RE: What should I do if I want to update the table list before each

Thanks Dave

My current solution is: register a alarm function to reload my table
repeatedly

snmp_alarm_register(30, SA_REPEAT, reload_Table, NULL);
/*reaload the entire table every 30 secs*/

My table is not massive, so I think there should be little performance
cost there.

So can I conclude that the agent never knows at which time they are
processing a retrieve of the whole table?
It just only knows the GETNEXTs and never has a separate bar between two
snmptable request?


Thanks again

//James



-----Original Message-----
From: dave.shield@googlemail.com [mailto:dave.shield@googlemail.com] On
Behalf Of Dave Shield
Sent: Monday, August 21, 2006 17:39
To: James Deng D (SH/CBC)
Cc: net-snmp-users@lists.sourceforge.net
Subject: Re: What should I do if I want to update the table list before
each request for the whole table

On 21/08/06, James Deng D (SH/CBC) <james.d.deng@ericsson.com> wrote:
> I want to update my table (which is a linked list) before each request

> for the whole table instead of each column, That's to say, I want to
> get the latest table list each time when I execute a snmptable
> command.

And what should the agent do when it gets a request for an individual
element of the table
(rather than someone walking the whole table)? Should it re-load the
table or not?


> For a scalar, I can use the get handler, and set the latest value each

> time when I get a MODE_GET request, is there a MODE_GET_LIST or
> something like that for me to track a request for a whole table?

No - as far as the agent is concerned, it receives a sequence of GETNEXT
requests (which may well be converted into MODE_GET by the time they
reach the MIB handler).

The usual approach in this situation is to cache the contents of the
table for a given period, and only reload this once the cache has
expired. If you set the timeout to be fairly short (say 2-3 s), then
that will probably have the same general effect - particularly if the
table isn't massive.

There's an example of this approach in (e.g) mibII/udpTable.c See the
end of 'init_udpTable()' and the routines 'udpTable_load' and
'udpTable_free'

Dave

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