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.async.RingBufferLogEvent; 031import org.apache.logging.log4j.core.config.AppenderControl; 032import org.apache.logging.log4j.core.config.AppenderRef; 033import org.apache.logging.log4j.core.config.Configuration; 034import org.apache.logging.log4j.core.config.ConfigurationException; 035import org.apache.logging.log4j.core.config.plugins.Plugin; 036import org.apache.logging.log4j.core.config.plugins.PluginAliases; 037import org.apache.logging.log4j.core.config.plugins.PluginAttribute; 038import org.apache.logging.log4j.core.config.plugins.PluginConfiguration; 039import org.apache.logging.log4j.core.config.plugins.PluginElement; 040import org.apache.logging.log4j.core.config.plugins.PluginFactory; 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 long serialVersionUID = 1L; 053 private static final int DEFAULT_QUEUE_SIZE = 128; 054 private static final String SHUTDOWN = "Shutdown"; 055 056 private final BlockingQueue<Serializable> queue; 057 private final int queueSize; 058 private final boolean blocking; 059 private final Configuration config; 060 private final AppenderRef[] appenderRefs; 061 private final String errorRef; 062 private final boolean includeLocation; 063 private AppenderControl errorAppender; 064 private AsyncThread thread; 065 private static final AtomicLong threadSequence = new AtomicLong(1); 066 private static ThreadLocal<Boolean> isAppenderThread = new ThreadLocal<>(); 067 068 069 private AsyncAppender(final String name, final Filter filter, final AppenderRef[] appenderRefs, 070 final String errorRef, final int queueSize, final boolean blocking, 071 final boolean ignoreExceptions, final Configuration config, 072 final boolean includeLocation) { 073 super(name, filter, null, ignoreExceptions); 074 this.queue = new ArrayBlockingQueue<>(queueSize); 075 this.queueSize = queueSize; 076 this.blocking = blocking; 077 this.config = config; 078 this.appenderRefs = appenderRefs; 079 this.errorRef = errorRef; 080 this.includeLocation = includeLocation; 081 } 082 083 @Override 084 public void start() { 085 final Map<String, Appender> map = config.getAppenders(); 086 final List<AppenderControl> appenders = new ArrayList<>(); 087 for (final AppenderRef appenderRef : appenderRefs) { 088 final Appender appender = map.get(appenderRef.getRef()); 089 if (appender != null) { 090 appenders.add(new AppenderControl(appender, appenderRef.getLevel(), appenderRef.getFilter())); 091 } else { 092 LOGGER.error("No appender named {} was configured", appenderRef); 093 } 094 } 095 if (errorRef != null) { 096 final Appender appender = map.get(errorRef); 097 if (appender != null) { 098 errorAppender = new AppenderControl(appender, null, null); 099 } else { 100 LOGGER.error("Unable to set up error Appender. No appender named {} was configured", errorRef); 101 } 102 } 103 if (appenders.size() > 0) { 104 thread = new AsyncThread(appenders, queue); 105 thread.setName("AsyncAppender-" + getName()); 106 } else if (errorRef == null) { 107 throw new ConfigurationException("No appenders are available for AsyncAppender " + getName()); 108 } 109 110 thread.start(); 111 super.start(); 112 } 113 114 @Override 115 public void stop() { 116 super.stop(); 117 LOGGER.trace("AsyncAppender stopping. Queue still has {} events.", queue.size()); 118 thread.shutdown(); 119 try { 120 thread.join(); 121 } catch (final InterruptedException ex) { 122 LOGGER.warn("Interrupted while stopping AsyncAppender {}", getName()); 123 } 124 LOGGER.trace("AsyncAppender stopped. Queue has {} events.", queue.size()); 125 } 126 127 /** 128 * Actual writing occurs here. 129 * 130 * @param logEvent 131 * The LogEvent. 132 */ 133 @Override 134 public void append(LogEvent logEvent) { 135 if (!isStarted()) { 136 throw new IllegalStateException("AsyncAppender " + getName() + " is not active"); 137 } 138 if (!(logEvent instanceof Log4jLogEvent)) { 139 if (!