#1059 virtual: replace qmp polling for event listening

Polling for a qmp port availability is undesirable, as QEMU only handles
one connection to the qmp port at a time, ogClient may interfere with
cloneer-manager.

Check vm thread now connects to a separate qmp tcp socket, listening for
a shutdown guest event.

When ogClient is run just after ogVDI installation (before guest
installation) it will try to connect until it's possible, ie: after an
iso is specified and a qemu vm is started that exposes the appropiate
qmp tcp port.

src/virtual/ogOperations.py

@@ -7,6 +7,7 @@
 # (at your option) any later version.
 
 from src.ogRest import ThreadState
+from src.virtual import poweroffd
 import socket
 import errno
 import select
@@ -223,15 +224,19 @@ class OgVirtualOperations:
         return installed_os
 
     def check_vm_state_loop(self, ogRest):
-        POLLING_WAIT_TIME = 12
+        # If we can't connect, wait until it's possible.
         while True:
-            time.sleep(POLLING_WAIT_TIME)
+            try:
-            state = self.check_vm_state()
+                with socket.create_connection((poweroffd.QMP_DEFAULT_HOST,
-            installed_os = self.get_installed_os()
+                                               poweroffd.QMP_DEFAULT_PORT)):
-            if state == OgVM.State.STOPPED and \
+                    break
-               ogRest.state == ThreadState.IDLE and \
+            except ConnectionRefusedError:
-               len(installed_os) > 0:
+                time.sleep(1)
-                self.poweroff_host()
+
+        qmpconn = poweroffd.init()
+        if poweroffd.run(qmpconn) < 0:
+            return
+        self.poweroff_host()
 
     def shellrun(self, request, ogRest):
         return

src/virtual/poweroffd.py

@@ -0,0 +1,53 @@
+#
+# Copyright (C) 2021 Soleta Networks <info@soleta.eu>
+#
+# This program is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the
+# Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+
+from src.virtual.qmp import QEMUMonitorProtocol
+from src.virtual.qmp import QMPCapabilitiesError, QMPConnectError
+
+QMP_DEFAULT_PORT = 4445
+QMP_DEFAULT_HOST = "127.0.0.1"
+
+def is_shutdown_event(qmp_ev):
+    """
+    """
+    return qmp_ev.get('event') == 'SHUTDOWN'
+
+
+def init(host=QMP_DEFAULT_HOST, port=QMP_DEFAULT_PORT):
+    """
+    """
+    qmpconn = QEMUMonitorProtocol((host, port))
+    try:
+        qmpconn.connect()
+    except ConnectionRefusedError:
+        print("Critical err: Connection refused")
+        return None
+    except QMPCapabilitiesError as e:
+        print("Error negotiating capabilities")
+        return None
+    return qmpconn
+
+
+def run(qmpconn):
+    """
+    """
+    while(True):
+        try:
+            qmp_ev = qmpconn.pull_event(wait=True)
+        except QMPConnectError as e:
+            print("Error trying to pull an event")
+            ret = -1
+            break
+        if is_shutdown_event(qmp_ev):
+            print("Detected guest shutdown, let's go")
+            ret = 0
+            break
+
+    qmpconn.close()
+    return ret

