[zeromq-dev] Seek clarification on return value from ticket handlers (zloop)

[Steven Butner]

This is an inquiry about the interface with ticket handlers and zloop.   
I am running what I believe to be the latest development master of czmq 
(downloaded Wed 2015/4/15 from github). My host is Ubuntu Linux 14.04LTS 
running on a 64-bit Intel Core-i7.

Prior to this I had been running the 3.0.0-rc1 version of CZMQ (dated 
2014/10/15) that is offered on 
http://czmq.zeromq.org/page:get-the-software.  I switched to the more 
recent version because there were some missing features appearing in the 
CZMQ manual pages but absent from 3.0.0-rc1 package, notably anything 
having to do with tickets.

My question has to do with the semantics of the return int value on 
ticket timer handlers

*typedef int (zloop_time_fn) (zloop_t *loop, int timer_id, void *arg);*

The synopsis is silent about the meaning of this int, though the 
synopsis comments about zloop_start() suggest that any handler that 
returns -1 will cause the reactor to break out of its loop.

My experimentation (augmented by a look into the source code) shows that 
the return code from ticket handlers takes a different path when -1 is 
returned than when 0 is returned ..... but that the return of a -1 does 
*not* make the zloop_start reactor break out of its loop.  I've also 
been having trouble interrupting the system.  My program seems to ignore 
interrupts, even though I can verify via gdb that the signals are 
getting delivered to my process.

My specific questions are:

1) What is the semantics of the return code emerging from ticket handlers?
2) When a ticket times out and the ticket handler is called, what should 
be the behavior of that ticket in the future?  In my ticket handler I am 
calling zloop_ticket_reset(zloop, ticket_handle) with the hope that the 
ticket expiry will be noted but activated again for catching future 
issues with the given service.  I've observed that if the ticket handler 
returns a 0, we never get any more calls to it whereas if the ticket 
handler returns a -1, we do get future calls.
3) Why is the second argument in the ticket handler interface using an 
int timer_id when the ticket interface elsewhere seems to be using void* 
handles?
4) Why do get different behavior with regard to Ctlr-C interruptions 
when my ticket handlers return -1 than when they return 0?

Thanks for any clarification on this interface. I'm happy to supply 
snippets of my usage code once I know what is needed. Though I am a 
long-time programmer, I am relatively new to ZMQ and CZMQ.  I thank you 
all for contributing and supporting this excellent software.

      Steve B

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