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From Berin Loritsch <blorit...@apache.org>
Subject Re: Adding Resource Monitor to Generators
Date Mon, 10 Dec 2001 14:21:04 GMT
Sylvain Wallez wrote:

> 
> Gerhard Froehlich a écrit :
> 
>>Hi,
>>I started to implement the Resource Monitor into
>>the caching process.
>>
>>One place are the Generators (FileGenerator, etc..), therefore
>>I have to lookup up the Monitor component.
>>Where shall I place the contextualize method in the Generator
>>derivation tree:
>>
>>ComposerGenerator
>>  AbstractGenerator
>>    AbstractXMLProducer
>>
>>?
>>
>>I ask, 'cause I don't want to rain in somebodies "Generator" party ;)
>>
>>Cheers
>>Gerhard
>>
>>
> Gerhard,
> 
> I'm happy you start working on Monitors : reducing filesystem lookup is
> a must-do to increase performance. But I have a few wonders about the
> way to introduce them in the engine.
> 
> I didn't went deep in Monitors, but is it good to use an active monitor
> ? From what I understand, an active monitor scans periodically (10 secs
> in cocoon.xconf) all its resources.


The period is configurable!  This is a very important concept.  In a
development environment, it would probably be set as little as every
minute or 5 minutes.  In a production environment, it would most likely
be set to 30 minutes or possibly 8 hours.


> This means that every 10 secs, Cocoon will scan *each and every* file
> monitored since the engine startup, even those that are unfrequently
> used. I'm afraid this will be worse than what we have today on large
> sites... but tell me if I'm wrong !


Your wrong!  It will only search the ones that are currently registered,
AND the time is configurable.  For the unit test, it is set to 10 secs
or lower so the unit test doesn't take for ever.


> It seems to me that the main benefit of ActiveMonitor is for resources
> that are systematically checked at each and every request : IMO, this
> should be limited to configuration files and sitemaps.


AND XSPs



> For less-frequently used resources, wouldn't it be a better solution to
> only call getLastModified() when the resource is actually used and the
> time since the last call to getLastModified() is greater than the
> refresh period ? This would be a kind of buffering in front of the
> filesystem. Also, can't this be integrated directly in Source ?


I would like to see Resource and Source merged.  Or at the _very_ least,
Source extending Resource.


> Last point : your changes in ProgramGenerator make the assumption that
> sources are files. This won't be true in unexpanded war files and will
> very likely break the engine ;)
> 
> What do you (and others) think ?


There is room for more Resource types.


They just have not been written yet.



-- 

"They that give up essential liberty to obtain a little temporary safety
  deserve neither liberty nor safety."
                 - Benjamin Franklin


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