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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements. See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache license, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License. You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the license for the specific language governing permissions and
15   * limitations under the license.
16   */
17  package org.apache.logging.log4j.core.async;
18  
19  import java.util.List;
20  
21  import org.apache.logging.log4j.Level;
22  import org.apache.logging.log4j.Marker;
23  import org.apache.logging.log4j.ThreadContext;
24  import org.apache.logging.log4j.ThreadContext.ContextStack;
25  import org.apache.logging.log4j.core.ContextDataInjector;
26  import org.apache.logging.log4j.core.Logger;
27  import org.apache.logging.log4j.core.LoggerContext;
28  import org.apache.logging.log4j.core.config.Configuration;
29  import org.apache.logging.log4j.core.config.Property;
30  import org.apache.logging.log4j.core.config.ReliabilityStrategy;
31  import org.apache.logging.log4j.core.impl.ContextDataFactory;
32  import org.apache.logging.log4j.core.impl.ContextDataInjectorFactory;
33  import org.apache.logging.log4j.core.util.Clock;
34  import org.apache.logging.log4j.core.util.ClockFactory;
35  import org.apache.logging.log4j.core.util.NanoClock;
36  import org.apache.logging.log4j.message.Message;
37  import org.apache.logging.log4j.message.MessageFactory;
38  import org.apache.logging.log4j.message.ReusableMessage;
39  import org.apache.logging.log4j.status.StatusLogger;
40  import org.apache.logging.log4j.util.StackLocatorUtil;
41  import org.apache.logging.log4j.util.StringMap;
42  
43  import com.lmax.disruptor.EventTranslatorVararg;
44  import com.lmax.disruptor.dsl.Disruptor;
45  
46  /**
47   * AsyncLogger is a logger designed for high throughput and low latency logging. It does not perform any I/O in the
48   * calling (application) thread, but instead hands off the work to another thread as soon as possible. The actual
49   * logging is performed in the background thread. It uses the LMAX Disruptor library for inter-thread communication. (<a
50   * href="http://lmax-exchange.github.com/disruptor/" >http://lmax-exchange.github.com/disruptor/</a>)
51   * <p>
52   * To use AsyncLogger, specify the System property
53   * {@code -DLog4jContextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector} before you obtain a
54   * Logger, and all Loggers returned by LogManager.getLogger will be AsyncLoggers.
55   * <p>
56   * Note that for performance reasons, this logger does not include source location by default. You need to specify
57   * {@code includeLocation="true"} in the configuration or any %class, %location or %line conversion patterns in your
58   * log4j.xml configuration will produce either a "?" character or no output at all.
59   * <p>
60   * For best performance, use AsyncLogger with the RandomAccessFileAppender or RollingRandomAccessFileAppender, with
61   * immediateFlush=false. These appenders have built-in support for the batching mechanism used by the Disruptor library,
62   * and they will flush to disk at the end of each batch. This means that even with immediateFlush=false, there will
63   * never be any items left in the buffer; all log events will all be written to disk in a very efficient manner.
64   */
65  public class AsyncLogger extends Logger implements EventTranslatorVararg<RingBufferLogEvent> {
66      // Implementation note: many methods in this class are tuned for performance. MODIFY WITH CARE!
67      // Specifically, try to keep the hot methods to 35 bytecodes or less:
68      // this is within the MaxInlineSize threshold and makes these methods candidates for
69      // immediate inlining instead of waiting until they are designated "hot enough".
70  
71      private static final StatusLogger LOGGER = StatusLogger.getLogger();
72      private static final Clock CLOCK = ClockFactory.getClock(); // not reconfigurable
73      private static final ContextDataInjector CONTEXT_DATA_INJECTOR = ContextDataInjectorFactory.createInjector();
74  
75      private static final ThreadNameCachingStrategy THREAD_NAME_CACHING_STRATEGY = ThreadNameCachingStrategy.create();
76  
77      private final ThreadLocal<RingBufferLogEventTranslator> threadLocalTranslator = new ThreadLocal<>();
78      private final AsyncLoggerDisruptor loggerDisruptor;
79  
80      private volatile boolean includeLocation; // reconfigurable
81      private volatile NanoClock nanoClock; // reconfigurable
82  
83      /**
84       * Constructs an {@code AsyncLogger} with the specified context, name and message factory.
