[Spice-devel] [server] streaming: Don't start streaming if there is no video encoder

[Uri Lublin]

On 07/25/2016 07:37 PM, Francois Gouget wrote:
> On Sun, 24 Jul 2016, Uri Lublin wrote:
> [...]
>> This patch prevents a crash as few lines below there is access
>> to agent->video_encoder->codec_type.
>>
>> I think it would be better to make the check it in
>> dcc_create_stream(), and replace the patch here to assert.
>
> I think it makes more sense to have it this way.
>
> Even if we fail in dcc_create_stream() the server will still keep
> detecting screen updates that look like a video. Without a corresponding
> stream, each time it will and try to create one and fail. Each attempt
> will waste time attempting to create not only the stream object itself,
> but potentially also the video encoder object[1].
>
> So it's better to keep the corresponding stream object around and skip
> attempts to recreate it.

No need to fail dcc_create_stream, just skip adding
the item to the pipe in such a case.
There is no point of adding an item of type
RED_PIPE_ITEM_TYPE_STREAM_CREATE to the pipe
just to ignore it later.

Theoretically, in such a scenario there is no need to
detect streams at all but that's a bigger change.

Anyway, the patch is good and does prevent a crash, so
ack from me.

Uri.