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author | Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> | 2011-05-25 19:48:01 +0100 |
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committer | Luiz Capitulino <lcapitulino@redhat.com> | 2011-06-01 11:43:18 -0300 |
commit | 37628f11c6b190ebb3082938868aadb23942ee3a (patch) | |
tree | 6c97f37b0f3262d6c32d0074699ce2651399cc10 /QMP/qmp.py | |
parent | 91b8eddf41fd62ecbc61cb901c40f50287126fac (diff) | |
download | hqemu-37628f11c6b190ebb3082938868aadb23942ee3a.zip hqemu-37628f11c6b190ebb3082938868aadb23942ee3a.tar.gz |
QMP: add server mode to QEMUMonitorProtocol
QEMU supports socket chardevs that establish connections like a server
or a client. The QEMUMonitorProtocol class only supports connecting as
a client. It is not possible to connect race-free when launching QEMU
since trying to connect before QEMU has bound and is listening on the
socket results in failure.
Add the QEMUMonitorProtocol(server=True) argument to bind and listen on
the socket. The QEMU process can then be launched and connects to the
already existing QMP socket without a race condition:
qmp = qmp.QEMUMonitorProtocol(monitor_path, server=True)
popen = subprocess.Popen(args)
qmp.accept()
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Diffstat (limited to 'QMP/qmp.py')
-rw-r--r-- | QMP/qmp.py | 43 |
1 files changed, 32 insertions, 11 deletions
@@ -22,19 +22,24 @@ class QMPCapabilitiesError(QMPError): pass class QEMUMonitorProtocol: - def __init__(self, address): + 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 - @note No connection is established, this is done by the connect() method + @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 = self.__sock.makefile() + if server: + self.__sock.bind(self.__address) + self.__sock.listen(1) def __get_sock(self): if isinstance(self.__address, tuple): @@ -43,6 +48,17 @@ class QEMUMonitorProtocol: family = socket.AF_UNIX return socket.socket(family, socket.SOCK_STREAM) + def __negotiate_capabilities(self): + self.__sockfile = self.__sock.makefile() + greeting = self.__json_read() + if greeting is None or not greeting.has_key('QMP'): + 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() @@ -67,14 +83,19 @@ class QEMUMonitorProtocol: @raise QMPCapabilitiesError if fails to negotiate capabilities """ self.__sock.connect(self.__address) - greeting = self.__json_read() - if greeting is None or not greeting.has_key('QMP'): - raise QMPConnectError - # Greeting seems ok, negotiate capabilities - resp = self.cmd('qmp_capabilities') - if "return" in resp: - return greeting - raise QMPCapabilitiesError + 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, _ = self.__sock.accept() + return self.__negotiate_capabilities() def cmd_obj(self, qmp_cmd): """ |