Horton

Re: Change GUC hashtable to use simplehash?

John Naylor <johncnaylorls@gmail.com>

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From: John Naylor <johncnaylorls@gmail.com>
To: "Anton A. Melnikov" <a.melnikov@postgrespro.ru>
Cc: Jeff Davis <pgsql@j-davis.com>, Ants Aasma <ants.aasma@cybertec.at>, Heikki Linnakangas <hlinnaka@iki.fi>, Junwang Zhao <zhjwpku@gmail.com>, jian he <jian.universality@gmail.com>, Andres Freund <andres@anarazel.de>, Tom Lane <tgl@sss.pgh.pa.us>, Gurjeet Singh <gurjeet@singh.im>, pgsql-hackers@postgresql.org
Date: 2024-12-19T09:48:27Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Silence warning in older versions of Valgrind

  2. Revert "Speed up tail processing when hashing aligned C strings, take two"

  3. Speed up tail processing when hashing aligned C strings, take two

  4. Teach fasthash_accum to use platform endianness for bytewise loads

  5. Add macro to disable address safety instrumentation

  6. Convert uses of hash_string_pointer to fasthash equivalent

  7. Speed up tail processing when hashing aligned C strings

  8. Add helper functions for dshash tables with string keys.

  9. Fix warnings in cpluspluscheck

  10. Further cosmetic review of hashfn_unstable.h

  11. Simplify initialization of incremental hash state

  12. Add optimized C string hashing

  13. Add inline incremental hash functions for in-memory use

  14. Make all Perl warnings fatal

I wrote:

> The offending code is not even my preferred way to handle the last
> word of the string (see f4ad0021af), so if the current way is still
> not valgrind-clean, I wonder if we should give up and add an
> exception, since we know any garbage bits are masked off.

That would actually be a maintenance headache because the function is
inlined, but here's a better idea: We already have a fallback path for
when the string is not suitably aligned, or in 32-bit builds. We could
just use that under Valgrind:

 static inline size_t
 fasthash_accum_cstring(fasthash_state *hs, const char *str)
 {
-#if SIZEOF_VOID_P >= 8
+#if SIZEOF_VOID_P >= 8 && !defined(USE_VALGRIND)

Any objections?

-- 
John Naylor
Amazon Web Services