001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements. See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache license, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License. You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the license for the specific language governing permissions and
015     * limitations under the license.
016     */
017    package org.apache.logging.log4j.core.impl;
018    
019    import java.net.URI;
020    
021    import org.apache.logging.log4j.core.LifeCycle;
022    import org.apache.logging.log4j.core.LoggerContext;
023    import org.apache.logging.log4j.core.config.Configuration;
024    import org.apache.logging.log4j.core.config.ConfigurationFactory;
025    import org.apache.logging.log4j.core.config.ConfigurationSource;
026    import org.apache.logging.log4j.core.selector.ClassLoaderContextSelector;
027    import org.apache.logging.log4j.core.selector.ContextSelector;
028    import org.apache.logging.log4j.core.util.Assert;
029    import org.apache.logging.log4j.core.util.Cancellable;
030    import org.apache.logging.log4j.core.util.Constants;
031    import org.apache.logging.log4j.core.util.DefaultShutdownCallbackRegistry;
032    import org.apache.logging.log4j.core.util.Loader;
033    import org.apache.logging.log4j.core.util.ShutdownCallbackRegistry;
034    import org.apache.logging.log4j.spi.LoggerContextFactory;
035    import org.apache.logging.log4j.status.StatusLogger;
036    import org.apache.logging.log4j.util.PropertiesUtil;
037    
038    /**
039     * Factory to locate a ContextSelector and then load a LoggerContext.
040     */
041    public class Log4jContextFactory implements LoggerContextFactory, ShutdownCallbackRegistry {
042    
043        private static final StatusLogger LOGGER = StatusLogger.getLogger();
044        private static final boolean SHUTDOWN_HOOK_ENABLED =
045            PropertiesUtil.getProperties().getBooleanProperty(ShutdownCallbackRegistry.SHUTDOWN_HOOK_ENABLED, true);
046    
047        private final ContextSelector selector;
048        private final ShutdownCallbackRegistry shutdownCallbackRegistry;
049    
050        /**
051         * Initializes the ContextSelector from system property {@link Constants#LOG4J_CONTEXT_SELECTOR}.
052         */
053        public Log4jContextFactory() {
054            this(createContextSelector(), createShutdownCallbackRegistry());
055        }
056    
057        /**
058         * Initializes this factory's ContextSelector with the specified selector.
059         * @param selector the selector to use
060         */
061        public Log4jContextFactory(final ContextSelector selector) {
062            this(selector, createShutdownCallbackRegistry());
063        }
064    
065        /**
066         * Constructs a Log4jContextFactory using the ContextSelector from {@link Constants#LOG4J_CONTEXT_SELECTOR}
067         * and the provided ShutdownRegistrationStrategy.
068         *
069         * @param shutdownCallbackRegistry the ShutdownRegistrationStrategy to use
070         * @since 2.1
071         */
072        public Log4jContextFactory(final ShutdownCallbackRegistry shutdownCallbackRegistry) {
073            this(createContextSelector(), shutdownCallbackRegistry);
074        }
075    
076        /**
077         * Constructs a Log4jContextFactory using the provided ContextSelector and ShutdownRegistrationStrategy.
078         *
079         * @param selector                     the selector to use
080         * @param shutdownCallbackRegistry the ShutdownRegistrationStrategy to use
081         * @since 2.1
082         */
083        public Log4jContextFactory(final ContextSelector selector,
084                                   final ShutdownCallbackRegistry shutdownCallbackRegistry) {
085            this.selector = Assert.requireNonNull(selector, "No ContextSelector provided");
086            this.shutdownCallbackRegistry = Assert.requireNonNull(shutdownCallbackRegistry,
087                "No ShutdownCallbackRegistry provided");
088            LOGGER.debug("Using ShutdownCallbackRegistry {}", shutdownCallbackRegistry.getClass());
089            initializeShutdownCallbackRegistry();
090        }
091    
092        private static ContextSelector createContextSelector() {
093            final String sel = PropertiesUtil.getProperties().getStringProperty(Constants.LOG4J_CONTEXT_SELECTOR);
094            if (sel != null) {
095                try {
096                    return Loader.newCheckedInstanceOf(sel, ContextSelector.class);
097                } catch (final Exception ex) {
098                    LOGGER.error("Unable to create context {}", sel, ex);
099                }
100            }
101            return new ClassLoaderContextSelector();
102        }
103    
104        private static ShutdownCallbackRegistry createShutdownCallbackRegistry() {
105            // TODO: this is such a common idiom it really deserves a utility method somewhere
106            final String registry = PropertiesUtil.getProperties().getStringProperty(
107                ShutdownCallbackRegistry.SHUTDOWN_CALLBACK_REGISTRY);
108            if (registry != null) {
109                try {
110                    return Loader.newCheckedInstanceOf(registry, ShutdownCallbackRegistry.class);
111                } catch (final Exception e) {
112                    LOGGER.error(SHUTDOWN_HOOK_MARKER,
113                        "There was an error loading the ShutdownCallbackRegistry [{}]. "
114                            + "Falling back to DefaultShutdownCallbackRegistry.", registry, e);
115                }
116            }
117            return new DefaultShutdownCallbackRegistry();
118        }
119    
120        private void initializeShutdownCallbackRegistry() {
121            if (SHUTDOWN_HOOK_ENABLED && this.shutdownCallbackRegistry instanceof LifeCycle) {
122                try {
123                    ((LifeCycle) this.shutdownCallbackRegistry).start();
124                } catch (final Exception e) {
125                    LOGGER.error("There was an error starting the ShutdownCallbackRegistry.", e);
126                }
127            }
128        }
129    
130        /**
131         * Loads the LoggerContext using the ContextSelector.
