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.async;
018    
019    import java.util.Map;
020    import java.util.concurrent.ExecutorService;
021    import java.util.concurrent.Executors;
022    
023    import org.apache.logging.log4j.Level;
024    import org.apache.logging.log4j.Marker;
025    import org.apache.logging.log4j.ThreadContext;
026    import org.apache.logging.log4j.core.Logger;
027    import org.apache.logging.log4j.core.LoggerContext;
028    import org.apache.logging.log4j.core.config.Property;
029    import org.apache.logging.log4j.core.impl.Log4jLogEvent;
030    import org.apache.logging.log4j.message.Message;
031    import org.apache.logging.log4j.message.MessageFactory;
032    import org.apache.logging.log4j.status.StatusLogger;
033    
034    import com.lmax.disruptor.BlockingWaitStrategy;
035    import com.lmax.disruptor.EventHandler;
036    import com.lmax.disruptor.ExceptionHandler;
037    import com.lmax.disruptor.RingBuffer;
038    import com.lmax.disruptor.SleepingWaitStrategy;
039    import com.lmax.disruptor.WaitStrategy;
040    import com.lmax.disruptor.YieldingWaitStrategy;
041    import com.lmax.disruptor.dsl.Disruptor;
042    import com.lmax.disruptor.dsl.ProducerType;
043    import com.lmax.disruptor.util.Util;
044    
045    /**
046     * AsyncLogger is a logger designed for high throughput and low latency logging.
047     * It does not perform any I/O in the calling (application) thread, but instead
048     * hands off the work to another thread as soon as possible. The actual logging
049     * is performed in the background thread. It uses the LMAX Disruptor library for
050     * inter-thread communication. (<a
051     * href="http://lmax-exchange.github.com/disruptor/"
052     * >http://lmax-exchange.github.com/disruptor/</a>)
053     * <p>
054     * To use AsyncLogger, specify the System property
055     * {@code -DLog4jContextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector}
056     * before you obtain a Logger, and all Loggers returned by LogManager.getLogger
057     * will be AsyncLoggers.
058     * <p>
059     * Note that for performance reasons, this logger does not include source
060     * location by default. You need to specify {@code includeLocation="true"} in
061     * the configuration or any %class, %location or %line conversion patterns in
062     * your log4j.xml configuration will produce either a "?" character or no output
063     * at all.
064     * <p>
065     * For best performance, use AsyncLogger with the FastFileAppender or
066     * FastRollingFileAppender, with immediateFlush=false. These appenders have
067     * built-in support for the batching mechanism used by the Disruptor library,
068     * and they will flush to disk at the end of each batch. This means that even
069     * with immediateFlush=false, there will never be any items left in the buffer;
070     * all log events will all be written to disk in a very efficient manner.
071     */
072    public class AsyncLogger extends Logger {
073        private static final int HALF_A_SECOND = 500;
074        private static final int MAX_DRAIN_ATTEMPTS_BEFORE_SHUTDOWN = 20;
075        private static final int RINGBUFFER_MIN_SIZE = 128;
076        private static final int RINGBUFFER_DEFAULT_SIZE = 256 * 1024;
077        private static final StatusLogger LOGGER = StatusLogger.getLogger();
078    
079        private static volatile Disruptor<RingBufferLogEvent> disruptor;
080        private static Clock clock = ClockFactory.getClock();
081    
082        private static ExecutorService executor = Executors
083                .newSingleThreadExecutor();
084        private ThreadLocal<Info> threadlocalInfo = new ThreadLocal<Info>();
085    
086        static {
087            int ringBufferSize = calculateRingBufferSize();
088    
089            WaitStrategy waitStrategy = createWaitStrategy();
090            disruptor = new Disruptor<RingBufferLogEvent>(
091                    RingBufferLogEvent.FACTORY, ringBufferSize, executor,
092                    ProducerType.MULTI, waitStrategy);
093            EventHandler<RingBufferLogEvent>[] handlers = new RingBufferLogEventHandler[] {//
094            new RingBufferLogEventHandler() };
095            disruptor.handleExceptionsWith(getExceptionHandler());
096            disruptor.handleEventsWith(handlers);
097    
098            LOGGER.debug(
099                    "Starting AsyncLogger disruptor with ringbuffer size {}...",
100                    disruptor.getRingBuffer().getBufferSize());
101            disruptor.start();
102        }
103    
104        private static int calculateRingBufferSize() {
105            int ringBufferSize = RINGBUFFER_DEFAULT_SIZE;
106            String userPreferredRBSize = System.getProperty(
107                    "AsyncLogger.RingBufferSize", String.valueOf(ringBufferSize));
108            try {
109                int size = Integer.parseInt(userPreferredRBSize);
110                if (size < RINGBUFFER_MIN_SIZE) {
111                    size = RINGBUFFER_MIN_SIZE;
112                    LOGGER.warn(
113                            "Invalid RingBufferSize {}, using minimum size {}.",
114                            userPreferredRBSize, RINGBUFFER_MIN_SIZE);
115                }
116                ringBufferSize = size;
117            } catch (Exception ex) {
118                LOGGER.warn("Invalid RingBufferSize {}, using default size {}.",
119                        userPreferredRBSize, ringBufferSize);
120            }
121            return Util.ceilingNextPowerOfTwo(ringBufferSize);
122        }
123    
124        private static WaitStrategy createWaitStrategy() {
125            String strategy = System.getProperty("AsyncLogger.WaitStrategy");
126            LOGGER.debug("property AsyncLogger.WaitStrategy={}", strategy);
127            if ("Sleep".equals(strategy)) {
128                LOGGER.debug("disruptor event handler uses SleepingWaitStrategy");
129                return new SleepingWaitStrategy();
130            } else if ("Yield".equals(strategy)) {
