attach_source
Description:
A utility function for dealing with async operations where you need to wait for a SocketSource to trigger.
Attaches source to this's MainContext
with this's [priority](iface.AsyncResult.html#io-priority), and sets source's callback to
callback, with this as the callback's `user_data`.
It will set the source’s name to the task’s name (as set with
set_name), if one has been set on the task and the source doesn’t yet have a name.
This takes a reference on this until source is destroyed.
Parameters:
| this |
a Task |
| source |
the source to attach |
| callback |
the callback to invoke when |