85       *
86       * @param context context of this logger
87       * @param name name of this logger
88       * @param messageFactory message factory of this logger
89       * @param loggerDisruptor helper class that logging can be delegated to. This object owns the Disruptor.
90       */
91      public AsyncLogger(final LoggerContext context, final String name, final MessageFactory messageFactory,
92              final AsyncLoggerDisruptor loggerDisruptor) {
93          super(context, name, messageFactory);
94          this.loggerDisruptor = loggerDisruptor;
95          includeLocation = privateConfig.loggerConfig.isIncludeLocation();
96          nanoClock = context.getConfiguration().getNanoClock();
97      }
98  
99      /*
100      * (non-Javadoc)
101      *
102      * @see org.apache.logging.log4j.core.Logger#updateConfiguration(org.apache.logging.log4j.core.config.Configuration)
103      */
104     @Override
105     protected void updateConfiguration(final Configuration newConfig) {
106         nanoClock = newConfig.getNanoClock();
107         includeLocation = newConfig.getLoggerConfig(name).isIncludeLocation();
108         super.updateConfiguration(newConfig);
109     }
110 
111     // package protected for unit tests
112     NanoClock getNanoClock() {
113         return nanoClock;
114     }
115 
116     private RingBufferLogEventTranslator getCachedTranslator() {
117         RingBufferLogEventTranslator result = threadLocalTranslator.get();
118         if (result == null) {
119             result = new RingBufferLogEventTranslator();
120             threadLocalTranslator.set(result);
121         }
122         return result;
123     }
124 
125     @Override
126     public void logMessage(final String fqcn, final Level level, final Marker marker, final Message message,
127             final Throwable thrown) {
128 
129         if (loggerDisruptor.isUseThreadLocals()) {
130             logWithThreadLocalTranslator(fqcn, level, marker, message, thrown);
131         } else {
132             // LOG4J2-1172: avoid storing non-JDK classes in ThreadLocals to avoid memory leaks in web apps
133             logWithVarargTranslator(fqcn, level, marker, message, thrown);
134         }
135     }
136 
137     private boolean isReused(final Message message) {
138         return message instanceof ReusableMessage;
139     }
140 
141     /**
142      * Enqueues the specified log event data for logging in a background thread.
143      * <p>
144      * This re-uses a {@code RingBufferLogEventTranslator} instance cached in a {@code ThreadLocal} to avoid creating
145      * unnecessary objects with each event.
146      *
147      * @param fqcn fully qualified name of the caller
148      * @param level level at which the caller wants to log the message
149      * @param marker message marker
150      * @param message the log message
151      * @param thrown a {@code Throwable} or {@code null}
152      */
153     private void logWithThreadLocalTranslator(final String fqcn, final Level level, final Marker marker,
154             final Message message, final Throwable thrown) {
155         // Implementation note: this method is tuned for performance. MODIFY WITH CARE!
