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From "Uwe Schindler (Resolved) (JIRA)" <>
Subject [jira] [Resolved] (LUCENE-3598) Improve InfoStream class in trunk to be more consistent with logging-frameworks like slf4j/log4j/commons-logging
Date Thu, 01 Dec 2011 12:54:39 GMT


Uwe Schindler resolved LUCENE-3598.

    Resolution: Fixed
      Assignee: Uwe Schindler

Committed trunk revision: 1209059

For improvements like JUL/SLF4J convenience impl I will open other issues.
> Improve InfoStream class in trunk to be more consistent with logging-frameworks like
> ----------------------------------------------------------------------------------------------------------------
>                 Key: LUCENE-3598
>                 URL:
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: core/index
>    Affects Versions: 4.0
>            Reporter: Uwe Schindler
>            Assignee: Uwe Schindler
>         Attachments: LUCENE-3598.patch, LUCENE-3598.patch, LUCENE-3598.patch, LUCENE-3598.patch
> Followup on a [thread by Shai Erea on java-dev@lao|]:
I already discussed with Robert about that, that there is one thing missing. Currently the
IW only checks if the infoStream!=null and then passes the message to the method, and that
*may* ignore it. For your requirement it is the case that this is enabled or disabled dynamically.
Unfortunately if the construction of the message is heavy, then this wastes resources.
> I would like to add another method to this class: abstract boolean isEnabled() that can
also be implemented. I would then replace all null checks in IW by this method. The default
config in IW would be changed to use a NoOutputInfoStream that returns false here and ignores
the message.
> A simple logger wrapper for e.g. log4j / slf4j then could look like (ignoring component,
could be enabled):
> {code:java}
> Loger log = YourLoggingFramework.getLogger(IndexWriter.class);
> public void message(String component, String message) {
>   log.debug(component + ": " + message);
> }
> public boolean isEnabled(String component) {
>   return log.isDebugEnabled();
> }
> {code}
> Using this you could enable/disable logging live by e.g. the log4j management console
of your app server by enabling/disabling IndexWriter.class logging.
> The changes are really simple:
> - PrintStreamInfoStream returns true, always, mabye make it dynamically enable/disable
to allow Shai's request
> - infoStream.getDefault() is never null and can never be set to null. Instead the default
is a singleton NoOutputInfoStream that returns false of isEnabled(component).
> - All null checks on infoStream should be replaced by infoStream.isEanbled(component),
this is possible as always != null. There are no slowdowns by this - it's like Collections.emptyList()
instead stupid null checks.

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