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.core.Filter; 020 import org.apache.logging.log4j.core.Layout; 021 import org.apache.logging.log4j.core.LogEvent; 022 023 import java.util.concurrent.locks.Lock; 024 import java.util.concurrent.locks.ReadWriteLock; 025 import java.util.concurrent.locks.ReentrantReadWriteLock; 026 027 /** 028 * Appends log events as bytes to a byte output stream. The stream encoding is defined in the layout. 029 */ 030 public abstract class AbstractOutputStreamAppender extends AbstractAppender { 031 032 /** 033 * Immediate flush means that the underlying writer or output stream 034 * will be flushed at the end of each append operation. Immediate 035 * flush is slower but ensures that each append request is actually 036 * written. If <code>immediateFlush</code> is set to 037 * {@code false}, then there is a good chance that the last few 038 * logs events are not actually written to persistent media if and 039 * when the application crashes. 040 */ 041 protected final boolean immediateFlush; 042 043 private volatile OutputStreamManager manager; 044 045 private final ReadWriteLock rwLock = new ReentrantReadWriteLock(); 046 private final Lock readLock = rwLock.readLock(); 047 private final Lock writeLock = rwLock.writeLock(); 048 049 /** 050 * Instantiate a WriterAppender and set the output destination to a 051 * new {@link java.io.OutputStreamWriter} initialized with <code>os</code> 052 * as its {@link java.io.OutputStream}. 053 * @param name The name of the Appender. 054 * @param layout The layout to format the message. 055 * @param manager The OutputStreamManager. 056 */ 057 protected AbstractOutputStreamAppender(final String name, final Layout layout, final Filter filter, 058 final boolean handleException, final boolean immediateFlush, 059 final OutputStreamManager manager) { 060 super(name, filter, layout, handleException); 061 if (layout != null) { 062 manager.setHeader(layout.getHeader()); 063 manager.setFooter(layout.getFooter()); 064 } 065 this.manager = manager; 066 this.immediateFlush = immediateFlush; 067 } 068 069 protected OutputStreamManager getManager() { 070 return manager; 071 } 072 073 protected void replaceManager(final OutputStreamManager newManager) { 074 075 writeLock.lock(); 076 try { 077 final OutputStreamManager old = manager; 078 manager = newManager; 079 old.release(); 080 } finally { 081 writeLock.unlock(); 082 } 083 084 } 085 086 @Override 087 public void start() { 088 if (getLayout() == null) { 089 LOGGER.error("No layout set for the appender named [" + getName() + "]."); 090 } 091 if (manager == null) { 092 LOGGER.error("No OutputStreamManager set for the appender named [" + getName() + "]."); 093 } 094 super.start(); 095 } 096 097 @Override 098 public void stop() { 099 super.stop(); 100 manager.release(); 101 } 102 103 /** 104 * Actual writing occurs here. 105 * <p/> 106 * <p>Most subclasses of <code>AbstractOutputStreamAppender</code> will need to 107 * override this method. 108 * @param event The LogEvent. 109 */ 110 public void append(final LogEvent event) { 111 readLock.lock(); 112 try { 113 final byte[] bytes = getLayout().toByteArray(event); 114 if (bytes.length > 0) { 115 manager.write(bytes); 116 if (this.immediateFlush) { 117 manager.flush(); 118 } 119 } 120 } catch (final AppenderRuntimeException ex) { 121 error("Unable to write to stream " + manager.getName() + " for appender " + getName()); 122 throw ex; 123 } finally { 124 readLock.unlock(); 125 } 126 } 127 }