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.routing;
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.appender.rewrite.RewritePolicy;
028    import org.apache.logging.log4j.core.config.AppenderControl;
029    import org.apache.logging.log4j.core.config.Configuration;
030    import org.apache.logging.log4j.core.config.Node;
031    import org.apache.logging.log4j.core.config.plugins.Plugin;
032    import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
033    import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
034    import org.apache.logging.log4j.core.config.plugins.PluginElement;
035    import org.apache.logging.log4j.core.config.plugins.PluginFactory;
036    import org.apache.logging.log4j.core.util.Booleans;
037    
038    /**
039     * This Appender "routes" between various Appenders, some of which can be references to
040     * Appenders defined earlier in the configuration while others can be dynamically created
041     * within this Appender as required. Routing is achieved by specifying a pattern on
042     * the Routing appender declaration. The pattern should contain one or more substitution patterns of
043     * the form "$${[key:]token}". The pattern will be resolved each time the Appender is called using
044     * the built in StrSubstitutor and the StrLookup plugin that matches the specified key.
045     */
046    @Plugin(name = "Routing", category = "Core", elementType = "appender", printObject = true)
047    public final class RoutingAppender extends AbstractAppender {
048        private static final String DEFAULT_KEY = "ROUTING_APPENDER_DEFAULT";
049        private final Routes routes;
050        private final Route defaultRoute;
051        private final Configuration config;
052        private final ConcurrentMap<String, AppenderControl> appenders =
053                new ConcurrentHashMap<String, AppenderControl>();
054        private final RewritePolicy rewritePolicy;
055    
056        private RoutingAppender(final String name, final Filter filter, final boolean ignoreExceptions, final Routes routes,
057                                final RewritePolicy rewritePolicy, final Configuration config) {
058            super(name, filter, null, ignoreExceptions);
059            this.routes = routes;
060            this.config = config;
061            this.rewritePolicy = rewritePolicy;
062            Route defRoute = null;
063            for (final Route route : routes.getRoutes()) {
064                if (route.getKey() == null) {
065                    if (defRoute == null) {
066                        defRoute = route;
067                    } else {
068                        error("Multiple default routes. Route " + route.toString() + " will be ignored");
069                    }
070                }
071            }
072            defaultRoute = defRoute;
073        }
074    
075        @Override
076        public void start() {
077            // Register all the static routes.
078            for (final Route route : routes.getRoutes()) {
079                if (route.getAppenderRef() != null) {
080                    final Appender appender = config.getAppender(route.getAppenderRef());
081                    if (appender != null) {
082                        final String key = route == defaultRoute ? DEFAULT_KEY : route.getKey();
083                        appenders.put(key, new AppenderControl(appender, null, null));
084                    } else {
085                        LOGGER.error("Appender " + route.getAppenderRef() + " cannot be located. Route ignored");
086                    }
087                }
088            }
089            super.start();
090        }
091    
092        @Override
093        public void stop() {
094            super.stop();
095            final Map<String, Appender> map = config.getAppenders();
096            for (final Map.Entry<String, AppenderControl> entry : appenders.entrySet()) {
097                final String name = entry.getValue().getAppender().getName();
098                if (!map.containsKey(name)) {
099                    entry.getValue().getAppender().stop();
100                }
101            }
102        }
103    
104        @Override
105        public void append(LogEvent event) {
106            if (rewritePolicy != null) {
107                event = rewritePolicy.rewrite(event);
108            }
109            final String key = config.getStrSubstitutor().replace(event, routes.getPattern());
110            final AppenderControl control = getControl(key, event);
111            if (control != null) {
112                control.callAppender(event);
113            }
114        }
115    
116        private synchronized AppenderControl getControl(final String key, final LogEvent event) {
117            AppenderControl control = appenders.get(key);
118            if (control != null) {
119                return control;
120            }
121            Route route = null;
122            for (final Route r : routes.getRoutes()) {
123                if (r.getAppenderRef() == null && key.equals(r.getKey())) {
124                    route = r;
125                    break;
126                }
127            }
128            if (route == null) {
129                route = defaultRoute;
130                control = appenders.get(DEFAULT_KEY);
131                if (control != null) {
132                    return control;
133                }
134            }
135            if (route != null) {
136                final Appender app = createAppender(route, event);
137                if (app == null) {
138                    return null;
139                }
140                control = new AppenderControl(app, null, null);
141                appenders.put(key, control);
142            }
143    
144            return control;
145        }
146    
147        private Appender createAppender(final Route route, final LogEvent event) {
148            final Node routeNode = route.getNode();
149            for (final Node node : routeNode.getChildren()) {
150                if (node.getType().getElementName().equals("appender")) {
151                    final Node appNode = new Node(node);
152                    config.createConfiguration(appNode, event);
153                    if (appNode.getObject() instanceof Appender) {
154                        final Appender app = (Appender) appNode.getObject();
155                        app.start();
156                        return app;
157                    }
158                    LOGGER.error("Unable to create Appender of type " + node.getName());
159                    return null;
160                }
161            }
162            LOGGER.error("No Appender was configured for route " + route.getKey());
163            return null;
164        }
165    
166        /**
167         * Create a RoutingAppender.
168         * @param name The name of the Appender.
169         * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise
170         *               they are propagated to the caller.
171         * @param routes The routing definitions.
172         * @param config The Configuration (automatically added by the Configuration).
173         * @param rewritePolicy A RewritePolicy, if any.
174         * @param filter A Filter to restrict events processed by the Appender or null.
175         * @return The RoutingAppender
176         */
177        @PluginFactory
178        public static RoutingAppender createAppender(
179                @PluginAttribute("name") final String name,
180                @PluginAttribute("ignoreExceptions") final String ignore,
181                @PluginElement("Routes") final Routes routes,
182                @PluginConfiguration final Configuration config,
183                @PluginElement("RewritePolicy") final RewritePolicy rewritePolicy,
184                @PluginElement("Filter") final Filter filter) {
185    
186            final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true);
187            if (name == null) {
188                LOGGER.error("No name provided for RoutingAppender");
189                return null;
190            }
191            if (routes == null) {
192                LOGGER.error("No routes defined for RoutingAppender");
193                return null;
194            }
195            return new RoutingAppender(name, filter, ignoreExceptions, routes, rewritePolicy, config);
196        }
197    }