Don't rely on Postgres casting the literal according to the context:
this doesn't work e.g. passing the object as function argument where a
function with the same name but taking a text exists. It doesn't work
either when the object is in an ARRAY construct.
Added test to check the type is respected in a complete Py -> PG -> Py
roundtrip without context.
Bug and solution reported by Peter Eisentraut.
Dropped set/unset nonblocking mode for copy and lobject operations:
lobjects don't work in nonblocking mode so they will hardly be supported
in green/async branches. Support for copy is still feasible, but it
will be done in other code paths (called by poll).
Failing in doing that broke notifications reception.
The responsibility for changing the async_status has been moved to the
poll function: this is consistent with how the async branch is
implemented.
With this commit all the test suite passes in "green" mode.
With the current implementation, at best they would silently block. They
actually hang everything.
Implementation posponed after some refactoring of the polling system,
because it will be probably possible to provide an implementation for
'poll()' during COPY which is good for both async and green modes.
The function is called without holding the GIL. Because it is necessary
to execute the Python callback if set, we need to re-acquire the GIL and
tnen release it again. In order to correctly bookkeep the thread state,
the pointer of the _save variable is passed to the function.
If the connection is sync, notices will be processed by pq_fetch()
downstream.
If the connection is async, here we have only sent the query: no result
is ready yet, and neither notices have had a chance to arrive: they will
be retrieved later by pq_is_busy().
Added tests to check the above statement don't break.
Instead, the code should be using the fileno() and poll() methods of
the cursor's connection. Handle the case when poll() is called on an
already built connection as a request to poll the asynchronous query
(if there is one) and get NOTIFY events.
Update the tests to reflect that change, add a test for NOTIFY.