(logEvent instanceof RingBufferLogEvent)) { 140 return; // only know how to Serialize Log4jLogEvents and RingBufferLogEvents 141 } 142 logEvent = ((RingBufferLogEvent) logEvent).createMemento(); 143 } 144 logEvent.getMessage().getFormattedMessage(); // LOG4J2-763: ask message to freeze parameters 145 final Log4jLogEvent coreEvent = (Log4jLogEvent) logEvent; 146 boolean appendSuccessful = false; 147 if (blocking) { 148 if (isAppenderThread.get() == Boolean.TRUE && queue.remainingCapacity() == 0) { 149 // LOG4J2-485: avoid deadlock that would result from trying 150 // to add to a full queue from appender thread 151 coreEvent.setEndOfBatch(false); // queue is definitely not empty! 152 appendSuccessful = thread.callAppenders(coreEvent); 153 } else { 154 final Serializable serialized = Log4jLogEvent.serialize(coreEvent, includeLocation); 155 try { 156 // wait for free slots in the queue 157 queue.put(serialized); 158 appendSuccessful = true; 159 } catch (final InterruptedException e) { 160 // LOG4J2-1049: Some applications use Thread.interrupt() to send 161 // messages between application threads. This does not necessarily 162 // mean that the queue is full. To prevent dropping a log message, 163 // quickly try to offer the event to the queue again. 164 // (Yes, this means there is a possibility the same event is logged twice.) 165 // 166 // Finally, catching the InterruptedException means the 167 // interrupted flag has been cleared on the current thread. 168 // This may interfere with the application's expectation of 169 // being interrupted, so when we are done, we set the interrupted 170 // flag again. 171 appendSuccessful = queue.offer(serialized); 172 if (!appendSuccessful) { 173 LOGGER.warn("Interrupted while waiting for a free slot in the AsyncAppender LogEvent-queue {}", 174 getName()); 175 } 176 // set the interrupted flag again. 177 Thread.currentThread().interrupt(); 178 } 179 } 180 } else { 181 appendSuccessful = queue.offer(Log4jLogEvent.serialize(coreEvent, includeLocation)); 182 if (!appendSuccessful) { 183 error("Appender " + getName() + " is unable to write primary appenders. queue is full"); 184 } 185 } 186 if (!appendSuccessful && errorAppender != null) { 187 errorAppender.callAppender(coreEvent); 188 } 189 } 190 191 /** 192 * Create an AsyncAppender. 193 * @param appenderRefs The Appenders to reference. 194 * @param errorRef An optional Appender to write to if the queue is full or other errors occur. 195 * @param blocking True if the Appender should wait when the queue is full. The default is true. 196 * @param size The size of the event queue. The default is 128. 197 * @param name The name of the Appender. 198 * @param includeLocation whether to include location information. The default is false. 199 * @param filter The Filter or null. 200 * @param config The Configuration. 201 * @param ignoreExceptions If {@code "true"} (default) exceptions encountered when appending events are logged; 202 * otherwise they are propagated to the caller. 203 * @return The AsyncAppender. 204 */ 205 @PluginFactory 206 public static AsyncAppender createAppender(@PluginElement("AppenderRef") final AppenderRef[] appenderRefs, 207 @PluginAttribute("errorRef") @PluginAliases("error-ref") final String errorRef, 208 @PluginAttribute(value = "blocking", defaultBoolean = true) final boolean blocking, 209 @PluginAttribute(value = "bufferSize", defaultInt = DEFAULT_QUEUE_SIZE) final int size, 210 @PluginAttribute("name") final String name, 211 @PluginAttribute(value = "includeLocation", defaultBoolean = false) final boolean includeLocation, 212 @PluginElement("Filter") final Filter filter, 213 @PluginConfiguration final Configuration config, 214 @PluginAttribute(value = "ignoreExceptions", defaultBoolean = true) final boolean ignoreExceptions) { 215 if (name == null) { 216 LOGGER.error("No name provided for AsyncAppender"); 217 return null; 218 } 219 if (appenderRefs == null) { 220 LOGGER.error("No appender references provided to AsyncAppender {}", name); 221 } 222 223 return new AsyncAppender(name, filter, appenderRefs, errorRef, 224 size, blocking, ignoreExceptions, config, includeLocation); 225 } 226 227 /** 228 * Thread that calls the Appenders. 