Datum
spoof_next_xid(PG_FUNCTION_ARGS)
{
TransactionId desiredXid = PG_GETARG_UINT32(0);
TransactionId oldXid = ShmemVariableCache->nextXid;
ShmemVariableCache->nextXid = desiredXid;
/*
* If we're raising the xid, the intent is presumably to cross some
* threshold and make assertions about expected behavior.
* On the other hand, lowering the xid is meant to be a tear down of
* a completed test case. Because of this distinction, only when
* we're raising the xid, do we take extra precaution to zero out
* the new pg_clog/pg_subtrans/pg_distributedlog files. (We don't
* want to zero out existing files...)
*/
if (TransactionIdFollows(desiredXid, oldXid))
{
/*
* The nature of xid arithmetic is such that we only bother zeroing out
* new pages of transaction files when we've crossed page boundaries.
* So, here we fool the following routines into zeroing out the desired
* pages of transaction metadata by lowering the input xid to the first
* of its corresponding page.
*/
#define CLOG_XACTS_PER_BYTE 4
#define CLOG_XACTS_PER_PAGE (BLCKSZ * CLOG_XACTS_PER_BYTE)
#define TransactionIdToPgIndex(xid) ((xid) % (TransactionId) CLOG_XACTS_PER_PAGE)
ExtendCLOG(desiredXid - TransactionIdToPgIndex(desiredXid));
#define SUBTRANS_XACTS_PER_PAGE (BLCKSZ / sizeof(SubTransData))
#define TransactionIdToEntry(xid) ((xid) % (uint32) SUBTRANS_XACTS_PER_PAGE)
ExtendSUBTRANS(desiredXid - TransactionIdToEntry(desiredXid));
#undef TransactionIdToEntry
#define ENTRIES_PER_PAGE (BLCKSZ / sizeof(DistributedLogEntry))
#define TransactionIdToEntry(localXid) ((localXid) % (TransactionId) ENTRIES_PER_PAGE)
DistributedLog_Extend(desiredXid - TransactionIdToEntry(desiredXid));
}
PG_RETURN_XID(oldXid);
}
Datum
gp_distributed_xid(PG_FUNCTION_ARGS __attribute__((unused)) )
{
PG_RETURN_XID(InvalidDistributedTransactionId);
}
Datum
get_wrap_limit(PG_FUNCTION_ARGS)
{
PG_RETURN_XID(ShmemVariableCache->xidWrapLimit);
}
Datum
get_vac_limit(PG_FUNCTION_ARGS)
{
PG_RETURN_XID(ShmemVariableCache->xidVacLimit);
}
Datum
get_next_xid(PG_FUNCTION_ARGS)
{
PG_RETURN_XID(ShmemVariableCache->nextXid);
}
Datum
get_oldest_xid(PG_FUNCTION_ARGS)
{
PG_RETURN_XID(ShmemVariableCache->oldestXid);
}
