[systemd-devel] sd_bus_add_match callback

[David J]

Question regarding sd_bus_add_match (sd-bus.c):



Is it acceptable (or recommended) to use the same callback for multiple signal match and then using the userdata parameter to distinguish among the different signals? See the sample code below for a reference of what I am trying to do.



/*Beginning=========================================*/
int callback(sd_bus_message *message, void *userdata, sd_bus_error *error) {
  //there should be a lock applied here?
  if(get_signal_id(userdata) == 1) {
    //do something
  }
}

int main(...) {
  r = sd_bus_add_match(bus, &slot, "type='signal'", test_callback, userdata);
  int r;
  sd_bus *bus = NULL;
  sd_event *event = NULL;
  sd_bus_slot *slot = NULL;

  r = sd_bus_default_system(&bus);
  assert(r >= 0);

  r = sd_event_default(&event);
  assert(r >= 0);

  void *userdata1 = set_signal_id(1);
  r = sd_bus_add_match(bus, &slot, "type='signal',interface='org.interface2'", callback, userdata1);

  void *userdata2 = set_signal_id(2);
  r = sd_bus_add_match(bus, &slot, "type='signal',interface='org.interface1'", callback, userdata2);

  r = sd_event_loop(event);
  assert(r >= 0);
 
  bus = sd_bus_flush_close_unref(bus);
  slot = sd_bus_slot_unref(slot);
  event = sd_event_unref(event);
}


/*End =========================================*/


I appreciate your help and your time.



Thank you,

David J (emacsd at icloud.com)


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