/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache license, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the license for the specific language governing permissions and
* limitations under the license.
*/
package org.apache.logging.log4j.core.async;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.status.StatusLogger;
import com.lmax.disruptor.BlockingWaitStrategy;
import com.lmax.disruptor.EventFactory;
import com.lmax.disruptor.EventHandler;
import com.lmax.disruptor.EventTranslator;
import com.lmax.disruptor.ExceptionHandler;
import com.lmax.disruptor.RingBuffer;
import com.lmax.disruptor.Sequence;
import com.lmax.disruptor.SequenceReportingEventHandler;
import com.lmax.disruptor.SleepingWaitStrategy;
import com.lmax.disruptor.WaitStrategy;
import com.lmax.disruptor.YieldingWaitStrategy;
import com.lmax.disruptor.dsl.Disruptor;
import com.lmax.disruptor.dsl.ProducerType;
import com.lmax.disruptor.util.Util;
/**
* Helper class decoupling the {@code AsyncLoggerConfig} class from the LMAX
* Disruptor library.
* <p>
* {@code AsyncLoggerConfig} is a plugin, and will be loaded even if users do
* not configure any {@code <asyncLogger>} or {@code <asyncRoot>} elements in
* the configuration. If {@code AsyncLoggerConfig} has inner classes that extend
* or implement classes from the Disruptor library, a
* {@code NoClassDefFoundError} is thrown if the Disruptor jar is not in the
* classpath when the PluginManager loads the {@code AsyncLoggerConfig} plugin
* from the pre-defined plugins definition file.
* <p>
* This class serves to make the dependency on the Disruptor optional, so that
* these classes are only loaded when the {@code AsyncLoggerConfig} is actually
* used.
*/
class AsyncLoggerConfigHelper {
private static final int MAX_DRAIN_ATTEMPTS_BEFORE_SHUTDOWN = 20;
private static final int HALF_A_SECOND = 500;
private static final int RINGBUFFER_MIN_SIZE = 128;
private static final int RINGBUFFER_DEFAULT_SIZE = 256 * 1024;
private static final Logger LOGGER = StatusLogger.getLogger();
private static volatile Disruptor<Log4jEventWrapper> disruptor;
private static ExecutorService executor = Executors.newSingleThreadExecutor();
private static volatile int count = 0;
/**
* Factory used to populate the RingBuffer with events. These event objects
* are then re-used during the life of the RingBuffer.
*/
private static final EventFactory<Log4jEventWrapper> FACTORY = new EventFactory<Log4jEventWrapper>() {
@Override
public Log4jEventWrapper newInstance() {
return new Log4jEventWrapper();
}
};
/**
* Object responsible for passing on data to a specific RingBuffer event.
*/
private final EventTranslator<Log4jEventWrapper> translator = new EventTranslator<Log4jEventWrapper>() {
@Override
public void translateTo(Log4jEventWrapper event, long sequence) {
event.event = currentLogEvent.get();
event.loggerConfig = asyncLoggerConfig;
}
};
private ThreadLocal<LogEvent> currentLogEvent = new ThreadLocal<LogEvent>();
private AsyncLoggerConfig asyncLoggerConfig;
public AsyncLoggerConfigHelper(AsyncLoggerConfig asyncLoggerConfig) {
this.asyncLoggerConfig = asyncLoggerConfig;
initDisruptor();
}
private static synchronized void initDisruptor() {
++count;
if (disruptor != null) {
return;
}
int ringBufferSize = calculateRingBufferSize();
WaitStrategy waitStrategy = createWaitStrategy();
disruptor = new Disruptor<Log4jEventWrapper>(FACTORY,
ringBufferSize, executor, ProducerType.MULTI, waitStrategy);
EventHandler<Log4jEventWrapper>[] handlers = new Log4jEventWrapperHandler[] {//
new Log4jEventWrapperHandler() };
disruptor.handleExceptionsWith(getExceptionHandler());
disruptor.handleEventsWith(handlers);
LOGGER.debug(
"Starting AsyncLoggerConfig disruptor with ringbuffer size {}...",
disruptor.getRingBuffer().getBufferSize());
disruptor.start();
}
private static WaitStrategy createWaitStrategy() {
String strategy = System.getProperty("AsyncLoggerConfig.WaitStrategy");
