Source Code for Apache Log4j Core Implementation

Apache Log4j Core Implementation provides the functional components of the logging system. Users are free to create their own plugins and include them in the logging configuration. Apache Log4j Core is a required module to use Apache Log4j.

Bytecode (Java 8) for Apache Log4j Core Implementation is provided in a separate JAR file like log4j-core-2.14.1.jar.

Source Code files for Apache Log4j API are provided in both binary packge like apache-log4j-2.14.1-bin.zip and source package like apache-log4j-2.14.1-src.zip. You can download them at Apache Log4j Website.

You can also browse Source Code files for Apache Log4j Core Implementation 2.14.1 below.

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org/apache/logging/log4j/core/async/AsyncLoggerConfig.java

/*
 * 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.Arrays;
import java.util.List;
import java.util.concurrent.TimeUnit;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.core.Core;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.AppenderRef;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.LoggerConfig;
import org.apache.logging.log4j.core.config.Node;
import org.apache.logging.log4j.core.config.Property;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
import org.apache.logging.log4j.core.config.plugins.PluginElement;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;
import org.apache.logging.log4j.core.config.plugins.validation.constraints.Required;
import org.apache.logging.log4j.core.jmx.RingBufferAdmin;
import org.apache.logging.log4j.core.util.Booleans;
import org.apache.logging.log4j.spi.AbstractLogger;
import org.apache.logging.log4j.util.Strings;

/**
 * Asynchronous Logger object that is created via configuration and can be
 * combined with synchronous loggers.
 * <p>
 * AsyncLoggerConfig is a logger designed for high throughput and low latency
 * logging. It does not perform any I/O in the calling (application) thread, but
 * instead hands off the work to another thread as soon as possible. The actual
 * logging is performed in the background thread. It uses the LMAX Disruptor
 * library for inter-thread communication. (<a
 * href="http://lmax-exchange.github.com/disruptor/"
 * >http://lmax-exchange.github.com/disruptor/</a>)
 * <p>
 * To use AsyncLoggerConfig, specify {@code <asyncLogger>} or
 * {@code <asyncRoot>} in configuration.
 * <p>
 * Note that for performance reasons, this logger does not include source
 * location by default. You need to specify {@code includeLocation="true"} in
 * the configuration or any %class, %location or %line conversion patterns in
 * your log4j.xml configuration will produce either a "?" character or no output
 * at all.
 * <p>
 * For best performance, use AsyncLoggerConfig with the RandomAccessFileAppender or
 * RollingRandomAccessFileAppender, with immediateFlush=false. These appenders have
 * built-in support for the batching mechanism used by the Disruptor library,
 * and they will flush to disk at the end of each batch. This means that even
 * with immediateFlush=false, there will never be any items left in the buffer;
 * all log events will all be written to disk in a very efficient manner.
 */
@Plugin(name = "asyncLogger", category = Node.CATEGORY, printObject = true)
public class AsyncLoggerConfig extends LoggerConfig {

    private static final ThreadLocal<Boolean> ASYNC_LOGGER_ENTERED = new ThreadLocal<Boolean>() {
        @Override
        protected Boolean initialValue() {
            return Boolean.FALSE;
        }
    };

    private final AsyncLoggerConfigDelegate delegate;

    protected AsyncLoggerConfig(final String name,
            final List<AppenderRef> appenders, final Filter filter,
            final Level level, final boolean additive,
            final Property[] properties, final Configuration config,
            final boolean includeLocation) {
        super(name, appenders, filter, level, additive, properties, config,
                includeLocation);
        delegate = config.getAsyncLoggerConfigDelegate();
        delegate.setLogEventFactory(getLogEventFactory());
    }

    @Override
    protected void log(final LogEvent event, final LoggerConfigPredicate predicate) {
        // See LOG4J2-2301
        if (predicate == LoggerConfigPredicate.ALL &&
                ASYNC_LOGGER_ENTERED.get() == Boolean.FALSE &&
                // Optimization: AsyncLoggerConfig is identical to LoggerConfig
                // when no appenders are present. Avoid splitting for synchronous
                // and asynchronous execution paths until encountering an
                // AsyncLoggerConfig with appenders.
                hasAppenders()) {
            // This is the first AsnycLoggerConfig encountered by this LogEvent
            ASYNC_LOGGER_ENTERED.set(Boolean.TRUE);
            try {
                // Detect the first time we encounter an AsyncLoggerConfig. We must log
                // to all non-async loggers first.
                super.log(event, LoggerConfigPredicate.SYNCHRONOUS_ONLY);
                // Then pass the event to the background thread where
                // all async logging is executed. It is important this
                // happens at most once and after all synchronous loggers
                // have been invoked, because we lose parameter references
                // from reusable messages.
                logToAsyncDelegate(event);
            } finally {
                ASYNC_LOGGER_ENTERED.set(Boolean.FALSE);
            }
        } else {
            super.log(event, predicate);
        }
    }

