/*
* 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 java.util.concurrent.TimeUnit;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.core.AbstractLifeCycle;
import org.apache.logging.log4j.core.jmx.RingBufferAdmin;
import org.apache.logging.log4j.core.util.ExecutorServices;
import org.apache.logging.log4j.core.util.Log4jThreadFactory;
import com.lmax.disruptor.ExceptionHandler;
import com.lmax.disruptor.RingBuffer;
import com.lmax.disruptor.TimeoutException;
import com.lmax.disruptor.WaitStrategy;
import com.lmax.disruptor.dsl.Disruptor;
import com.lmax.disruptor.dsl.ProducerType;
/**
* Helper class for async loggers: AsyncLoggerDisruptor handles the mechanics of working with the LMAX Disruptor, and
* works with its associated AsyncLoggerContext to synchronize the life cycle of the Disruptor and its thread with the
* life cycle of the context. The AsyncLoggerDisruptor of the context is shared by all AsyncLogger objects created by
* that AsyncLoggerContext.
*/
class AsyncLoggerDisruptor extends AbstractLifeCycle {
private static final int SLEEP_MILLIS_BETWEEN_DRAIN_ATTEMPTS = 50;
private static final int MAX_DRAIN_ATTEMPTS_BEFORE_SHUTDOWN = 200;
private volatile Disruptor<RingBufferLogEvent> disruptor;
private ExecutorService executor;
private String contextName;
private boolean useThreadLocalTranslator = true;
private long backgroundThreadId;
private AsyncQueueFullPolicy asyncQueueFullPolicy;
private int ringBufferSize;
AsyncLoggerDisruptor(final String contextName) {
this.contextName = contextName;
}
public String getContextName() {
return contextName;
}
public void setContextName(final String name) {
contextName = name;
}
Disruptor<RingBufferLogEvent> getDisruptor() {
return disruptor;
}
/**
* Creates and starts a new Disruptor and associated thread if none currently exists.
*
* @see #stop()
*/
@Override
public synchronized void start() {
if (disruptor != null) {
LOGGER.trace(
"[{}] AsyncLoggerDisruptor not starting new disruptor for this context, using existing object.",
contextName);
return;
}
LOGGER.trace("[{}] AsyncLoggerDisruptor creating new disruptor for this context.", contextName);
ringBufferSize = DisruptorUtil.calculateRingBufferSize("AsyncLogger.RingBufferSize");
final WaitStrategy waitStrategy = DisruptorUtil.createWaitStrategy("AsyncLogger.WaitStrategy");
executor = Executors.newSingleThreadExecutor(Log4jThreadFactory.createDaemonThreadFactory("AsyncLogger[" + contextName + "]"));
backgroundThreadId = DisruptorUtil.getExecutorThreadId(executor);
asyncQueueFullPolicy = AsyncQueueFullPolicyFactory.create();
disruptor = new Disruptor<>(RingBufferLogEvent.FACTORY, ringBufferSize, executor, ProducerType.MULTI,
waitStrategy);
final ExceptionHandler<RingBufferLogEvent> errorHandler = DisruptorUtil.getAsyncLoggerExceptionHandler();
disruptor.handleExceptionsWith(errorHandler);
final RingBufferLogEventHandler[] handlers = {new RingBufferLogEventHandler()};
disruptor.handleEventsWith(handlers);
LOGGER.debug("[{}] Starting AsyncLogger disruptor for this context with ringbufferSize={}, waitStrategy={}, "
+ "exceptionHandler={}...", contextName, disruptor.getRingBuffer().getBufferSize(), waitStrategy
.getClass().getSimpleName(), errorHandler);
disruptor.start();
LOGGER.trace("[{}] AsyncLoggers use a {} translator", contextName, useThreadLocalTranslator ? "threadlocal"
: "vararg");
super.start();
}
/**
* Decreases the reference count. If the reference count reached zero, the Disruptor and its associated thread are
* shut down and their references set to {@code null}.
*/
@Override
public boolean stop(final long timeout, final TimeUnit timeUnit) {
final Disruptor<RingBufferLogEvent> temp = getDisruptor();
if (temp == null) {
LOGGER.trace("[{}] AsyncLoggerDisruptor: disruptor for this context already shut down.", contextName);
return true; // disruptor was already shut down by another thread
}
setStopping();
LOGGER.debug("[{}] AsyncLoggerDisruptor: shutting down disruptor for this context.", contextName);
// We 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. This is by design.
