Function ExecAsyncNotify

src/backend/executor/execAsync.c:87–111

* Call the asynchronous node back when a relevant event has occurred. */

 * Call the asynchronous node back when a relevant event has occurred.
 */
void
ExecAsyncNotify(AsyncRequest *areq)
{
	/* must provide our own instrumentation support */
	if (areq->requestee->instrument)
		InstrStartNode(areq->requestee->instrument);

	switch (nodeTag(areq->requestee))
	{
		case T_ForeignScanState:
			ExecAsyncForeignScanNotify(areq);
			break;
		default:
			/* If the node doesn't support async, caller messed up. */
			elog(ERROR, "unrecognized node type: %d",
				 (int) nodeTag(areq->requestee));
	}

	ExecAsyncResponse(areq);

	/* must provide our own instrumentation support */
	if (areq->requestee->instrument)
		InstrStopNode(areq->requestee->instrument,
					  TupIsNull(areq->result) ? 0.0 : 1.0);
}

/*
 * Call the requestor back when an asynchronous node has produced a result.