Function buildWaitGraph

src/backend/utils/gdd/gddbackend.c:251–387

}

static void
buildWaitGraph(GddCtx *ctx)
{
	SPITupleTable *tuptable;
	TupleDesc	tupdesc;
	List		*gxids;
	bool		isnull;
	int			tuple_num;
	int			i;
	int         res;
	volatile bool connected = false;

	/*
	 * SPI_connect() will switch to SPI memory context
	 */

	PG_TRY();
	{
		if (SPI_OK_CONNECT != SPI_connect())
		{
			ereport(ERROR,
					(errcode(ERRCODE_INTERNAL_ERROR),
					 errmsg("unable to connect to execute internal query")));
		}

		connected = true;

		PushActiveSnapshot(GetTransactionSnapshot());

		res = SPI_execute("select * from gp_dist_wait_status();", true, 0);

		PopActiveSnapshot();

		if (res == SPI_OK_SELECT && SPI_tuptable != NULL)
		{
			tuple_num = (int) SPI_processed;
			tupdesc = SPI_tuptable->tupdesc;
			tuptable = SPI_tuptable;

			elogif(tuple_num > 0, LOG,
				 "GDD get %d wait relationship from all segments.", tuple_num);

			/*
			 * Switch back to gdd memory context otherwise the graphs will be
			 * created in SPI memory context and freed in SPI_finish().
			 */
			MemoryContextSwitchTo(gddContext);

			/* Get all valid gxids, any other gxids are considered invalid. */
			gxids = ListAllGxid();

			for (i = 0; i < tuple_num; i++)
			{
				DistributedTransactionId  waiter_xid;
				DistributedTransactionId  holder_xid;
				HeapTuple	   tuple;
				Datum		   d;
				bool		   solidedge;