Ideally it would only be called once, and in future maybe it can, but
right now we need to cope with these cases:
* Downstream parent notifies us of disconnection (DEL_ROUTE)
* We notify ourself of disconnection
* We notify ourself and so does downstream parent
It's case 3 that causes the error.
Using _lock we can know for certain whether the Broker has received a
wakeup byte yet. If it has, we can skip the wasted system call.
Now on_receive() can exactly read the single byte that can possibly
exist (modulo FD sharing bugs -- this could be improved on later)
Now poller is start enough to know a start_receive() during an iteration
does not cause events yielded by that iteration to associate with the
wrong descriptor.
These changes are tangentially related to the associated ticket, but
event versioning is still the underlying issue.
Receiving DEL_ROUTE without a corresponding ADD_ROUTE is now legit
behaviour, so don't print an error in this case.
Don't print an error for dropped messages if the reply_to indicates the
sender doesn't care about a response (dead and no_reply)
When unpickling a context, arrange for there to be a single instance
representing that context, managed by the corresponding router. This
context_by_id() was already in use by parent.py, it just needs to move
down.
This to eventually reach the point where a single Context exists that
needs 'disconnect' fired on it, so all sleeping receivers are definitely
woken.
If thread A is about to wake as thread B is about to sleep, and A loses
the GIL at an inopportune moment, it was possible for two latches to
share the same socketpair, causing wakeups routed to the wrong latch.
The pair was returned to the 'idle sockets' list before .recv() had been
called. This manifested as TimeoutError() thrown rarely with many active
threads and the host is heavily loaded (such as Travis CI).
Add more documentation and stop writing single wake bytes. Instead the
recipient's identity is written instead, making it simpler to detect
future bugs.
Previously it was possible for a thread to call Waker.defer() after
Broker has torns its Waker down, and the underlying file descriptor
reallocated by the OS to some other component.
This manifested as latches of a subsequent test invocation receiving the
waker byte (' ') rather than their expected byte '\x7f'.
This doesn't fix the problem, it just significantly reduces the chance
of it occurring. In future Side.write()/read()/close() must be
synchronized with a lock.
Previously the problem could be reliably triggered with:
while :; do
python tests/call_function_test.py -vf CallFunctionTest.{test_aborted_on_local_broker_shutdown,test_aborted_on_local_context_disconnect}
done
e81b3bd0652b5eb125eb224ceca281b9d540dd5e
The whitelist check must happen /after/ the other checks, otherwise we
unconditionally retunr self for crap like 'ansible.module_utils.json'.
David Wilson