Am 17.01.2020 um 08:57 hat Markus Armbruster geschrieben: > Kevin Wolf <kw...@redhat.com> writes: > > > Am 16.01.2020 um 14:00 hat Markus Armbruster geschrieben: > >> Kevin Wolf <kw...@redhat.com> writes: > >> > I have no idea if we will eventually get a case where the command wants > >> > to behave different between the two modes and actually has use for a > >> > coroutine. I hope not. > >> > > >> > But using two bools rather than a single enum keeps the code simple and > >> > leaves us all options open if it turns out that we do have a use case. > >> > >> I can buy the argument "the two are conceptually orthogonal, although we > >> don't haven't found a use for one of the four cases". > >> > >> Let's review the four combinations of the two flags once more: > >> > >> * allow-oob: false, coroutine: false > >> > >> Handler runs in main loop, outside coroutine context. Okay. > >> > >> * allow-oob: false, coroutine: true > >> > >> Handler runs in main loop, in coroutine context. Okay. > >> > >> * allow-oob: true, coroutine: false > >> > >> Handler may run in main loop or in iothread, outside coroutine > >> context. Okay. > >> > >> * allow-oob: true, coroutine: true > >> > >> Handler may run (in main loop, in coroutine context) or (in iothread, > >> outside coroutine context). This "in coroutine context only with > >> execute, not with exec-oob" behavior is a bit surprising. > >> > >> We could document it, noting that it may change to always run in > >> coroutine context. Or we simply reject this case as "not > >> implemented". Since we have no uses, I'm leaning towards reject. One > >> fewer case to test then. > > > > What would be the right mode of rejecting it? > > > > I assume we should catch it somewhere in the QAPI generator (where?) and > > check_flags() in expr.py?
Looks like the right place, thanks. > > then just assert in the C code that both flags aren't set at the same > > time? > > I think you already do, in do_qmp_dispatch(): > > assert(!(oob && qemu_in_coroutine())); > > Not sure that's the best spot. Let's see when I review PATCH 3. This asserts that exec-oob handlers aren't executed in coroutine context. It doesn't assert that the handler doesn't have QCO_COROUTINE and QCO_ALLOW_OOB set at the same time. > >> >> > @@ -194,8 +195,9 @@ out: > >> >> > return ret > >> >> > > >> >> > > >> >> > -def gen_register_command(name, success_response, allow_oob, > >> >> > allow_preconfig): > >> >> > - options = [] > >> >> > +def gen_register_command(name: str, success_response: bool, > >> >> > allow_oob: bool, > >> >> > + allow_preconfig: bool, coroutine: bool) -> > >> >> > str: > >> >> > + options = [] # type: List[str] > >> > >> One more: this is a PEP 484 type hint. With Python 3, we can use PEP > >> 526 instead: > >> > >> options: List[str] = [] > >> > >> I think we should. > > > > This requires Python 3.6, unfortunately. The minimum requirement for > > building QEMU is 3.5. > > *Sigh* One of the reasons why I would have preferred 3.6 as the minimum, but our policy says that Debian oldstabe is still relevant for another two years. *shrug* Kevin