// Calling Disruptor.shutdown() will wait until all enqueued events are fully processed,
// but this waiting happens in a busy-spin. To avoid (postpone) wasting CPU,
// we sleep in short chunks, up to 10 seconds, waiting for the ringbuffer to drain.
for (int i = 0; hasBacklog(temp) && i < MAX_DRAIN_ATTEMPTS_BEFORE_SHUTDOWN; i++) {
try {
Thread.sleep(SLEEP_MILLIS_BETWEEN_DRAIN_ATTEMPTS); // give up the CPU for a while
} catch (final InterruptedException e) { // ignored
}
}
try {
// busy-spins until all events currently in the disruptor have been processed
temp.shutdown(timeout, timeUnit);
} catch (final TimeoutException e) {
temp.shutdown();
}
LOGGER.trace("[{}] AsyncLoggerDisruptor: shutting down disruptor executor.", contextName);
// finally, kill the processor thread
ExecutorServices.shutdown(executor, timeout, timeUnit, toString());
executor = null;
if (DiscardingAsyncQueueFullPolicy.getDiscardCount(asyncQueueFullPolicy) > 0) {
LOGGER.trace("AsyncLoggerDisruptor: {} discarded {} events.", asyncQueueFullPolicy,
DiscardingAsyncQueueFullPolicy.getDiscardCount(asyncQueueFullPolicy));
}
setStopped();
return true;
}
/**
* Returns {@code true} if the specified disruptor still has unprocessed events.
*/
private static boolean hasBacklog(final Disruptor<?> theDisruptor) {
final RingBuffer<?> ringBuffer = theDisruptor.getRingBuffer();
return !ringBuffer.hasAvailableCapacity(ringBuffer.getBufferSize());
}
/**
* Creates and returns a new {@code RingBufferAdmin} that instruments the ringbuffer of the {@code AsyncLogger}.
*
* @param jmxContextName name of the {@code AsyncLoggerContext}
* @return a new {@code RingBufferAdmin} that instruments the ringbuffer
*/
public RingBufferAdmin createRingBufferAdmin(final String jmxContextName) {
final RingBuffer<RingBufferLogEvent> ring = disruptor == null ? null : disruptor.getRingBuffer();
return RingBufferAdmin.forAsyncLogger(ring, jmxContextName);
}
EventRoute getEventRoute(final Level logLevel) {
final int remainingCapacity = remainingDisruptorCapacity();
if (remainingCapacity < 0) {
return EventRoute.DISCARD;
}
return asyncQueueFullPolicy.getRoute(backgroundThreadId, logLevel);
}
private int remainingDisruptorCapacity() {
final Disruptor<RingBufferLogEvent> temp = disruptor;
if (hasLog4jBeenShutDown(temp)) {
return -1;
}
return (int) temp.getRingBuffer().remainingCapacity();
}
/**
* Returns {@code true} if the specified disruptor is null.
*/
private boolean hasLog4jBeenShutDown(final Disruptor<RingBufferLogEvent> aDisruptor) {
if (aDisruptor == null) { // LOG4J2-639
LOGGER.warn("Ignoring log event after log4j was shut down");
return true;
}
return false;
}
public boolean tryPublish(final RingBufferLogEventTranslator translator) {
// LOG4J2-639: catch NPE if disruptor field was set to null in stop()
try {
return disruptor.getRingBuffer().tryPublishEvent(translator);
} catch (final NullPointerException npe) {
LOGGER.warn("[{}] Ignoring log event after log4j was shut down.", contextName);
return false;
}
}
void enqueueLogMessageInfo(final RingBufferLogEventTranslator translator) {
// LOG4J2-639: catch NPE if disruptor field was set to null in stop()
try {
// Note: we deliberately access the volatile disruptor field afresh here.
// Avoiding this and using an older reference could result in adding a log event to the disruptor after it
// was shut down, which could cause the publishEvent method to hang and never return.
disruptor.publishEvent(translator);
} catch (final NullPointerException npe) {
LOGGER.warn("[{}] Ignoring log event after log4j was shut down.", contextName);
}
}
/**
* Returns whether it is allowed to store non-JDK classes in ThreadLocal objects for efficiency.
*
* @return whether AsyncLoggers are allowed to use ThreadLocal objects
* @since 2.5
* @see <a href="https://issues.apache.org/jira/browse/LOG4J2-1172">LOG4J2-1172</a>
*/
public boolean isUseThreadLocals() {
return useThreadLocalTranslator;
}
/**
* Signals this AsyncLoggerDisruptor whether it is allowed to store non-JDK classes in ThreadLocal objects for
* efficiency.
* <p>
* This property may be modified after the {@link #start()} method has been called.
* </p>
*
* @param allow whether AsyncLoggers are allowed to use ThreadLocal objects
* @since 2.5
* @see <a href="https://issues.apache.org/jira/browse/LOG4J2-1172">LOG4J2-1172</a>
*/
public void setUseThreadLocals(final boolean allow) {
useThreadLocalTranslator = allow;
LOGGER.trace("[{}] AsyncLoggers have been modified to use a {} translator", contextName,
useThreadLocalTranslator ? "threadlocal" : "vararg");
}
}