On 19/08/14 09:07, Juha Heinanen wrote:
Daniel-Constantin Mierla writes:
+ Example 1.11. t_precheck_trans usage
+...
+ # handle retransmissions
+ if(t_precheck_trans()) {
+ t_check_trans();
+ exit;
+ }
+ t_check_trans();
why t_check_trans() is called when t_precheck_trans() returns true? why
exit is not enough?
The purpose of t_check_trans() there is for the case when the
transaction was already created by another process, resulting in
retransmitting back the last reply (what rfc recommends).
Practically, t_precheck_trans() stores the
callid/from-tag/cseq/via-branch in a shared memory structure and checks
if another process has the same values. It can be the case of a match,
but the other process can be ahead with processing and the transaction
was created for that request.
I considered of doing t_check_trans() from inside t_precheck_trans(),
but then I thought it gives more flexibility via config.
t_precheck_trans() should be very fast, these structures are indexed by
call id in a hash table, only when a child handles a request with
request_route.
If you just want to drop the retransmission, you can skip
t_check_trans() inside the if.
Cheers,
Daniel
--
Daniel-Constantin Mierla
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