156 
157         final RingBufferLogEventTranslator translator = getCachedTranslator();
158         initTranslator(translator, fqcn, level, marker, message, thrown);
159         initTranslatorThreadValues(translator);
160         publish(translator);
161     }
162 
163     private void publish(final RingBufferLogEventTranslator translator) {
164         if (!loggerDisruptor.tryPublish(translator)) {
165             handleRingBufferFull(translator);
166         }
167     }
168 
169     private void handleRingBufferFull(final RingBufferLogEventTranslator translator) {
170         if (Logger.getRecursionDepth() > 1) { // LOG4J2-1518, LOG4J2-2031
171             // If queue is full AND we are in a recursive call, call appender directly to prevent deadlock
172             final Message message = AsyncQueueFullMessageUtil.transform(translator.message);
173             logMessageInCurrentThread(translator.fqcn, translator.level, translator.marker, message,
174                     translator.thrown);
175             return;
176         }
177         final EventRoute eventRoute = loggerDisruptor.getEventRoute(translator.level);
178         switch (eventRoute) {
179             case ENQUEUE:
180                 loggerDisruptor.enqueueLogMessageInfo(translator);
181                 break;
182             case SYNCHRONOUS:
183                 logMessageInCurrentThread(translator.fqcn, translator.level, translator.marker, translator.message,
184                         translator.thrown);
185                 break;
186             case DISCARD:
187                 break;
188             default:
189                 throw new IllegalStateException("Unknown EventRoute " + eventRoute);
190         }
191     }
192 
193     private void initTranslator(final RingBufferLogEventTranslator translator, final String fqcn,
194             final Level level, final Marker marker, final Message message, final Throwable thrown) {
195 
196         translator.setBasicValues(this, name, marker, fqcn, level, message, //
197                 // don't construct ThrowableProxy until required
198                 thrown,
199 
200                 // needs shallow copy to be fast (LOG4J2-154)
201                 ThreadContext.getImmutableStack(), //
202 
203                 // location (expensive to calculate)
204                 calcLocationIfRequested(fqcn), //
205                 CLOCK.currentTimeMillis(), //
206                 nanoClock.nanoTime() //
207         );
208     }
209 
210     private void initTranslatorThreadValues(final RingBufferLogEventTranslator translator) {
211         // constant check should be optimized out when using default (CACHED)
212         if (THREAD_NAME_CACHING_STRATEGY == ThreadNameCachingStrategy.UNCACHED) {
213             translator.updateThreadValues();
214         }
215     }
216 
217     /**
218      * Returns the caller location if requested, {@code null} otherwise.
219      *
220      * @param fqcn fully qualified caller name.
221      * @return the caller location if requested, {@code null} otherwise.
222      */
223     private StackTraceElement calcLocationIfRequested(final String fqcn) {
224         // location: very expensive operation. LOG4J2-153:
225         // Only include if "includeLocation=true" is specified,
226         // exclude if not specified or if "false" was specified.
227         return includeLocation ? StackLocatorUtil.calcLocation(fqcn) : null;
228     }
229 
230     /**
231      * Enqueues the specified log event data for logging in a background thread.
232      * <p>
233      * This creates a new varargs Object array for each invocation, but does not store any non-JDK classes in a
234      * {@code ThreadLocal} to avoid memory leaks in web applications (see LOG4J2-1172).
235      *
236      * @param fqcn fully qualified name of the caller
237      * @param level level at which the caller wants to log the message
238      * @param marker message marker
239      * @param message the log message
240      * @param thrown a {@code Throwable} or {@code null}
241      */
242     private void logWithVarargTranslator(final String fqcn, final Level level, final Marker marker,
243             final Message message, final Throwable thrown) {
244         // Implementation note: candidate for optimization: exceeds 35 bytecodes.
245 
246         final Disruptor<RingBufferLogEvent> disruptor = loggerDisruptor.getDisruptor();
247         if (disruptor == null) {
248             LOGGER.error("Ignoring log event after Log4j has been shut down.");
249             return;
250         }
251         // if the Message instance is reused, there is no point in freezing its message here
252         if (!isReused(message)) {
253             InternalAsyncUtil.makeMessageImmutable(message);
254         }
255         StackTraceElement location = null;
256         // calls the translateTo method on this AsyncLogger
257         if (!disruptor.getRingBuffer().tryPublishEvent(this,
258                 this, // asyncLogger: 0
259                 (location = calcLocationIfRequested(fqcn)), // location: 1
260                 fqcn, // 2
261                 level, // 3
262                 marker, // 4
263                 message, // 5
264                 thrown)) { // 6
265             handleRingBufferFull(location, fqcn, level, marker, message, thrown);
266         }
267     }
268 
269     /*
270      * (non-Javadoc)
271      *
272      * @see com.lmax.disruptor.EventTranslatorVararg#translateTo(java.lang.Object, long, java.lang.Object[])
273      */
274     @Override
275     public void translateTo(final RingBufferLogEvent event, final long sequence, final Object... args) {
276         // Implementation note: candidate for optimization: exceeds 35 bytecodes.
