Re: [Xen-devel] [PATCH] tools/xenstore-watch: Add new timeout parameter

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Mar 16, 2016 at 08:52:57PM +0200, Razvan Cojocaru wrote:
> On 03/16/2016 08:46 PM, Wei Liu wrote:
> > On Wed, Mar 16, 2016 at 05:50:46PM +0200, Razvan Cojocaru wrote:
> > [...]
> >>  }
> >>  
> >> @@ -273,27 +274,49 @@ do_chmod(char *path, struct xs_permissions *perms, 
> >> int nperms, int upto,
> >>  }
> >>  
> >>  static void
> >> -do_watch(struct xs_handle *xsh, int max_events)
> >> +do_watch(struct xs_handle *xsh, int max_events, int timeout)
> >>  {
> >> -    int count = 0;
> >> +    int rc, ms_timeout = timeout * 1000;
> >>      char **vec = NULL;
> >> +    struct pollfd fd;
> >>  
> >> -    for ( count = 0; max_events == -1 || count < max_events; count++ ) {
> >> -  unsigned int num;
> >> +    fd.fd = xs_fileno(xsh);
> >> +    fd.events = POLLIN | POLLERR;
> >>  
> >> -  vec = xs_read_watch(xsh, &num);
> >> -  if (vec == NULL)
> >> -      continue;
> >> +    do {
> >> +        rc = poll(&fd, 1, 100);
> >>  
> >> -  printf("%s\n", vec[XS_WATCH_PATH]);
> >> -  fflush(stdout);
> >> -  free(vec);
> >> -    }
> >> +        if (rc == 0 || (rc < 0 && errno == EINTR)) {
> >> +            ms_timeout -= 100;
> > 
> > Shouldn't you just exit the loop when getting EINTR?
> 
> I don't think so, an EINTR means that a signal has been caught during
> poll() - it's not really a failure case.
> 

What about Ctrl-C ? I think it is reasonable that user want to interrupt
the process.

> > And as others have mentioned, please also patch manpage.
> 
> As Andrew has pointed out, there is no man page to patch. I agree that
> adding one would be great, but I hope this patch can get through without
> it being required - it can be added later.
> 

Yes, follow-up patch is OK.

Wei.

> 
> Thanks,
> Razvan
> 
> 
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