132         * @param fqcn The fully qualified class name of the caller.
133         * @param loader The ClassLoader to use or null.
134         * @param currentContext If true returns the current Context, if false returns the Context appropriate
135         * for the caller if a more appropriate Context can be determined.
136         * @param externalContext An external context (such as a ServletContext) to be associated with the LoggerContext.
137         * @return The LoggerContext.
138         */
139        @Override
140        public LoggerContext getContext(final String fqcn, final ClassLoader loader, final Object externalContext,
141                                        final boolean currentContext) {
142            final LoggerContext ctx = selector.getContext(fqcn, loader, currentContext);
143            if (externalContext != null && ctx.getExternalContext() == null) {
144                ctx.setExternalContext(externalContext);
145            }
146            if (ctx.getState() == LifeCycle.State.INITIALIZED) {
147                ctx.start();
148            }
149            return ctx;
150        }
151    
152        /**
153         * Loads the LoggerContext using the ContextSelector.
154         * @param fqcn The fully qualified class name of the caller.
155         * @param loader The ClassLoader to use or null.
156         * @param externalContext An external context (such as a ServletContext) to be associated with the LoggerContext.
157         * @param currentContext If true returns the current Context, if false returns the Context appropriate
158         * for the caller if a more appropriate Context can be determined.
159         * @param source The configuration source.
160         * @return The LoggerContext.
161         */
162        public LoggerContext getContext(final String fqcn, final ClassLoader loader, final Object externalContext,
163                                        final boolean currentContext, final ConfigurationSource source) {
164            final LoggerContext ctx = selector.getContext(fqcn, loader, currentContext, null);
165            if (externalContext != null && ctx.getExternalContext() == null) {
166                ctx.setExternalContext(externalContext);
167            }
168            if (ctx.getState() == LifeCycle.State.INITIALIZED) {
169                if (source != null) {
170                    ContextAnchor.THREAD_CONTEXT.set(ctx);
171                    final Configuration config = ConfigurationFactory.getInstance().getConfiguration(source);
172                    LOGGER.debug("Starting LoggerContext[name={}] from configuration {}", ctx.getName(), source);
173                    ctx.start(config);
174                    ContextAnchor.THREAD_CONTEXT.remove();
175                } else {
176                    ctx.start();
177                }
178            }
179            return ctx;
180        }
181    
182        /**
183         * Loads the LoggerContext using the ContextSelector.
184         * @param fqcn The fully qualified class name of the caller.
185         * @param loader The ClassLoader to use or null.
186         * @param externalContext An external context (such as a ServletContext) to be associated with the LoggerContext.
187         * @param currentContext If true returns the current Context, if false returns the Context appropriate
188         * for the caller if a more appropriate Context can be determined.
189         * @param configLocation The location of the configuration for the LoggerContext.
190         * @return The LoggerContext.
191         */
192        @Override
193        public LoggerContext getContext(final String fqcn, final ClassLoader loader, final Object externalContext,
194                                        final boolean currentContext, final URI configLocation, final String name) {
195            final LoggerContext ctx = selector.getContext(fqcn, loader, currentContext, configLocation);
196            if (externalContext != null && ctx.getExternalContext() == null) {
197                ctx.setExternalContext(externalContext);
198            }
199            if (ctx.getState() == LifeCycle.State.INITIALIZED) {
200                if (configLocation != null || name != null) {
201                    ContextAnchor.THREAD_CONTEXT.set(ctx);
202                    final Configuration config = ConfigurationFactory.getInstance().getConfiguration(name, configLocation);
203                    LOGGER.debug("Starting LoggerContext[name={}] from configuration at {}", ctx.getName(), configLocation);
204                    ctx.start(config);
205                    ContextAnchor.THREAD_CONTEXT.remove();
206                } else {
207                    ctx.start();
208                }
209            }
210            return ctx;
211        }
212    
213        /**
214         * Returns the ContextSelector.
215         * @return The ContextSelector.
216         */
217        public ContextSelector getSelector() {
218            return selector;
219        }
220    
221        /**
222         * Removes knowledge of a LoggerContext.
223         *
224         * @param context The context to remove.
225         */
226        @Override
227        public void removeContext(final org.apache.logging.log4j.spi.LoggerContext context) {
228            if (context instanceof LoggerContext) {
229                selector.removeContext((LoggerContext) context);
230            }
231        }
232    
233        @Override
234        public Cancellable addShutdownCallback(final Runnable callback) {
235            return SHUTDOWN_HOOK_ENABLED ? shutdownCallbackRegistry.addShutdownCallback(callback) : null;
236        }
237    }