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.IOException; 020import java.io.Writer; 021 022import org.apache.logging.log4j.core.StringLayout; 023 024/** 025 * Manages a Writer so that it can be shared by multiple Appenders and will 026 * allow appenders to reconfigure without requiring a new writer. 027 */ 028public class WriterManager extends AbstractManager { 029 030 /** 031 * Creates a Manager. 032 * 033 * @param name The name of the stream to manage. 034 * @param data The data to pass to the Manager. 035 * @param factory The factory to use to create the Manager. 036 * @param <T> The type of the WriterManager. 037 * @return A WriterManager. 038 */ 039 public static <T> WriterManager getManager(final String name, final T data, 040 final ManagerFactory<? extends WriterManager, T> factory) { 041 return AbstractManager.getManager(name, factory, data); 042 } 043 protected final StringLayout layout; 044 045 private volatile Writer writer; 046 047 public WriterManager(final Writer writer, final String streamName, final StringLayout layout, 048 final boolean writeHeader) { 049 super(streamName); 050 this.writer = writer; 051 this.layout = layout; 052 if (writeHeader && layout != null) { 053 final byte[] header = layout.getHeader(); 054 if (header != null) { 055 try { 056 this.writer.write(new String(header, layout.getCharset())); 057 } catch (final IOException e) { 058 logError("Unable to write header", e); 059 } 060 } 061 } 062 } 063 064 protected synchronized void close() { 065 final Writer w = writer; // access volatile field only once per method 066 try { 067 w.close(); 068 } catch (final IOException ex) { 069 logError("Unable to close stream", ex); 070 } 071 } 072 073 /** 074 * Flushes any buffers. 075 */ 076 public synchronized void flush() { 077 try { 078 writer.flush(); 079 } catch (final IOException ex) { 080 final String msg = "Error flushing stream " + getName(); 081 throw new AppenderLoggingException(msg, ex); 082 } 083 } 084 085 protected Writer getWriter() { 086 return writer; 087 } 088 089 /** 090 * Returns the status of the stream. 091 * @return true if the stream is open, false if it is not. 092 */ 093 public boolean isOpen() { 094 return getCount() > 0; 095 } 096 097 /** 098 * Default hook to write footer during close. 099 */ 100 @Override 101 public void releaseSub() { 102 writeFooter(); 103 close(); 104 } 105 106 protected void setWriter(final Writer writer) { 107 final byte[] header = layout.getHeader(); 108 if (header != null) { 109 try { 110 writer.write(new String(header, layout.getCharset())); 111 this.writer = writer; // only update field if writer.write() succeeded 112 } catch (final IOException ioe) { 113 logError("Unable to write header", ioe); 114 } 115 } else { 116 this.writer = writer; 117 } 118 } 119 120 /** 121 * Some output streams synchronize writes while others do not. Synchronizing here insures that 122 * log events won't be intertwined. 123 * @param bytes The serialized Log event. 124 * @param offset The offset into the byte array. 125 * @param length The number of bytes to write. 126 * @throws AppenderLoggingException if an error occurs. 127 */ 128 protected synchronized void write(final String str) { 129 try { 130 writer.write(str); 131 } catch (final IOException ex) { 132 final String msg = "Error writing to stream " + getName(); 133 throw new AppenderLoggingException(msg, ex); 134 } 135 } 136 137 /** 138 * Writes the footer. 139 */ 140 protected void writeFooter() { 141 if (layout == null) { 142 return; 143 } 144 final byte[] footer = layout.getFooter(); 145 if (footer != null && footer.length > 0) { 146 write(new String(footer, layout.getCharset())); 147 } 148 } 149}