1 files changed, 413 insertions, 0 deletions
diff --git a/src/backend/access/hash/hashfunc.c b/src/backend/access/hash/hashfunc.c
new file mode 100644
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--- /dev/null
+++ b/src/backend/access/hash/hashfunc.c
@@ -0,0 +1,413 @@
+/*-------------------------------------------------------------------------
+ *
+ * hashfunc.c
+ *	  Support functions for hash access method.
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/hash/hashfunc.c
+ *
+ * NOTES
+ *	  These functions are stored in pg_amproc.  For each operator class
+ *	  defined for hash indexes, they compute the hash value of the argument.
+ *
+ *	  Additional hash functions appear in /utils/adt/ files for various
+ *	  specialized datatypes.
+ *
+ *	  It is expected that every bit of a hash function's 32-bit result is
+ *	  as random as every other; failure to ensure this is likely to lead
+ *	  to poor performance of hash joins, for example.  In most cases a hash
+ *	  function should use hash_any() or its variant hash_uint32().
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/hash.h"
+#include "catalog/pg_collation.h"
+#include "common/hashfn.h"
+#include "utils/builtins.h"
+#include "utils/float.h"
+#include "utils/pg_locale.h"
+
+/*
+ * Datatype-specific hash functions.
+ *
+ * These support both hash indexes and hash joins.
+ *
+ * NOTE: some of these are also used by catcache operations, without
+ * any direct connection to hash indexes.  Also, the common hash_any
+ * routine is also used by dynahash tables.
+ */
+
+/* Note: this is used for both "char" and boolean datatypes */
+Datum
+hashchar(PG_FUNCTION_ARGS)
+{
+	return hash_uint32((int32) PG_GETARG_CHAR(0));
+}
+
+Datum
+hashcharextended(PG_FUNCTION_ARGS)
+{
+	return hash_uint32_extended((int32) PG_GETARG_CHAR(0), PG_GETARG_INT64(1));
+}
+
+Datum
+hashint2(PG_FUNCTION_ARGS)
+{
+	return hash_uint32((int32) PG_GETARG_INT16(0));
+}
+
+Datum
+hashint2extended(PG_FUNCTION_ARGS)
+{
+	return hash_uint32_extended((int32) PG_GETARG_INT16(0), PG_GETARG_INT64(1));
+}
+
+Datum
+hashint4(PG_FUNCTION_ARGS)
+{
+	return hash_uint32(PG_GETARG_INT32(0));
+}
+
+Datum
+hashint4extended(PG_FUNCTION_ARGS)
+{
+	return hash_uint32_extended(PG_GETARG_INT32(0), PG_GETARG_INT64(1));
+}
+
+Datum
+hashint8(PG_FUNCTION_ARGS)
+{
+	/*
+	 * The idea here is to produce a hash value compatible with the values
+	 * produced by hashint4 and hashint2 for logically equal inputs; this is
+	 * necessary to support cross-type hash joins across these input types.
+	 * Since all three types are signed, we can xor the high half of the int8
+	 * value if the sign is positive, or the complement of the high half when
+	 * the sign is negative.
+	 */
+	int64		val = PG_GETARG_INT64(0);
+	uint32		lohalf = (uint32) val;
+	uint32		hihalf = (uint32) (val >> 32);
+
+	lohalf ^= (val >= 0) ? hihalf : ~hihalf;
+
+	return hash_uint32(lohalf);
+}
+
+Datum
+hashint8extended(PG_FUNCTION_ARGS)
+{
+	/* Same approach as hashint8 */
+	int64		val = PG_GETARG_INT64(0);
+	uint32		lohalf = (uint32) val;
+	uint32		hihalf = (uint32) (val >> 32);
+
+	lohalf ^= (val >= 0) ? hihalf : ~hihalf;
+
+	return hash_uint32_extended(lohalf, PG_GETARG_INT64(1));
+}
+
+Datum
+hashoid(PG_FUNCTION_ARGS)
+{
+	return hash_uint32((uint32) PG_GETARG_OID(0));
+}
+
+Datum
+hashoidextended(PG_FUNCTION_ARGS)
+{
+	return hash_uint32_extended((uint32) PG_GETARG_OID(0), PG_GETARG_INT64(1));
+}
+
+Datum
+hashenum(PG_FUNCTION_ARGS)
+{
+	return hash_uint32((uint32) PG_GETARG_OID(0));
+}
+
+Datum
+hashenumextended(PG_FUNCTION_ARGS)
+{
+	return hash_uint32_extended((uint32) PG_GETARG_OID(0), PG_GETARG_INT64(1));
+}
+
+Datum
+hashfloat4(PG_FUNCTION_ARGS)
+{
+	float4		key = PG_GETARG_FLOAT4(0);
+	float8		key8;
+
+	/*
+	 * On IEEE-float machines, minus zero and zero have different bit patterns
+	 * but should compare as equal.  We must ensure that they have the same
+	 * hash value, which is most reliably done this way:
+	 */
+	if (key == (float4) 0)
+		PG_RETURN_UINT32(0);
+
+	/*
+	 * To support cross-type hashing of float8 and float4, we want to return
+	 * the same hash value hashfloat8 would produce for an equal float8 value.
+	 * So, widen the value to float8 and hash that.  (We must do this rather
+	 * than have hashfloat8 try to narrow its value to float4; that could fail
+	 * on overflow.)
