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Posted to dev@httpd.apache.org by Steve Kemp <sk...@tardis.ed.ac.uk> on 2002/09/30 23:50:13 UTC
Keeping per-virtual host data?
Hi All,
I've written a module for Apache which will limit the
amount of data the server may transfer in a given time
period. (OK that's a simplistic overview anyway ;)
To do this I make use of the information gathered by
mod_status, and when the data transferred goes over a
given threshhold I cause the server to simply respond
to all requests with a redirect.
This works fine on a per-server basis.
I'd like to re-code my module to work with virtual
hosts; so I believe I need some way of keeping track of
the size of data which has been transferred on a
per-vhost basis.
(Or failing that find another module, like mod_status,
which contains the necessary magic which I can piggy back
upon).
Is this possible, and if so does anybody have a pointer
to a method I could use?
All of the modules I've studied seem to manage to operate
without having per vhost static data which makes me think
either I'm missing something obvious, or it's not possible.
Either way I'd love to be enlightened.
It does cross my mind that the forking may rule out persistant
static data of the kind I want; but temporary files could be used
I guess..
For those who might be interested my code is online at:
http://www.steve.org.uk/Software/mod_curb/
(Just be gentle; it's my first module ;)
Steve
---
www.steve.org.uk
Re: Keeping per-virtual host data?
Posted by Ian Holsman <li...@holsman.net>.
On Mon, 30 Sep 2002 22:50:13 +0100, Steve Kemp wrote:
> Hi All,
>
> I've written a module for Apache which will limit the
> amount of data the server may transfer in a given time
> period. (OK that's a simplistic overview anyway ;)
>
> To do this I make use of the information gathered by
> mod_status, and when the data transferred goes over a
> given threshhold I cause the server to simply respond
> to all requests with a redirect.
>
> This works fine on a per-server basis.
>
> I'd like to re-code my module to work with virtual
> hosts; so I believe I need some way of keeping track of
> the size of data which has been transferred on a
> per-vhost basis.
>
> (Or failing that find another module, like mod_status,
> which contains the necessary magic which I can piggy back
> upon).
>
> Is this possible, and if so does anybody have a pointer
> to a method I could use?
>
> All of the modules I've studied seem to manage to operate
> without having per vhost static data which makes me think
> either I'm missing something obvious, or it's not possible.
> Either way I'd love to be enlightened.
>
it's hard, as there is no way 'in-process' to manage that information
without using a mutex lock to protect the data structure (imagine two
processes/threads serving the same URL for a virtual host) or having some
kind per-thread per-vhost structure which your module would summarize.
mod-status avoids a lock as each thread writes it's server stats to a
thread-specifc area which mod-status sums up.
> It does cross my mind that the forking may rule out persistant
> static data of the kind I want; but temporary files could be used
> I guess..
>
> For those who might be interested my code is online at:
> http://www.steve.org.uk/Software/mod_curb/
>
> (Just be gentle; it's my first module ;)
>
> Steve
> ---
> www.steve.org.uk
Re: Keeping per-virtual host data?
Posted by Steve Kemp <sk...@tardis.ed.ac.uk>.
Hi Harrie,
On Tue, Oct 01, 2002 at 10:42:57AM +0200, Harrie Hazewinkel wrote:
> www.mod-snmp.com This is an SNMP module that does per v-host
> statistics. With some modifications one could use this for the
> purpose you want.
Thanks for the pointer. I've had a quick look at this just now
and it's quite nice.
(Maybe it'd be a good idea to have the source unpack into it's
own directory ;)
> The only problem you encounter is that the statistics exist in a
> side process and you have to make some connection from each
> Apache child to the side process.
Sure.
> If you are willing to put all the data into temp files that could
> be OK. However, in order to avoid dead-locks and many locks for access
> to this you better fork of a process that only writes into it where
> all children just can read it.
After a bit of trial and error I've managed to get the effect I
want. My big mistake was using 'per_dir_config' rather than the
per server config. Once I'd corrected that the rest flowed fairly
easily.
(Reading the virtual host from the mod_status is trivial, and that
allows me to do everything I need to do).
Steve
---
# GNU MP3 Streaming
http://www.gnump3d.org/
Re: Keeping per-virtual host data?
Posted by Harrie Hazewinkel <ha...@lisanza.net>.
Hi Steve,
--On Monday, September 30, 2002 10:50 PM +0100 Steve Kemp
<sk...@tardis.ed.ac.uk> wrote:
> Hi All,
>
> I've written a module for Apache which will limit the
> amount of data the server may transfer in a given time
> period. (OK that's a simplistic overview anyway ;)
>
> To do this I make use of the information gathered by
> mod_status, and when the data transferred goes over a
> given threshhold I cause the server to simply respond
> to all requests with a redirect.
>
> This works fine on a per-server basis.
>
> I'd like to re-code my module to work with virtual
> hosts; so I believe I need some way of keeping track of
> the size of data which has been transferred on a
> per-vhost basis.
>
> (Or failing that find another module, like mod_status,
> which contains the necessary magic which I can piggy back
> upon).
>
> Is this possible, and if so does anybody have a pointer
> to a method I could use?
www.mod-snmp.com This is an SNMP module that does per v-host
statistics. With some modifications one could use this for the
purpose you want.
>
> All of the modules I've studied seem to manage to operate
> without having per vhost static data which makes me think
> either I'm missing something obvious, or it's not possible.
> Either way I'd love to be enlightened.
The only problem you encounter is that the statistics exist in a
side process and you have to make some connection from each
Apache child to the side process.
>
> It does cross my mind that the forking may rule out persistant
> static data of the kind I want; but temporary files could be used
> I guess..
If you are willing to put all the data into temp files that could
be OK. However, in order to avoid dead-locks and many locks for access
to this you better fork of a process that only writes into it where
all children just can read it.
>
> For those who might be interested my code is online at:
> http://www.steve.org.uk/Software/mod_curb/
>
> (Just be gentle; it's my first module ;)
>
> Steve
> ---
> www.steve.org.uk
>
Harrie
Internet Management Consulting
mailto: harrie@lisanza.net http://www.lisanza.net/
--------------------------------------------------------------------
Author of MOD-SNMP, enabling SNMP management the Apache HTTP server