    @Override
    protected void callAppenders(final LogEvent event) {
        super.callAppenders(event);
    }

    private void logToAsyncDelegate(final LogEvent event) {
        if (!isFiltered(event)) {
            // Passes on the event to a separate thread that will call
            // asyncCallAppenders(LogEvent).
            populateLazilyInitializedFields(event);
            if (!delegate.tryEnqueue(event, this)) {
                handleQueueFull(event);
            }
        }
    }

    private void handleQueueFull(final LogEvent event) {
        if (AbstractLogger.getRecursionDepth() > 1) { // LOG4J2-1518, LOG4J2-2031
            // If queue is full AND we are in a recursive call, call appender directly to prevent deadlock
            AsyncQueueFullMessageUtil.logWarningToStatusLogger();
            logToAsyncLoggerConfigsOnCurrentThread(event);
        } else {
            // otherwise, we leave it to the user preference
            final EventRoute eventRoute = delegate.getEventRoute(event.getLevel());
            eventRoute.logMessage(this, event);
        }
    }

    private void populateLazilyInitializedFields(final LogEvent event) {
        event.getSource();
        event.getThreadName();
    }

    void logInBackgroundThread(final LogEvent event) {
        delegate.enqueueEvent(event, this);
    }

    /**
     * Called by AsyncLoggerConfigHelper.RingBufferLog4jEventHandler.
     *
     * This method will log the provided event to only configs of type {@link AsyncLoggerConfig} (not
     * default {@link LoggerConfig} definitions), which will be invoked on the <b>calling thread</b>.
     */
    void logToAsyncLoggerConfigsOnCurrentThread(final LogEvent event) {
        log(event, LoggerConfigPredicate.ASYNCHRONOUS_ONLY);
    }

    private String displayName() {
        return LogManager.ROOT_LOGGER_NAME.equals(getName()) ? LoggerConfig.ROOT : getName();
    }

    @Override
    public void start() {
        LOGGER.trace("AsyncLoggerConfig[{}] starting...", displayName());
        super.start();
    }

    @Override
    public boolean stop(final long timeout, final TimeUnit timeUnit) {
        setStopping();
        super.stop(timeout, timeUnit, false);
        LOGGER.trace("AsyncLoggerConfig[{}] stopping...", displayName());
        setStopped();
        return true;
    }

    /**
     * Creates and returns a new {@code RingBufferAdmin} that instruments the
     * ringbuffer of this {@code AsyncLoggerConfig}.
     *
     * @param contextName name of the {@code LoggerContext}
     * @return a new {@code RingBufferAdmin} that instruments the ringbuffer
     */
    public RingBufferAdmin createRingBufferAdmin(final String contextName) {
        return delegate.createRingBufferAdmin(contextName, getName());
    }

    /**
     * Factory method to create a LoggerConfig.
     *
     * @param additivity True if additive, false otherwise.
     * @param levelName The Level to be associated with the Logger.
     * @param loggerName The name of the Logger.
     * @param includeLocation "true" if location should be passed downstream
     * @param refs An array of Appender names.
     * @param properties Properties to pass to the Logger.
     * @param config The Configuration.
     * @param filter A Filter.
     * @return A new LoggerConfig.
     * @deprecated use {@link #createLogger(boolean, Level, String, String, AppenderRef[], Property[], Configuration, Filter)}
     */
    @Deprecated
    public static LoggerConfig createLogger(
            final String additivity,
            final String levelName,
            final String loggerName,
            final String includeLocation,
            final AppenderRef[] refs,
            final Property[] properties,
            final Configuration config,
            final Filter filter) {
        if (loggerName == null) {
            LOGGER.error("Loggers cannot be configured without a name");
            return null;
        }

        final List<AppenderRef> appenderRefs = Arrays.asList(refs);
        Level level;
        try {
            level = Level.toLevel(levelName, Level.ERROR);
        } catch (final Exception ex) {
            LOGGER.error(
                    "Invalid Log level specified: {}. Defaulting to Error",
                    levelName);
            level = Level.ERROR;
        }
        final String name = loggerName.equals(LoggerConfig.ROOT) ? Strings.EMPTY : loggerName;
        final boolean additive = Booleans.parseBoolean(additivity, true);

        return new AsyncLoggerConfig(name, appenderRefs, filter, level,
                additive, properties, config, includeLocation(includeLocation));
    }

