[libvirt] [PATCH 01/11] Process all pending I/O for a RPC client before checking EOF

[Jiri Denemark]

On Fri, Jul 27, 2012 at 13:33:06 +0100, Daniel P. Berrange wrote:
> On Thu, Jul 26, 2012 at 04:00:22PM +0200, Jiri Denemark wrote:
> > On Tue, Jul 24, 2012 at 14:22:43 +0100, Daniel P. Berrange wrote:
> > > From: "Daniel P. Berrange" <berrange at redhat.com>
> > > 
> > > In the socket event handler for the RPC client we must deal
> > > with read/write events, before checking for EOF, otherwise
> > > we might close the socket before we've read & acted upon the
> > > last RPC messages
> > > 
> > > Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> > > ---
> > >  src/rpc/virnetclient.c |   20 ++++++++++----------
> > >  1 file changed, 10 insertions(+), 10 deletions(-)
> > > 
> > > diff --git a/src/rpc/virnetclient.c b/src/rpc/virnetclient.c
> > > index aba58ec..f5d8189 100644
> > > --- a/src/rpc/virnetclient.c
> > > +++ b/src/rpc/virnetclient.c
> > > @@ -1694,16 +1694,6 @@ void virNetClientIncomingEvent(virNetSocketPtr sock,
> > >  
> > >      VIR_DEBUG("Event fired %p %d", sock, events);
> > >  
> > > -    if (events & (VIR_EVENT_HANDLE_HANGUP | VIR_EVENT_HANDLE_ERROR)) {
> > > -        VIR_DEBUG("%s : VIR_EVENT_HANDLE_HANGUP or "
> > > -                  "VIR_EVENT_HANDLE_ERROR encountered", __FUNCTION__);
> > > -        virNetClientMarkClose(client,
> > > -                              (events & VIR_EVENT_HANDLE_HANGUP) ?
> > > -                              VIR_CONNECT_CLOSE_REASON_EOF :
> > > -                              VIR_CONNECT_CLOSE_REASON_ERROR);
> > > -        goto done;
> > > -    }
> > > -
> > >      if (events & VIR_EVENT_HANDLE_WRITABLE) {
> > >          if (virNetClientIOHandleOutput(client) < 0)
> > >              virNetClientMarkClose(client, VIR_CONNECT_CLOSE_REASON_ERROR);
> > > @@ -1714,6 +1704,16 @@ void virNetClientIncomingEvent(virNetSocketPtr sock,
> > >              virNetClientMarkClose(client, VIR_CONNECT_CLOSE_REASON_ERROR);
> > >      }
> > >  
> > > +    if (events & (VIR_EVENT_HANDLE_HANGUP | VIR_EVENT_HANDLE_ERROR)) {
> > > +        VIR_DEBUG("%s : VIR_EVENT_HANDLE_HANGUP or "
> > > +                  "VIR_EVENT_HANDLE_ERROR encountered", __FUNCTION__);
> > 
> > I know you are just copy&pasting but __FUNCTION__ is redundant here.
> > 
> > > +        virNetClientMarkClose(client,
> > > +                              (events & VIR_EVENT_HANDLE_HANGUP) ?
> > > +                              VIR_CONNECT_CLOSE_REASON_EOF :
> > > +                              VIR_CONNECT_CLOSE_REASON_ERROR);
> > > +        goto done;
> > > +    }
> > > +
> > >      /* Remove completed calls or signal their threads. */
> > >      virNetClientCallRemovePredicate(&client->waitDispatch,
> > >                                      virNetClientIOEventLoopRemoveDone,
> > 
> > This is a good change but I think it's incomplete. If something fails (e.g.
> > the connection is closed) while we are inside virNetClientIOHandleOutput(), we
> > will still skip reading any data possibly waiting for us.
> 
> 
> No, we should be ok in that respect, since we see the error,
> but don't 'goto', so we'll still run the input code
> 
>     if (events & VIR_EVENT_HANDLE_WRITABLE) {
>         if (virNetClientIOHandleOutput(client) < 0)
>             virNetClientMarkClose(client, VIR_CONNECT_CLOSE_REASON_ERROR);
>     }
> 
>     if (events & VIR_EVENT_HANDLE_READABLE) {
>         if (virNetClientIOHandleInput(client) < 0)
>             virNetClientMarkClose(client, VIR_CONNECT_CLOSE_REASON_ERROR);
>     }

Oh, right. ACK then.

Jirka