src/virtual/qmp.py

@@ -0,0 +1,256 @@
+# QEMU Monitor Protocol Python class
+#
+# Copyright (C) 2009, 2010 Red Hat Inc.
+#
+# Authors:
+#  Luiz Capitulino <lcapitulino@redhat.com>
+#
+# This work is licensed under the terms of the GNU GPL, version 2.  See
+# the COPYING file in the top-level directory.
+
+import json
+import errno
+import socket
+import logging
+
+
+class QMPError(Exception):
+    pass
+
+
+class QMPConnectError(QMPError):
+    pass
+
+
+class QMPCapabilitiesError(QMPError):
+    pass
+
+
+class QMPTimeoutError(QMPError):
+    pass
+
+
+class QEMUMonitorProtocol(object):
+
+    #: Logger object for debugging messages
+    logger = logging.getLogger('QMP')
+    #: Socket's error class
+    error = socket.error
+    #: Socket's timeout
+    timeout = socket.timeout
+
+    def __init__(self, address, server=False):
+        """
+        Create a QEMUMonitorProtocol class.
+
+        @param address: QEMU address, can be either a unix socket path (string)
+                        or a tuple in the form ( address, port ) for a TCP
+                        connection
+        @param server: server mode listens on the socket (bool)
+        @raise socket.error on socket connection errors
+        @note No connection is established, this is done by the connect() or
+              accept() methods
+        """
+        self.__events = []
+        self.__address = address
+        self.__sock = self.__get_sock()
+        self.__sockfile = None
+        if server:
+            self.__sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+            self.__sock.bind(self.__address)
+            self.__sock.listen(1)
+
+    def __get_sock(self):
+        if isinstance(self.__address, tuple):
+            family = socket.AF_INET
+        else:
+            family = socket.AF_UNIX
+        return socket.socket(family, socket.SOCK_STREAM)
+
+    def __negotiate_capabilities(self):
+        greeting = self.__json_read()
+        if greeting is None or "QMP" not in greeting:
+            raise QMPConnectError
+        # Greeting seems ok, negotiate capabilities
+        resp = self.cmd('qmp_capabilities')
+        if "return" in resp:
+            return greeting
+        raise QMPCapabilitiesError
+
+    def __json_read(self, only_event=False):
+        while True:
+            data = self.__sockfile.readline()
+            if not data:
+                return
+            resp = json.loads(data)
+            if 'event' in resp:
+                self.logger.debug("<<< %s", resp)
+                self.__events.append(resp)
+                if not only_event:
+                    continue
+            return resp
+
+    def __get_events(self, wait=False):
+        """
+        Check for new events in the stream and cache them in __events.
+
+        @param wait (bool): block until an event is available.
+        @param wait (float): If wait is a float, treat it as a timeout value.
+
+        @raise QMPTimeoutError: If a timeout float is provided and the timeout
+                                period elapses.
+        @raise QMPConnectError: If wait is True but no events could be
+                                retrieved or if some other error occurred.
+        """
+
+        # Check for new events regardless and pull them into the cache:
+        self.__sock.setblocking(0)
+        try:
+            self.__json_read()
+        except socket.error as err:
+            if err[0] == errno.EAGAIN:
+                # No data available
+                pass
+        self.__sock.setblocking(1)
+
+        # Wait for new events, if needed.
+        # if wait is 0.0, this means "no wait" and is also implicitly false.
+        if not self.__events and wait:
+            if isinstance(wait, float):
+                self.__sock.settimeout(wait)
+            try:
+                ret = self.__json_read(only_event=True)
+            except socket.timeout:
+                raise QMPTimeoutError("Timeout waiting for event")
+            except:
+                raise QMPConnectError("Error while reading from socket")
+            if ret is None:
+                raise QMPConnectError("Error while reading from socket")
+            self.__sock.settimeout(None)
+
+    def connect(self, negotiate=True):
+        """
+        Connect to the QMP Monitor and perform capabilities negotiation.
+
+        @return QMP greeting dict
+        @raise socket.error on socket connection errors
+        @raise QMPConnectError if the greeting is not received
+        @raise QMPCapabilitiesError if fails to negotiate capabilities
+        """
+        self.__sock.connect(self.__address)
+        self.__sockfile = self.__sock.makefile()
+        if negotiate:
+            return self.__negotiate_capabilities()
+
+    def accept(self):
+        """
+        Await connection from QMP Monitor and perform capabilities negotiation.
+
+        @return QMP greeting dict
+        @raise socket.error on socket connection errors
+        @raise QMPConnectError if the greeting is not received
+        @raise QMPCapabilitiesError if fails to negotiate capabilities
+        """
+        self.__sock.settimeout(15)
+        self.__sock, _ = self.__sock.accept()
+        self.__sockfile = self.__sock.makefile()
+        return self.__negotiate_capabilities()
+
+    def cmd_obj(self, qmp_cmd):
+        """
+        Send a QMP command to the QMP Monitor.
+
+        @param qmp_cmd: QMP command to be sent as a Python dict
+        @return QMP response as a Python dict or None if the connection has
+                been closed
+        """
+        self.logger.debug(">>> %s", qmp_cmd)
+        try:
+            self.__sock.sendall(json.dumps(qmp_cmd).encode('utf-8'))
+        except socket.error as err:
+            if err[0] == errno.EPIPE:
+                return
+            raise socket.error(err)
+        resp = self.__json_read()
+        self.logger.debug("<<< %s", resp)
+        return resp
+
+    def cmd(self, name, args=None, cmd_id=None):
+        """
+        Build a QMP command and send it to the QMP Monitor.
+
+        @param name: command name (string)
+        @param args: command arguments (dict)
+        @param cmd_id: command id (dict, list, string or int)
+        """
+        qmp_cmd = {'execute': name}
+        if args:
+            qmp_cmd['arguments'] = args
+        if cmd_id:
+            qmp_cmd['id'] = cmd_id
+        return self.cmd_obj(qmp_cmd)
+
+    def command(self, cmd, **kwds):
+        """
+        Build and send a QMP command to the monitor, report errors if any
+        """
+        ret = self.cmd(cmd, kwds)
+        if "error" in ret:
+            raise Exception(ret['error']['desc'])
+        return ret['return']
+
+    def pull_event(self, wait=False):
+        """
+        Pulls a single event.
+
+        @param wait (bool): block until an event is available.
+        @param wait (float): If wait is a float, treat it as a timeout value.
+
+        @raise QMPTimeoutError: If a timeout float is provided and the timeout
+                                period elapses.
+        @raise QMPConnectError: If wait is True but no events could be
+                                retrieved or if some other error occurred.
+
+        @return The first available QMP event, or None.
+        """
+        self.__get_events(wait)
+
+        if self.__events:
+            return self.__events.pop(0)
+        return None
+
+    def get_events(self, wait=False):
+        """
+        Get a list of available QMP events.
+
+        @param wait (bool): block until an event is available.
+        @param wait (float): If wait is a float, treat it as a timeout value.
+
+        @raise QMPTimeoutError: If a timeout float is provided and the timeout
+                                period elapses.
+        @raise QMPConnectError: If wait is True but no events could be
+                                retrieved or if some other error occurred.
+
+        @return The list of available QMP events.
+        """
+        self.__get_events(wait)
+        return self.__events
+
+    def clear_events(self):
+        """
+        Clear current list of pending events.
+        """
+        self.__events = []
+
+    def close(self):
+        self.__sock.close()
+        self.__sockfile.close()
+
+    def settimeout(self, timeout):
+        self.__sock.settimeout(timeout)
+
+    def get_sock_fd(self):
+        return self.__sock.fileno()
+
+    def is_scm_available(self):
+        return self.__sock.family == socket.AF_UNIX