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 */ 017package org.apache.logging.log4j.core.appender; 018 019import java.io.Serializable; 020import java.util.ArrayList; 021import java.util.List; 022import java.util.Map; 023import java.util.concurrent.ArrayBlockingQueue; 024import java.util.concurrent.BlockingQueue; 025import java.util.concurrent.atomic.AtomicLong; 026 027import org.apache.logging.log4j.core.Appender; 028import org.apache.logging.log4j.core.Filter; 029import org.apache.logging.log4j.core.LogEvent; 030import org.apache.logging.log4j.core.config.AppenderControl; 031import org.apache.logging.log4j.core.config.AppenderRef; 032import org.apache.logging.log4j.core.config.Configuration; 033import org.apache.logging.log4j.core.config.ConfigurationException; 034import org.apache.logging.log4j.core.config.plugins.Plugin; 035import org.apache.logging.log4j.core.config.plugins.PluginAliases; 036import org.apache.logging.log4j.core.config.plugins.PluginAttribute; 037import org.apache.logging.log4j.core.config.plugins.PluginConfiguration; 038import org.apache.logging.log4j.core.config.plugins.PluginElement; 039import org.apache.logging.log4j.core.config.plugins.PluginFactory; 040import org.apache.logging.log4j.core.helpers.Booleans; 041import org.apache.logging.log4j.core.impl.Log4jLogEvent; 042 043/** 044 * Appends to one or more Appenders asynchronously. You can configure an 045 * AsyncAppender with one or more Appenders and an Appender to append to if the 046 * queue is full. The AsyncAppender does not allow a filter to be specified on 047 * the Appender references. 048 */ 049@Plugin(name = "Async", category = "Core", elementType = "appender", printObject = true) 050public final class AsyncAppender extends AbstractAppender { 051 052 private static final int DEFAULT_QUEUE_SIZE = 128; 053 private static final String SHUTDOWN = "Shutdown"; 054 055 private final BlockingQueue<Serializable> queue; 056 private final int queueSize; 057 private final boolean blocking; 058 private final Configuration config; 059 private final AppenderRef[] appenderRefs; 060 private final String errorRef; 061 private final boolean includeLocation; 062 private AppenderControl errorAppender; 063 private AsyncThread thread; 064 private static final AtomicLong threadSequence = new AtomicLong(1); 065 private static ThreadLocal<Boolean> isAppenderThread = new ThreadLocal<Boolean>(); 066 067 068 private AsyncAppender(final String name, final Filter filter, final AppenderRef[] appenderRefs, 069 final String errorRef, final int queueSize, final boolean blocking, 070 final boolean ignoreExceptions, final Configuration config, 071 final boolean includeLocation) { 072 super(name, filter, null, ignoreExceptions); 073 this.queue = new ArrayBlockingQueue<Serializable>(queueSize); 074 this.queueSize = queueSize; 075 this.blocking = blocking; 076 this.config = config; 077 this.appenderRefs = appenderRefs; 078 this.errorRef = errorRef; 079 this.includeLocation = includeLocation; 080 } 081 082 @Override 083 public void start() { 084 final Map<String, Appender> map = config.getAppenders(); 085 final List<AppenderControl> appenders = new ArrayList<AppenderControl>(); 086 for (final AppenderRef appenderRef : appenderRefs) { 087 if (map.containsKey(appenderRef.getRef())) { 088 appenders.add(new AppenderControl(map.get(appenderRef.getRef()), appenderRef.getLevel(), 089 appenderRef.getFilter())); 090 } else { 091 LOGGER.error("No appender named {} was configured", appenderRef); 092 } 093 } 094 if (errorRef != null) { 095 if (map.containsKey(errorRef)) { 096 errorAppender = new AppenderControl(map.get(errorRef), null, null); 097 } else { 098 LOGGER.error("Unable to set up error Appender. No appender named {} was configured", errorRef); 099 } 100 } 101 if (appenders.size() > 0) { 102 thread = new AsyncThread(appenders, queue); 103 thread.setName("AsyncAppender-" + getName()); 104 } else if (errorRef == null) { 105 throw new ConfigurationException("No appenders are available for AsyncAppender " + getName()); 106 } 107 108 thread.start(); 109 super.start(); 110 } 111 112 @Override 113 public void stop() { 114 super.stop(); 115 thread.shutdown(); 116 try { 117 thread.join(); 118 } catch (final InterruptedException ex) { 119 LOGGER.warn("Interrupted while stopping AsyncAppender {}", getName()); 120 } 121 } 122 123 /** 124 * Actual writing occurs here. 125 * <p/> 126 * @param evt The LogEvent. 