Re: Streaming I/O, vectored I/O (WIP)

Hi,

On Sat, 16 Mar 2024 at 02:53, Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
>
> I am planning to push the bufmgr.c patch soon. At that point the new
> API won't have any direct callers yet, but the traditional
> ReadBuffer() family of functions will internally reach
> StartReadBuffers(nblocks=1) followed by WaitReadBuffers(),
> ZeroBuffer() or nothing as appropriate. Any more thoughts or
> objections? Naming, semantics, correctness of buffer protocol,
> sufficiency of comments, something else?

+ if (StartReadBuffers(bmr,
+ &buffer,
+ forkNum,
+ blockNum,
+ &nblocks,
+ strategy,
+ flags,
+ &operation))
+ WaitReadBuffers(&operation);

I think we need to call WaitReadBuffers when 'mode !=
RBM_ZERO_AND_CLEANUP_LOCK && mode != RBM_ZERO_AND_LOCK' or am I
missing something?

Couple of nitpicks:

It would be nice to explain what the PrepareReadBuffer function does
with a comment.

+ if (nblocks == 0)
+ return; /* nothing to do */
It is guaranteed that nblocks will be bigger than 0. Can't we just use
Assert(operation->io_buffers_len > 0);?

--
Regards,
Nazir Bilal Yavuz
Microsoft