Re: [XTF PATCH v2] xtf-runner: support two modes for getting output

[Wei Liu <wei.liu2@citrix.com>]

On Thu, Aug 11, 2016 at 06:17:31PM +0100, Ian Jackson wrote:
> Wei Liu writes ("Re: [XTF PATCH v2] xtf-runner: support two modes for getting output"):
> > On Thu, Aug 11, 2016 at 05:27:56PM +0100, Ian Jackson wrote:
> > > This is perverse.  Why not just open it O_CREAT|O_RDONLY ?  If Python
> > > can't do that then unconditionally opening it O_CREAT|O_RDWR would do.
> > 
> > The open call doesn't accept O_CREAT|O_RDONLY.
> 
> open("t", O_RDONLY|O_CREAT, 0666)       = 3
> 
> But maybe you mean Python's open doesn't.
> 
> > Andy my experiment showed that "rb" doesn't create the file.
> 
> Yes, it wouldn't.  If you want a fopen mode, "a+" may be of some use.
> 
> > > > +    logfile.seek(0, 2) # Go to end of file
> > > 
> > > Does Python not have SEEK_END somewhere ?
> > 
> > There is one, but that's in os module.
> > Python official document is using numeric values directly.
> 
> Seriously?  Fine, whatever.
> 
> > > > +    lines = logfile.readlines()
> > > > +    logfile.close()
> > > > +
> > > > +    if len(lines) == 0:
> > > > +        raise RunnerError("Test output empty")
> > > 
> > > I think you are racing with xenconsoled here.  How do you know that
> > > all the output has arrived ?
> > 
> > Unfortunately there doesn't seem to be a direct way to synchronise
> > between the two.
> > 
> > Maybe the best bet is to watch the tty node for it to go away?
> 
> Does xenconsole write the remaining output to the logfile before
> deleting the tty node from xenstore ?
> 

Unfortunately no, watching tty node in xenstore won't work.  In fact,
xenconsoled doesn't delete the tty node at all. It's libxl that deletes
it AFAICT.

It is sure that xenconsoled will close the tty before closing the file,
so stat'ing the actual device node won't work either.

I'm pretty out of idea here.

Wei.

> Ian.

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel