[Spice-devel] [spice v1 1/2] display-channel: monitors_config: add 200ms delay

[Frediano Ziglio]

> 
> From: Victor Toso <me at victortoso.com>
> 
> The device driver might take a few interactions to reconfigure all
> displays but in each change it can send it down to spice-server. The
> client is not interested in temporary states, only the final monitor
> config can be helpful.
> 
> This patch adds a 200ms delay to wait for more changes from guest
> device. Tested only with QXL in Fedora 29.
> 

Which kind of guest? Windows or Linux?

> Simple example below, with 4 displays enabled but removing the display 1
> (starting from 0), spice server receives:
> 
>  | 16:50:14.964: display-channel.c:173:monitors_config_unref: freeing
>  | monitors config
>  | 16:50:14.964: display-channel.c:181:monitors_config_debug: monitors config
>  | count:3 max:4
>  | 16:50:14.964: display-channel.c:185:monitors_config_debug: +0+0 960x997
>  | 16:50:14.964: display-channel.c:185:monitors_config_debug: +960+0 1024x740
>  | 16:50:14.964: display-channel.c:185:monitors_config_debug: +1984+0
>  | 1024x740
> 
> Sends to the client #1
> 
>  | 16:50:14.965: display-channel.c:173:monitors_config_unref: freeing
>  | monitors config
>  | 16:50:14.965: display-channel.c:181:monitors_config_debug: monitors config
>  | count:3 max:4
>  | 16:50:14.965: display-channel.c:185:monitors_config_debug: +0+0 960x997
>  | 16:50:14.965: display-channel.c:185:monitors_config_debug: +0+0 0x0
>  | 16:50:14.965: display-channel.c:185:monitors_config_debug: +1984+0
>  | 1024x740
> 
> Sends to the client #2
> 
>  | 16:50:14.966: red-worker.c:475:dev_create_primary_surface: trace
>  | 16:50:14.967: display-channel.c:173:monitors_config_unref: freeing
>  | monitors config
>  | 16:50:14.967: display-channel.c:181:monitors_config_debug: monitors config
>  | count:1 max:4
>  | 16:50:14.967: display-channel.c:185:monitors_config_debug: +0+0 3008x997
>  | 16:50:14.972: display-channel.c:173:monitors_config_unref: freeing
>  | monitors config
>  | 16:50:14.972: display-channel.c:181:monitors_config_debug: monitors config
>  | count:3 max:4
>  | 16:50:14.972: display-channel.c:185:monitors_config_debug: +0+0 960x997
>  | 16:50:14.973: display-channel.c:185:monitors_config_debug: +0+0 0x0
>  | 16:50:14.973: display-channel.c:185:monitors_config_debug: +960+0 1024x740
> 
> Sends to the client #3
> 
>  | 16:50:14.973:
>  | display-channel.c:2462:display_channel_update_monitors_config: Will
>  | update monitors in 200ms ~~
>  | 16:50:14.975: display-channel.c:173:monitors_config_unref: freeing
>  | monitors config
>  | 16:50:14.975: display-channel.c:181:monitors_config_debug: monitors config
>  | count:4 max:4
>  | 16:50:14.975: display-channel.c:185:monitors_config_debug: +0+0 960x997
>  | 16:50:14.975: display-channel.c:185:monitors_config_debug: +0+0 0x0
>  | 16:50:14.975: display-channel.c:185:monitors_config_debug: +960+0 1024x740
>  | 16:50:14.975: display-channel.c:185:monitors_config_debug: +1984+0
>  | 1024x740
> 
> Sends to the client #4 and final
> 
> With this patch, only the last one is sent.
> Resolves: rhbz#1673072
> Signed-off-by: Victor Toso <victortoso at redhat.com>
> ---
>  server/display-channel-private.h |  2 ++
>  server/display-channel.c         | 16 +++++++++++++---
>  server/display-channel.h         |  2 +-
>  3 files changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/server/display-channel-private.h
> b/server/display-channel-private.h
> index 58179531..f1a4314c 100644
> --- a/server/display-channel-private.h
> +++ b/server/display-channel-private.h
> @@ -118,6 +118,8 @@ struct DisplayChannelPrivate
>  
>      int gl_draw_async_count;
>  
> +    guint monitors_config_update_delay_id;
> +
>  /* TODO: some day unify this, make it more runtime.. */
>      stat_info_t add_stat;
>      stat_info_t exclude_stat;
> diff --git a/server/display-channel.c b/server/display-channel.c
> index e68ed10f..7e2584ec 100644
> --- a/server/display-channel.c
> +++ b/server/display-channel.c
> @@ -2430,13 +2430,17 @@ gboolean
> display_channel_validate_surface(DisplayChannel *display, uint32_t surf
>      return TRUE;
>  }
>  
> -void display_channel_push_monitors_config(DisplayChannel *display)
> +gboolean display_channel_push_monitors_config(gpointer userdata)
>  {
>      DisplayChannelClient *dcc;
> +    DisplayChannel *display = userdata;
> +
> +    display->priv->monitors_config_update_delay_id = 0;
>  
>      FOREACH_DCC(display, dcc) {
>          dcc_push_monitors_config(dcc);
>      }
> +    return G_SOURCE_REMOVE;
>  }
>  
>  void display_channel_update_monitors_config(DisplayChannel *display,
> @@ -2444,13 +2448,19 @@ void
> display_channel_update_monitors_config(DisplayChannel *display,
>                                              uint16_t count, uint16_t
>                                              max_allowed)
>  {
>  
> -    if (display->priv->monitors_config)
> +    if (display->priv->monitors_config) {
>          monitors_config_unref(display->priv->monitors_config);
> +    }
>  
>      display->priv->monitors_config =
>          monitors_config_new(config->heads, count, max_allowed);
>  
> -    display_channel_push_monitors_config(display);
> +    if (display->priv->monitors_config_update_delay_id != 0) {
> +        g_source_remove(display->priv->monitors_config_update_delay_id);
> +    }
> +
> +    display->priv->monitors_config_update_delay_id =
> +        g_timeout_add (200, display_channel_push_monitors_config, display);

Don't use g_timeout_add, it adds the source to the main context so the function
won't be executed in DisplayChannel thread causing thread race conditions.
I don't see the part of code that remove the source in case DisplayChannel
is destroyed.

>  }
>  
>  void display_channel_set_monitors_config_to_primary(DisplayChannel *display)
> diff --git a/server/display-channel.h b/server/display-channel.h
> index 948018cf..1d64afce 100644
> --- a/server/display-channel.h
> +++ b/server/display-channel.h
> @@ -149,7 +149,7 @@ void                       display_channel_gl_draw_done
> (DisplayCha
>  void display_channel_update_monitors_config(DisplayChannel *display,
>  QXLMonitorsConfig *config,
>                                              uint16_t count, uint16_t
>                                              max_allowed);
>  void display_channel_set_monitors_config_to_primary(DisplayChannel
>  *display);
> -void display_channel_push_monitors_config(DisplayChannel *display);
> +gboolean display_channel_push_monitors_config(gpointer display);
>  
>  gboolean display_channel_validate_surface(DisplayChannel *display, uint32_t
>  surface_id);
>  gboolean display_channel_surface_has_canvas(DisplayChannel *display,
>  uint32_t surface_id);

Otherwise the patch seems good.

Frediano