From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B5CEEC432BE for ; Thu, 5 Aug 2021 21:03:37 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0AD2C60ED6 for ; Thu, 5 Aug 2021 21:03:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 0AD2C60ED6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:54038 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mBkWd-0002U9-P1 for qemu-devel@archiver.kernel.org; Thu, 05 Aug 2021 17:03:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37658) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mBkW4-0001oD-7f for qemu-devel@nongnu.org; Thu, 05 Aug 2021 17:03:00 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:57073) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mBkW0-0004AP-HB for qemu-devel@nongnu.org; Thu, 05 Aug 2021 17:02:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1628197375; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=AGSTfUdjU9VCvpFGiZEjSe9fJWwGUkJmaCETdzGIiTc=; b=fxsOx830+L6KL19RL0au1A584Arm8osbcgXdYWj9uWlo71nrtsNrQE5fv19zI3otZRl+Uj g4eJHc9lD8mzkcwn8I93yu8VAXLjrs3djdeo33CQ1Vpq+zarUL6/Cqq2Z717s9OUgFLVYn tM5PTL/MpFpb0PBGsocYLBPxFBC46Qc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-2-kskdFf4aNjOFVHr3Lip7Ow-1; Thu, 05 Aug 2021 17:02:52 -0400 X-MC-Unique: kskdFf4aNjOFVHr3Lip7Ow-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E58CC87D541; Thu, 5 Aug 2021 21:02:51 +0000 (UTC) Received: from redhat.com (ovpn-112-138.phx2.redhat.com [10.3.112.138]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 851995C1B4; Thu, 5 Aug 2021 21:02:43 +0000 (UTC) Date: Thu, 5 Aug 2021 16:02:41 -0500 From: Eric Blake To: John Snow Subject: Re: [PATCH v3 06/25] python/aqmp: add runstate state machine to AsyncProtocol Message-ID: <20210805210241.ey36xvb57clvl3r5@redhat.com> References: <20210803182941.504537-1-jsnow@redhat.com> <20210803182941.504537-7-jsnow@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210803182941.504537-7-jsnow@redhat.com> User-Agent: NeoMutt/20210205-687-0ed190 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.699, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Willian Rampazzo , Markus Armbruster , Wainer dos Santos Moschetta , qemu-devel@nongnu.org, "Niteesh G . S ." , Stefan Hajnoczi , Cleber Rosa , Eduardo Habkost Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Aug 03, 2021 at 02:29:22PM -0400, John Snow wrote: > This serves a few purposes: > > 1. Protect interfaces when it's not safe to call them (via @require) > > 2. Add an interface by which an async client can determine if the state > has changed, for the purposes of connection management. > > Signed-off-by: John Snow > --- > python/qemu/aqmp/__init__.py | 6 +- > python/qemu/aqmp/protocol.py | 159 ++++++++++++++++++++++++++++++++++- > 2 files changed, 160 insertions(+), 5 deletions(-) > > +++ b/python/qemu/aqmp/protocol.py > + > +F = TypeVar('F', bound=Callable[..., Any]) # pylint: disable=invalid-name > + > + > +# Don't Panic. > +def require(required_state: Runstate) -> Callable[[F], F]: Technically, the definition of F is integral to the definition of require, so I might have put the 'Don't Panic' note a bit sooner. And it took me a while before I noticed... > + """ > + Decorator: protect a method so it can only be run in a certain `Runstate`. > + > + :param required_state: The `Runstate` required to invoke this method. > + :raise StateError: When the required `Runstate` is not met. > + """ > + def _decorator(func: F) -> F: > + # _decorator is the decorator that is built by calling the > + # require() decorator factory; e.g.: > + # > + # @require(Runstate.IDLE) def # foo(): ... Is that second # intentional? > + # will replace 'foo' with the result of '_decorator(foo)'. > + > + @wraps(func) > + def _wrapper(proto: 'AsyncProtocol[Any]', > + *args: Any, **kwargs: Any) -> Any: > + # _wrapper is the function that gets executed prior to the > + # decorated method. > + > + name = type(proto).__name__ > + > + if proto.runstate != required_state: > + if proto.runstate == Runstate.CONNECTING: > + emsg = f"{name} is currently connecting." > + elif proto.runstate == Runstate.DISCONNECTING: > + emsg = (f"{name} is disconnecting." > + " Call disconnect() to return to IDLE state.") > + elif proto.runstate == Runstate.RUNNING: > + emsg = f"{name} is already connected and running." > + elif proto.runstate == Runstate.IDLE: > + emsg = f"{name} is disconnected and idle." > + else: > + assert False > + raise StateError(emsg, proto.runstate, required_state) > + # No StateError, so call the wrapped method. > + return func(proto, *args, **kwargs) > + > + # Return the decorated method; > + # Transforming Func to Decorated[Func]. > + return cast(F, _wrapper) > + > + # Return the decorator instance from the decorator factory. Phew! > + return _decorator ...that it paired with this comment, explaining what looks like a monstrosity, but in reality is a fairly typical and boilerplate implementation of a function decorator (not that you write one every day - the whole point of the decorator is to have a one-word abstraction already implemented so you DON'T have to reimplement the decoration yourself ;). > + > + > class AsyncProtocol(Generic[T]): > """ > AsyncProtocol implements a generic async message-based protocol. > @@ -118,7 +202,24 @@ def __init__(self) -> None: > #: exit. > self._dc_task: Optional[asyncio.Future[None]] = None > > + self._runstate = Runstate.IDLE > + self._runstate_changed: Optional[asyncio.Event] = None > + > + @property # @upper_half Is it intentional to leave the @upper_half decorator commented out? But that's minor enough that I trust you to handle it as you see fit. Reviewed-by: Eric Blake -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org