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The Apache Log4j Implementation
/*
* 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.appender;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.AbstractLifeCycle;
import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.config.ConfigurationException;
import org.apache.logging.log4j.message.Message;
import org.apache.logging.log4j.status.StatusLogger;
/**
* Abstract base class used to register managers.
*
* This class implements {@link AutoCloseable} mostly to allow unit tests to be written safely and succinctly. While
* managers do need to allocate resources (usually on construction) and then free these resources, a manager is longer
* lived than other auto-closeable objects like streams. None the less, making a manager AutoCloseable forces readers to
* be aware of the pattern: allocate resources on construction and call {@link #close()} at some point.
*
*/
public abstract class AbstractManager implements AutoCloseable {
/**
* Allow subclasses access to the status logger without creating another instance.
*/
protected static final Logger LOGGER = StatusLogger.getLogger();
// Need to lock that map instead of using a ConcurrentMap due to stop removing the
// manager from the map and closing the stream, requiring the whole stop method to be locked.
private static final Map MAP = new HashMap<>();
private static final Lock LOCK = new ReentrantLock();
/**
* Number of Appenders using this manager.
*/
protected int count;
private final String name;
private final LoggerContext loggerContext;
protected AbstractManager(final LoggerContext loggerContext, final String name) {
this.loggerContext = loggerContext;
this.name = name;
LOGGER.debug("Starting {} {}", this.getClass().getSimpleName(), name);
}
/**
* Called to signify that this Manager is no longer required by an Appender.
*/
@Override
public void close() {
stop(AbstractLifeCycle.DEFAULT_STOP_TIMEOUT, AbstractLifeCycle.DEFAULT_STOP_TIMEUNIT);
}
public boolean stop(final long timeout, final TimeUnit timeUnit) {
boolean stopped = true;
LOCK.lock();
try {
--count;
if (count <= 0) {
MAP.remove(name);
LOGGER.debug("Shutting down {} {}", this.getClass().getSimpleName(), getName());
stopped = releaseSub(timeout, timeUnit);
LOGGER.debug("Shut down {} {}, all resources released: {}", this.getClass().getSimpleName(), getName(), stopped);
}
} finally {
LOCK.unlock();
}
return stopped;
}
/**
* Retrieves a Manager if it has been previously created or creates a new Manager.
* @param name The name of the Manager to retrieve.
* @param factory The Factory to use to create the Manager.
* @param data An Object that should be passed to the factory when creating the Manager.
* @param The Type of the Manager to be created.
* @param The type of the Factory data.
* @return A Manager with the specified name and type.
*/
// @SuppressWarnings("resource"): this is a factory method, the resource is allocated and released elsewhere.
@SuppressWarnings("resource")
public static M getManager(final String name, final ManagerFactory factory,
final T data) {
LOCK.lock();
try {
@SuppressWarnings("unchecked")
M manager = (M) MAP.get(name);
if (manager == null) {
manager = Objects.requireNonNull(factory, "factory").createManager(name, data);
if (manager == null) {
throw new IllegalStateException("ManagerFactory [" + factory + "] unable to create manager for ["
+ name + "] with data [" + data + "]");
}
MAP.put(name, manager);
} else {
manager.updateData(data);
}
manager.count++;
return manager;
} finally {
LOCK.unlock();
}
}
/**
* Used by Log4j to update the Manager during reconfiguration. This method should be considered private.
* Implementations may not be thread safe. This method may be made protected in a future release.
* @param data The data to update.
*/
public void updateData(final Object data) {
// This default implementation does nothing.
}
/**
* Determines if a Manager with the specified name exists.
* @param name The name of the Manager.
* @return True if the Manager exists, false otherwise.
*/
public static boolean hasManager(final String name) {
LOCK.lock();
try {
return MAP.containsKey(name);
} finally {
LOCK.unlock();
}
}
/**
* Returns the specified manager, cast to the specified narrow type.
* @param narrowClass the type to cast to
* @param manager the manager object to return
* @param the narrow type
* @return the specified manager, cast to the specified narrow type
* @throws ConfigurationException if the manager cannot be cast to the specified type, which only happens when
* the configuration has multiple incompatible appenders pointing to the same resource
* @since 2.9
* @see LOG4J2-1908
*/
protected static M narrow(final Class narrowClass, final AbstractManager manager) {
if (narrowClass.isAssignableFrom(manager.getClass())) {
return (M) manager;
}
throw new ConfigurationException(
"Configuration has multiple incompatible Appenders pointing to the same resource '" +
manager.getName() + "'");
}
protected static StatusLogger logger() {
return StatusLogger.getLogger();
}
/**
* May be overridden by managers to perform processing while the manager is being released and the
* lock is held. A timeout is passed for implementors to use as they see fit.
* @param timeout timeout
* @param timeUnit timeout time unit
* @return true if all resources were closed normally, false otherwise.
*/
protected boolean releaseSub(final long timeout, final TimeUnit timeUnit) {
// This default implementation does nothing.
return true;
}
protected int getCount() {
return count;
}
/**
* Gets the logger context used to create this instance or null. The logger context is usually set when an appender
* creates a manager and that appender is given a Configuration. Not all appenders are given a Configuration by
* their factory method or builder.
*
* @return the logger context used to create this instance or null.
*/
public LoggerContext getLoggerContext() {
return loggerContext;
}
/**
* Called to signify that this Manager is no longer required by an Appender.
* @deprecated In 2.7, use {@link #close()}.
*/
@Deprecated
public void release() {
close();
}
/**
* Returns the name of the Manager.
* @return The name of the Manager.
*/
public String getName() {
return name;
}
/**
* Provide a description of the content format supported by this Manager. Default implementation returns an empty
* (unspecified) Map.
*
* @return a Map of key/value pairs describing the Manager-specific content format, or an empty Map if no content
* format descriptors are specified.
*/
public Map getContentFormat() {
return new HashMap<>();
}
protected void log(final Level level, final String message, final Throwable throwable) {
final Message m = LOGGER.getMessageFactory().newMessage("{} {} {}: {}",
getClass().getSimpleName(), getName(), message, throwable);
LOGGER.log(level, m, throwable);
}
protected void logDebug(final String message, final Throwable throwable) {
log(Level.DEBUG, message, throwable);
}
protected void logError(final String message, final Throwable throwable) {
log(Level.ERROR, message, throwable);
}
protected void logWarn(final String message, final Throwable throwable) {
log(Level.WARN, message, throwable);
}
}