Function VIO_intermediate_gc

src/jrd/vio.cpp:2555–2779

void VIO_intermediate_gc(thread_db* tdbb, record_param* rpb, jrd_tra* transaction)
{
/**************************************
 *
 *	V I O _ i n t e r m e d i a t e _ g c
 *
 **************************************
 *
 * Functional description
 *  Garbage-collect committed versions that are not needed for anyone.
 *  This function shall be called with active RPB, and exits with inactive RPB
 *
 **************************************/
	Database *dbb = tdbb->getDatabase();
	Attachment* att = tdbb->getAttachment();

	// If current record is not a primary version, release it and fetch primary version
	if (rpb->rpb_flags & rpb_chained)
	{
		CCH_RELEASE(tdbb, &rpb->getWindow(tdbb));
		if (!DPM_get(tdbb, rpb, LCK_read))
			return;
	}

	// If head version is being backed out - do not interfere with this process
	if (rpb->rpb_flags & rpb_gc_active)
	{
		CCH_RELEASE(tdbb, &rpb->getWindow(tdbb));
		return;
	}

	// Read data for all versions of a record
	RecordStack staying, going;
	list_staying(tdbb, rpb, staying, LS_ACTIVE_RPB | LS_NO_RESTART);

	// We can only garbage collect here if there is more than one version of a record
	if (!staying.hasMore(1))
	{
		clearRecordStack(staying);
		return;
	}

#ifdef VIO_DEBUG
	VIO_trace(DEBUG_TRACE,
		"VIO_intermediate_gc (record_param %" SQUADFORMAT", transaction %"
		SQUADFORMAT")\n",
		rpb->rpb_number.getValue(), transaction ? transaction->tra_number : 0);

	VIO_trace(DEBUG_TRACE_INFO,
		"   record  %" SLONGFORMAT":%d, rpb_trans %" SQUADFORMAT
		", flags %d, back %" SLONGFORMAT":%d, fragment %" SLONGFORMAT":%d\n",
		rpb->rpb_page, rpb->rpb_line, rpb->rpb_transaction_nr,
		rpb->rpb_flags, rpb->rpb_b_page, rpb->rpb_b_line,
		rpb->rpb_f_page, rpb->rpb_f_line);
#endif

	TipCache* tipCache = dbb->dbb_tip_cache;
	tipCache->updateActiveSnapshots(tdbb, &att->att_active_snapshots);