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.io.Serializable; 020import java.util.concurrent.locks.Lock; 021import java.util.concurrent.locks.ReadWriteLock; 022import java.util.concurrent.locks.ReentrantReadWriteLock; 023 024import org.apache.logging.log4j.core.Filter; 025import org.apache.logging.log4j.core.Layout; 026import org.apache.logging.log4j.core.LogEvent; 027 028/** 029 * Appends log events as bytes to a byte output stream. The stream encoding is defined in the layout. 030 * 031 * @param <M> The kind of {@link OutputStreamManager} under management 032 */ 033public abstract class AbstractOutputStreamAppender<M extends OutputStreamManager> extends AbstractAppender { 034 035 private static final long serialVersionUID = 1L; 036 037 /** 038 * Immediate flush means that the underlying writer or output stream 039 * will be flushed at the end of each append operation. Immediate 040 * flush is slower but ensures that each append request is actually 041 * written. If <code>immediateFlush</code> is set to 042 * {@code false}, then there is a good chance that the last few 043 * logs events are not actually written to persistent media if and 044 * when the application crashes. 045 */ 046 protected final boolean immediateFlush; 047 048 private final M manager; 049 050 private final ReadWriteLock rwLock = new ReentrantReadWriteLock(); 051 private final Lock readLock = rwLock.readLock(); 052 053 /** 054 * Instantiate a WriterAppender and set the output destination to a 055 * new {@link java.io.OutputStreamWriter} initialized with <code>os</code> 056 * as its {@link java.io.OutputStream}. 057 * @param name The name of the Appender. 058 * @param layout The layout to format the message. 059 * @param manager The OutputStreamManager. 060 */ 061 protected AbstractOutputStreamAppender(final String name, final Layout<? extends Serializable> layout, final Filter filter, 062 final boolean ignoreExceptions, final boolean immediateFlush, 063 final M manager) { 064 super(name, filter, layout, ignoreExceptions); 065 this.manager = manager; 066 this.immediateFlush = immediateFlush; 067 } 068 069 /** 070 * Gets the manager. 071 * 072 * @return the manager. 073 */ 074 public M getManager() { 075 return manager; 076 } 077 078 @Override 079 public void start() { 080 if (getLayout() == null) { 081 LOGGER.error("No layout set for the appender named [" + getName() + "]."); 082 } 083 if (manager == null) { 084 LOGGER.error("No OutputStreamManager set for the appender named [" + getName() + "]."); 085 } 086 super.start(); 087 } 088 089 @Override 090 public void stop() { 091 super.stop(); 092 manager.release(); 093 } 094 095 /** 096 * Actual writing occurs here. 097 * <p> 098 * Most subclasses of <code>AbstractOutputStreamAppender</code> will need to override this method. 099 * </p> 100 * 101 * @param event 102 * The LogEvent. 103 */ 104 @Override 105 public void append(final LogEvent event) { 106 readLock.lock(); 107 try { 108 final byte[] bytes = getLayout().toByteArray(event); 109 if (bytes.length > 0) { 110 manager.write(bytes); 111 if (this.immediateFlush || event.isEndOfBatch()) { 112 manager.flush(); 113 } 114 } 115 } catch (final AppenderLoggingException ex) { 116 error("Unable to write to stream " + manager.getName() + " for appender " + getName()); 117 throw ex; 118 } finally { 119 readLock.unlock(); 120 } 121 } 122}