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.appender; 018 019 import java.util.HashMap; 020 import java.util.Map; 021 import java.util.concurrent.locks.Lock; 022 import java.util.concurrent.locks.ReentrantLock; 023 024 import org.apache.logging.log4j.Logger; 025 import org.apache.logging.log4j.status.StatusLogger; 026 027 /** 028 * Abstract base class used to register managers. 029 */ 030 public abstract class AbstractManager { 031 032 /** 033 * Allow subclasses access to the status logger without creating another instance. 034 */ 035 protected static final Logger LOGGER = StatusLogger.getLogger(); 036 037 // Need to lock that map instead of using a ConcurrentMap due to stop removing the 038 // manager from the map and closing the stream, requiring the whole stop method to be locked. 039 private static final Map<String, AbstractManager> MAP = new HashMap<String, AbstractManager>(); 040 041 private static final Lock LOCK = new ReentrantLock(); 042 043 /** 044 * Number of Appenders using this manager. 045 */ 046 protected int count; 047 048 private final String name; 049 050 protected AbstractManager(final String name) { 051 this.name = name; 052 LOGGER.debug("Starting {} {}", this.getClass().getSimpleName(), name); 053 } 054 055 /** 056 * Retrieves a Manager if it has been previously created or creates a new Manager. 057 * @param name The name of the Manager to retrieve. 058 * @param factory The Factory to use to create the Manager. 059 * @param data An Object that should be passed to the factory when creating the Manager. 060 * @param <M> The Type of the Manager to be created. 061 * @param <T> The type of the Factory data. 062 * @return A Manager with the specified name and type. 063 */ 064 public static <M extends AbstractManager, T> M getManager(final String name, final ManagerFactory<M, T> factory, 065 final T data) { 066 LOCK.lock(); 067 try { 068 @SuppressWarnings("unchecked") 069 M manager = (M) MAP.get(name); 070 if (manager == null) { 071 manager = factory.createManager(name, data); 072 if (manager == null) { 073 throw new IllegalStateException("Unable to create a manager"); 074 } 075 MAP.put(name, manager); 076 } 077 manager.count++; 078 return manager; 079 } finally { 080 LOCK.unlock(); 081 } 082 } 083 084 /** 085 * Determines if a Manager with the specified name exists. 086 * @param name The name of the Manager. 087 * @return True if the Manager exists, false otherwise. 088 */ 089 public static boolean hasManager(final String name) { 090 LOCK.lock(); 091 try { 092 return MAP.containsKey(name); 093 } finally { 094 LOCK.unlock(); 095 } 096 } 097 098 /** 099 * May be overridden by Managers to perform processing while the Manager is being released and the 100 * lock is held. 101 */ 102 protected void releaseSub() { 103 } 104 105 protected int getCount() { 106 return count; 107 } 108 109 /** 110 * Called to signify that this Manager is no longer required by an Appender. 111 */ 112 public void release() { 113 LOCK.lock(); 114 try { 115 --count; 116 if (count <= 0) { 117 MAP.remove(name); 118 LOGGER.debug("Shutting down {} {}", this.getClass().getSimpleName(), getName()); 119 releaseSub(); 120 } 121 } finally { 122 LOCK.unlock(); 123 } 124 } 125 126 /** 127 * Returns the name of the Manager. 128 * @return The name of the Manager. 129 */ 130 public String getName() { 131 return name; 132 } 133 134 /** 135 * Provide a description of the content format supported by this Manager. Default implementation returns an empty 136 * (unspecified) Map. 137 * 138 * @return a Map of key/value pairs describing the Manager-specific content format, or an empty Map if no content 139 * format descriptors are specified. 140 */ 141 public Map<String, String> getContentFormat() { 142 return new HashMap<String, String>(); 143 } 144 }