127 */ 128 @Override 129 public void append(final LogEvent evt) { 130 if (!isStarted()) { 131 throw new IllegalStateException("AsyncAppender " + getName() + " is not active"); 132 } 133 if (!(evt instanceof Log4jLogEvent)) { 134 return; // only know how to Serialize Log4jLogEvents 135 } 136 Log4jLogEvent event = (Log4jLogEvent) evt; 137 boolean appendSuccessful = false; 138 if (blocking) { 139 if (isAppenderThread.get() == Boolean.TRUE && queue.remainingCapacity() == 0) { 140 // LOG4J2-485: avoid deadlock that would result from trying 141 // to add to a full queue from appender thread 142 event.setEndOfBatch(false); // queue is definitely not empty! 143 appendSuccessful = thread.callAppenders(event); 144 } else { 145 try { 146 // wait for free slots in the queue 147 queue.put(Log4jLogEvent.serialize(event, includeLocation)); 148 appendSuccessful = true; 149 } catch (final InterruptedException e) { 150 LOGGER.warn("Interrupted while waiting for a free slot in the AsyncAppender LogEvent-queue {}", 151 getName()); 152 } 153 } 154 } else { 155 appendSuccessful = queue.offer(Log4jLogEvent.serialize(event, includeLocation)); 156 if (!appendSuccessful) { 157 error("Appender " + getName() + " is unable to write primary appenders. queue is full"); 158 } 159 } 160 if (!appendSuccessful && errorAppender != null) { 161 errorAppender.callAppender(event); 162 } 163 } 164 165 /** 166 * Create an AsyncAppender. 167 * @param appenderRefs The Appenders to reference. 168 * @param errorRef An optional Appender to write to if the queue is full or other errors occur. 169 * @param blocking True if the Appender should wait when the queue is full. The default is true. 170 * @param size The size of the event queue. The default is 128. 171 * @param name The name of the Appender. 172 * @param includeLocation whether to include location information. The default is false. 173 * @param filter The Filter or null. 174 * @param config The Configuration. 175 * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise 176 * they are propagated to the caller. 177 * @return The AsyncAppender. 178 */ 179 @PluginFactory 180 public static AsyncAppender createAppender(@PluginElement("AppenderRef") final AppenderRef[] appenderRefs, 181 @PluginAttribute("errorRef") @PluginAliases("error-ref") final String errorRef, 182 @PluginAttribute("blocking") final String blocking, 183 @PluginAttribute("bufferSize") final String size, 184 @PluginAttribute("name") final String name, 185 @PluginAttribute("includeLocation") final String includeLocation, 186 @PluginElement("Filter") final Filter filter, 187 @PluginConfiguration final Configuration config, 188 @PluginAttribute("ignoreExceptions") final String ignore) { 189 if (name == null) { 190 LOGGER.error("No name provided for AsyncAppender"); 191 return null; 192 } 193 if (appenderRefs == null) { 194 LOGGER.error("No appender references provided to AsyncAppender {}", name); 195 } 196 197 final boolean isBlocking = Booleans.parseBoolean(blocking, true); 198 final int queueSize = AbstractAppender.parseInt(size, DEFAULT_QUEUE_SIZE); 199 final boolean isIncludeLocation = Boolean.parseBoolean(includeLocation); 200 final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true); 201 202 return new AsyncAppender(name, filter, appenderRefs, errorRef, 203 queueSize, isBlocking, ignoreExceptions, config, isIncludeLocation); 204 } 205 206 /** 207 * Thread that calls the Appenders. 