[Spice-devel] [PATCH spice-server 09/10] red-channel-client: Simplify red_channel_client_wait_pipe_item_sent

[Christophe Fergeau]

On Mon, Sep 11, 2017 at 11:15:46AM +0100, Frediano Ziglio wrote:
> Instead of inserting the marker after the item (the tail of the queue
> is the first item to send) and then have to wait again if for
> the specific item place the marker before the item so waiting for
> the marker to be sent assure that we sent also the item.
> This avoids having to call red_channel_client_wait_outgoing_item
> and possibly the case where the item was not queued and
> red_channel_client_wait_outgoing_item returning TRUE even if
> the item was not sent as required.

As usual, I'd rework a bit the commit log (more punctuation/new lines, more
accurate references to typenames/variable names, ..):

"Currently, red_channel_client_wait_pipe_item_sent() inserts a MarkerItem which
will sent before the item we want to wait for: the tail of the queue is
the first item to send, and the function uses
red_channel_client_pipe_add_before_pos(). Then, if the marker has been
successfully sent, the function calls red_channel_client_wait_outgoing_item
to wait for 'item' to be sent.

Instead of doing this, we can add the MarkerItem to the queue so that
it's sent after 'item' (ie, insert it _before_ 'item' in the queue).
This way, when the marker is marked as having been sent, we'll also know
that 'item' has been sent.

This avoids having to call red_channel_client_wait_outgoing_item
and possibly the case where the item was not queued and
red_channel_client_wait_outgoing_item returning TRUE even if
the item was not sent as required."

I believe the way this function works now is a result of the last hunk of
https://cgit.freedesktop.org/spice/spice/commit/?id=c59b2884a2f7fc953fdb263085830b65e8bdcaef
+ the introduction of MarkerItem (I guess when switching to using a
GQueue).

Acked-by: Christophe Fergeau <cfergeau at redhat.com>

Christophe

> Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> ---
>  server/red-channel-client.c | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/server/red-channel-client.c b/server/red-channel-client.c
> index f0a25ecfd..d9333ba6f 100644
> --- a/server/red-channel-client.c
> +++ b/server/red-channel-client.c
> @@ -1569,6 +1569,19 @@ void red_channel_client_pipe_add_after_pos(RedChannelClient *rcc,
>      g_queue_insert_after(&rcc->priv->pipe, pipe_item_pos, item);
>  }
>  
> +static void
> +red_channel_client_pipe_add_before_pos(RedChannelClient *rcc,
> +                                       RedPipeItem *item,
> +                                       GList *pipe_item_pos)
> +{
> +    spice_assert(pipe_item_pos);
> +    if (!prepare_pipe_add(rcc, item)) {
> +        return;
> +    }
> +
> +    g_queue_insert_before(&rcc->priv->pipe, pipe_item_pos, item);
> +}
> +
>  void red_channel_client_pipe_add_after(RedChannelClient *rcc,
>                                         RedPipeItem *item,
>                                         RedPipeItem *pos)
> @@ -1779,7 +1792,7 @@ bool red_channel_client_wait_pipe_item_sent(RedChannelClient *rcc,
>      red_pipe_item_init(&mark_item->base, RED_PIPE_ITEM_TYPE_MARKER);
>      mark_item->item_in_pipe = true;
>      red_pipe_item_ref(&mark_item->base);
> -    red_channel_client_pipe_add_after_pos(rcc, &mark_item->base, item_pos);
> +    red_channel_client_pipe_add_before_pos(rcc, &mark_item->base, item_pos);
>  
>      for (;;) {
>          red_channel_client_receive(rcc);
> @@ -1799,10 +1812,8 @@ bool red_channel_client_wait_pipe_item_sent(RedChannelClient *rcc,
>          // still on the queue
>          spice_warning("timeout");
>          return FALSE;
> -    } else {
> -        return red_channel_client_wait_outgoing_item(rcc,
> -                                                     timeout == -1 ? -1 : end_time - spice_get_monotonic_time_ns());
>      }
> +    return TRUE;
>  }
>  
>  bool red_channel_client_wait_outgoing_item(RedChannelClient *rcc,
> -- 
> 2.13.5
> 
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