[zeromq-dev] zactor destroy sequence

[Pieter Hintjens]

Like I said, the exit signal is sent by the wrapper inside zactor and
not the actor itself. The echo actor was correct. (Otherwise the test
case would not work).

On Sun, Nov 2, 2014 at 1:11 PM, Arnaud Loonstra <arnaud at sphaero.org> wrote:
> Then am I correct that the echo_actor example is not signaling the pipe
> on exit while it should like this?
>
> static void
> echo_actor (zsock_t *pipe, void *args)
> {
>      //  Do some initialization
>      assert (streq ((char *) args, "Hello, World"));
>      zsock_signal (pipe, 0);
>
>      bool terminated = false;
>      while (!terminated) {
>          zmsg_t *msg = zmsg_recv (pipe);
>          if (!msg)
>              break;              //  Interrupted
>          char *command = zmsg_popstr (msg);
>          //  All actors must handle $TERM in this way
>          if (streq (command, "$TERM"))
>              terminated = true;
>          else
>          //  This is an example command for our test actor
>          if (streq (command, "ECHO"))
>              zmsg_send (&msg, pipe);
>          else {
>              puts ("E: invalid message to actor");
>              assert (false);
>          }
>          free (command);
>          zmsg_destroy (&msg);
>      }
> +   // send signal to actor to confirm exit
> +   zsock_signal (pipe, 0);
> }
>
>
> On 11/02/2014 12:41 PM, Pieter Hintjens wrote:
>> If you send and wait without a timeout, it happens that the actor
>> thread is gone, and its pair socket destroyed, before you get here.
>> Then the calling thread blocks waiting for a reply that never arrives.
>>
>> The return signalling is done by the zactor wrapper, not the actor
>> itself. This isn't entirely symmetrical, that's true.
>>
>> On Sat, Nov 1, 2014 at 10:18 PM, Arnaud Loonstra <arnaud at sphaero.org> wrote:
>>> Hi all,
>>>
>>> I'm going through the zactor class to understand it better. I'm slightly
>>> confused by the destroy sequence:
>>>
>>> At line 182 of zactor.c:
>>>           //  Signal the actor to end and wait for the thread exit code
>>>           //  If the pipe isn't connected any longer, assume child thread
>>>           //  has already quit due to other reasons and don't collect the
>>>           //  exit signal.
>>>           zsock_set_sndtimeo (self->pipe, 0);
>>>           if (zstr_send (self->pipe, "$TERM") == 0)
>>>               zsock_wait (self->pipe);
>>>           zsock_destroy (&self->pipe);
>>>
>>> So when destroy is called the actor method will receive the $TERM
>>> command. The destroy sequence waits for a signal from the actor command.
>>>
>>> But why the == 0. Doesn't that mean that the zstr_send send 0 bytes thus
>>> failed sending?
>>>
>>> Then the echo_actor example just sets: (line 268)
>>>               terminated = true;
>>> It nevers signals back.
>>>
>>> It does work that's why I'm confused about what's happening.
>>> Can anybody turn the light on? :)
>>>
>>> Rg,
>>>
>>> Arnaud
>>> --
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>
>
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