Add a pg_lsn data type, to represent an LSN.

Robert Haas and Michael Paquier

1 files changed, 180 insertions, 0 deletions

diff --git a/src/backend/utils/adt/pg_lsn.c b/src/backend/utils/adt/pg_lsn.c
new file mode 100644
index 00000000000..39e22931362
--- /dev/null
+++ b/src/backend/utils/adt/pg_lsn.c
@@ -0,0 +1,180 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_lsn.c
+ *	  Internal PostgreSQL LSN operations
+ *
+ * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/adt/pg_lsn.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "funcapi.h"
+#include "libpq/pqformat.h"
+#include "utils/builtins.h"
+#include "utils/pg_lsn.h"
+
+#define MAXPG_LSNLEN			17
+#define MAXPG_LSNCOMPONENT	8
+
+/*----------------------------------------------------------
+ * Formatting and conversion routines.
+ *---------------------------------------------------------*/
+
+Datum
+pg_lsn_in(PG_FUNCTION_ARGS)
+{
+	char	   *str = PG_GETARG_CSTRING(0);
+	int			len1, len2;
+	uint32		id, off;
+	XLogRecPtr	result;
+
+	/* Sanity check input format. */
+	len1 = strspn(str, "0123456789abcdefABCDEF");
+	if (len1 < 1 || len1 > MAXPG_LSNCOMPONENT || str[len1] != '/')
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
+				 errmsg("invalid input syntax for transaction log location: \"%s\"", str)));
+	len2 = strspn(str + len1 + 1, "0123456789abcdefABCDEF");
+	if (len2 < 1 || len2 > MAXPG_LSNCOMPONENT || str[len1 + 1 + len2] != '\0')
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
+				 errmsg("invalid input syntax for transaction log location: \"%s\"", str)));
+
+	/* Decode result. */
+	id = (uint32) strtoul(str, NULL, 16);
+	off = (uint32) strtoul(str + len1 + 1, NULL, 16);
+	result = (XLogRecPtr) ((uint64) id << 32) | off;
+
+	PG_RETURN_PG_LSN(result);
+}
+
+Datum
+pg_lsn_out(PG_FUNCTION_ARGS)
+{
+	XLogRecPtr	lsn = (XLogRecPtr) PG_GETARG_PG_LSN(0);
+	char		buf[MAXPG_LSNLEN + 1];
+	char	   *result;
+	uint32		id, off;
+
+	/* Decode ID and offset */
+	id = (uint32) (lsn >> 32);
+	off = (uint32) lsn;
+
+	snprintf(buf, sizeof buf, "%X/%X", id, off);
+	result = pstrdup(buf);
+	PG_RETURN_CSTRING(result);
+}
+
+Datum
+pg_lsn_recv(PG_FUNCTION_ARGS)
+{
+	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);
+	XLogRecPtr	result;
+
+	result = pq_getmsgint64(buf);
+	PG_RETURN_PG_LSN(result);
+}
+
+Datum
+pg_lsn_send(PG_FUNCTION_ARGS)
+{
+	XLogRecPtr lsn = (XLogRecPtr) PG_GETARG_PG_LSN(0);
+	StringInfoData buf;
+
+	pq_begintypsend(&buf);
+	pq_sendint64(&buf, lsn);
+	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
+}
+
+
+/*----------------------------------------------------------
+ *	Operators for PostgreSQL LSNs
+ *---------------------------------------------------------*/
+
+Datum
+pg_lsn_eq(PG_FUNCTION_ARGS)
+{
+	XLogRecPtr lsn1 = (XLogRecPtr) PG_GETARG_PG_LSN(0);
+	XLogRecPtr lsn2 = (XLogRecPtr) PG_GETARG_PG_LSN(1);
+
+	PG_RETURN_BOOL(lsn1 == lsn2);
+}
+
+Datum
+pg_lsn_ne(PG_FUNCTION_ARGS)
+{
+	XLogRecPtr lsn1 = (XLogRecPtr) PG_GETARG_PG_LSN(0);
+	XLogRecPtr lsn2 = (XLogRecPtr) PG_GETARG_PG_LSN(1);
+
+	PG_RETURN_BOOL(lsn1 != lsn2);
+}
+
+Datum
+pg_lsn_lt(PG_FUNCTION_ARGS)
+{
+	XLogRecPtr lsn1 = (XLogRecPtr) PG_GETARG_PG_LSN(0);
+	XLogRecPtr lsn2 = (XLogRecPtr) PG_GETARG_PG_LSN(1);
+
+	PG_RETURN_BOOL(lsn1 < lsn2);
+}
+
+Datum
+pg_lsn_gt(PG_FUNCTION_ARGS)
+{
+	XLogRecPtr lsn1 = (XLogRecPtr) PG_GETARG_PG_LSN(0);
+	XLogRecPtr lsn2 = (XLogRecPtr) PG_GETARG_PG_LSN(1);
+
+	PG_RETURN_BOOL(lsn1 > lsn2);
+}
+
+Datum
+pg_lsn_le(PG_FUNCTION_ARGS)
+{
+	XLogRecPtr lsn1 = (XLogRecPtr) PG_GETARG_PG_LSN(0);
+	XLogRecPtr lsn2 = (XLogRecPtr) PG_GETARG_PG_LSN(1);
+
+	PG_RETURN_BOOL(lsn1 <= lsn2);
+}
+
+Datum
+pg_lsn_ge(PG_FUNCTION_ARGS)
+{
+	XLogRecPtr lsn1 = (XLogRecPtr) PG_GETARG_PG_LSN(0);
+	XLogRecPtr lsn2 = (XLogRecPtr) PG_GETARG_PG_LSN(1);
+
+	PG_RETURN_BOOL(lsn1 >= lsn2);
+}
+
+
+/*----------------------------------------------------------
+ *	Arithmetic operators on PostgreSQL LSNs.
+ *---------------------------------------------------------*/
+
+Datum
+pg_lsn_mi(PG_FUNCTION_ARGS)
+{
+	XLogRecPtr lsn1 = (XLogRecPtr) PG_GETARG_PG_LSN(0);
+	XLogRecPtr lsn2 = (XLogRecPtr) PG_GETARG_PG_LSN(1);
+	char		buf[256];
+	Datum		result;
+
+	/* Negative results are not allowed. */
+	if (lsn1 < lsn2)
+		ereport(ERROR,
+				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
+				 errmsg("transaction log location out of range")));
+
+	/* Convert to numeric. */
+	snprintf(buf, sizeof buf, UINT64_FORMAT, lsn1 - lsn2);
+	result = DirectFunctionCall3(numeric_in,
+								 CStringGetDatum(buf),
+								 ObjectIdGetDatum(0),
+								 Int32GetDatum(-1));
+
+	return result;
+}