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.util.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 for (final AppenderRef ref : appenderRefs) {
059 final String name = ref.getRef();
060 final Appender appender = config.getAppender(name);
061 if (appender != null) {
062 final Filter filter = appender instanceof AbstractAppender ?
063 ((AbstractAppender) appender).getFilter() : null;
064 appenders.put(name, new AppenderControl(appender, ref.getLevel(), filter));
065 } else {
066 LOGGER.error("Appender " + ref + " cannot be located. Reference ignored");
067 }
068 }
069 super.start();
070 }
071
072 @Override
073 public void stop() {
074 super.stop();
075 }
076
077 /**
078 * Modify the event and pass to the subordinate Appenders.
079 * @param event The LogEvent.
080 */
081 @Override
082 public void append(LogEvent event) {
083 if (rewritePolicy != null) {
084 event = rewritePolicy.rewrite(event);
085 }
086 for (final AppenderControl control : appenders.values()) {
087 control.callAppender(event);
088 }
089 }
090
091 /**
092 * Create a RewriteAppender.
093 * @param name The name of the Appender.
094 * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise
095 * they are propagated to the caller.
096 * @param appenderRefs An array of Appender names to call.
097 * @param config The Configuration.
098 * @param rewritePolicy The policy to use to modify the event.
099 * @param filter A Filter to filter events.
100 * @return The created RewriteAppender.
101 */
102 @PluginFactory
103 public static RewriteAppender createAppender(
104 @PluginAttribute("name") final String name,
105 @PluginAttribute("ignoreExceptions") final String ignore,
106 @PluginElement("AppenderRef") final AppenderRef[] appenderRefs,
107 @PluginConfiguration final Configuration config,
108 @PluginElement("RewritePolicy") final RewritePolicy rewritePolicy,
109 @PluginElement("Filter") final Filter filter) {
110
111 final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true);
112 if (name == null) {
113 LOGGER.error("No name provided for RewriteAppender");
114 return null;
115 }
116 if (appenderRefs == null) {
117 LOGGER.error("No appender references defined for RewriteAppender");
118 return null;
119 }
120 return new RewriteAppender(name, filter, ignoreExceptions, appenderRefs, rewritePolicy, config);
121 }
122 }