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.

⏎ org/apache/logging/log4j/core/script/ScriptManager.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.script;

import java.io.File;
import java.io.Serializable;
import java.nio.file.Path;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import javax.script.Bindings;
import javax.script.Compilable;
import javax.script.CompiledScript;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import javax.script.SimpleBindings;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.util.FileWatcher;
import org.apache.logging.log4j.core.util.WatchManager;
import org.apache.logging.log4j.status.StatusLogger;
import org.apache.logging.log4j.util.Strings;

/**
 * Manages the scripts use by the Configuration.
 */
public class ScriptManager implements FileWatcher, Serializable {

    private abstract class AbstractScriptRunner implements ScriptRunner {

        private static final String KEY_STATUS_LOGGER = "statusLogger";
        private static final String KEY_CONFIGURATION = "configuration";

        @Override
        public Bindings createBindings() {
            final SimpleBindings bindings = new SimpleBindings();
            bindings.put(KEY_CONFIGURATION, configuration);
            bindings.put(KEY_STATUS_LOGGER, logger);
            return bindings;
        }

    }

    private static final long serialVersionUID = -2534169384971965196L;
    private static final String KEY_THREADING = "THREADING";
    private static final Logger logger = StatusLogger.getLogger();

    private final Configuration configuration;
    private final ScriptEngineManager manager = new ScriptEngineManager();
    private final ConcurrentMap<String, ScriptRunner> scriptRunners = new ConcurrentHashMap<>();
    private final String languages;
    private final WatchManager watchManager;

    public ScriptManager(final Configuration configuration, final WatchManager watchManager) {
        this.configuration = configuration;
        this.watchManager = watchManager;
        final List<ScriptEngineFactory> factories = manager.getEngineFactories();
        if (logger.isDebugEnabled()) {
            final StringBuilder sb = new StringBuilder();
            final int factorySize = factories.size();
            logger.debug("Installed {} script engine{}", factorySize, factorySize != 1 ? "s" : Strings.EMPTY);
            for (final ScriptEngineFactory factory : factories) {
                String threading = Objects.toString(factory.getParameter(KEY_THREADING), null);
                if (threading == null) {
                    threading = "Not Thread Safe";
                }
                final StringBuilder names = new StringBuilder();
                final List<String> languageNames = factory.getNames();
                for (final String name : languageNames) {
                    if (names.length() > 0) {
                        names.append(", ");
                    }
                    names.append(name);
                }
                if (sb.length() > 0) {
                    sb.append(", ");
                }
                sb.append(names);
                final boolean compiled = factory.getScriptEngine() instanceof Compilable;
                logger.debug("{} version: {}, language: {}, threading: {}, compile: {}, names: {}, factory class: {}",
                        factory.getEngineName(), factory.getEngineVersion(), factory.getLanguageName(), threading,
                        compiled, languageNames, factory.getClass().getName());
            }
            languages = sb.toString();
        } else {
            final StringBuilder names = new StringBuilder();
            for (final ScriptEngineFactory factory : factories) {
                for (final String name : factory.getNames()) {
                    if (names.length() > 0) {
                        names.append(", ");
                    }
                    names.append(name);
                }
            }
            languages = names.toString();
        }
    }

    public void addScript(final AbstractScript script) {
        final ScriptEngine engine = manager.getEngineByName(script.getLanguage());
        if (engine == null) {
            logger.error("No ScriptEngine found for language " + script.getLanguage() + ". Available languages are: "
                    + languages);
            return;
        }
        if (engine.getFactory().getParameter(KEY_THREADING) == null) {
            scriptRunners.put(script.getName(), new ThreadLocalScriptRunner(script));
        } else {
            scriptRunners.put(script.getName(), new MainScriptRunner(engine, script));
        }

        if (script instanceof ScriptFile) {
            final ScriptFile scriptFile = (ScriptFile) script;
            final Path path = scriptFile.getPath();
            if (scriptFile.isWatched() && path != null) {
                watchManager.watchFile(path.toFile(), this);
            }
        }
    }

    public Bindings createBindings(final AbstractScript script) {
        return getScriptRunner(script).createBindings();
    }

    public AbstractScript getScript(final String name) {
        final ScriptRunner runner = scriptRunners.get(name);
        return runner != null ? runner.getScript() : null;
    }

