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; 018 019 import java.io.Serializable; 020 import java.util.ArrayList; 021 import java.util.List; 022 import java.util.Map; 023 import java.util.concurrent.ArrayBlockingQueue; 024 import java.util.concurrent.BlockingQueue; 025 import java.util.concurrent.atomic.AtomicLong; 026 027 import org.apache.logging.log4j.core.Appender; 028 import org.apache.logging.log4j.core.Filter; 029 import org.apache.logging.log4j.core.LogEvent; 030 import org.apache.logging.log4j.core.async.RingBufferLogEvent; 031 import org.apache.logging.log4j.core.config.AppenderControl; 032 import org.apache.logging.log4j.core.config.AppenderRef; 033 import org.apache.logging.log4j.core.config.Configuration; 034 import org.apache.logging.log4j.core.config.ConfigurationException; 035 import org.apache.logging.log4j.core.config.plugins.Plugin; 036 import org.apache.logging.log4j.core.config.plugins.PluginAliases; 037 import org.apache.logging.log4j.core.config.plugins.PluginAttribute; 038 import org.apache.logging.log4j.core.config.plugins.PluginConfiguration; 039 import org.apache.logging.log4j.core.config.plugins.PluginElement; 040 import org.apache.logging.log4j.core.config.plugins.PluginFactory; 041 import 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) 050 public 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 LOGGER.trace("AsyncAppender stopping. Queue still has {} events.", queue.size()); 116 thread.shutdown(); 117 try { 118 thread.join(); 119 } catch (final InterruptedException ex) { 120 LOGGER.warn("Interrupted while stopping AsyncAppender {}", getName()); 121 } 122 LOGGER.trace("AsyncAppender stopped. Queue has {} events.", queue.size()); 123 } 124 125 /** 126 * Actual writing occurs here. 127 * <p/> 128 * @param logEvent The LogEvent. 129 */ 130 @Override 131 public void append(LogEvent logEvent) { 132 if (!isStarted()) { 133 throw new IllegalStateException("AsyncAppender " + getName() + " is not active"); 134 } 135 if (!(logEvent instanceof Log4jLogEvent)) { 136 if (!(logEvent instanceof RingBufferLogEvent)) { 137 return; // only know how to Serialize Log4jLogEvents and RingBufferLogEvents 138 } 139 logEvent = ((RingBufferLogEvent) logEvent).createMemento(); 140 } 141 Log4jLogEvent coreEvent = (Log4jLogEvent) logEvent; 142 boolean appendSuccessful = false; 143 if (blocking) { 144 if (isAppenderThread.get() == Boolean.TRUE && queue.remainingCapacity() == 0) { 145 // LOG4J2-485: avoid deadlock that would result from trying 146 // to add to a full queue from appender thread 147 coreEvent.setEndOfBatch(false); // queue is definitely not empty! 148 appendSuccessful = thread.callAppenders(coreEvent); 149 } else { 150 try { 151 // wait for free slots in the queue 152 queue.put(Log4jLogEvent.serialize(coreEvent, includeLocation)); 153 appendSuccessful = true; 154 } catch (final InterruptedException e) { 155 LOGGER.warn("Interrupted while waiting for a free slot in the AsyncAppender LogEvent-queue {}", 156 getName()); 157 } 158 } 159 } else { 160 appendSuccessful = queue.offer(Log4jLogEvent.serialize(coreEvent, includeLocation)); 161 if (!appendSuccessful) { 162 error("Appender " + getName() + " is unable to write primary appenders. queue is full"); 163 } 164 } 165 if (!appendSuccessful && errorAppender != null) { 166 errorAppender.callAppender(coreEvent); 167 } 168 } 169 170 /** 171 * Create an AsyncAppender. 172 * @param appenderRefs The Appenders to reference. 173 * @param errorRef An optional Appender to write to if the queue is full or other errors occur. 174 * @param blocking True if the Appender should wait when the queue is full. The default is true. 175 * @param size The size of the event queue. The default is 128. 176 * @param name The name of the Appender. 177 * @param includeLocation whether to include location information. The default is false. 178 * @param filter The Filter or null. 179 * @param config The Configuration. 180 * @param ignoreExceptions If {@code "true"} (default) exceptions encountered when appending events are logged; 181 * otherwise they are propagated to the caller. 182 * @return The AsyncAppender. 