+	 */
+	key8 = key;
+
+	/*
+	 * Similarly, NaNs can have different bit patterns but they should all
+	 * compare as equal.  For backwards-compatibility reasons we force them to
+	 * have the hash value of a standard float8 NaN.  (You'd think we could
+	 * replace key with a float4 NaN and then widen it; but on some old
+	 * platforms, that way produces a different bit pattern.)
+	 */
+	if (isnan(key8))
+		key8 = get_float8_nan();
+
+	return hash_any((unsigned char *) &key8, sizeof(key8));
+}
+
+Datum
+hashfloat4extended(PG_FUNCTION_ARGS)
+{
+	float4		key = PG_GETARG_FLOAT4(0);
+	uint64		seed = PG_GETARG_INT64(1);
+	float8		key8;
+
+	/* Same approach as hashfloat4 */
+	if (key == (float4) 0)
+		PG_RETURN_UINT64(seed);
+	key8 = key;
+	if (isnan(key8))
+		key8 = get_float8_nan();
+
+	return hash_any_extended((unsigned char *) &key8, sizeof(key8), seed);
+}
+
+Datum
+hashfloat8(PG_FUNCTION_ARGS)
+{
+	float8		key = PG_GETARG_FLOAT8(0);
+
+	/*
+	 * On IEEE-float machines, minus zero and zero have different bit patterns
+	 * but should compare as equal.  We must ensure that they have the same
+	 * hash value, which is most reliably done this way:
+	 */
+	if (key == (float8) 0)
+		PG_RETURN_UINT32(0);
+
+	/*
+	 * Similarly, NaNs can have different bit patterns but they should all
+	 * compare as equal.  For backwards-compatibility reasons we force them to
+	 * have the hash value of a standard NaN.
+	 */
+	if (isnan(key))
+		key = get_float8_nan();
+
+	return hash_any((unsigned char *) &key, sizeof(key));
+}
+
+Datum
+hashfloat8extended(PG_FUNCTION_ARGS)
+{
+	float8		key = PG_GETARG_FLOAT8(0);
+	uint64		seed = PG_GETARG_INT64(1);
+
+	/* Same approach as hashfloat8 */
+	if (key == (float8) 0)
+		PG_RETURN_UINT64(seed);
+	if (isnan(key))
+		key = get_float8_nan();
+
+	return hash_any_extended((unsigned char *) &key, sizeof(key), seed);
+}
+
+Datum
+hashoidvector(PG_FUNCTION_ARGS)
+{
+	oidvector  *key = (oidvector *) PG_GETARG_POINTER(0);
+
+	return hash_any((unsigned char *) key->values, key->dim1 * sizeof(Oid));
+}
+
+Datum
+hashoidvectorextended(PG_FUNCTION_ARGS)
+{
+	oidvector  *key = (oidvector *) PG_GETARG_POINTER(0);
+
+	return hash_any_extended((unsigned char *) key->values,
+							 key->dim1 * sizeof(Oid),
+							 PG_GETARG_INT64(1));
+}
+
+Datum
+hashname(PG_FUNCTION_ARGS)
+{
+	char	   *key = NameStr(*PG_GETARG_NAME(0));
+
+	return hash_any((unsigned char *) key, strlen(key));
+}
+
+Datum
+hashnameextended(PG_FUNCTION_ARGS)
+{
+	char	   *key = NameStr(*PG_GETARG_NAME(0));
+
+	return hash_any_extended((unsigned char *) key, strlen(key),
+							 PG_GETARG_INT64(1));
+}
+
+Datum
+hashtext(PG_FUNCTION_ARGS)
+{
+	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t mylocale = 0;
+	Datum		result;
+
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (!lc_collate_is_c(collid))
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any((unsigned char *) VARDATA_ANY(key),
+						  VARSIZE_ANY_EXHDR(key));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t    *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+			pfree(uchar);
+
+			result = hash_any(buf, bsize);
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
+
+	/* Avoid leaking memory for toasted inputs */
+	PG_FREE_IF_COPY(key, 0);
+
+	return result;
+}
+
+Datum
+hashtextextended(PG_FUNCTION_ARGS)
+{
+	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t mylocale = 0;
+	Datum		result;
+
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (!lc_collate_is_c(collid))
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
+								   VARSIZE_ANY_EXHDR(key),
+								   PG_GETARG_INT64(1));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t    *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+			pfree(uchar);
+
+			result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
+
+	PG_FREE_IF_COPY(key, 0);
+
+	return result;
+}
+
+/*
+ * hashvarlena() can be used for any varlena datatype in which there are
+ * no non-significant bits, ie, distinct bitpatterns never compare as equal.
+ */
+Datum
+hashvarlena(PG_FUNCTION_ARGS)
+{
+	struct varlena *key = PG_GETARG_VARLENA_PP(0);
+	Datum		result;
+
+	result = hash_any((unsigned char *) VARDATA_ANY(key),
+					  VARSIZE_ANY_EXHDR(key));
+
+	/* Avoid leaking memory for toasted inputs */
+	PG_FREE_IF_COPY(key, 0);
+
+	return result;
+}
+
+Datum
+hashvarlenaextended(PG_FUNCTION_ARGS)
+{
+	struct varlena *key = PG_GETARG_VARLENA_PP(0);
+	Datum		result;
+
+	result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
+							   VARSIZE_ANY_EXHDR(key),
+							   PG_GETARG_INT64(1));
+
+	PG_FREE_IF_COPY(key, 0);
+
+	return result;
+}