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.layout; 018 019import java.io.Serializable; 020import java.nio.ByteBuffer; 021import java.util.HashMap; 022import java.util.Map; 023 024import org.apache.logging.log4j.Logger; 025import org.apache.logging.log4j.core.Layout; 026import org.apache.logging.log4j.core.LogEvent; 027import org.apache.logging.log4j.core.config.Configuration; 028import org.apache.logging.log4j.status.StatusLogger; 029 030/** 031 * Abstract base class for Layouts. 032 * 033 * @param <T> 034 * The Class that the Layout will format the LogEvent into. 035 */ 036public abstract class AbstractLayout<T extends Serializable> implements Layout<T> { 037 038 /** 039 * Allow subclasses access to the status logger without creating another instance. 040 */ 041 protected static final Logger LOGGER = StatusLogger.getLogger(); 042 043 /** 044 * The current Configuration. 045 */ 046 protected final Configuration configuration; 047 048 /** 049 * The number of events successfully processed by this layout. 050 */ 051 protected long eventCount; 052 053 /** 054 * The footer to add when the stream is closed. May be null. 055 */ 056 protected final byte[] footer; 057 058 /** 059 * The header to include when the stream is opened. May be null. 060 */ 061 protected final byte[] header; 062 063 /** 064 * Constructs a layout with an optional header and footer. 065 * 066 * @param header 067 * The header to include when the stream is opened. May be null. 068 * @param footer 069 * The footer to add when the stream is closed. May be null. 070 * @deprecated Use {@link #AbstractLayout(Configuration, byte[], byte[])} 071 */ 072 @Deprecated 073 public AbstractLayout(final byte[] header, final byte[] footer) { 074 this(null, header, footer); 075 } 076 077 /** 078 * Constructs a layout with an optional header and footer. 079 * 080 * @param configuration 081 * The configuration 082 * @param header 083 * The header to include when the stream is opened. May be null. 084 * @param footer 085 * The footer to add when the stream is closed. May be null. 086 */ 087 public AbstractLayout(final Configuration configuration, final byte[] header, final byte[] footer) { 088 super(); 089 this.configuration = configuration; 090 this.header = header; 091 this.footer = footer; 092 } 093 094 public Configuration getConfiguration() { 095 return configuration; 096 } 097 098 @Override 099 public Map<String, String> getContentFormat() { 100 return new HashMap<>(); 101 } 102 103 /** 104 * Returns the footer, if one is available. 105 * 106 * @return A byte array containing the footer. 107 */ 108 @Override 109 public byte[] getFooter() { 110 return footer; 111 } 112 113 /** 114 * Returns the header, if one is available. 115 * 116 * @return A byte array containing the header. 117 */ 118 @Override 119 public byte[] getHeader() { 120 return header; 121 } 122 123 protected void markEvent() { 124 eventCount++; 125 } 126 127 /** 128 * Encodes the specified source LogEvent to some binary representation and writes the result to the specified 129 * destination. 130 * <p> 131 * The default implementation of this method delegates to the {@link #toByteArray(LogEvent)} method which allocates 132 * temporary objects. 133 * </p><p> 134 * Subclasses can override this method to provide a garbage-free implementation. For text-based layouts, 135 * {@code AbstractStringLayout} provides various convenience methods to help with this: 136 * </p> 137 * <pre>@Plugin(name = "MyLayout", category = Node.CATEGORY, elementType = Layout.ELEMENT_TYPE, printObject = true) 138 * public final class MyLayout extends AbstractStringLayout { 139 * @Override 140 * public void encode(LogEvent event, ByteBufferDestination destination) { 141 * StringBuilder text = getStringBuilder(); 142 * convertLogEventToText(event, text); 143 * getStringBuilderEncoder().encode(text, destination); 144 * } 145 * 146 * private void convertLogEventToText(LogEvent event, StringBuilder destination) { 147 * ... // append a text representation of the log event to the StringBuilder 148 * } 149 * } 150 * </pre> 151 * 152 * @param event the LogEvent to encode. 153 * @param destination holds the ByteBuffer to write into. 154 * @see AbstractStringLayout#getStringBuilder() 155 * @see AbstractStringLayout#getStringBuilderEncoder() 156 */ 157 @Override 158 public void encode(final LogEvent event, final ByteBufferDestination destination) { 159 final byte[] data = toByteArray(event); 160 writeTo(data, 0, data.length, destination); 161 } 162 163 /** 164 * Writes the specified data to the specified destination. 165 * 166 * @param data the data to write 167 * @param offset where to start in the specified data array 168 * @param length the number of bytes to write 169 * @param destination the {@code ByteBufferDestination} to write to 170 */ 171 public static void writeTo(final byte[] data, int offset, int length, final ByteBufferDestination destination) { 172 int chunk = 0; 173 ByteBuffer buffer = destination.getByteBuffer(); 174 do { 175 if (length > buffer.remaining()) { 176 buffer = destination.drain(buffer); 177 } 178 chunk = Math.min(length, buffer.remaining()); 179 buffer.put(data, offset, chunk); 180 offset += chunk; 181 length -= chunk; 182 } while (length > 0); 183 } 184}