On 11/02/2012 8:34 a.m., Pieter De Wit wrote:
Hi Guys,
So I saw on the mailing list the question about quotas came up again.
I thought I would give it a shot (planning etc) and I was wondering,
does "Squid" have a way to store data ?
In Quota you will have Bandwidth (bytes, not per second) that has to
be checked/adjusted and updated to disk. Instead of writing my own
routines to store this in my "own" format, it would be nice to have
something that grows with Squid.
Discard the idea of disk formats for quota control. You are dealing with
individual packet read/writes at this level. Everything of importance
needs to be in RAM. Squid has a client_db memory cache which stores
statistics and details about each unique client. Several transaction
state controllers (ConnStateData, TunnelStateData, *ServerData) already
interact with that for per-client bandwidth reporting.
At the more abstracted level, semi-accurate quotas would need the
client_db to be backed up on disk or somewhere periodically. (oh yay,
yet another event to cause "squid keeps pausing" bugs).
Or alternatively, the design I worked out a years or so ago uses a
helper process to query some database or system managing client quotas.
There is a lot of interest in RADIUS and ActiveDirectory backends
controlling this type of thing, and a helper interface is much more
flexible than pre-determined config formats. You can query this helper
on each new client to receive a quota value which gets used up then
re-checked. We still get some slowdown from the lookups, but it is up to
the admin to configure how much quota bytes the helper requests each
cycle and thus how much overhead they add.
Amos
