Add new parallel message type to progress reporting.

This commit adds a new type of parallel message 'P' to allow a
parallel worker to poke at a leader to update the progress.

Currently it supports only incremental progress reporting but it's
possible to allow for supporting of other backend progress APIs in the
future.

There are no users of this new message type as of this commit. That
will follow in future commits.

Idea from Andres Freund.

Author: Sami Imseih
Reviewed by: Michael Paquier, Masahiko Sawada
Discussion: https://www.postgresql.org/message-id/flat/5478DFCD-2333-401A-B2F0-0D186AB09228@amazon.com

1 files changed, 18 insertions, 0 deletions

diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c
index 2b8bc2f58dd..2bd04bd1773 100644
--- a/src/backend/access/transam/parallel.c
+++ b/src/backend/access/transam/parallel.c
@@ -24,6 +24,7 @@
 #include "catalog/pg_enum.h"
 #include "catalog/storage.h"
 #include "commands/async.h"
+#include "commands/progress.h"
 #include "commands/vacuum.h"
 #include "executor/execParallel.h"
 #include "libpq/libpq.h"
@@ -1199,6 +1200,23 @@ HandleParallelMessage(ParallelContext *pcxt, int i, StringInfo msg)
 				break;
 			}
 
+		case 'P':				/* Parallel progress reporting */
+			{
+				/*
+				 * Only incremental progress reporting is currently supported.
+				 * However, it's possible to add more fields to the message to
+				 * allow for handling of other backend progress APIs.
+				 */
+				int			index = pq_getmsgint(msg, 4);
+				int64		incr = pq_getmsgint64(msg);
+
+				pq_getmsgend(msg);
+
+				pgstat_progress_incr_param(index, incr);
+
+				break;
+			}
+
 		case 'X':				/* Terminate, indicating clean exit */
 			{
 				shm_mq_detach(pcxt->worker[i].error_mqh);