Re: Reducing the chunk header sizes on all memory context types

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: David Rowley <dgrowleyml(at)gmail(dot)com>
Cc: Andres Freund <andres(at)anarazel(dot)de>, Julien Rouhaud <rjuju123(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Yura Sokolov <y(dot)sokolov(at)postgrespro(dot)ru>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Reducing the chunk header sizes on all memory context types
Date: 2022-10-06 18:19:21
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One more thing: based on what I saw in working with my pending guc.c
changes, the assertions in GetMemoryChunkMethodID are largely useless
for detecting bogus pointers. I think we should do something more
like the attached, which will result in a clean failure if the method
ID bits are invalid.

I'm a little tempted also to rearrange the MemoryContextMethodID enum
so that likely bit patterns like 000 are not valid IDs.

While I didn't change it here, I wonder why GetMemoryChunkMethodID is
publicly exposed at all. AFAICS it could be static inside mcxt.c.

regards, tom lane

Attachment Content-Type Size
more-mcxt-robustness-1.patch text/x-diff 4.9 KB

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