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 */
017package org.apache.logging.log4j.core.appender;
018
019import java.util.HashMap;
020import java.util.Map;
021import java.util.concurrent.TimeUnit;
022import java.util.concurrent.locks.Lock;
023import java.util.concurrent.locks.ReentrantLock;
024
025import org.apache.logging.log4j.Level;
026import org.apache.logging.log4j.Logger;
027import org.apache.logging.log4j.core.AbstractLifeCycle;
028import org.apache.logging.log4j.core.LoggerContext;
029import org.apache.logging.log4j.core.config.ConfigurationException;
030import org.apache.logging.log4j.message.Message;
031import org.apache.logging.log4j.status.StatusLogger;
032
033/**
034 * Abstract base class used to register managers.
035 * <p>
036 * This class implements {@link AutoCloseable} mostly to allow unit tests to be written safely and succinctly. While
037 * managers do need to allocate resources (usually on construction) and then free these resources, a manager is longer
038 * lived than other auto-closeable objects like streams. None the less, making a manager AutoCloseable forces readers to
039 * be aware of the the pattern: allocate resources on construction and call {@link #close()} at some point.
040 * </p>
041 */
042public abstract class AbstractManager implements AutoCloseable {
043
044    /**
045     * Allow subclasses access to the status logger without creating another instance.
046     */
047    protected static final Logger LOGGER = StatusLogger.getLogger();
048
049    // Need to lock that map instead of using a ConcurrentMap due to stop removing the
050    // manager from the map and closing the stream, requiring the whole stop method to be locked.
051    private static final Map<String, AbstractManager> MAP = new HashMap<>();
052
053    private static final Lock LOCK = new ReentrantLock();
054
055    /**
056     * Number of Appenders using this manager.
057     */
058    protected int count;
059
060    private final String name;
061
062    private final LoggerContext loggerContext;
063
064    protected AbstractManager(final LoggerContext loggerContext, final String name) {
065        this.loggerContext = loggerContext;
066        this.name = name;
067        LOGGER.debug("Starting {} {}", this.getClass().getSimpleName(), name);
068    }
069
070    /**
071     * Called to signify that this Manager is no longer required by an Appender.
072     */
073    @Override
074    public void close() {
075        stop(AbstractLifeCycle.DEFAULT_STOP_TIMEOUT, AbstractLifeCycle.DEFAULT_STOP_TIMEUNIT);
076    }
077
078    public boolean stop(final long timeout, final TimeUnit timeUnit) {
079        boolean stopped = true;
080        LOCK.lock();
081        try {
082            --count;
083            if (count <= 0) {
084                MAP.remove(name);
085                LOGGER.debug("Shutting down {} {}", this.getClass().getSimpleName(), getName());
086                stopped = releaseSub(timeout, timeUnit);
087                LOGGER.debug("Shut down {} {}, all resources released: {}", this.getClass().getSimpleName(), getName(), stopped);
088            }
089        } finally {
090            LOCK.unlock();
091        }
092        return stopped;
093    }
094
095    /**
096     * Retrieves a Manager if it has been previously created or creates a new Manager.
097     * @param name The name of the Manager to retrieve.
098     * @param factory The Factory to use to create the Manager.
099     * @param data An Object that should be passed to the factory when creating the Manager.
100     * @param <M> The Type of the Manager to be created.
101     * @param <T> The type of the Factory data.
102     * @return A Manager with the specified name and type.
103     */
104    // @SuppressWarnings("resource"): this is a factory method, the resource is allocated and released elsewhere.
105    @SuppressWarnings("resource")
106    public static <M extends AbstractManager, T> M getManager(final String name, final ManagerFactory<M, T> factory,
107                                                              final T data) {
108        LOCK.lock();
109        try {
110            @SuppressWarnings("unchecked")
111            M manager = (M) MAP.get(name);
112            if (manager == null) {
113                manager = factory.createManager(name, data);
114                if (manager == null) {
115                    throw new IllegalStateException("ManagerFactory [" + factory + "] unable to create manager for ["
116                            + name + "] with data [" + data + "]");
117                }
118                MAP.put(name, manager);
119            } else {
120                manager.updateData(data);
121            }
122            manager.count++;
123            return manager;
124        } finally {
125            LOCK.unlock();
126        }
127    }
128
129    public void updateData(final Object data) {
130        // This default implementation does nothing.
