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.concurrent.locks.Lock; 020import java.util.concurrent.locks.ReadWriteLock; 021import java.util.concurrent.locks.ReentrantReadWriteLock; 022 023import org.apache.logging.log4j.core.Filter; 024import org.apache.logging.log4j.core.LogEvent; 025import org.apache.logging.log4j.core.StringLayout; 026 027/** 028 * Appends log events as strings to a writer. 029 * 030 * @param <M> 031 * The kind of {@link WriterManager} under management 032 */ 033public abstract class AbstractWriterAppender<M extends WriterManager> extends AbstractAppender { 034 035 /** 036 * Immediate flush means that the underlying writer will be flushed at the 037 * end of each append operation. Immediate flush is slower but ensures that 038 * each append request is actually written. If <code>immediateFlush</code> 039 * is set to {@code false}, then there is a good chance that the last few 040 * logs events are not actually written to persistent media if and when the 041 * application crashes. 042 */ 043 protected final boolean immediateFlush; 044 private final M manager; 045 private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock(); 046 private final Lock readLock = readWriteLock.readLock(); 047 048 /** 049 * Instantiates. 050 * 051 * @param name 052 * The name of the Appender. 053 * @param layout 054 * The layout to format the message. 055 * @param manager 056 * The OutputStreamManager. 057 */ 058 protected AbstractWriterAppender(final String name, final StringLayout layout, final Filter filter, 059 final boolean ignoreExceptions, final boolean immediateFlush, final M manager) { 060 super(name, filter, layout, ignoreExceptions); 061 this.manager = manager; 062 this.immediateFlush = immediateFlush; 063 } 064 065 /** 066 * Actual writing occurs here. 067 * <p> 068 * Most subclasses will need to override this method. 069 * </p> 070 * 071 * @param event 072 * The LogEvent. 073 */ 074 @Override 075 public void append(final LogEvent event) { 076 readLock.lock(); 077 try { 078 final String str = getStringLayout().toSerializable(event); 079 if (str.length() > 0) { 080 manager.write(str); 081 if (this.immediateFlush || event.isEndOfBatch()) { 082 manager.flush(); 083 } 084 } 085 } catch (final AppenderLoggingException ex) { 086 error("Unable to write " + manager.getName() + " for appender " + getName() + ": " + ex); 087 throw ex; 088 } finally { 089 readLock.unlock(); 090 } 091 } 092 093 /** 094 * Gets the manager. 095 * 096 * @return the manager. 097 */ 098 public M getManager() { 099 return manager; 100 } 101 102 public StringLayout getStringLayout() { 103 return (StringLayout) getLayout(); 104 } 105 106 @Override 107 public void start() { 108 if (getLayout() == null) { 109 LOGGER.error("No layout set for the appender named [{}].", getName()); 110 } 111 if (manager == null) { 112 LOGGER.error("No OutputStreamManager set for the appender named [{}].", getName()); 113 } 114 super.start(); 115 } 116 117 @Override 118 public void stop() { 119 super.stop(); 120 manager.release(); 121 } 122}