183 */ 184 @PluginFactory 185 public static AsyncAppender createAppender(@PluginElement("AppenderRef") final AppenderRef[] appenderRefs, 186 @PluginAttribute("errorRef") @PluginAliases("error-ref") final String errorRef, 187 @PluginAttribute(value = "blocking", defaultBoolean = true) final boolean blocking, 188 @PluginAttribute(value = "bufferSize", defaultInt = DEFAULT_QUEUE_SIZE) final int size, 189 @PluginAttribute("name") final String name, 190 @PluginAttribute(value = "includeLocation", defaultBoolean = false) final boolean includeLocation, 191 @PluginElement("Filter") final Filter filter, 192 @PluginConfiguration final Configuration config, 193 @PluginAttribute(value = "ignoreExceptions", defaultBoolean = true) final boolean ignoreExceptions) { 194 if (name == null) { 195 LOGGER.error("No name provided for AsyncAppender"); 196 return null; 197 } 198 if (appenderRefs == null) { 199 LOGGER.error("No appender references provided to AsyncAppender {}", name); 200 } 201 202 return new AsyncAppender(name, filter, appenderRefs, errorRef, 203 size, blocking, ignoreExceptions, config, includeLocation); 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 LOGGER.trace("AsyncAppender.AsyncThread shutting down. Processing remaining {} queue events.", 250 queue.size()); 251 int count= 0; 252 int ignored = 0; 253 while (!queue.isEmpty()) { 254 try { 255 final Serializable s = queue.take(); 256 if (Log4jLogEvent.canDeserialize(s)) { 257 final Log4jLogEvent event = Log4jLogEvent.deserialize(s); 258 event.setEndOfBatch(queue.isEmpty()); 259 callAppenders(event); 260 count++; 261 } else { 262 ignored++; 263 LOGGER.trace("Ignoring event of class {}", s.getClass().getName()); 264 } 265 } catch (final InterruptedException ex) { 266 // May have been interrupted to shut down. 267 } 268 } 269 LOGGER.trace("AsyncAppender.AsyncThread stopped. Queue has {} events remaining. " + 270 "Processed {} and ignored {} events since shutdown started.", 271 queue.size(), count, ignored); 272 } 273 274 /** 275 * Calls {@link AppenderControl#callAppender(LogEvent) callAppender} on 276 * all registered {@code AppenderControl} objects, and returns {@code true} 277 * if at least one appender call was successful, {@code false} otherwise. 278 * Any exceptions are silently ignored. 279 * 280 * @param event the event to forward to the registered appenders 281 * @return {@code true} if at least one appender call succeeded, {@code false} otherwise 282 */ 283 boolean callAppenders(final Log4jLogEvent event) { 284 boolean success = false; 285 for (final AppenderControl control : appenders) { 286 try { 287 control.callAppender(event); 288 success = true; 289 } catch (final Exception ex) { 290 // If no appender is successful the error appender will get it. 291 } 292 } 293 return success; 294 } 295 296 public void shutdown() { 297 shutdown = true; 298 if (queue.isEmpty()) { 299 queue.offer(SHUTDOWN); 300 } 301 } 302 } 303 304 /** 305 * Returns the names of the appenders that this asyncAppender delegates to 306 * as an array of Strings. 307 * @return the names of the sink appenders 308 */ 309 public String[] getAppenderRefStrings() { 310 final String[] result = new String[appenderRefs.length]; 311 for (int i = 0; i < result.length; i++) { 312 result[i] = appenderRefs[i].getRef(); 313 } 314 return result; 315 } 316 317 /** 318 * Returns {@code true} if this AsyncAppender will take a snapshot of the stack with 319 * every log event to determine the class and method where the logging call 320 * was made. 321 * @return {@code true} if location is included with every event, {@code false} otherwise 322 */ 323 public boolean isIncludeLocation() { 324 return includeLocation; 325 } 326 327 /** 328 * Returns {@code true} if this AsyncAppender will block when the queue is full, 329 * or {@code false} if events are dropped when the queue is full. 330 * @return whether this AsyncAppender will block or drop events when the queue is full. 331 */ 332 public boolean isBlocking() { 333 return blocking; 334 } 335 336 /** 337 * Returns the name of the appender that any errors are logged to or {@code null}. 338 * @return the name of the appender that any errors are logged to or {@code null} 339 */ 340 public String getErrorRef() { 341 return errorRef; 342 } 343 344 public int getQueueCapacity() { 345 return queueSize; 346 } 347 348 public int getQueueRemainingCapacity() { 349 return queue.remainingCapacity(); 350 } 351 }