    @Override
    public void fileModified(final File file) {
        final ScriptRunner runner = scriptRunners.get(file.toString());
        if (runner == null) {
            logger.info("{} is not a running script");
            return;
        }
        final ScriptEngine engine = runner.getScriptEngine();
        final AbstractScript script = runner.getScript();
        if (engine.getFactory().getParameter(KEY_THREADING) == null) {
            scriptRunners.put(script.getName(), new ThreadLocalScriptRunner(script));
        } else {
            scriptRunners.put(script.getName(), new MainScriptRunner(engine, script));
        }

    }

    public Object execute(final String name, final Bindings bindings) {
        final ScriptRunner scriptRunner = scriptRunners.get(name);
        if (scriptRunner == null) {
            logger.warn("No script named {} could be found");
            return null;
        }
        return AccessController.doPrivileged((PrivilegedAction<Object>) () -> scriptRunner.execute(bindings));
    }

    private interface ScriptRunner {

        Bindings createBindings();

        Object execute(Bindings bindings);

        AbstractScript getScript();

        ScriptEngine getScriptEngine();
    }

    private class MainScriptRunner extends AbstractScriptRunner {
        private final AbstractScript script;
        private final CompiledScript compiledScript;
        private final ScriptEngine scriptEngine;

        public MainScriptRunner(final ScriptEngine scriptEngine, final AbstractScript script) {
            this.script = script;
            this.scriptEngine = scriptEngine;
            CompiledScript compiled = null;
            if (scriptEngine instanceof Compilable) {
                logger.debug("Script {} is compilable", script.getName());
                compiled = AccessController.doPrivileged((PrivilegedAction<CompiledScript>) () -> {
                    try {
                        return ((Compilable) scriptEngine).compile(script.getScriptText());
                    } catch (final Throwable ex) {
                        /*
                         * ScriptException is what really should be caught here. However, beanshell's ScriptEngine
                         * implements Compilable but then throws Error when the compile method is called!
                         */
                        logger.warn("Error compiling script", ex);
                        return null;
                    }
                });
            }
            compiledScript = compiled;
        }

        @Override
        public ScriptEngine getScriptEngine() {
            return this.scriptEngine;
        }

        @Override
        public Object execute(final Bindings bindings) {
            if (compiledScript != null) {
                try {
                    return compiledScript.eval(bindings);
                } catch (final ScriptException ex) {
                    logger.error("Error running script " + script.getName(), ex);
                    return null;
                }
            }
            try {
                return scriptEngine.eval(script.getScriptText(), bindings);
            } catch (final ScriptException ex) {
                logger.error("Error running script " + script.getName(), ex);
                return null;
            }
        }

        @Override
        public AbstractScript getScript() {
            return script;
        }
    }

    private class ThreadLocalScriptRunner extends AbstractScriptRunner {
        private final AbstractScript script;

        private final ThreadLocal<MainScriptRunner> runners = new ThreadLocal<MainScriptRunner>() {
            @Override
            protected MainScriptRunner initialValue() {
                final ScriptEngine engine = manager.getEngineByName(script.getLanguage());
                return new MainScriptRunner(engine, script);
            }
        };

        public ThreadLocalScriptRunner(final AbstractScript script) {
            this.script = script;
        }

        @Override
        public Object execute(final Bindings bindings) {
            return runners.get().execute(bindings);
        }

        @Override
        public AbstractScript getScript() {
            return script;
        }

        @Override
        public ScriptEngine getScriptEngine() {
            return runners.get().getScriptEngine();
        }
    }

    private ScriptRunner getScriptRunner(final AbstractScript script) {
        return scriptRunners.get(script.getName());
    }
}

⏎ org/apache/logging/log4j/core/script/ScriptManager.java

Or download all of them as a single archive file:

File name: log4j-core-2.14.1-sources.jar
File size: 1281358 bytes
Release date: 2021-03-06
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