This add a wrapper around the lua interpreter so that function
executions are interruptible and return futures.
With this patch it is possible to write and use simple UDFs that take
and return integer values.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
This adds a requires_thread predicate to functions and propagates that
up until we get to code that already returns futures.
We can then use the predicate to decide if we need to use
seastar::async.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
With this it is possible to create user defined functions and
aggregates and they are saved to disk and the schema change is
propagated.
It is just not possible to call them yet.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