131    }
132
133    /**
134     * Determines if a Manager with the specified name exists.
135     * @param name The name of the Manager.
136     * @return True if the Manager exists, false otherwise.
137     */
138    public static boolean hasManager(final String name) {
139        LOCK.lock();
140        try {
141            return MAP.containsKey(name);
142        } finally {
143            LOCK.unlock();
144        }
145    }
146
147    /**
148     * Returns the specified manager, cast to the specified narrow type.
149     * @param narrowClass the type to cast to
150     * @param manager the manager object to return
151     * @param <M> the narrow type
152     * @return the specified manager, cast to the specified narrow type
153     * @throws ConfigurationException if the manager cannot be cast to the specified type, which only happens when
154     *          the configuration has multiple incompatible appenders pointing to the same resource
155     * @since 2.9
156     * @see <a href="https://issues.apache.org/jira/browse/LOG4J2-1908">LOG4J2-1908</a>
157     */
158    protected static <M extends AbstractManager> M narrow(final Class<M> narrowClass, final AbstractManager manager) {
159        if (narrowClass.isAssignableFrom(manager.getClass())) {
160            return (M) manager;
161        }
162        throw new ConfigurationException(
163                "Configuration has multiple incompatible Appenders pointing to the same resource '" +
164                        manager.getName() + "'");
165    }
166
167    /**
168     * May be overridden by managers to perform processing while the manager is being released and the
169     * lock is held. A timeout is passed for implementors to use as they see fit.
170     * @param timeout timeout
171     * @param timeUnit timeout time unit
172     * @return true if all resources were closed normally, false otherwise.
173     */
174    protected boolean releaseSub(final long timeout, final TimeUnit timeUnit) {
175        // This default implementation does nothing.
176        return true;
177    }
178
179    protected int getCount() {
180        return count;
181    }
182
183    /**
184     * Gets the logger context used to create this instance or null. The logger context is usually set when an appender
185     * creates a manager and that appender is given a Configuration. Not all appenders are given a Configuration by
186     * their factory method or builder.
187     *
188     * @return the logger context used to create this instance or null.
189     */
190    public LoggerContext getLoggerContext() {
191        return loggerContext;
192    }
193
194    /**
195     * Called to signify that this Manager is no longer required by an Appender.
196     * @deprecated In 2.7, use {@link #close()}.
197     */
198    @Deprecated
199    public void release() {
200        close();
201    }
202
203    /**
204     * Returns the name of the Manager.
205     * @return The name of the Manager.
206     */
207    public String getName() {
208        return name;
209    }
210
211    /**
212     * Provide a description of the content format supported by this Manager.  Default implementation returns an empty
213     * (unspecified) Map.
214     *
215     * @return a Map of key/value pairs describing the Manager-specific content format, or an empty Map if no content
216     * format descriptors are specified.
217     */
218    public Map<String, String> getContentFormat() {
219        return new HashMap<>();
220    }
221
222    protected void log(final Level level, final String message, final Throwable throwable) {
223        final Message m = LOGGER.getMessageFactory().newMessage("{} {} {}: {}",
224                getClass().getSimpleName(), getName(), message, throwable);
225        LOGGER.log(level, m, throwable);
226    }
227
228    protected void logDebug(final String message, final Throwable throwable) {
229        log(Level.DEBUG, message, throwable);
230    }
231
232    protected void logError(final String message, final Throwable throwable) {
233        log(Level.ERROR, message, throwable);
234    }
235
236    protected void logWarn(final String message, final Throwable throwable) {
237        log(Level.WARN, message, throwable);
238    }
239
240}