229 */ 230 private class AsyncThread extends Thread { 231 232 private volatile boolean shutdown = false; 233 private final List<AppenderControl> appenders; 234 private final BlockingQueue<Serializable> queue; 235 236 public AsyncThread(final List<AppenderControl> appenders, final BlockingQueue<Serializable> queue) { 237 this.appenders = appenders; 238 this.queue = queue; 239 setDaemon(true); 240 setName("AsyncAppenderThread" + threadSequence.getAndIncrement()); 241 } 242 243 @Override 244 public void run() { 245 isAppenderThread.set(Boolean.TRUE); // LOG4J2-485 246 while (!shutdown) { 247 Serializable s; 248 try { 249 s = queue.take(); 250 if (s != null && s instanceof String && SHUTDOWN.equals(s.toString())) { 251 shutdown = true; 252 continue; 253 } 254 } catch (final InterruptedException ex) { 255 break; // LOG4J2-830 256 } 257 final Log4jLogEvent event = Log4jLogEvent.deserialize(s); 258 event.setEndOfBatch(queue.isEmpty()); 259 final boolean success = callAppenders(event); 260 if (!success && errorAppender != null) { 261 try { 262 errorAppender.callAppender(event); 263 } catch (final Exception ex) { 264 // Silently accept the error. 265 } 266 } 267 } 268 // Process any remaining items in the queue. 269 LOGGER.trace("AsyncAppender.AsyncThread shutting down. Processing remaining {} queue events.", 270 queue.size()); 271 int count= 0; 272 int ignored = 0; 273 while (!queue.isEmpty()) { 274 try { 275 final Serializable s = queue.take(); 276 if (Log4jLogEvent.canDeserialize(s)) { 277 final Log4jLogEvent event = Log4jLogEvent.deserialize(s); 278 event.setEndOfBatch(queue.isEmpty()); 279 callAppenders(event); 280 count++; 281 } else { 282 ignored++; 283 LOGGER.trace("Ignoring event of class {}", s.getClass().getName()); 284 } 285 } catch (final InterruptedException ex) { 286 // May have been interrupted to shut down. 287 // Here we ignore interrupts and try to process all remaining events. 288 } 289 } 290 LOGGER.trace("AsyncAppender.AsyncThread stopped. Queue has {} events remaining. " + 291 "Processed {} and ignored {} events since shutdown started.", 292 queue.size(), count, ignored); 293 } 294 295 /** 296 * Calls {@link AppenderControl#callAppender(LogEvent) callAppender} on 297 * all registered {@code AppenderControl} objects, and returns {@code true} 298 * if at least one appender call was successful, {@code false} otherwise. 299 * Any exceptions are silently ignored. 300 * 301 * @param event the event to forward to the registered appenders 302 * @return {@code true} if at least one appender call succeeded, {@code false} otherwise 303 */ 304 boolean callAppenders(final Log4jLogEvent event) { 305 boolean success = false; 306 for (final AppenderControl control : appenders) { 307 try { 308 control.callAppender(event); 309 success = true; 310 } catch (final Exception ex) { 311 // If no appender is successful the error appender will get it. 312 } 313 } 314 return success; 315 } 316 317 public void shutdown() { 318 shutdown = true; 319 if (queue.isEmpty()) { 320 queue.offer(SHUTDOWN); 321 } 322 } 323 } 324 325 /** 326 * Returns the names of the appenders that this asyncAppender delegates to 327 * as an array of Strings. 328 * @return the names of the sink appenders 329 */ 330 public String[] getAppenderRefStrings() { 331 final String[] result = new String[appenderRefs.length]; 332 for (int i = 0; i < result.length; i++) { 333 result[i] = appenderRefs[i].getRef(); 334 } 335 return result; 336 } 337 338 /** 339 * Returns {@code true} if this AsyncAppender will take a snapshot of the stack with 340 * every log event to determine the class and method where the logging call 341 * was made. 342 * @return {@code true} if location is included with every event, {@code false} otherwise 343 */ 344 public boolean isIncludeLocation() { 345 return includeLocation; 346 } 347 348 /** 349 * Returns {@code true} if this AsyncAppender will block when the queue is full, 350 * or {@code false} if events are dropped when the queue is full. 351 * @return whether this AsyncAppender will block or drop events when the queue is full. 352 */ 353 public boolean isBlocking() { 354 return blocking; 355 } 356 357 /** 358 * Returns the name of the appender that any errors are logged to or {@code null}. 359 * @return the name of the appender that any errors are logged to or {@code null} 360 */ 361 public String getErrorRef() { 362 return errorRef; 363 } 364 365 public int getQueueCapacity() { 366 return queueSize; 367 } 368 369 public int getQueueRemainingCapacity() { 370 return queue.remainingCapacity(); 371 } 372}