From ad25c43c264c5857bf41cbf056ac7d4ab0995b40 Mon Sep 17 00:00:00 2001 From: John Naylor Date: Sun, 21 Jan 2024 17:49:22 +0700 Subject: [PATCH v15 3/4] Use fasthash for guc_name_hash --- src/backend/utils/misc/guc.c | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-) diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 8f65ef3d89..e76ab52618 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -33,6 +33,7 @@ #include "catalog/objectaccess.h" #include "catalog/pg_authid.h" #include "catalog/pg_parameter_acl.h" +#include "common/hashfn_unstable.h" #include "guc_internal.h" #include "libpq/pqformat.h" #include "parser/scansup.h" @@ -1324,22 +1325,34 @@ guc_name_compare(const char *namea, const char *nameb) static uint32 guc_name_hash(const void *key, Size keysize) { - uint32 result = 0; const char *name = *(const char *const *) key; + const char *const start = name; + fasthash_state hs; + + fasthash_init(&hs, 0); while (*name) { - char ch = *name++; + int chunk_len = 0; - /* Case-fold in the same way as guc_name_compare */ - if (ch >= 'A' && ch <= 'Z') - ch += 'a' - 'A'; + while (chunk_len < FH_SIZEOF_ACCUM && name[chunk_len] != '\0') + { + chunk_len++; + hs.accum <<= BITS_PER_BYTE; + hs.accum |= name[chunk_len]; + } - /* Merge into hash ... not very bright, but it needn't be */ - result = pg_rotate_left32(result, 5); - result ^= (uint32) ch; + /* Quick ASCII-only downcasing */ + hs.accum |= 0x2020202020202020; + + /* merge into hash and reset for next iteration */ + fasthash_combine(&hs); + hs.accum = 0; + + name += chunk_len; } - return result; + + return fasthash_final32(&hs, name - start); } /* -- 2.43.0