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.Logger; 025import org.apache.logging.log4j.status.StatusLogger; 026 027/** 028 * Abstract base class used to register managers. 029 */ 030public 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 if (factory == null) { 067 throw new IllegalArgumentException("factory cannot be null"); 068 } 069 LOCK.lock(); 070 try { 071 @SuppressWarnings("unchecked") 072 M manager = (M) MAP.get(name); 073 if (manager == null) { 074 manager = factory.createManager(name, data); 075 if (manager == null) { 076 throw new IllegalStateException("Unable to create a manager"); 077 } 078 MAP.put(name, manager); 079 } 080 manager.count++; 081 return manager; 082 } finally { 083 LOCK.unlock(); 084 } 085 } 086 087 /** 088 * Determines if a Manager with the specified name exists. 089 * @param name The name of the Manager. 090 * @return True if the Manager exists, false otherwise. 091 */ 092 public static boolean hasManager(final String name) { 093 LOCK.lock(); 094 try { 095 return MAP.containsKey(name); 096 } finally { 097 LOCK.unlock(); 098 } 099 } 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}