LOGGER.debug("property AsyncLoggerConfig.WaitStrategy={}", strategy);
if ("Sleep".equals(strategy)) {
LOGGER.debug("disruptor event handler uses SleepingWaitStrategy");
return new SleepingWaitStrategy();
} else if ("Yield".equals(strategy)) {
LOGGER.debug("disruptor event handler uses YieldingWaitStrategy");
return new YieldingWaitStrategy();
} else if ("Block".equals(strategy)) {
LOGGER.debug("disruptor event handler uses BlockingWaitStrategy");
return new BlockingWaitStrategy();
}
LOGGER.debug("disruptor event handler uses SleepingWaitStrategy");
return new SleepingWaitStrategy();
}
private static int calculateRingBufferSize() {
int ringBufferSize = RINGBUFFER_DEFAULT_SIZE;
String userPreferredRBSize = System.getProperty(
"AsyncLoggerConfig.RingBufferSize",
String.valueOf(ringBufferSize));
try {
int size = Integer.parseInt(userPreferredRBSize);
if (size < RINGBUFFER_MIN_SIZE) {
size = RINGBUFFER_MIN_SIZE;
LOGGER.warn(
"Invalid RingBufferSize {}, using minimum size {}.",
userPreferredRBSize, RINGBUFFER_MIN_SIZE);
}
ringBufferSize = size;
} catch (Exception ex) {
LOGGER.warn("Invalid RingBufferSize {}, using default size {}.",
userPreferredRBSize, ringBufferSize);
}
return Util.ceilingNextPowerOfTwo(ringBufferSize);
}
private static ExceptionHandler getExceptionHandler() {
String cls = System.getProperty("AsyncLoggerConfig.ExceptionHandler");
if (cls == null) {
LOGGER.debug("No AsyncLoggerConfig.ExceptionHandler specified");
return null;
}
try {
@SuppressWarnings("unchecked")
Class<? extends ExceptionHandler> klass = (Class<? extends ExceptionHandler>) Class
.forName(cls);
ExceptionHandler result = klass.newInstance();
LOGGER.debug("AsyncLoggerConfig.ExceptionHandler=" + result);
return result;
} catch (Exception ignored) {
LOGGER.debug(
"AsyncLoggerConfig.ExceptionHandler not set: error creating "
+ cls + ": ", ignored);
return null;
}
}
/**
* RingBuffer events contain all information necessary to perform the work
* in a separate thread.
*/
private static class Log4jEventWrapper {
private AsyncLoggerConfig loggerConfig;
private LogEvent event;
}
/**
* EventHandler performs the work in a separate thread.
*/
private static class Log4jEventWrapperHandler implements
SequenceReportingEventHandler<Log4jEventWrapper> {
private static final int NOTIFY_PROGRESS_THRESHOLD = 50;
private Sequence sequenceCallback;
private int counter;
@Override
public void setSequenceCallback(Sequence sequenceCallback) {
this.sequenceCallback = sequenceCallback;
}
@Override
public void onEvent(Log4jEventWrapper event, long sequence,
boolean endOfBatch) throws Exception {
event.event.setEndOfBatch(endOfBatch);
event.loggerConfig.asyncCallAppenders(event.event);
// notify the BatchEventProcessor that the sequence has progressed.
// Without this callback the sequence would not be progressed
// until the batch has completely finished.
if (++counter > NOTIFY_PROGRESS_THRESHOLD) {
sequenceCallback.set(sequence);
counter = 0;
}
}
}
public synchronized void shutdown() {
if (--count > 0) {
return;
}
Disruptor<Log4jEventWrapper> temp = disruptor;
if (temp == null) {
return; // disruptor was already shut down by another thread
}
// Must guarantee that publishing to the RingBuffer has stopped
// before we call disruptor.shutdown()
disruptor = null; // client code fails with NPE if log after stop = OK
temp.shutdown();
// wait up to 10 seconds for the ringbuffer to drain
RingBuffer<Log4jEventWrapper> ringBuffer = temp.getRingBuffer();
for (int i = 0; i < MAX_DRAIN_ATTEMPTS_BEFORE_SHUTDOWN; i++) {
if (ringBuffer.hasAvailableCapacity(ringBuffer.getBufferSize())) {
break;
}
try {
// give ringbuffer some time to drain...
Thread.sleep(HALF_A_SECOND);
} catch (InterruptedException e) {
// ignored
}
}
executor.shutdown(); // finally, kill the processor thread
}
public void callAppendersFromAnotherThread(LogEvent event) {
currentLogEvent.set(event);
disruptor.publishEvent(translator);
}
}