277         final AsyncLogger asyncLogger = (AsyncLogger) args[0];
278         final StackTraceElement location = (StackTraceElement) args[1];
279         final String fqcn = (String) args[2];
280         final Level level = (Level) args[3];
281         final Marker marker = (Marker) args[4];
282         final Message message = (Message) args[5];
283         final Throwable thrown = (Throwable) args[6];
284 
285         // needs shallow copy to be fast (LOG4J2-154)
286         final ContextStack contextStack = ThreadContext.getImmutableStack();
287 
288         final Thread currentThread = Thread.currentThread();
289         final String threadName = THREAD_NAME_CACHING_STRATEGY.getThreadName();
290         event.setValues(asyncLogger, asyncLogger.getName(), marker, fqcn, level, message, thrown,
291                 // config properties are taken care of in the EventHandler thread
292                 // in the AsyncLogger#actualAsyncLog method
293                 CONTEXT_DATA_INJECTOR.injectContextData(null, (StringMap) event.getContextData()),
294                 contextStack, currentThread.getId(), threadName, currentThread.getPriority(), location,
295                 CLOCK.currentTimeMillis(), nanoClock.nanoTime());
296     }
297 
298     /**
299      * LOG4J2-471: prevent deadlock when RingBuffer is full and object being logged calls Logger.log() from its
300      * toString() method
301      *
302      * @param fqcn fully qualified caller name
303      * @param level log level
304      * @param marker optional marker
305      * @param message log message
306      * @param thrown optional exception
307      */
308     void logMessageInCurrentThread(final String fqcn, final Level level, final Marker marker,
309             final Message message, final Throwable thrown) {
310         // bypass RingBuffer and invoke Appender directly
311         final ReliabilityStrategy strategy = privateConfig.loggerConfig.getReliabilityStrategy();
312         strategy.log(this, getName(), fqcn, marker, level, message, thrown);
313     }
314 
315     private void handleRingBufferFull(final StackTraceElement location,
316                                       final String fqcn,
317                                       final Level level,
318                                       final Marker marker,
319                                       final Message msg,
320                                       final Throwable thrown) {
321         if (Logger.getRecursionDepth() > 1) { // LOG4J2-1518, LOG4J2-2031
322             // If queue is full AND we are in a recursive call, call appender directly to prevent deadlock
323             final Message message = AsyncQueueFullMessageUtil.transform(msg);
324             logMessageInCurrentThread(fqcn, level, marker, message, thrown);
325             return;
326         }
327         final EventRoute eventRoute = loggerDisruptor.getEventRoute(level);
328         switch (eventRoute) {
329             case ENQUEUE:
330                 loggerDisruptor.getDisruptor().getRingBuffer().publishEvent(this,
331                         this, // asyncLogger: 0
332                         location, // location: 1
333                         fqcn, // 2
334                         level, // 3
335                         marker, // 4
336                         msg, // 5
337                         thrown); // 6
338                 break;
339             case SYNCHRONOUS:
340                 logMessageInCurrentThread(fqcn, level, marker, msg, thrown);
341                 break;
342             case DISCARD:
343                 break;
344             default:
345                 throw new IllegalStateException("Unknown EventRoute " + eventRoute);
346         }
347     }
348 
349     /**
350      * This method is called by the EventHandler that processes the RingBufferLogEvent in a separate thread.
351      * Merges the contents of the configuration map into the contextData, after replacing any variables in the property
352      * values with the StrSubstitutor-supplied actual values.
353      *
354      * @param event the event to log
355      */
356     public void actualAsyncLog(final RingBufferLogEvent event) {
357         final List<Property> properties = privateConfig.loggerConfig.getPropertyList();
358 
359         if (properties != null) {
360             StringMap contextData = (StringMap) event.getContextData();
361             if (contextData.isFrozen()) {
362                 final StringMap temp = ContextDataFactory.createContextData();
363                 temp.putAll(contextData);
364                 contextData = temp;
365             }
366             for (int i = 0; i < properties.size(); i++) {
367                 final Property prop = properties.get(i);
368                 if (contextData.getValue(prop.getName()) != null) {
369                     continue; // contextMap overrides config properties
370                 }
371                 final String value = prop.isValueNeedsLookup() //
372                         ? privateConfig.config.getStrSubstitutor().replace(event, prop.getValue()) //
373                         : prop.getValue();
374                 contextData.putValue(prop.getName(), value);
375             }
376             event.setContextData(contextData);
377         }
378 
379         final ReliabilityStrategy strategy = privateConfig.loggerConfig.getReliabilityStrategy();
380         strategy.log(this, event);
381     }
382 }