131                LOGGER.debug("disruptor event handler uses YieldingWaitStrategy");
132                return new YieldingWaitStrategy();
133            } else if ("Block".equals(strategy)) {
134                LOGGER.debug("disruptor event handler uses BlockingWaitStrategy");
135                return new BlockingWaitStrategy();
136            }
137            LOGGER.debug("disruptor event handler uses SleepingWaitStrategy");
138            return new SleepingWaitStrategy();
139        }
140    
141        private static ExceptionHandler getExceptionHandler() {
142            String cls = System.getProperty("AsyncLogger.ExceptionHandler");
143            if (cls == null) {
144                LOGGER.debug("No AsyncLogger.ExceptionHandler specified");
145                return null;
146            }
147            try {
148                @SuppressWarnings("unchecked")
149                Class<? extends ExceptionHandler> klass = (Class<? extends ExceptionHandler>) Class
150                        .forName(cls);
151                ExceptionHandler result = klass.newInstance();
152                LOGGER.debug("AsyncLogger.ExceptionHandler=" + result);
153                return result;
154            } catch (Exception ignored) {
155                LOGGER.debug(
156                        "AsyncLogger.ExceptionHandler not set: error creating "
157                                + cls + ": ", ignored);
158                return null;
159            }
160        }
161    
162        /**
163         * Constructs an {@code AsyncLogger} with the specified context, name and
164         * message factory.
165         * 
166         * @param context context of this logger
167         * @param name name of this logger
168         * @param messageFactory message factory of this logger
169         */
170        public AsyncLogger(LoggerContext context, String name,
171                MessageFactory messageFactory) {
172            super(context, name, messageFactory);
173        }
174    
175        /**
176         * Tuple with the event translator and thread name for a thread.
177         */
178        private static class Info {
179            private RingBufferLogEventTranslator translator;
180            private String cachedThreadName;
181        }
182    
183        @Override
184        public void log(Marker marker, String fqcn, Level level, Message data,
185                Throwable t) {
186            Info info = threadlocalInfo.get();
187            if (info == null) {
188                info = new Info();
189                info.translator = new RingBufferLogEventTranslator();
190                info.cachedThreadName = Thread.currentThread().getName();
191                threadlocalInfo.set(info);
192            }
193    
194            Boolean includeLocation = config.loggerConfig.isIncludeLocation();
195            info.translator.setValues(this, getName(), marker, fqcn, level, data,
196                    t, //
197    
198                    // config properties are taken care of in the EventHandler
199                    // thread in the #actualAsyncLog method
200    
201                    // needs shallow copy to be fast (LOG4J2-154)
202                    ThreadContext.getImmutableContext(), //
203    
204                    // needs shallow copy to be fast (LOG4J2-154)
205                    ThreadContext.getImmutableStack(), //
206    
207                    // Thread.currentThread().getName(), //
208                    info.cachedThreadName, //
209    
210                    // location: very expensive operation. LOG4J2-153:
211                    // Only include if "includeLocation=true" is specified,
212                    // exclude if not specified or if "false" was specified.
213                    includeLocation != null && includeLocation ? location(fqcn)
214                            : null,
215    
216                    // System.currentTimeMillis());
217                    // CoarseCachedClock: 20% faster than system clock, 16ms gaps
218                    // CachedClock: 10% faster than system clock, smaller gaps
219                    clock.currentTimeMillis());
220    
221            disruptor.publishEvent(info.translator);
222        }
223    
224        private StackTraceElement location(String fqcnOfLogger) {
225            return Log4jLogEvent.calcLocation(fqcnOfLogger);
226        }
227    
228        /**
229         * This method is called by the EventHandler that processes the
230         * RingBufferLogEvent in a separate thread.
231         * 
232         * @param event the event to log
233         */
234        public void actualAsyncLog(RingBufferLogEvent event) {
235            Map<Property, Boolean> properties = config.loggerConfig.getProperties();
236            event.mergePropertiesIntoContextMap(properties,
237                    config.config.getSubst());
238            config.logEvent(event);
239        }
240    
241        public static void stop() {
242            Disruptor<RingBufferLogEvent> temp = disruptor;
243    
244            // Must guarantee that publishing to the RingBuffer has stopped
245            // before we call disruptor.shutdown()
246            disruptor = null; // client code fails with NPE if log after stop = OK
247            temp.shutdown();
248    
249            // wait up to 10 seconds for the ringbuffer to drain
250            RingBuffer<RingBufferLogEvent> ringBuffer = temp.getRingBuffer();
251            for (int i = 0; i < MAX_DRAIN_ATTEMPTS_BEFORE_SHUTDOWN; i++) {
252                if (ringBuffer.hasAvailableCapacity(ringBuffer.getBufferSize())) {
253                    break;
254                }
255                try {
256                    // give ringbuffer some time to drain...
257                    Thread.sleep(HALF_A_SECOND);
258                } catch (InterruptedException e) {
259                    // ignored
260                }
261            }
262            executor.shutdown(); // finally, kill the processor thread
263        }
264    }