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dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:57462 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kQExE-0005Uo-7i for qemu-devel@archiver.kernel.org; Wed, 07 Oct 2020 15:18:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52422) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kQEwA-0004ay-EY for qemu-devel@nongnu.org; Wed, 07 Oct 2020 15:17:18 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:53294) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kQEw7-0006Qk-VQ for qemu-devel@nongnu.org; Wed, 07 Oct 2020 15:17:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602098234; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=mum544dG8yZ2KjV6+g4J2EnHu/A69+Eox0a//bwLX1E=; b=ep2C/GpCfBnaFBDFOodnJ9/NKQuCgzYplJcvKYMxnm9iteZG3Z95Do03xtDlHsr0PTRULD cSwM4xV0Vz2zDUnaXH0bh+dxbR2Xr/22udPO2Ne79sxxnDqzyf+5oiMQb7z/iHLumGyvQI +RPwMlsjRlC/KdsqKvrLr6o4HI4adMk= 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-99-CKLkoO4RPKmy_4qsCjNRpQ-1; Wed, 07 Oct 2020 15:17:13 -0400 X-MC-Unique: CKLkoO4RPKmy_4qsCjNRpQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0AD38186DD32; Wed, 7 Oct 2020 19:17:12 +0000 (UTC) Received: from [10.10.120.38] (ovpn-120-38.rdu2.redhat.com [10.10.120.38]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4D26A100164C; Wed, 7 Oct 2020 19:17:11 +0000 (UTC) Subject: Re: [PATCH 18/20] python/qemu/qmp.py: re-raise OSError when encountered To: Kevin Wolf References: <20201006235817.3280413-1-jsnow@redhat.com> <20201006235817.3280413-19-jsnow@redhat.com> <20201007113043.GL7212@linux.fritz.box> From: John Snow Message-ID: Date: Wed, 7 Oct 2020 15:17:10 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20201007113043.GL7212@linux.fritz.box> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jsnow@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=jsnow@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/07 00:54:30 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.742, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: qemu-block@nongnu.org, Max Reitz , qemu-devel@nongnu.org, Eduardo Habkost , Cleber Rosa Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 10/7/20 7:30 AM, Kevin Wolf wrote: > Am 07.10.2020 um 01:58 hat John Snow geschrieben: >> Nested if conditions don't change when the exception block fires; we >> need to explicitly re-raise the error if we didn't intend to capture and >> suppress it. >> >> Signed-off-by: John Snow >> --- >> python/qemu/qmp.py | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py >> index d911999da1f..bdbd1e9bdbb 100644 >> --- a/python/qemu/qmp.py >> +++ b/python/qemu/qmp.py >> @@ -169,9 +169,9 @@ def __get_events(self, wait: Union[bool, float] = False) -> None: >> try: >> self.__json_read() >> except OSError as err: >> - if err.errno == errno.EAGAIN: >> - # No data available >> - pass >> + # EAGAIN: No data available; not critical >> + if err.errno != errno.EAGAIN: >> + raise > > Hm, if we re-raise the exception here, the socket remains non-blocking. > I think we intended to have it like that only temporarily. > Whoops. Yep, no good to go from one kind of broken to a different kind of broken. > The same kind of exception would raise QMPConnectError below instead of > directly OSError. Should we try to make this consistent? > Yeah, honestly I'm a bit confused about the error plumbing myself. We like to return "None" a lot, and I have been trying to remove that whenever possible, because the nature of what None can mean semantically is ambiguous. I need to sit down with this code and learn all of the different ways it can actually and genuinely fail, and what each failure actually semantically means. I suspect it would probably be best to always catch socket errors and wrap them in QMPConnectError just to be consistent about that. I also need to revise the docstrings to be clear about what errors get raised where, when, and why. I almost included that for this series, but decided against it because I need to also adjust the docstring formatting and so on -- and pending discussion in the qapi series -- felt it would be best to tackle that just a little bit later. Here's a docstring convention question: I think that any method that directly raises an exception should always mention that with :raise X:. How far up the call chain, however, should anticipated exceptions be documented with :raise:? My gut feeling is that it should stop at the first public call boundary, so accept() should repeat any :raise: comments that appear in private helpers. >> self.__sock.setblocking(True) >> >> # Wait for new events, if needed. > > Kevin > Thanks for the review! Things seem like they're looking good. --js