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From Stefan Fritsch ...@sfritsch.de>
Subject Re: Error log format configuration syntax
Date Tue, 27 Jul 2010 21:11:39 GMT
On Wednesday 21 July 2010, William A. Rowe Jr. wrote:
> On 7/21/2010 4:35 PM, Stefan Fritsch wrote:
> > And I agree that a unified logging formatter would be nice, but
> > this is not something that will be done before 2.3.7 and it
> > would likely mean an incompatible API change for modules
> > providing handlers for mod_log_config. IMHO, this can wait until
> > 3.0.
> 
> IMHO, it must not.  The simple reason is that the more code
> duplication we introduce, the more opportunity for flaws and
> maintenance headaches during the 2.4 lifecycle.  I'd accept
> waiting for this entire custom error log feature for 3.0, but
> really would rather introduce it sooner and not later.

I fear a unified logging formatter may either delay 2.4 or not make it 
into 2.4. In 2.4, we really need some way to omit some of the fields 
we currently have in the error log prefix (> 100 chars of prefix is 
insane). But as I had less time in the last few days than I hoped, it 
does not look like my (non-unified) errorlog formatter would be ready 
for 2.3.7 in any case. So we will have time until 2.3.8 to decide what 
to do.

> If there is a resulting API change, I think everyone is willing to
> accept this during the 2.3-alpha/beta cycle.  2.4.0 is our
> 'lockdown'.
> 
> I'm willing to help with this code, although I'm just starting to
> dig out of the hole from my two recent hand surgeries.  6-finger
> typing isn't all that efficient :)

I think there are more important things that could use your and my 
attention than avoiding this bit of code duplication.


Buf if you want to start a bit of technical discussion: The main 
technical difference between error and access log is that for the 
access log, everything is allocated from the request pool and then 
written to the log file (i.e. there is no length limit). For the error
log, there is a fixed 8K buffer (allocated on the stack). For the
error log, it is not possible to use any of the existing pools to
avoid unbounded memory usage. The unified log formatter would either
have to use a pre-allocated buffer or a temp pool.

For my work on the error log formatter, I have stayed with the pre- 
allocated buffer. Would this be a reasonable solution for the unified 
logger? It would mean a fixed limit for the access logs lines (though 
the access log could use a larger buffer than the error log, I guess 
16 or 32K would be enough even for the access log). The pool approach 
would require a per-thread temp logging pool (using 
apr_threadkey_private_create or the like) or creating and destroying a 
sub-pool for every log line.

Which solution looks better to you?


Cheers,
Stefan

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