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.locks.Lock;
022import java.util.concurrent.locks.ReentrantLock;
023
024import org.apache.logging.log4j.Level;
025import org.apache.logging.log4j.Logger;
026import org.apache.logging.log4j.message.Message;
027import org.apache.logging.log4j.status.StatusLogger;
028
029/**
030 * Abstract base class used to register managers.
031 */
032public abstract class AbstractManager {
033
034    /**
035     * Allow subclasses access to the status logger without creating another instance.
036     */
037    protected static final Logger LOGGER = StatusLogger.getLogger();
038
039    // Need to lock that map instead of using a ConcurrentMap due to stop removing the
040    // manager from the map and closing the stream, requiring the whole stop method to be locked.
041    private static final Map<String, AbstractManager> MAP = new HashMap<>();
042
043    private static final Lock LOCK = new ReentrantLock();
044
045    /**
046     * Number of Appenders using this manager.
047     */
048    protected int count;
049
050    private final String name;
051
052    protected AbstractManager(final String name) {
053        this.name = name;
054        LOGGER.debug("Starting {} {}", this.getClass().getSimpleName(), name);
055    }
056
057    /**
058     * Retrieves a Manager if it has been previously created or creates a new Manager.
059     * @param name The name of the Manager to retrieve.
060     * @param factory The Factory to use to create the Manager.
061     * @param data An Object that should be passed to the factory when creating the Manager.
062     * @param <M> The Type of the Manager to be created.
063     * @param <T> The type of the Factory data.
064     * @return A Manager with the specified name and type.
065     */
066    public static <M extends AbstractManager, T> M getManager(final String name, final ManagerFactory<M, T> factory,
067                                                              final T data) {
068        LOCK.lock();
069        try {
070            @SuppressWarnings("unchecked")
071            M manager = (M) MAP.get(name);
072            if (manager == null) {
073                manager = factory.createManager(name, data);
074                if (manager == null) {
075                    throw new IllegalStateException("ManagerFactory [" + factory + "] unable to create manager for ["
076                            + name + "] with data [" + data + "]");
077                }
078                MAP.put(name, manager);
079            } else {
080                manager.updateData(data);
081            }
082            manager.count++;
083            return manager;
084        } finally {
085            LOCK.unlock();
086        }
087    }
088
089    public void updateData(final Object data) {
090    }
091
092    /**
093     * Determines if a Manager with the specified name exists.
094     * @param name The name of the Manager.
095     * @return True if the Manager exists, false otherwise.
096     */
097    public static boolean hasManager(final String name) {
098        LOCK.lock();
099        try {
100            return MAP.containsKey(name);
101        } finally {
102            LOCK.unlock();
103        }
104    }
105
106    /**
107     * May be overridden by Managers to perform processing while the Manager is being released and the
108     * lock is held.
109     */
110    protected void releaseSub() {
111    }
112
113    protected int getCount() {
114        return count;
115    }
116
117    /**
118     * Called to signify that this Manager is no longer required by an Appender.
119     */
120    public void release() {
121        LOCK.lock();
122        try {
123            --count;
124            if (count <= 0) {
125                MAP.remove(name);
126                LOGGER.debug("Shutting down {} {}", this.getClass().getSimpleName(), getName());
127                releaseSub();
128            }
129        } finally {
130            LOCK.unlock();
131        }
132    }
133
134    /**
135     * Returns the name of the Manager.
136     * @return The name of the Manager.
137     */
138    public String getName() {
139        return name;
140    }
141
142    /**
143     * Provide a description of the content format supported by this Manager.  Default implementation returns an empty
144     * (unspecified) Map.
145     *
146     * @return a Map of key/value pairs describing the Manager-specific content format, or an empty Map if no content
147     * format descriptors are specified.
148     */
149    public Map<String, String> getContentFormat() {
150        return new HashMap<>();
151    }
152
153    protected void log(final Level level, final String message, final Throwable throwable) {
154        final Message m = LOGGER.getMessageFactory().newMessage("{} {} {}: {}",
155                getClass().getSimpleName(), getName(), message, throwable);
156        LOGGER.log(level, m, throwable);
157    }
158
159    protected void logDebug(final String message, final Throwable throwable) {
160        log(Level.DEBUG, message, throwable);
161    }
162
163    protected void logError(final String message, final Throwable throwable) {
164        log(Level.ERROR, message, throwable);
165    }
166
167    protected void logWarn(final String message, final Throwable throwable) {
168        log(Level.WARN, message, throwable);
169    }
170
171}