[FFmpeg-devel] [RFC][PATCH 18/18] avcodec/avpacket: make the AVPacketList API thread safe

[Marton Balint]

On Wed, 18 Nov 2020, James Almer wrote:

> On 11/18/2020 5:08 PM, Marton Balint wrote:
>> 
>> 
>> On Wed, 18 Nov 2020, James Almer wrote:
>> 
>>> Signed-off-by: James Almer <jamrial at gmail.com>
>>> ---
>>> I don't know if this is necessary, so i'm sending it as an RFC.
>> 
>> I don't think this API should provide locking by default, maybe as an 
>> option. But considering that it was not often needed so far, and the API 
>> can be wrapped into locked versions (like decklink does) relatively 
>> easily, I think it is fine as is.
>
> My worry was adding a linked list public API that's not thread safe.
>
> The other example we have is AVBufferPool, which does locking 
> unconditionally by itself before adding or removing elements from the 
> list, so it's valid to assume this one should maybe do the same.

AVBufferPool has to be thread safe because the AVBufferRef free function 
has to be thread safe as well.

Maybe a better example is av_fifo_generic_read/write which is not thread 
safe... Do you know if the overhead of making this thread safe is 
significant/measureable? Because obviously that is my primary concern.

Thanks,
Marton