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/*-------------------------------------------------------------------------
*
* xid.c
* POSTGRES transaction identifier and command identifier datatypes.
*
* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/utils/adt/xid.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <limits.h>
#include "access/transam.h"
#include "access/xact.h"
#include "libpq/pqformat.h"
#include "utils/builtins.h"
#define PG_GETARG_TRANSACTIONID(n) DatumGetTransactionId(PG_GETARG_DATUM(n))
#define PG_RETURN_TRANSACTIONID(x) return TransactionIdGetDatum(x)
#define PG_GETARG_COMMANDID(n) DatumGetCommandId(PG_GETARG_DATUM(n))
#define PG_RETURN_COMMANDID(x) return CommandIdGetDatum(x)
Datum
xidin(PG_FUNCTION_ARGS)
{
char *str = PG_GETARG_CSTRING(0);
PG_RETURN_TRANSACTIONID((TransactionId) strtoul(str, NULL, 0));
}
Datum
xidout(PG_FUNCTION_ARGS)
{
TransactionId transactionId = PG_GETARG_TRANSACTIONID(0);
/* maximum 32 bit unsigned integer representation takes 10 chars */
char *str = palloc(11);
snprintf(str, 11, "%lu", (unsigned long) transactionId);
PG_RETURN_CSTRING(str);
}
/*
* xidrecv - converts external binary format to xid
*/
Datum
xidrecv(PG_FUNCTION_ARGS)
{
StringInfo buf = (StringInfo) PG_GETARG_POINTER(0);
PG_RETURN_TRANSACTIONID((TransactionId) pq_getmsgint(buf, sizeof(TransactionId)));
}
/*
* xidsend - converts xid to binary format
*/
Datum
xidsend(PG_FUNCTION_ARGS)
{
TransactionId arg1 = PG_GETARG_TRANSACTIONID(0);
StringInfoData buf;
pq_begintypsend(&buf);
pq_sendint(&buf, arg1, sizeof(arg1));
PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}
/*
* xideq - are two xids equal?
*/
Datum
xideq(PG_FUNCTION_ARGS)
{
TransactionId xid1 = PG_GETARG_TRANSACTIONID(0);
TransactionId xid2 = PG_GETARG_TRANSACTIONID(1);
PG_RETURN_BOOL(TransactionIdEquals(xid1, xid2));
}
/*
* xid_age - compute age of an XID (relative to current xact)
*/
Datum
xid_age(PG_FUNCTION_ARGS)
{
TransactionId xid = PG_GETARG_TRANSACTIONID(0);
TransactionId now = GetTopTransactionId();
/* Permanent XIDs are always infinitely old */
if (!TransactionIdIsNormal(xid))
PG_RETURN_INT32(INT_MAX);
PG_RETURN_INT32((int32) (now - xid));
}
/*
* xidComparator
* qsort comparison function for XIDs
*
* We can't use wraparound comparison for XIDs because that does not respect
* the triangle inequality! Any old sort order will do.
*/
int
xidComparator(const void *arg1, const void *arg2)
{
TransactionId xid1 = *(const TransactionId *) arg1;
TransactionId xid2 = *(const TransactionId *) arg2;
if (xid1 > xid2)
return 1;
if (xid1 < xid2)
return -1;
return 0;
}
/*****************************************************************************
* COMMAND IDENTIFIER ROUTINES *
*****************************************************************************/
/*
* cidin - converts CommandId to internal representation.
*/
Datum
cidin(PG_FUNCTION_ARGS)
{
char *s = PG_GETARG_CSTRING(0);
CommandId c;
c = atoi(s);
PG_RETURN_COMMANDID(c);
}
/*
* cidout - converts a cid to external representation.
*/
Datum
cidout(PG_FUNCTION_ARGS)
{
CommandId c = PG_GETARG_COMMANDID(0);
char *result = (char *) palloc(16);
snprintf(result, 16, "%u", (unsigned int) c);
PG_RETURN_CSTRING(result);
}
/*
* cidrecv - converts external binary format to cid
*/
Datum
cidrecv(PG_FUNCTION_ARGS)
{
StringInfo buf = (StringInfo) PG_GETARG_POINTER(0);
PG_RETURN_COMMANDID((CommandId) pq_getmsgint(buf, sizeof(CommandId)));
}
/*
* cidsend - converts cid to binary format
*/
Datum
cidsend(PG_FUNCTION_ARGS)
{
CommandId arg1 = PG_GETARG_COMMANDID(0);
StringInfoData buf;
pq_begintypsend(&buf);
pq_sendint(&buf, arg1, sizeof(arg1));
PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}
Datum
cideq(PG_FUNCTION_ARGS)
{
CommandId arg1 = PG_GETARG_COMMANDID(0);
CommandId arg2 = PG_GETARG_COMMANDID(1);
PG_RETURN_BOOL(arg1 == arg2);
}
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