Re: [proposal] de-TOAST'ing using a iterator

Hi John,

> >> Also, I don't think
> >> the new logic for the ctrl/c variables is an improvement:
> >>
> >> 1. iter->ctrlc is intialized with '8' (even in the uncompressed case,
> >> which is confusing). Any time you initialize with something not 0 or
> >> 1, it's a magic number, and here it's far from where the loop variable
> >> is used. This is harder to read.
> >
> > `iter->ctrlc` is used to record the value of `ctrl` in pglz_decompress
> at the end of
> > the last iteration(or loop). In the pglz_decompress, `ctrlc`’s valid
> value is 0~7,
> > When `ctrlc` reaches 8,  a control byte is read from the source
> > buffer to `ctrl` then set `ctrlc` to 0. And a control bytes should be
> read from the
> > source buffer to `ctrlc` on the first iteration. So `iter->ctrlc` should
> be intialized with '8'.
>
> My point here is it looks strange out of context, but "0" looked
> normal. Maybe a comment in init_detoast_buffer(), something like "8
> means read a control byte from the source buffer on the first
> iteration, see pg_lzdecompress_iterate()".
>
> Or, possibly, we could have a macro like INVALID_CTRLC. That might
> even improve the readability of the original function. This is just an
> idea, and maybe others would disagree, so you don't need to change it
> for now.
>

All in all, the idea is much better than a magic number 8. So, I've
implemented it.


> At this point, there are no functional things that I think we need to
> change. It's close to ready-for-committer. For the next version, I'd
> like you go through the comments and edit for grammar, spelling, and
> clarity as you see fit. I know you're not a native speaker of English,
> so I can help you with anything that remains.


I've tried my best to improve the comments, but there should be room for
further improvement
I hope you can help me perfect it.


> Also note we use braces
> on their own lines
> {
>     like this
> }
>
> Done.
-- 
Best regards,
Binguo Bao