December 2011 - logback-user

Filtering stacktraces by evaluating packages
by Christopher BROWN 05 Dec '11

05 Dec '11

Hello, I would like to simplify stacktraces when errors occur in an application. For example, with a hypothetical stack such as: com.xyz.Wombat.doSomething javax.servlet.http.HttpServlet.service org.appserver.JspCompiler.handleJsp org.appserver.ServletEngine.handleServlet java.lang.Thread.run ...going down from top-to-bottom, I'd like to detect that line "org.appserver.JspCompiler.handleJsp" has been found, and exclude it -- and all subsequent "lower down" stack frames -- from logging output. Looking at http://logback.qos.ch/manual/layouts.html#Evaluators I assume it must be possible with EventEvaluator because of the syntax %xEx{evaluator-n} but I can't find an example. Furthermore, as I set up LogBack programmatically (and not via XML or any of bundled "configurator"), I'd be happiest if I could be directed towards an API-based example. If it's of any use, here are two methods extracted from the class that I use to configure LogBack (incomplete but should help see what I'm trying to do, and how): private synchronized boolean maybeInitialize(final Logger logger, String pattern) { // will throw ClassCastException if our configuration is incorrect (or accessed from wrong classloader) // that's OK, it's what should happen... final ch.qos.logback.classic.Logger impl = (ch.qos.logback.classic.Logger)logger; // if there's an appender, then the logger seems to have been configured Iterator<Appender<ILoggingEvent>> it = impl.iteratorForAppenders(); if (it.hasNext()) { return false; } String logFileName = impl.getName(); if (logFileName.startsWith(LOG_FILE_STDPREFIX) && logFileName.length() > LOG_FILE_STDPREFIX.length()) { logFileName = logFileName.substring(LOG_FILE_STDPREFIX.length()); } logFileName += LOG_FILE_EXTENSION; Appender<ILoggingEvent> appender; if (CONFIG_VALUE_ROLL_TYPE_DATE.equals(_rollType)) { appender = createRollByDateFileAppender(logFileName, pattern != null ? pattern : PATTERN_FOR_DATE); } else if (CONFIG_VALUE_ROLL_TYPE_SIZE.equals(_rollType)) { appender = createRollBySizeFileAppender(logFileName, pattern); } else { appender = createFileAppender(logFileName, pattern); } appender.start(); impl.addAppender(appender); impl.setLevel(_level); impl.setAdditive(false); return true; } private synchronized boolean maybeInitialize(final Logger logger, String pattern) { // will throw ClassCastException if our configuration is incorrect (or accessed from wrong classloader) // that's OK, it's what should happen... final ch.qos.logback.classic.Logger impl = (ch.qos.logback.classic.Logger)logger; // if there's an appender, then the logger seems to have been configured Iterator<Appender<ILoggingEvent>> it = impl.iteratorForAppenders(); if (it.hasNext()) { return false; } String logFileName = impl.getName(); if (logFileName.startsWith(LOG_FILE_STDPREFIX) && logFileName.length() > LOG_FILE_STDPREFIX.length()) { logFileName = logFileName.substring(LOG_FILE_STDPREFIX.length()); } logFileName += LOG_FILE_EXTENSION; Appender<ILoggingEvent> appender; if (CONFIG_VALUE_ROLL_TYPE_DATE.equals(_rollType)) { appender = createRollByDateFileAppender(logFileName, pattern != null ? pattern : PATTERN_FOR_DATE); } else if (CONFIG_VALUE_ROLL_TYPE_SIZE.equals(_rollType)) { appender = createRollBySizeFileAppender(logFileName, pattern); } else { appender = createFileAppender(logFileName, pattern); } appender.start(); impl.addAppender(appender); impl.setLevel(_level); impl.setAdditive(false); return true; } Thanks, Christopher

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Substituting class/method names in logback log files with original names when deploying obfuscated code
by Christopher BROWN 05 Dec '11

05 Dec '11

Hello, What would be the best way to handle logging with logback when deploying obfuscated code? For example, with YGuard, when the obfuscator runs, it outputs a mapping file of obfuscated code (class names, method names, etc) to unobfuscated code. When a stacktrace or just any logging trace is output, the class/method names are obviously obfuscated. As it's possible to deploy this mapping with the code, say embedded in the same ".jar", all the information I would need is available. Without too much re-writing of code (default formatting with logback), what would be the best way to dynamically replace matching class/method names? Thanks, Christopher

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FileAppender : change log filename at runtime with a datePattern
by Alessio Pollero 04 Dec '11

04 Dec '11

Hi to all, i just switched to logback from log4j now and i want to change at runtime some settings contained in the logback.xml configuration file. I have a logback.xml configuration file that looks like the following : <configuration> <property name="defaultPattern" value="%d{dd/MM/yyyy HH:mm:ss.SSS} [%thread] %-5level - %msg%n" />  <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender"> <target>System.err</target> <filter class="com.aleroot.ErrOutFilter" /> <encoder> <pattern>${defaultPattern}</pattern> </encoder> </appender> <appender name="FILE" class="ch.qos.logback.core.FileAppender"> <file>aleroot.log</file> <append>true</append> <encoder> <pattern>${defaultPattern}</pattern> </encoder> </appender>  <root level="debug"> <appender-ref ref="FILE" /> <appender-ref ref="CONSOLE"/> </root> <logger name="mainLogger" level="debug"> <appender-ref ref="FILE" /> <appender-ref ref="CONSOLE"/> </logger> </configuration> i want to change the file property of the FILE appender at runtime and add a DatePattern to the filename, i've tried with this code : LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory(); ch.qos.logback.classic.Logger logbackLogger = lc.getLogger("mainLogger"); FileAppender<ILoggingEvent> fileAppender = (FileAppender<ILoggingEvent>) logbackLogger.getAppender("FILE"); if(fileAppender != null) { fileAppender.stop(); fileAppender.setFile("aleroot-ddMMyyyy.log"); fileAppender.setContext(lc); fileAppender.start(); } The problem is that the file aleroot.log is created anyway also if i have changed the filename, furthermore i get another file that is named exactly : aleroot-ddMMyyyy.log while i want to have a filename like aleroot-04122011.log . How can i achieve that ? Is there a settings to avoid that the log file will be created at the LoggerFactory.getLogger("mainLogger") call ? I want that the log file will be created only the first time that i write into the log files, there is no need to create an empty log file . The log file should be created the first time that i log something to the log, for example at the first logger.debug("Something.log") , Is there a settings to achieve that ? Thanks.

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