Horton

Re: Large writable variables

Andres Freund <andres@anarazel.de>

View thread View on postgr.es
From: Andres Freund <andres@anarazel.de>
To: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Cc: pgsql-hackers@postgresql.org, Thomas Munro <thomas.munro@enterprisedb.com>
Date: 2018-10-18T20:29:39Z
Lists: pgsql-hackers 
On 2018-10-18 22:20:29 +0200, Peter Eisentraut wrote:
> On 18/10/2018 22:17, Peter Eisentraut wrote:
> > On 17/10/2018 23:51, Andres Freund wrote:
> >>> __builtin_types_compatible_p(const char *, char *) returns false (0) for me.
> >>
> >> Right, that's why I added a const, inside the macro,  to the type
> >> specified in the unconstify argument. So typeof() yields a const char *,
> >> and the return type is specified as char *, and adding a const in the
> >> argument also yields a const char *.
> >
> > Yeah, that works.  The C++-inspired version also allowed casting from
> > not-const to const, which we don't really need.
>
> > Attached is my previous patch adapted to your macro.
>
> Oh, I forgot to mention, your version doesn't work for this code in
> pqexpbuffer.c:
>
>     str->data = (char *) oom_buffer;

That kind of seems correct ;). Can easily be done via unconstify(char *,
&oom_buffer[0]), if necessary.

> That's probably not a big deal though.

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.