From patchwork Tue Aug 3 18:29:36 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Snow X-Patchwork-Id: 12417069 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=-13.6 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 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 3D93FC4338F for ; Tue, 3 Aug 2021 18:48:26 +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 9C1F460F58 for ; Tue, 3 Aug 2021 18:48:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 9C1F460F58 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]:60674 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mAzSi-0005xa-Qt for qemu-devel@archiver.kernel.org; Tue, 03 Aug 2021 14:48:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53820) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mAzBe-0005OQ-LI for qemu-devel@nongnu.org; Tue, 03 Aug 2021 14:30:51 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:38368) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mAzBY-0006QV-Pr for qemu-devel@nongnu.org; Tue, 03 Aug 2021 14:30:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1628015440; 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=96uqxhV92Jke8jzqctwH7yNCYwtlheAdKBtuC7Zyraw=; b=Pa4EqfHwnv+ZDSsRU0iyFuddda/oksOuDixrMcnMGlDCTRf28gm0YATwj/kudduUCR2lKw X+ZUdLpEVXAWZ/EeILBkpGnszKBxmDPVf4hY5gAiDIhVC+InFz7HA32fgyCAaE8tEqzwHy Yx/7p/sqabmML58InhYO7+IU3xy8e7I= 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-260-IMwu1BrVMTGQs0FLrAKDuw-1; Tue, 03 Aug 2021 14:30:38 -0400 X-MC-Unique: IMwu1BrVMTGQs0FLrAKDuw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EE4E3C7400; Tue, 3 Aug 2021 18:30:37 +0000 (UTC) Received: from scv.redhat.com (unknown [10.22.11.3]) by smtp.corp.redhat.com (Postfix) with ESMTP id BBD3D60854; Tue, 3 Aug 2021 18:30:36 +0000 (UTC) From: John Snow To: qemu-devel@nongnu.org Subject: [PATCH v3 20/25] python/aqmp: add execute() interfaces Date: Tue, 3 Aug 2021 14:29:36 -0400 Message-Id: <20210803182941.504537-21-jsnow@redhat.com> In-Reply-To: <20210803182941.504537-1-jsnow@redhat.com> References: <20210803182941.504537-1-jsnow@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 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 Received-SPF: pass client-ip=170.10.133.124; envelope-from=jsnow@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, 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: Willian Rampazzo , Eric Blake , Markus Armbruster , Wainer dos Santos Moschetta , "Niteesh G . S ." , Stefan Hajnoczi , Cleber Rosa , John Snow , Eduardo Habkost Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Add execute() and execute_msg(). _execute() is split into _issue() and _reply() halves so that hypothetical subclasses of QMP that want to support different execution paradigms can do so. I anticipate a synchronous interface may have need of separating the send/reply phases. However, I do not wish to expose that interface here and want to actively discourage it, so they remain private interfaces. Signed-off-by: John Snow --- python/qemu/aqmp/__init__.py | 4 +- python/qemu/aqmp/qmp_client.py | 202 +++++++++++++++++++++++++++++++-- 2 files changed, 198 insertions(+), 8 deletions(-) diff --git a/python/qemu/aqmp/__init__.py b/python/qemu/aqmp/__init__.py index d975c752eaa..4b7df53e006 100644 --- a/python/qemu/aqmp/__init__.py +++ b/python/qemu/aqmp/__init__.py @@ -25,7 +25,7 @@ from .events import EventListener from .message import Message from .protocol import ConnectError, Runstate, StateError -from .qmp_client import QMPClient +from .qmp_client import ExecInterruptedError, ExecuteError, QMPClient # The order of these fields impact the Sphinx documentation order. @@ -40,4 +40,6 @@ 'AQMPError', 'StateError', 'ConnectError', + 'ExecuteError', + 'ExecInterruptedError', ) diff --git a/python/qemu/aqmp/qmp_client.py b/python/qemu/aqmp/qmp_client.py index fa0cc7c5ae5..879348feaaa 100644 --- a/python/qemu/aqmp/qmp_client.py +++ b/python/qemu/aqmp/qmp_client.py @@ -7,8 +7,7 @@ accept an incoming connection from that server. """ -# The import workarounds here are fixed in the next commit. -import asyncio # pylint: disable=unused-import # noqa +import asyncio import logging from typing import ( Dict, @@ -22,8 +21,8 @@ from .error import AQMPError, ProtocolError from .events import Events from .message import Message -from .models import Greeting -from .protocol import AsyncProtocol +from .models import ErrorResponse, Greeting +from .protocol import AsyncProtocol, Runstate, require from .util import ( bottom_half, exception_summary, @@ -65,11 +64,32 @@ class NegotiationError(_WrappedProtocolError): """ +class ExecuteError(AQMPError): + """ + Exception raised by `QMPClient.execute()` on RPC failure. + + :param error_response: The RPC error response object. + :param sent: The sent RPC message that caused the failure. + :param received: The raw RPC error reply received. + """ + def __init__(self, error_response: ErrorResponse, + sent: Message, received: Message): + super().__init__(error_response.error.desc) + #: The sent `Message` that caused the failure + self.sent: Message = sent + #: The received `Message` that indicated failure + self.received: Message = received + #: The parsed error response + self.error: ErrorResponse = error_response + #: The QMP error class + self.error_class: str = error_response.error.class_ + + class ExecInterruptedError(AQMPError): """ - Exception raised when an RPC is interrupted. + Exception raised by `execute()` (et al) when an RPC is interrupted. - This error is raised when an execute() statement could not be + This error is raised when an `execute()` statement could not be completed. This can occur because the connection itself was terminated before a reply was received. @@ -112,6 +132,27 @@ class ServerParseError(_MsgProtocolError): """ +class BadReplyError(_MsgProtocolError): + """ + An execution reply was successfully routed, but not understood. + + If a QMP message is received with an 'id' field to allow it to be + routed, but is otherwise malformed, this exception will be raised. + + A reply message is malformed if it is missing either the 'return' or + 'error' keys, or if the 'error' value has missing keys or members of + the wrong type. + + :param error_message: Human-readable string describing the error. + :param msg: The malformed reply that was received. + :param sent: The message that was sent that prompted the error. + """ + def __init__(self, error_message: str, msg: Message, sent: Message): + super().