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From "Manish Marathe" <python.r...@gmail.com>
Subject Re: DailyRollingFileAppender.java enhancement
Date Thu, 24 Jan 2008 18:45:18 GMT
On Jan 22, 2008 11:51 PM, Simon Park <simon_park_mail@yahoo.co.uk> wrote:

> Hi Manish,
>
> I contributed some code a few months ago that might fit the bill.  It's an
> appender that behaves similarly to the DailyRollingFileAppender, yet it also
> deletes older files.  You can configure the number of files you wish to
> keep.  A daemon thread periodically scans the files based upon the "root" of
> the filename, i.e. it's independent of the pattern.  Code available at
> http://www.simonsite.org.uk/resources/lib/log4j-rolling-appender.jar and
> Javadoc at
> http://www.simonsite.org.uk/javadoc/org/apache/log4j/appender/TimeAndSizeRollingAppender.html.
> This code has been running in production on an SMP platform for just under a
> year, without incident
>

Simon,

That looks cool. Although I didn't go through great detail but just a
question. Suppose the "root" name of my log file is "net.log". I initially
use a date pattern yyyy-MM-dd for some time, giving no.of files to keep say
10. On the 11th night, just before midnight, I change the pattern to yyyy-ww
and restart tomcat/my-app. Now I have 10 rolled-over log files with date
pattern yyyy-MM-dd, since no.of files to keep is 10 no files will be
deleted. On the 12th night, does TimeAndSizeRollingAppender deletes the
oldest log file which had pattern yyyy-MM-dd or will it not consider those
rolled over log files to delete at all because they are not in accordance
with the pattern set in the configuration file?

If TimeAndSizeRollingAppender is just looking for root file name, in my case
"net.log", will it also delete older rolled-over log files with older
pattern?

-Manish



> ----- Original Message ----
> From: Manish Marathe <python.ruby@gmail.com>
> To: Log4J Developers List <log4j-dev@logging.apache.org>
> Sent: Monday, 21 January, 2008 12:14:04 AM
> Subject: Re: DailyRollingFileAppender.java enhancement
>
>
> On Jan 20, 2008 2:50 PM, Curt Arnold <carnold@apache.org> wrote:
>
> >
> > On Jan 20, 2008, at 3:42 PM, Manish Marathe wrote:
> >
> > > Hello All,
> > >
> > > Currently the Appender, DailyRollingFileAppender, rolls over the log
> > > file as per the "datePattern" set in the configuration file,
> > > although the rolled-over files never get deleted unlike if we use
> > > RollingFileAppender but in case of RollingFileAppender we cannot use
> > > the datePattern.
> > >
> > > In one of our products in my company, SpikeSource Inc, I needed a
> > > feature to delete the rolled over oldest files so I extended
> > > DailyRollingFIleAppender.java to add SET and GET methods for
> > > maxBackupIndex, one of the parameters we can set in the
> > > configuration file, and implemented and the deletion of rolled over
> > > "oldest".
> > >
> > > I would be happy to give this back to log4j community unless someone
> > > has already added the feature.
> > >
> > > I am a developer from SpikeSource Inc and I plan to blog about it on
> > http://developer.spikesource.com
> > >  and make it available from there but its better to include in the
> > > library itself and make it available to the whole community.
> > > Actually the feature add and implementation is so simple and less of
> > > a code, if given permission I can actually modify
> > > DailyRollingFileAppender.java and give it back.
> > >
> > > Hopefully this will be helpful to someone.
> > >
> > >
> > > Thanks
> > > Manish
> > >
> > > SpikeSource, Inc
> > > http://developer.spikesource.com
> > > http://www.spikesource.com
> >
> >
> > It would be interesting to hear your approach.  It has been a
> > frequently asked enhancement, but the flexibility of using date
> > patterns made implementing an algorithm to find the
> > "oldest" (particularly for patterns that omitted significant portions
> > of the date) difficult to do in a way that would work consistently.
>
>
>
> Yes, I actually searched a lot and happen to learn from some of the
> replies of Log4J developers explaining the same point that finding an oldest
> file with respect to the date pattern set is quite difficult and that too
> consistently and I agree with that. Also I am sure implementing what I state
> below must have been thought earlier and for some good reason discarded.
>
> My approach was simple, may be specific because of specific needs for the
> product I was working on and that made the implementation easier. Although
> here is the simple approach.
>
> In my implementation, I supported, the following date patterns:
>
> 1) yyyy-MM-dd
> 2) yyyy-MM-dd-HH
> 3) yyyy-MM-dd-a
> 4) yyyy-MM-dd-HH-mm
> 5) yyyy-MM
> 6) yyyy-ww
>
> Looking at the DailyRollingFileAppender, I am afraid the above one's are
> the basic date patterns supported by DailyRollingFileAppender and
> essentially all those that SimpleDatePattern supports. Using the above date
> patterns I check for all the rolled over log file names that has the
> original filename as its substring and also matches with the pattern
> ".*[0-9][0-9][0-9][0-9]-[0-1][0-9]-[0-3][0-9].*" for example if we consider
> the date pattern set in the configuration file is yyyy-MM-dd, the default
> one set in DailyRollingFileAppender as well.
>
> Using .lastModified method of a File object, we can sort a list of all the
> rolled over log files we get above and delete the oldest with respect to the
> maxBackupIndex.
>
> Now If someone wants to use a date pattern other than mentioned above, one
> can also added a  regex pattern for that date-pattern using some parameter
> in the configuration file. That can be retrieved in the Appender's code and
> used to matched with the rolled-over log files.
>
> Lastly if someone wants no rolled over log files to get deleted, one can
> simply set maxBackupIndex set to -1.
>
>
> The best place for such an enhancement would be in "extras" companion (
> > http://logging.apache.org/log4j/companions/extras
> > ) which is a collection of new features and enhancements that can be
> > used with log4j 1.2.x deployments (back to at least 1.2.9, but may
> > work back further).   The extras has the
> > org.apache.log4j.rolling.RollingFileAppender (notice the
> > extra .rolling. in the package name) framework that was back-ported
> > from the abandoned log4j 1.3 development.  It would be best to do any
> > enhancement in that framework instead since it already addresses many
> > issues with the main-line RFA and DRFA.
>
>
>
> Sure thanks Curt, I will do that if this is really useful and that the
> implementation of the approach above is not too specific for my needs only.
>
>
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