Thanks Dave for the quick clarification. The hooks(xxx_load, xxx_free) and the
handler are called sequentially from the same thread.
I am getting this doubt as I found that strlen() is crashing on Solaris
10(*only*) and that is only if I run the sub-agent as master agent. It works
well when it runs as sub-agent of snmpd. I am sure xxx_load() has properly
created the memory. messageId is char* , It can be quite long and null
terminated .
This is with Net-SNMP(5.4) . do you see any issue ?
case MODE_GET:
for (request=requests; request; request=request->next) {
table_entry = (struct messageTable_entry *)
netsnmp_extract_iterator_context(request);
table_info = netsnmp_extract_table_info( request);
if ( !table_entry ) {
netsnmp_set_request_error(reqinfo, request,
SNMP_NOSUCHINSTANCE);
continue;
}
switch (table_info->colnum) {
case COLUMN_messageID:
snmp_set_var_typed_value( request->requestvb, ASN_OCTET_STR,
(u_char*)table_entry->messageId,
strlen(table_entry->messageId));
________________________________
From: Dave Shield <[email protected]>
To: sujata patra <[email protected]>
Cc: net-snmp-coders <[email protected]>
Sent: Thu, February 24, 2011 2:30:47 PM
Subject: Re: Transient Data ?
On 24 February 2011 06:35, sujata patra <[email protected]> wrote:
> If I use cache , is it a concern?
No.
> The time handler is processing a request
> and expiry of cahe can free the data at the same time . right ?
No.
The check on whether the cache is valid is done once,
*before* calling the iterator hooks, and then the handler itself.
If the cache timeout hasn't expired (even by a nanosecond),
then this check will pass, and the cache won't be reloaded.
The iterator hooks and the handler will not subsequently
check the cache timeout - they assume this has already been done.
So the cache contents will remain valid for the processing of that
request - even if the expiry timeout has since elapsed.
But the *next* incoming request (possibly part of the same
"snmpwalk" command) _will_ trigger the cache timeout and reload.
Dave
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