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Diffstat (limited to 'velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/LogContext.java')
-rw-r--r-- | velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/LogContext.java | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/LogContext.java b/velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/LogContext.java new file mode 100644 index 00000000..455f2675 --- /dev/null +++ b/velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/LogContext.java @@ -0,0 +1,140 @@ +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.util.introspection.Info; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; +import org.slf4j.MDC; + +import java.util.ArrayDeque; +import java.util.Deque; + +/** + * <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(LogContext.class); + + 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(Object src, Info info) + { + this.src = src; + this.info = info; + } + + protected Object src; + protected int count = 1; + protected Info info; + } + + public void pushLogContext(Object 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); + } +} |