FileAppender.java
/**
* Logback: the reliable, generic, fast and flexible logging framework.
* Copyright (C) 1999-2015, QOS.ch. All rights reserved.
*
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
*
* or (per the licensee's choosing)
*
* under the terms of the GNU Lesser General Public License version 2.1
* as published by the Free Software Foundation.
*/
package ch.qos.logback.core;
import static ch.qos.logback.core.CoreConstants.CODES_URL;
import static ch.qos.logback.core.CoreConstants.MORE_INFO_PREFIX;
import java.io.File;
import java.io.IOException;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.util.Map;
import java.util.Map.Entry;
import ch.qos.logback.core.recovery.ResilientFileOutputStream;
import ch.qos.logback.core.util.ContextUtil;
import ch.qos.logback.core.util.FileSize;
import ch.qos.logback.core.util.FileUtil;
/**
* FileAppender appends log events to a file.
*
* For more information about this appender, please refer to the online manual
* at http://logback.qos.ch/manual/appenders.html#FileAppender
*
* @author Ceki Gülcü
*/
public class FileAppender<E> extends OutputStreamAppender<E> {
public static final long DEFAULT_BUFFER_SIZE = 8192;
static protected String COLLISION_WITH_EARLIER_APPENDER_URL = CODES_URL + "#earlier_fa_collision";
/**
* Append to or truncate the file? The default value for this variable is
* <code>true</code>, meaning that by default a <code>FileAppender</code> will
* append to an existing file and not truncate it.
*/
protected boolean append = true;
/**
* The name of the active log file.
*/
protected String fileName = null;
private boolean prudent = false;
private FileSize bufferSize = new FileSize(DEFAULT_BUFFER_SIZE);
/**
* The <b>File</b> property takes a string value which should be the name of the
* file to append to.
*/
public void setFile(String file) {
if (file == null) {
fileName = file;
} else {
// Trim spaces from both ends. The users probably does not want
// trailing spaces in file names.
fileName = file.trim();
}
}
/**
* Returns the value of the <b>Append</b> property.
*/
public boolean isAppend() {
return append;
}
/**
* This method is used by derived classes to obtain the raw file property.
* Regular users should not be calling this method.
*
* @return the value of the file property
*/
final public String rawFileProperty() {
return fileName;
}
/**
* Returns the value of the <b>File</b> property.
*
* <p>
* This method may be overridden by derived classes.
*
*/
public String getFile() {
return fileName;
}
/**
* If the value of <b>File</b> is not <code>null</code>, then {@link #openFile}
* is called with the values of <b>File</b> and <b>Append</b> properties.
*/
public void start() {
int errors = 0;
if (getFile() != null) {
addInfo("File property is set to [" + fileName + "]");
if (prudent) {
if (!isAppend()) {
setAppend(true);
addWarn("Setting \"Append\" property to true on account of \"Prudent\" mode");
}
}
if (checkForFileCollisionInPreviousFileAppenders()) {
addError("Collisions detected with FileAppender/RollingAppender instances defined earlier. Aborting.");
addError(MORE_INFO_PREFIX + COLLISION_WITH_EARLIER_APPENDER_URL);
errors++;
} else {
// file should be opened only if collision free
try {
openFile(getFile());
} catch (java.io.IOException e) {
errors++;
addError("openFile(" + fileName + "," + append + ") call failed.", e);
}
}
} else {
errors++;
addError("\"File\" property not set for appender named [" + name + "].");
}
if (errors == 0) {
super.start();
}
}
@Override
public void stop() {
if(!isStarted())
return;
super.stop();
Map<String, String> map = ContextUtil.getFilenameCollisionMap(context);
if (map == null || getName() == null)
return;
map.remove(getName());
}
protected boolean checkForFileCollisionInPreviousFileAppenders() {
boolean collisionsDetected = false;
if (fileName == null) {
return false;
}
@SuppressWarnings("unchecked")
Map<String, String> previousFilesMap = (Map<String, String>) context
.getObject(CoreConstants.FA_FILENAME_COLLISION_MAP);
if (previousFilesMap == null) {
return collisionsDetected;
}
for (Entry<String, String> entry : previousFilesMap.entrySet()) {
if (fileName.equals(entry.getValue())) {
addErrorForCollision("File", entry.getValue(), entry.getKey());
collisionsDetected = true;
}
}
if (name != null) {
previousFilesMap.put(getName(), fileName);
}
return collisionsDetected;
}
protected void addErrorForCollision(String optionName, String optionValue, String appenderName) {
addError("'" + optionName + "' option has the same value \"" + optionValue + "\" as that given for appender ["
+ appenderName + "] defined earlier.");
}
/**
* <p>
* Sets and <i>opens</i> the file where the log output will go. The specified
* file must be writable.
*
* <p>
* If there was already an opened file, then the previous file is closed first.
*
* <p>
* <b>Do not use this method directly. To configure a FileAppender or one of its
* subclasses, set its properties one by one and then call start().</b>
*
* @param file_name The path to the log file.
*/
public void openFile(String file_name) throws IOException {
streamWriteLock.lock();
try {
File file = new File(file_name);
boolean result = FileUtil.createMissingParentDirectories(file);
if (!result) {
addError("Failed to create parent directories for [" + file.getAbsolutePath() + "]");
}
ResilientFileOutputStream resilientFos = new ResilientFileOutputStream(file, append, bufferSize.getSize());
resilientFos.setContext(context);
setOutputStream(resilientFos);
} finally {
streamWriteLock.unlock();
}
}
/**
* @see #setPrudent(boolean)
*
* @return true if in prudent mode
*/
public boolean isPrudent() {
return prudent;
}
/**
* When prudent is set to true, file appenders from multiple JVMs can safely
* write to the same file.
*
* @param prudent
*/
public void setPrudent(boolean prudent) {
this.prudent = prudent;
}
public void setAppend(boolean append) {
this.append = append;
}
public void setBufferSize(FileSize bufferSize) {
addInfo("Setting bufferSize to [" + bufferSize.toString() + "]");
this.bufferSize = bufferSize;
}
@Override
protected void writeOut(E event) throws IOException {
if (prudent) {
safeWriteOut(event);
} else {
super.writeOut(event);
}
}
private void safeWriteOut(E event) {
byte[] byteArray = this.encoder.encode(event);
if (byteArray == null || byteArray.length == 0)
return;
streamWriteLock.lock();
try {
safeWriteBytes(byteArray);
} finally {
streamWriteLock.unlock();
}
}
private void safeWriteBytes(byte[] byteArray) {
ResilientFileOutputStream resilientFOS = (ResilientFileOutputStream) getOutputStream();
FileChannel fileChannel = resilientFOS.getChannel();
if (fileChannel == null) {
return;
}
// Clear any current interrupt (see LOGBACK-875)
boolean interrupted = Thread.interrupted();
FileLock fileLock = null;
try {
fileLock = fileChannel.lock();
long position = fileChannel.position();
long size = fileChannel.size();
if (size != position) {
fileChannel.position(size);
}
writeByteArrayToOutputStreamWithPossibleFlush(byteArray);
} catch (IOException e) {
// Mainly to catch FileLockInterruptionExceptions (see LOGBACK-875)
resilientFOS.postIOFailure(e);
} finally {
releaseFileLock(fileLock);
// Re-interrupt if we started in an interrupted state (see LOGBACK-875)
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
private void releaseFileLock(FileLock fileLock) {
if (fileLock != null && fileLock.isValid()) {
try {
fileLock.release();
} catch (IOException e) {
addError("failed to release lock", e);
}
}
}
}