    /**
     * Factory method to create a LoggerConfig.
     *
     * @param additivity True if additive, false otherwise.
     * @param level The Level to be associated with the Logger.
     * @param loggerName The name of the Logger.
     * @param includeLocation "true" if location should be passed downstream
     * @param refs An array of Appender names.
     * @param properties Properties to pass to the Logger.
     * @param config The Configuration.
     * @param filter A Filter.
     * @return A new LoggerConfig.
     * @since 3.0
     */
    @PluginFactory
    public static LoggerConfig createLogger(
            @PluginAttribute(value = "additivity", defaultBoolean = true) final boolean additivity,
            @PluginAttribute("level") final Level level,
            @Required(message = "Loggers cannot be configured without a name") @PluginAttribute("name") final String loggerName,
            @PluginAttribute("includeLocation") final String includeLocation,
            @PluginElement("AppenderRef") final AppenderRef[] refs,
            @PluginElement("Properties") final Property[] properties,
            @PluginConfiguration final Configuration config,
            @PluginElement("Filter") final Filter filter) {
        final String name = loggerName.equals(ROOT) ? Strings.EMPTY : loggerName;
        return new AsyncLoggerConfig(name, Arrays.asList(refs), filter, level, additivity, properties, config,
                includeLocation(includeLocation));
    }

    // Note: for asynchronous loggers, includeLocation default is FALSE
    protected static boolean includeLocation(final String includeLocationConfigValue) {
        return Boolean.parseBoolean(includeLocationConfigValue);
    }

    /**
     * An asynchronous root Logger.
     */
    @Plugin(name = "asyncRoot", category = Core.CATEGORY_NAME, printObject = true)
    public static class RootLogger extends LoggerConfig {

        /**
         * @deprecated use {@link #createLogger(String, Level, String, AppenderRef[], Property[], Configuration, Filter)}
         */
        @Deprecated
        public static LoggerConfig createLogger(
                final String additivity,
                final String levelName,
                final String includeLocation,
                final AppenderRef[] refs,
                final Property[] properties,
                final Configuration config,
                final Filter filter) {
            final List<AppenderRef> appenderRefs = Arrays.asList(refs);
            Level level = null;
            try {
                level = Level.toLevel(levelName, Level.ERROR);
            } catch (final Exception ex) {
                LOGGER.error("Invalid Log level specified: {}. Defaulting to Error", levelName);
                level = Level.ERROR;
            }
            final boolean additive = Booleans.parseBoolean(additivity, true);
            return new AsyncLoggerConfig(LogManager.ROOT_LOGGER_NAME,
                    appenderRefs, filter, level, additive, properties, config,
                    AsyncLoggerConfig.includeLocation(includeLocation));
        }

        /**
         * @since 3.0
         */
        @PluginFactory
        public static LoggerConfig createLogger(
                @PluginAttribute("additivity") final String additivity,
                @PluginAttribute("level") final Level level,
                @PluginAttribute("includeLocation") final String includeLocation,
                @PluginElement("AppenderRef") final AppenderRef[] refs,
                @PluginElement("Properties") final Property[] properties,
                @PluginConfiguration final Configuration config,
                @PluginElement("Filter") final Filter filter) {
            final List<AppenderRef> appenderRefs = Arrays.asList(refs);
            final Level actualLevel = level == null ? Level.ERROR : level;
            final boolean additive = Booleans.parseBoolean(additivity, true);
            return new AsyncLoggerConfig(LogManager.ROOT_LOGGER_NAME, appenderRefs, filter, actualLevel, additive,
                    properties, config, AsyncLoggerConfig.includeLocation(includeLocation));
        }
    }
}

org/apache/logging/log4j/core/async/AsyncLoggerConfig.java

 

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File name: log4j-core-2.14.1-sources.jar
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Release date: 2021-03-06
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