Revert refactoring of hex code to src/common/

This is a combined revert of the following commits:
- c3826f8, a refactoring piece that moved the hex decoding code to
src/common/.  This code was cleaned up by aef8948, as it originally
included no overflow checks in the same way as the base64 routines in
src/common/ used by SCRAM, making it unsafe for its purpose.
- aef8948, a more advanced refactoring of the hex encoding/decoding code
to src/common/ that added sanity checks on the result buffer for hex
decoding and encoding.  As reported by Hans Buschmann, those overflow
checks are expensive, and it is possible to see a performance drop in
the decoding/encoding of bytea or LOs the longer they are.  Simple SQLs
working on large bytea values show a clear difference in perf profile.
- ccf4e27, a cleanup made possible by aef8948.

The reverts of all those commits bring back the performance of hex
decoding and encoding back to what it was in ~13.  Fow now and
post-beta3, this is the simplest option.

Reported-by: Hans Buschmann
Discussion: https://postgr.es/m/1629039545467.80333@nidsa.net
Backpatch-through: 14

1 files changed, 4 insertions, 0 deletions

diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index f3ce4fb1739..40fcb0ab6d7 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -31,6 +31,10 @@ extern void domain_check(Datum value, bool isnull, Oid domainType,
 extern int	errdatatype(Oid datatypeOid);
 extern int	errdomainconstraint(Oid datatypeOid, const char *conname);
 
+/* encode.c */
+extern uint64 hex_encode(const char *src, size_t len, char *dst);
+extern uint64 hex_decode(const char *src, size_t len, char *dst);
+
 /* int.c */
 extern int2vector *buildint2vector(const int16 *int2s, int n);