogContext()
{
MDC.remove(MDC_FILE);
MDC.remove(MDC_LINE);
MDC.remove(MDC_COLUMN);
}
private static final String STACKTRACE_LINE = " %s at %s[line %d, column %d]";
public String[] getStackTrace()
{
if (!trackLocation)
{
return null;
}
Deque<StackElement> stack = contextStack.get();
List<String> levels = new ArrayList<>();
for (StackElement level : stack)
{
String line = String.format(STACKTRACE_LINE,
level.src.literal(),
level.info.getTemplateName(),
level.info.getLine(),
level.info.getColumn());
levels.add(line);
}
return levels.size() > 0 ? levels.toArray(new String[levels.size()]) : null;
}
}
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