[Python-ideas] The async API of the future

Guido van Rossum guido at python.org
Sat Nov 3 23:06:26 CET 2012

This is awesome! I have to make time to understand in more detail how
it works and what needs to change in the platform-independent API -- I
want to get to the point where the *only* thing you change is the
pollster/proactor (both kind of lame terms :-). I am guessing that the
socket operations (or the factory for the transport class) needs to be
made part of the pollster; the Twisted folks are telling me the same

FWIW, I've been studying other event loops. It's interesting to see
the similarities (and differences) between e.g. the tulip eventloop,
pyftpd's ioloop, Tornado's IOLoop, and 0MQ's IOLoop. The latter two
look very similar, except that 0MQ makes the poller pluggable, but
generally there are lots of similarities between the structure of all
four. Twisted, as usual, stands apart. :-)


On Sat, Nov 3, 2012 at 2:20 PM, Richard Oudkerk <shibturn at gmail.com> wrote:
> On 02/11/2012 11:59pm, Guido van Rossum wrote:
>> Working code or it didn't happen. (And it should scale too.)
> I have some (mostly) working code which replaces tulip's "pollster" classes
> with "proactor" classes for select(), poll(), epoll() and IOCP.  See
> https://bitbucket.org/sbt/tulip-proactor/changeset/c64ff42bf0f2679437838ee7795adb85
> The IOCP proactor does not support ssl (or ipv6) so main.py does not succeed
> in downloading from xkcd.com using ssl.  Using the other proactors it works
> correctly.
> The basic interface for the proactor looks like
>     class Proactor:
>         def recv(self, sock, n): ...
>         def send(self, sock, buf): ...
>         def connect(self, sock, address): ...
>         def accept(self, sock): ...
>         def poll(self, timeout=None): ...
>         def pollable(self): ...
> recv(), send(), connect() and accept() initiate io operations and return
> futures.  poll() returns a list of ready futures.  pollable() returns true
> if there are any outstanding operations registered with the proactor.  You
> use a pattern like
>     f = proactor.recv(sock, 100)
>     if not f.done():
>         yield from scheduling.block_future(f)
>     res = f.result()
> --
> Richard
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--Guido van Rossum (python.org/~guido)

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