__init__(error_message, msg) + #: The sent `Message` that caused the failure + self.sent = sent + + class QMPClient(AsyncProtocol[Message], Events): """ Implements a QMP client connection. @@ -174,6 +215,9 @@ def __init__(self, name: Optional[str] = None) -> None: # Cached Greeting, if one was awaited. self._greeting: Optional[Greeting] = None + # Command ID counter + self._execute_id = 0 + # Incoming RPC reply messages. self._pending: Dict[ Union[str, None], @@ -363,12 +407,135 @@ def _do_send(self, msg: Message) -> None: assert self._writer is not None self._writer.write(bytes(msg)) + @upper_half + def _get_exec_id(self) -> str: + exec_id = f"__aqmp#{self._execute_id:05d}" + self._execute_id += 1 + return exec_id + + @upper_half + async def _issue(self, msg: Message) -> Union[None, str]: + """ + Issue a QMP `Message` and do not wait for a reply. + + :param msg: The QMP `Message` to send to the server. + + :return: The ID of the `Message` sent. + """ + msg_id: Optional[str] = None + if 'id' in msg: + assert isinstance(msg['id'], str) + msg_id = msg['id'] + + self._pending[msg_id] = asyncio.Queue(maxsize=1) + await self._outgoing.put(msg) + + return msg_id + + @upper_half + async def _reply(self, msg_id: Union[str, None]) -> Message: + """ + Await a reply to a previously issued QMP message. + + :param msg_id: The ID of the previously issued message. + + :return: The reply from the server. + :raise ExecInterruptedError: + When the reply could not be retrieved because the connection + was lost, or some other problem. + """ + queue = self._pending[msg_id] + result = await queue.get() + + try: + if isinstance(result, ExecInterruptedError): + raise result + return result + finally: + del self._pending[msg_id] + + @upper_half + async def _execute(self, msg: Message, assign_id: bool = True) -> Message: + """ + Send a QMP `Message` to the server and await a reply. + + This method *assumes* you are sending some kind of an execute + statement that *will* receive a reply. + + An execution ID will be assigned if assign_id is `True`. It can be + disabled, but this requires that an ID is manually assigned + instead. For manually assigned IDs, you must not use the string + '__aqmp#' anywhere in the ID. + + :param msg: The QMP `Message` to execute. + :param assign_id: If True, assign a new execution ID. + + :return: Execution reply from the server. + :raise ExecInterruptedError: + When the reply could not be retrieved because the connection + was lost, or some other problem. + """ + if assign_id: + msg['id'] = self._get_exec_id() + elif 'id' in msg: + assert isinstance(msg['id'], str) + assert '__aqmp#' not in msg['id'] + + exec_id = await self._issue(msg) + return await self._reply(exec_id) + + @upper_half + @require(Runstate.RUNNING) + async def execute_msg(self, msg: Message) -> object: + """ + Execute a QMP command and return its value. + + :param msg: The QMP `Message` to execute. + + :return: + The command execution return value from the server. The type of + object returned depends on the command that was issued, + though most in QEMU return a `dict`. + :raise ValueError: + If the QMP `Message` does not have either the 'execute' or + 'exec-oob' fields set. + :raise ExecuteError: When the server returns an error response. + :raise ExecInterruptedError: if the connection was terminated early. + """ + if not ('execute' in msg or 'exec-oob' in msg): + raise ValueError("Requires 'execute' or 'exec-oob' message") + + # Copy the Message so that the ID assigned by _execute() is + # local to this method; allowing the ID to be seen in raised + # Exceptions but without modifying the caller's held copy. + msg = Message(msg) + reply = await self._execute(msg) + + if 'error' in reply: + try: + error_response = ErrorResponse(reply) + except (KeyError, TypeError) as err: + # Error response was malformed. + raise BadReplyError( + "QMP error reply is malformed", reply, msg, + ) from err + + raise ExecuteError(error_response, msg, reply) + + if 'return' not in reply: + raise BadReplyError( + "QMP reply is missing a 'error' or 'return' member", + reply, msg, + ) + + return reply['return'] + @classmethod def make_execute_msg(cls, cmd: str, arguments: Optional[Mapping[str, object]] = None, oob: bool = False) -> Message: """ - Create an executable message to be sent later. + Create an executable message to be sent by `execute_msg` later. :param cmd: QMP command name. :param arguments: Arguments (if any). Must be JSON-serializable. @@ -380,3 +547,24 @@ def make_execute_msg(cls, cmd: str, if arguments is not None: msg['arguments'] = arguments return msg + + @upper_half + async def execute(self, cmd: str, + arguments: Optional[Mapping[str, object]] = None, + oob: bool = False) -> object: + """ + Execute a QMP command and return its value. + + :param cmd: QMP command name. + :param arguments: Arguments (if any). Must be JSON-serializable. + :param oob: If `True`, execute "out of band". + + :return: + The command execution return value from the server. The type of + object returned depends on the command that was issued, + though most in QEMU return a `dict`. + :raise ExecuteError: When the server returns an error response. + :raise ExecInterruptedError: if the connection was terminated early. + """ + msg = self.make_execute_msg(cmd, arguments, oob=oob) + return await self.execute_msg(msg)