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 org.apache.logging.log4j.Logger; 020 import org.apache.logging.log4j.status.StatusLogger; 021 022 import java.util.HashMap; 023 import java.util.Map; 024 import java.util.concurrent.locks.Lock; 025 import java.util.concurrent.locks.ReentrantLock; 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 M manager = (M) MAP.get(name); 069 if (manager == null) { 070 manager = factory.createManager(name, data); 071 if (manager == null) { 072 throw new IllegalStateException("Unable to create a manager"); 073 } 074 MAP.put(name, manager); 075 } 076 manager.count++; 077 return manager; 078 } finally { 079 LOCK.unlock(); 080 } 081 } 082 083 /** 084 * Determines if a Manager with the specified name exists. 085 * @param name The name of the Manager. 086 * @return True if the Manager exists, false otherwise. 087 */ 088 public static boolean hasManager(final String name) { 089 LOCK.lock(); 090 try { 091 return MAP.containsKey(name); 092 } finally { 093 LOCK.unlock(); 094 } 095 } 096 097 /** 098 * May be overriden by Managers to perform processing while the Manager is being released and the 099 * 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 }