208 */ 209 private class AsyncThread extends Thread { 210 211 private volatile boolean shutdown = false; 212 private final List<AppenderControl> appenders; 213 private final BlockingQueue<Serializable> queue; 214 215 public AsyncThread(final List<AppenderControl> appenders, final BlockingQueue<Serializable> queue) { 216 this.appenders = appenders; 217 this.queue = queue; 218 setDaemon(true); 219 setName("AsyncAppenderThread" + threadSequence.getAndIncrement()); 220 } 221 222 @Override 223 public void run() { 224 isAppenderThread.set(Boolean.TRUE); // LOG4J2-485 225 while (!shutdown) { 226 Serializable s; 227 try { 228 s = queue.take(); 229 if (s != null && s instanceof String && SHUTDOWN.equals(s.toString())) { 230 shutdown = true; 231 continue; 232 } 233 } catch (final InterruptedException ex) { 234 // No good reason for this. 235 continue; 236 } 237 final Log4jLogEvent event = Log4jLogEvent.deserialize(s); 238 event.setEndOfBatch(queue.isEmpty()); 239 boolean success = callAppenders(event); 240 if (!success && errorAppender != null) { 241 try { 242 errorAppender.callAppender(event); 243 } catch (final Exception ex) { 244 // Silently accept the error. 245 } 246 } 247 } 248 // Process any remaining items in the queue. 249 while (!queue.isEmpty()) { 250 try { 251 final Serializable s = queue.take(); 252 if (s instanceof Log4jLogEvent) { 253 final Log4jLogEvent event = Log4jLogEvent.deserialize(s); 254 event.setEndOfBatch(queue.isEmpty()); 255 callAppenders(event); 256 } 257 } catch (final InterruptedException ex) { 258 // May have been interrupted to shut down. 259 } 260 } 261 } 262 263 /** 264 * Calls {@link AppenderControl#callAppender(LogEvent) callAppender} on 265 * all registered {@code AppenderControl} objects, and returns {@code true} 266 * if at least one appender call was successful, {@code false} otherwise. 267 * Any exceptions are silently ignored. 268 * 269 * @param event the event to forward to the registered appenders 270 * @return {@code true} if at least one appender call succeeded, {@code false} otherwise 271 */ 272 boolean callAppenders(final Log4jLogEvent event) { 273 boolean success = false; 274 for (final AppenderControl control : appenders) { 275 try { 276 control.callAppender(event); 277 success = true; 278 } catch (final Exception ex) { 279 // If no appender is successful the error appender will get it. 280 } 281 } 282 return success; 283 } 284 285 public void shutdown() { 286 shutdown = true; 287 if (queue.isEmpty()) { 288 queue.offer(SHUTDOWN); 289 } 290 } 291 } 292 293 /** 294 * Returns the names of the appenders that this asyncAppender delegates to 295 * as an array of Strings. 296 * @return the names of the sink appenders 297 */ 298 public String[] getAppenderRefStrings() { 299 final String[] result = new String[appenderRefs.length]; 300 for (int i = 0; i < result.length; i++) { 301 result[i] = appenderRefs[i].getRef(); 302 } 303 return result; 304 } 305 306 /** 307 * Returns {@code true} if this AsyncAppender will take a snapshot of the stack with 308 * every log event to determine the class and method where the logging call 309 * was made. 310 * @return {@code true} if location is included with every event, {@code false} otherwise 311 */ 312 public boolean isIncludeLocation() { 313 return includeLocation; 314 } 315 316 /** 317 * Returns {@code true} if this AsyncAppender will block when the queue is full, 318 * or {@code false} if events are dropped when the queue is full. 319 * @return whether this AsyncAppender will block or drop events when the queue is full. 320 */ 321 public boolean isBlocking() { 322 return blocking; 323 } 324 325 /** 326 * Returns the name of the appender that any errors are logged to or {@code null}. 327 * @return the name of the appender that any errors are logged to or {@code null} 328 */ 329 public String getErrorRef() { 330 return errorRef; 331 } 332 333 public int getQueueCapacity() { 334 return queueSize; 335 } 336 337 public int getQueueRemainingCapacity() { 338 return queue.remainingCapacity(); 339 } 340}