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 org.apache.logging.log4j.Logger; 20 import org.apache.logging.log4j.status.StatusLogger; 21 22 import java.util.HashMap; 23 import java.util.Map; 24 import java.util.concurrent.locks.Lock; 25 import java.util.concurrent.locks.ReentrantLock; 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 LOCK.lock(); 67 try { 68 M manager = (M) MAP.get(name); 69 if (manager == null) { 70 manager = factory.createManager(name, data); 71 if (manager == null) { 72 throw new IllegalStateException("Unable to create a manager"); 73 } 74 MAP.put(name, manager); 75 } 76 manager.count++; 77 return manager; 78 } finally { 79 LOCK.unlock(); 80 } 81 } 82 83 /** 84 * Determines if a Manager with the specified name exists. 85 * @param name The name of the Manager. 86 * @return True if the Manager exists, false otherwise. 87 */ 88 public static boolean hasManager(final String name) { 89 LOCK.lock(); 90 try { 91 return MAP.containsKey(name); 92 } finally { 93 LOCK.unlock(); 94 } 95 } 96 97 /** 98 * May be overridden by Managers to perform processing while the Manager is being released and the 99 * lock is held. 100 */ 101 protected void releaseSub() { 102 } 103 104 protected int getCount() { 105 return count; 106 } 107 108 /** 109 * Called to signify that this Manager is no longer required by an Appender. 110 */ 111 public void release() { 112 LOCK.lock(); 113 try { 114 --count; 115 if (count <= 0) { 116 MAP.remove(name); 117 LOGGER.debug("Shutting down {} {}", this.getClass().getSimpleName(), getName()); 118 releaseSub(); 119 } 120 } finally { 121 LOCK.unlock(); 122 } 123 } 124 125 /** 126 * Returns the name of the Manager. 127 * @return The name of the Manager. 128 */ 129 public String getName() { 130 return name; 131 } 132 133 /** 134 * Provide a description of the content format supported by this Manager. Default implementation returns an empty (unspecified) Map. 135 * 136 * @return a Map of key/value pairs describing the Manager-specific content format, or an empty Map if no content format descriptors are specified. 137 * 138 */ 139 public Map<String, String> getContentFormat() { 140 return new HashMap<String, String>(); 141 } 142 }