Re: Using read stream in autoprewarm

Hi,

Thanks for looking into this!

On Thu, 31 Oct 2024 at 21:18, Andrey M. Borodin <x4mmm(at)yandex-team(dot)ru> wrote:
>
> > On 8 Aug 2024, at 11:32, Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com> wrote:
> >
> > Any feedback would be appreciated.
>
> I've took a look into the patch. It seems to me that you add new block numbers to the read stream until you have buffers. So when there are no more buffers you will still have some queued blocks.
> Maybe can you change the logic so that number of free buffers must be enough to allocate all blocks in look-ahead distance?

I see what you mean. When the have_free_buffer() function returns
false in the callback, there are still queued blocks in the stream
although there are no free buffers in the buffer pool. I think the
best way to solve this is to get the number of free buffers in the
buffer pool by 'BufferStrategyControl.lastFreeBuffer -
BufferStrategyControl.firstFreeBuffer' and then compare it with
'stream->pending_read_nblocks'. When the 'stream->pending_read_nblocks
== number_of_free_buffers_in_buffer_pool', end the stream. The problem
with that is stream->pending_read_nblocks isn't public, also I am not
sure whether 'BufferStrategyControl.lastFreeBuffer -
BufferStrategyControl.firstFreeBuffer' is safe to use.

--
Regards,
Nazir Bilal Yavuz
Microsoft