001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017 package org.apache.logging.log4j.core.appender.rewrite;
018
019 import java.util.Map;
020 import java.util.concurrent.ConcurrentHashMap;
021 import java.util.concurrent.ConcurrentMap;
022
023 import org.apache.logging.log4j.core.Appender;
024 import org.apache.logging.log4j.core.Filter;
025 import org.apache.logging.log4j.core.LogEvent;
026 import org.apache.logging.log4j.core.appender.AbstractAppender;
027 import org.apache.logging.log4j.core.config.AppenderControl;
028 import org.apache.logging.log4j.core.config.AppenderRef;
029 import org.apache.logging.log4j.core.config.Configuration;
030 import org.apache.logging.log4j.core.config.plugins.Plugin;
031 import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
032 import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
033 import org.apache.logging.log4j.core.config.plugins.PluginElement;
034 import org.apache.logging.log4j.core.config.plugins.PluginFactory;
035 import org.apache.logging.log4j.core.helpers.Booleans;
036
037 /**
038 * This Appender allows the logging event to be manipulated before it is processed by other Appenders.
039 */
040 @Plugin(name = "Rewrite", category = "Core", elementType = "appender", printObject = true)
041 public final class RewriteAppender extends AbstractAppender {
042 private final Configuration config;
043 private final ConcurrentMap<String, AppenderControl> appenders = new ConcurrentHashMap<String, AppenderControl>();
044 private final RewritePolicy rewritePolicy;
045 private final AppenderRef[] appenderRefs;
046
047 private RewriteAppender(final String name, final Filter filter, final boolean ignoreExceptions,
048 final AppenderRef[] appenderRefs, final RewritePolicy rewritePolicy,
049 final Configuration config) {
050 super(name, filter, null, ignoreExceptions);
051 this.config = config;
052 this.rewritePolicy = rewritePolicy;
053 this.appenderRefs = appenderRefs;
054 }
055
056 @Override
057 public void start() {
058 final Map<String, Appender> map = config.getAppenders();
059 for (final AppenderRef ref : appenderRefs) {
060 final String name = ref.getRef();
061 final Appender appender = map.get(name);
062 if (appender != null) {
063 final Filter filter = appender instanceof AbstractAppender ?
064 ((AbstractAppender) appender).getFilter() : null;
065 appenders.put(name, new AppenderControl(appender, ref.getLevel(), filter));
066 } else {
067 LOGGER.error("Appender " + ref + " cannot be located. Reference ignored");
068 }
069 }
070 super.start();
071 }
072
073 @Override
074 public void stop() {
075 super.stop();
076 }
077
078 /**
079 * Modify the event and pass to the subordinate Appenders.
080 * @param event The LogEvent.
081 */
082 @Override
083 public void append(LogEvent event) {
084 if (rewritePolicy != null) {
085 event = rewritePolicy.rewrite(event);
086 }
087 for (final AppenderControl control : appenders.values()) {
088 control.callAppender(event);
089 }
090 }
091
092 /**
093 * Create a RewriteAppender.
094 * @param name The name of the Appender.
095 * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise
096 * they are propagated to the caller.
097 * @param appenderRefs An array of Appender names to call.
098 * @param config The Configuration.
099 * @param rewritePolicy The policy to use to modify the event.
100 * @param filter A Filter to filter events.
101 * @return The created RewriteAppender.
102 */
103 @PluginFactory
104 public static RewriteAppender createAppender(
105 @PluginAttribute("name") final String name,
106 @PluginAttribute("ignoreExceptions") final String ignore,
107 @PluginElement("AppenderRef") final AppenderRef[] appenderRefs,
108 @PluginConfiguration final Configuration config,
109 @PluginElement("RewritePolicy") final RewritePolicy rewritePolicy,
110 @PluginElement("Filter") final Filter filter) {
111
112 final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true);
113 if (name == null) {
114 LOGGER.error("No name provided for RewriteAppender");
115 return null;
116 }
117 if (appenderRefs == null) {
118 LOGGER.error("No appender references defined for RewriteAppender");
119 return null;
120 }
121 return new RewriteAppender(name, filter, ignoreExceptions, appenderRefs, rewritePolicy, config);
122 }
123 }