On Wed, Aug 15, 2012 at 10:57:57PM +0300, Marc-André Lureau wrote:
> Add a new arbitrary keyboard scancodes message.
>
> For now, it will be used to avoid unwanted key repeatition when there
> is jitter in the network and too much time between DOWN and UP
> messages, instead the client will send the press & release scancode in
> a sequence from a single message.
>
> If the server doesn't support INPUTS_CAP_KEY_SCANCODE, the client is
> responsible to handle a fallback mode with the exisiting KEY_DOWN and
> KEY_UP messages.
ACK all, just one note we discussed offline (and this is a huge
improvement btw regardless of what I'm about to say): When two keys are
pressed, A followed by B, and B is released, the current behavior is to
send A press. Then when A is eventually released we still have the old
behavior of a separate messages, and so we are susceptible to network
jitter. Even worse, there is no solution for it that also enforces the
order of events (i.e. if A was pressed before B in the client, it must
be the same order in the guest). We could still do a little better then
the current code, by waiting for B release instead of B press to send
the A press (since maybe A release will happen meanwhile, and then we
have the regular case that this patchset solves).
Example:
t=0 A press
t=0.05 B press
t=0.1 B release <- send ScanCode{A_press,B_press,B_release}
Case 1: after 9.9 seconds A release happens - then we are optimal:
t=10 A release <- send ScanCode{A_release}
Case 2: after 0.05 seconds A release happens - then we are susceptible
to jitter in these 0.05 seconds:
t=0.15 A release <- send ScanCode{A_release}
>
> See also: https://bugzilla.redhat.com/show_bug.cgi?id=812347
> ---
> spice/enums.h | 1 +
> spice/protocol.h | 4 ++++
> 2 files changed, 5 insertions(+)
>
> diff --git a/spice/enums.h b/spice/enums.h
> index c4e38aa..129f9b7 100644
> --- a/spice/enums.h
> +++ b/spice/enums.h
> @@ -453,6 +453,7 @@ enum {
> SPICE_MSGC_INPUTS_KEY_DOWN = 101,
> SPICE_MSGC_INPUTS_KEY_UP,
> SPICE_MSGC_INPUTS_KEY_MODIFIERS,
> + SPICE_MSGC_INPUTS_KEY_SCANCODE,
> SPICE_MSGC_INPUTS_MOUSE_MOTION = 111,
> SPICE_MSGC_INPUTS_MOUSE_POSITION,
> SPICE_MSGC_INPUTS_MOUSE_PRESS,
> diff --git a/spice/protocol.h b/spice/protocol.h
> index c0d33e6..fafd015 100644
> --- a/spice/protocol.h
> +++ b/spice/protocol.h
> @@ -127,6 +127,10 @@ enum {
> SPICE_DISPLAY_CAP_MONITORS_CONFIG,
> };
>
> +enum {
> + SPICE_INPUTS_CAP_KEY_SCANCODE,
> +};
> +
> #include <spice/end-packed.h>
>
> #endif /* _H_SPICE_PROTOCOL */
> --
> 1.7.10.4
>
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