Hi Vincent, Just of curiosity, XWiki uses 2 approaches for declaring logger: 1) via dependency injection 2) as a static member via slf4j's factory method However slf4j explicitly recommends using factory method [1]
What's the rationale behind approach 1)? (couldn’t find it explicitly stated in mailing thread [2] ) Roman [1] http://www.slf4j.org/faq.html#declared_static [2] http://xwiki.475771.n2.nabble.com/Proposal-Switch-to-injecting-Loggers-td6348177.html -----Original Message----- From: devs [mailto:[email protected]] On Behalf Of [email protected] Sent: Tuesday, February 18, 2014 19:39 PM To: XWiki Developers Subject: Re: [xwiki-devs] [Proposal] Java logging best practices additions I’ve updated http://dev.xwiki.org/xwiki/bin/view/Community/JavaCodeStyle#HLoggingBestPractices Thanks -Vincent On 15 Feb 2014 at 18:13:36, [email protected] ([email protected](mailto:[email protected])) wrote: > Hi devs, > > On > http://dev.xwiki.org/xwiki/bin/view/Community/JavaCodeStyle#HLoggingBestPractices > we have some best practices defined for logging. > > I’d like to propose some additions. > > Best practices: > > * Use SLF4J > * If you’re in a component get the logger injected using @Inject private > Logger logger otherwise use: > private static final Logger LOGGER = LoggerFactory.getLogger(My.class); > * Use logger.info() when it’s absolutely necessary for the user to see the > message in the logs. Usually only used at startup and we want to limit what > the user sees to the absolute necessary to avoid swamping him. > * Use logger.warning() when an error happens but it doesn’t compromise the > stability and general working of an XWiki instance. A warning just shows the > user that something has gone wrong and it should provide him with as much > information as possible to solve the issue. Do not print a stack trace when > you output a warning since stack traces fill the logs and should be reserved > for errors. In the view of users stack traces are synonymous with errors. We > want it to be easy for admins to visually check the log files and see > important problems (ie errors). > * Use logger.error() when there’s an important problem that compromises the > stability of the XWiki instance or that prevent an important system from > working and that should not have happened. Always pass a stack trace when > logging errors since it’s something that shouldn’t have happened an a > developer will need to debug the problem to fix it. > * Always log as much information as possible to make it easier to understand > what’s going on. > * Surround parameters with “[]” in order to separate visually the text from > the parameters and also clearly notice when leading/trailing spaces are > located in parameters. > * For improved performances, always use the vararg signature of SLF4J for > logging parameters and do not concatenate them manually: > > this.logger.debug("Test message with [{}] and [{}]", param1, param2); > > vs > > this.logger.debug("Test message with [“ + param1 + "] and [“ + param2 + “]", > param1, param2); > > * When logging a warning, we don’t want to log the full stack trace but it’s > still interesting from time to time to display the root issue. If you do the > following you won’t get the root issue: > > LOGGER.warn("Failed to determine if the index exists: [{}]. Trying to > recreate the index..”, e.getMessage()); > > Instead use ExceptionUtils from commons lang: > > LOGGER.warn("Failed to determine if the index exists: [{}]. Trying to > recreate the index..”, ExceptionUtils.getRootCauseMessage(e)); > > WDYT? > > Thanks > -Vincent > > > > > > _______________________________________________ devs mailing list [email protected] http://lists.xwiki.org/mailman/listinfo/devs _______________________________________________ devs mailing list [email protected] http://lists.xwiki.org/mailman/listinfo/devs
