Horton

Re: Large writable variables

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@postgresql.org
Date: 2018-10-16T04:12:40Z
Lists: pgsql-hackers

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Hi,

On 2018-10-15 16:45:03 -0700, Andres Freund wrote:
> I've a patch making .data variables constant, fwiw. Will post in a
> bit. Just so we don't duplicate work too much.

I pushed a few very obvious ones.

An additional fix, for the system attributes in heap.c, is attached. But
that's a bit more invasive, so I wanted to get some input.

I think all of the changes are fairly obvious and the new const
attributes just document what already had to be the case.  But to
correctly propagate the const through typedef-the-pointer-away typedefs,
I had to use the underlying type (e.g. use const NameData *n2 instad of
Name n2). To me that's the correct fix, but then I hate these typedefs
with a passion anyway.  An alternative fix is to add additional
typedefs like ConstName, but I don't find that particularly
advantageous.

Comments?

Arguably we should use consts more aggresively in signatures anyway, but
I think that's a separate effort.

Greetings,

Andres Freund

Commits

  1. Apply unconstify() in more places

  2. Improve unconstify() documentation

  3. Drop const cast from dlsym() calls

  4. Const-ify a few more large static tables.

  5. Improve tzparse's handling of TZDEFRULES ("posixrules") zone data.

  6. Avoid statically allocating statement cache in ecpglib/prepare.c.

  7. Reorder FmgrBuiltin members, saving 25% in size.

  8. Add macro to cast away const without allowing changes to underlying type.

  9. Mark constantly allocated dest receiver as const.

  10. Avoid statically allocating formatting.c's format string caches.

  11. Correct constness of system attributes in heap.c & prerequisites.

  12. Avoid statically allocating gmtsub()'s timezone workspace.

  13. Correct constness of a few variables.

  14. Move the replication lag tracker into heap memory.