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 will be flushed at the end of each append 039 * operation. Immediate flush is slower but ensures that each append request is actually written. If 040 * <code>immediateFlush</code> is set to {@code false}, then there is a good chance that the last few logs events 041 * are not actually written to persistent media if and when the application crashes. 042 */ 043 protected final boolean immediateFlush; 044 045 private final M manager; 046 047 private final ReadWriteLock rwLock = new ReentrantReadWriteLock(); 048 private final Lock readLock = rwLock.readLock(); 049 050 /** 051 * Instantiate a WriterAppender and set the output destination to a new {@link java.io.OutputStreamWriter} 052 * initialized with <code>os</code> as its {@link java.io.OutputStream}. 053 * 054 * @param name The name of the Appender. 055 * @param layout The layout to format the message. 056 * @param manager The OutputStreamManager. 057 */ 058 protected AbstractOutputStreamAppender(final String name, final Layout<? extends Serializable> layout, 059 final Filter filter, 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 * Gets the manager. 067 * 068 * @return the manager. 069 */ 070 public M getManager() { 071 return manager; 072 } 073 074 @Override 075 public void start() { 076 if (getLayout() == null) { 077 LOGGER.error("No layout set for the appender named [" + getName() + "]."); 078 } 079 if (manager == null) { 080 LOGGER.error("No OutputStreamManager set for the appender named [" + getName() + "]."); 081 } 082 super.start(); 083 } 084 085 @Override 086 public void stop() { 087 super.stop(); 088 manager.release(); 089 } 090 091 /** 092 * Actual writing occurs here. 093 * <p> 094 * Most subclasses of <code>AbstractOutputStreamAppender</code> will need to override this method. 095 * </p> 096 * 097 * @param event The LogEvent. 098 */ 099 @Override 100 public void append(final LogEvent event) { 101 readLock.lock(); 102 try { 103 final byte[] bytes = getLayout().toByteArray(event); 104 if (bytes.length > 0) { 105 manager.write(bytes); 106 if (this.immediateFlush || event.isEndOfBatch()) { 107 manager.flush(); 108 } 109 } 110 } catch (final AppenderLoggingException ex) { 111 error("Unable to write to stream " + manager.getName() + " for appender " + getName()); 112 throw ex; 113 } finally { 114 readLock.unlock(); 115 } 116 } 117}