[libvirt] Python stream callback removal

Dave Allan dallan at redhat.com
Mon Aug 8 22:04:50 UTC 2011


I'm trying to write an example serial console implementation in python
(attached), but I'm having some trouble getting stream events to do
what I want.  The console itself works fine as long as the domain
stays up, but as soon as the domain shuts down the python script goes
into a tight loop repeatedly calling the stream event callback.
Debugging indicates that the stream event callback is being requested
to be removed, but it never actually is removed which makes me think I
am not properly releasing some resource, but I was under the
impression that an error on a stream resulting in the stream aborting
was supposed to free all the resources for me.  Is that not correct?

Thanks for any help anybody can provide,
Dave
-------------- next part --------------
#!/usr/bin/python -u
import sys, os, libvirt, tty, termios, atexit

def reset_term():
    termios.tcsetattr(0, termios.TCSADRAIN, attrs)

def stdin_callback(watch, fd, events, unused):
    global run_console
    readbuf = os.read(fd, 1024)
    if readbuf.startswith(""):
        run_console = False
        return
    stream.send(readbuf)

def stream_callback(stream, events, unused):
    if events & libvirt.VIR_EVENT_HANDLE_READABLE:
        receivedData = stream.recv(1024)
    os.write(0, receivedData)

libvirt.virEventRegisterDefaultImpl()
atexit.register(reset_term)
attrs = termios.tcgetattr(0)
tty.setraw(0)

connection = libvirt.open(sys.argv[1])
domain = connection.lookupByUUIDString(sys.argv[2])
stream = connection.newStream(libvirt.VIR_STREAM_NONBLOCK)
domain.openConsole(None, stream, 0)
run_console = True
stdin_watch = libvirt.virEventAddHandle(0, libvirt.VIR_EVENT_HANDLE_READABLE, stdin_callback, None)
stream.eventAddCallback(libvirt.VIR_STREAM_EVENT_READABLE, stream_callback, None)

while run_console:
    libvirt.virEventRunDefaultImpl()


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