[sr-dev] Fwd: notify process-dialogs() problem

[Shane Harrison]

Hi all,
I have a situation where subscriptions do not get notified and have tracked
it down to a problem with the polled notify processing. Can you advise if
this is a bug or correct my understanding of the code.

I am using kamailio 3.3.3 and have 1 notify process. I have enhanced
the support for the ua-profile event (rfc 6080) , although I don't believe
I have made any changes that directly impact the problem I am seeing.

When a new subscription arrives it is added to the active_watchers table,
the 'updated' column is assigned a number in the range 0 - N-1, where N is
effectively the total number of polled update tasks that are called in a
round-robin fashion, distributed across the notify processes. In this case
updated = 7.

In subscribe.c:
int update_subscription_notifier(struct sip_msg* msg, subs_t* subs, int
to_tag_gen, int* sent_reply)
{
...
 /* Set the notifier/update fields for the subscription */
subs->updated = core_hash(&subs->callid, &subs->from_tag, 0) %
 (pres_waitn_time * pres_notifier_poll_rate
* pres_notifier_processes);

The notify process periodically calls pres_timer_send_notify(), which
calculates the round (the update task number) and does the notify update by
checking the active_watchers table for entries with updated = round. The
update is done twice, first for the event then for event.winfo.

In notify.c:
void pres_timer_send_notify(unsigned int ticks, void *param)
{
int process_num = *((int *) param);
int round = subset + (pres_waitn_time * pres_notifier_poll_rate
 * process_num);
if (process_dialogs(round, 0) < 0)
{
 LM_ERR("Handling non presence.winfo dialogs\n");
return;
}
 if (process_dialogs(round, 1) < 0)
{
LM_ERR("Handling presence.winfo dialogs\n");
 return;
}
}

In this instance process_num = 0, so round = subset. However subset is
incremented in process_dialogs() in notify.c:

if (++subset > (pres_waitn_time * pres_notifier_poll_rate) -1)
subset = 0;

This means that round is incremented twice between calls to
process_dialogs(round, 0), in my case round is always even, hence not
detecting the subscription with updated = 7.

It seems that the subset increment should be done in
pres_timer_send_notify() rather than in process_dialogs(). Is this correct?

Additionally, is there a need for the second call that only handles
presence.winfo subscriptions? The code could be simplified by only making
one call and processing all subscriptions for the round.

Kind regards
Shane Harrison


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