1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache license, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the license for the specific language governing permissions and 15 * limitations under the license. 16 */ 17 package org.apache.logging.log4j.core.layout; 18 19 import java.io.Serializable; 20 import java.nio.ByteBuffer; 21 import java.util.HashMap; 22 import java.util.Map; 23 24 import org.apache.logging.log4j.Logger; 25 import org.apache.logging.log4j.core.Layout; 26 import org.apache.logging.log4j.core.LogEvent; 27 import org.apache.logging.log4j.core.config.Configuration; 28 import org.apache.logging.log4j.status.StatusLogger; 29 30 /** 31 * Abstract base class for Layouts. 32 * 33 * @param <T> 34 * The Class that the Layout will format the LogEvent into. 35 */ 36 public abstract class AbstractLayout<T extends Serializable> implements Layout<T> { 37 38 /** 39 * Allow subclasses access to the status logger without creating another instance. 40 */ 41 protected static final Logger LOGGER = StatusLogger.getLogger(); 42 43 /** 44 * The current Configuration. 45 */ 46 protected final Configuration configuration; 47 48 /** 49 * The number of events successfully processed by this layout. 50 */ 51 protected long eventCount; 52 53 /** 54 * The footer to add when the stream is closed. May be null. 55 */ 56 protected final byte[] footer; 57 58 /** 59 * The header to include when the stream is opened. May be null. 60 */ 61 protected final byte[] header; 62 63 /** 64 * Constructs a layout with an optional header and footer. 65 * 66 * @param header 67 * The header to include when the stream is opened. May be null. 68 * @param footer 69 * The footer to add when the stream is closed. May be null. 70 * @deprecated Use {@link #AbstractLayout(Configuration, byte[], byte[])} 71 */ 72 @Deprecated 73 public AbstractLayout(final byte[] header, final byte[] footer) { 74 this(null, header, footer); 75 } 76 77 /** 78 * Constructs a layout with an optional header and footer. 79 * 80 * @param configuration 81 * The configuration 82 * @param header 83 * The header to include when the stream is opened. May be null. 84 * @param footer 85 * The footer to add when the stream is closed. May be null. 86 */ 87 public AbstractLayout(final Configuration configuration, final byte[] header, final byte[] footer) { 88 super(); 89 this.configuration = configuration; 90 this.header = header; 91 this.footer = footer; 92 } 93 94 public Configuration getConfiguration() { 95 return configuration; 96 } 97 98 @Override 99 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 }