[Spice-devel] [PATCH] UpgradeItem: use base PipeItem for refcounting

[Jonathon Jongsma]

On Thu, 2016-04-21 at 12:41 +0100, Frediano Ziglio wrote:
> From: Jonathon Jongsma <jjongsma at redhat.com>
> 
> No need to re-implement refcounting in this subclass. However, I needed
> to add a new 'dcc' member to UpgradeItem to be able to unref properly.
> ---
>  server/dcc.c             | 18 +-----------------
>  server/display-channel.c |  4 +---
>  server/display-channel.h |  7 ++++++-
>  server/stream.c          | 15 +++++++++++++--
>  4 files changed, 21 insertions(+), 23 deletions(-)
> 
> diff --git a/server/dcc.c b/server/dcc.c
> index 91c3f82..5193c17 100644
> --- a/server/dcc.c
> +++ b/server/dcc.c
> @@ -1591,29 +1591,15 @@ int dcc_handle_migrate_data(DisplayChannelClient *dcc,
> uint32_t size, void *mess
>      return TRUE;
>  }
>  
> -static void upgrade_item_unref(DisplayChannel *display, UpgradeItem *item)
> -{
> -    if (--item->refs != 0)
> -        return;
> -
> -    display_channel_drawable_unref(display, item->drawable);
> -    free(item->rects);
> -    free(item);
> -}
> -
>  static void release_item_after_push(DisplayChannelClient *dcc, PipeItem
> *item)
>  {
> -    DisplayChannel *display = DCC_TO_DC(dcc);
> -
>      switch (item->type) {
>      case PIPE_ITEM_TYPE_DRAW:
>      case PIPE_ITEM_TYPE_IMAGE:
>      case PIPE_ITEM_TYPE_STREAM_CLIP:
>      case PIPE_ITEM_TYPE_MONITORS_CONFIG:
> -        pipe_item_unref(item);
> -        break;
>      case PIPE_ITEM_TYPE_UPGRADE:
> -        upgrade_item_unref(display, (UpgradeItem *)item);
> +        pipe_item_unref(item);
>          break;
>      case PIPE_ITEM_TYPE_GL_SCANOUT:
>      case PIPE_ITEM_TYPE_GL_DRAW:
> @@ -1651,8 +1637,6 @@ static void
> release_item_before_push(DisplayChannelClient *dcc, PipeItem *item)
>      }
>      case PIPE_ITEM_TYPE_STREAM_CLIP:
>      case PIPE_ITEM_TYPE_UPGRADE:
> -        upgrade_item_unref(display, (UpgradeItem *)item);
> -        break;
>      case PIPE_ITEM_TYPE_IMAGE:
>      case PIPE_ITEM_TYPE_MONITORS_CONFIG:
>          pipe_item_unref(item);
> diff --git a/server/display-channel.c b/server/display-channel.c
> index 88dbc74..98b4a43 100644
> --- a/server/display-channel.c
> +++ b/server/display-channel.c
> @@ -1973,10 +1973,8 @@ static void hold_item(RedChannelClient *rcc, PipeItem
> *item)
>      case PIPE_ITEM_TYPE_DRAW:
>      case PIPE_ITEM_TYPE_IMAGE:
>      case PIPE_ITEM_TYPE_STREAM_CLIP:
> -        pipe_item_ref(item);
> -        break;
>      case PIPE_ITEM_TYPE_UPGRADE:
> -        ((UpgradeItem *)item)->refs++;
> +        pipe_item_ref(item);
>          break;
>      default:
>          spice_warn_if_reached();
> diff --git a/server/display-channel.h b/server/display-channel.h
> index 6b053de..00e8a53 100644
> --- a/server/display-channel.h
> +++ b/server/display-channel.h
> @@ -244,7 +244,12 @@ typedef struct SurfaceDestroyItem {
>  
>  typedef struct UpgradeItem {
>      PipeItem base;
> -    int refs;
> +    /**
> +     * Pointer to the display from which the drawable is allocated.
> +     * This pointer is safe to be retained as DisplayChannel
> +     * lifespan is bigger than all drawables.
> +     */
> +    DisplayChannel *display;

OK, that seems reasonable to me with minor comment change: s/bigger/longer/

Although now I'm wondering if we shouldn't just modify Drawable to store the
DisplayChannel* instead. And then change

display_channel_drawable_unref(DisplayChannel*, Drawable*)
{
	/* do stuff */
}

to

drawable_unref(Drawable*)
{
	DisplayChannel *display = drawable->display;
	/* do stuff */
}

>      Drawable *drawable;
>      SpiceClipRects *rects;
>  } UpgradeItem;
> diff --git a/server/stream.c b/server/stream.c
> index ae37a62..f8d0abe 100644
> --- a/server/stream.c
> +++ b/server/stream.c
> @@ -758,6 +758,16 @@ void stream_agent_stop(StreamAgent *agent)
>      }
>  }
>  
> +static void upgrade_item_free(UpgradeItem *item)
> +{
> +    g_return_if_fail(item != NULL);
> +    g_return_if_fail(item->base.refcount != 0);
> +
> +    display_channel_drawable_unref(item->display, item->drawable);
> +    free(item->rects);
> +    free(item);
> +}
> +
>  /*
>   * after dcc_detach_stream_gracefully is called for all the display channel
> clients,
>   * detach_stream should be called. See comment (1).
> @@ -798,10 +808,11 @@ static void
> dcc_detach_stream_gracefully(DisplayChannelClient *dcc,
>          rect_debug(&stream->current->red_drawable->bbox);
>          rcc = RED_CHANNEL_CLIENT(dcc);
>          upgrade_item = spice_new(UpgradeItem, 1);
> -        upgrade_item->refs = 1;
> -        pipe_item_init(&upgrade_item->base, PIPE_ITEM_TYPE_UPGRADE);
> +        pipe_item_init_full(&upgrade_item->base, PIPE_ITEM_TYPE_UPGRADE,
> +                            (GDestroyNotify)upgrade_item_free);
>          upgrade_item->drawable = stream->current;
>          upgrade_item->drawable->refs++;
> +        upgrade_item->display = display;
>          n_rects = pixman_region32_n_rects(&upgrade_item->drawable
> ->tree_item.base.rgn);
>          upgrade_item->rects = spice_malloc_n_m(n_rects, sizeof(SpiceRect),
> sizeof(SpiceClipRects));
>          upgrade_item->rects->num_rects = n_rects;