1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache license, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the license for the specific language governing permissions and 15 * limitations under the license. 16 */ 17 package org.apache.logging.log4j.core.appender; 18 19 import java.util.HashMap; 20 import java.util.Map; 21 import java.util.concurrent.locks.Lock; 22 import java.util.concurrent.locks.ReentrantLock; 23 24 import org.apache.logging.log4j.Logger; 25 import org.apache.logging.log4j.status.StatusLogger; 26 27 /** 28 * Abstract base class used to register managers. 29 */ 30 public abstract class AbstractManager { 31 32 /** 33 * Allow subclasses access to the status logger without creating another instance. 34 */ 35 protected static final Logger LOGGER = StatusLogger.getLogger(); 36 37 // Need to lock that map instead of using a ConcurrentMap due to stop removing the 38 // manager from the map and closing the stream, requiring the whole stop method to be locked. 39 private static final Map<String, AbstractManager> MAP = new HashMap<String, AbstractManager>(); 40 41 private static final Lock LOCK = new ReentrantLock(); 42 43 /** 44 * Number of Appenders using this manager. 45 */ 46 protected int count; 47 48 private final String name; 49 50 protected AbstractManager(final String name) { 51 this.name = name; 52 LOGGER.debug("Starting {} {}", this.getClass().getSimpleName(), name); 53 } 54 55 /** 56 * Retrieves a Manager if it has been previously created or creates a new Manager. 57 * @param name The name of the Manager to retrieve. 58 * @param factory The Factory to use to create the Manager. 59 * @param data An Object that should be passed to the factory when creating the Manager. 60 * @param <M> The Type of the Manager to be created. 61 * @param <T> The type of the Factory data. 62 * @return A Manager with the specified name and type. 63 */ 64 public static <M extends AbstractManager, T> M getManager(final String name, final ManagerFactory<M, T> factory, 65 final T data) { 66 if (factory == null) { 67 throw new IllegalArgumentException("factory cannot be null"); 68 } 69 LOCK.lock(); 70 try { 71 @SuppressWarnings("unchecked") 72 M manager = (M) MAP.get(name); 73 if (manager == null) { 74 manager = factory.createManager(name, data); 75 if (manager == null) { 76 throw new IllegalStateException("Unable to create a manager"); 77 } 78 MAP.put(name, manager); 79 } 80 manager.count++; 81 return manager; 82 } finally { 83 LOCK.unlock(); 84 } 85 } 86 87 /** 88 * Determines if a Manager with the specified name exists. 89 * @param name The name of the Manager. 90 * @return True if the Manager exists, false otherwise. 91 */ 92 public static boolean hasManager(final String name) { 93 LOCK.lock(); 94 try { 95 return MAP.containsKey(name); 96 } finally { 97 LOCK.unlock(); 98 } 99 } 100 101 /** 102 * May be overridden by Managers to perform processing while the Manager is being released and the 103 * lock is held. 104 */ 105 protected void releaseSub() { 106 } 107 108 protected int getCount() { 109 return count; 110 } 111 112 /** 113 * Called to signify that this Manager is no longer required by an Appender. 114 */ 115 public void release() { 116 LOCK.lock(); 117 try { 118 --count; 119 if (count <= 0) { 120 MAP.remove(name); 121 LOGGER.debug("Shutting down {} {}", this.getClass().getSimpleName(), getName()); 122 releaseSub(); 123 } 124 } finally { 125 LOCK.unlock(); 126 } 127 } 128 129 /** 130 * Returns the name of the Manager. 131 * @return The name of the Manager. 132 */ 133 public String getName() { 134 return name; 135 } 136 137 /** 138 * Provide a description of the content format supported by this Manager. Default implementation returns an empty 139 * (unspecified) Map. 140 * 141 * @return a Map of key/value pairs describing the Manager-specific content format, or an empty Map if no content 142 * format descriptors are specified. 143 */ 144 public Map<String, String> getContentFormat() { 145 return new HashMap<String, String>(); 146 } 147 }