From 035781482d139face53c81f70ca4591b5292c4b4 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Fri, 25 Jun 2021 13:26:43 -0400
Subject: [PATCH v2 3/4] test nosync

---
 .../modules/libpq_pipeline/libpq_pipeline.c   | 92 +++++++++++++++++++
 1 file changed, 92 insertions(+)

diff --git a/src/test/modules/libpq_pipeline/libpq_pipeline.c b/src/test/modules/libpq_pipeline/libpq_pipeline.c
index 71eedb6dbb..00d6b9f401 100644
--- a/src/test/modules/libpq_pipeline/libpq_pipeline.c
+++ b/src/test/modules/libpq_pipeline/libpq_pipeline.c
@@ -230,6 +230,95 @@ test_multi_pipelines(PGconn *conn)
 	fprintf(stderr, "ok\n");
 }
 
+/*
+ * Test behavior when a pipeline dispatches a number of commands that are
+ * not flushed by a sync point.
+ */
+static void
+test_nosync(PGconn *conn)
+{
+	int		numqueries = 0;
+	int		results = 0;
+	int		sock = PQsocket(conn);
+
+	fprintf(stderr, "nosync... ");
+
+	if (sock < 0)
+		pg_fatal("invalid socket");
+
+	if (PQenterPipelineMode(conn) != 1)
+		pg_fatal("could not enter pipeline mode");
+	for (;;)
+	{
+		fd_set		input_mask;
+		struct timeval	tv;
+
+		if (PQsendQueryParams(conn, "SELECT repeat('xyzxz', 12)",
+							  0, NULL, NULL, NULL, NULL, 0) != 1)
+			pg_fatal("error sending select: %s", PQerrorMessage(conn));
+		PQflush(conn);
+
+		numqueries++;
+
+		/*
+		 * If the server has written anything to us, read (some of) it now.
+		 */
+		FD_ZERO(&input_mask);
+		FD_SET(sock, &input_mask);
+		tv.tv_sec = 0;
+		tv.tv_usec = 0;
+		if (select(sock + 1, &input_mask, NULL, NULL, &tv) < 0)
+		{
+			fprintf(stderr, "select() failed: %s\n", strerror(errno));
+			exit_nicely(conn);
+		}
+		if (FD_ISSET(sock, &input_mask) && PQconsumeInput(conn) != 1)
+			pg_fatal("failed to read from server: %s", PQerrorMessage(conn));
+
+		if (numqueries >= 500)
+			break;
+	}
+
+	PQrequestFlush(conn);
+
+	/* Now read all results */
+	for (;;)
+	{
+		PGresult *res;
+
+		res = PQgetResult(conn);
+
+		/* NULL results are only expected after a TUPLES_OK */
+		if (res == NULL)
+			pg_fatal("got unexpected NULL result after %d results", results);
+
+		/* We expect exacly one TUPLES_OK result for each query we sent */
+		if (PQresultStatus(res) == PGRES_TUPLES_OK)
+		{
+			PGresult *res2;
+
+			/* and one NULL result should follow each */
+			res2 = PQgetResult(conn);
+			if (res2 != NULL)
+				pg_fatal("expected NULL, got %s",
+						 PQresStatus(PQresultStatus(res2)));
+			PQclear(res);
+			results++;
+
+			/* if we're done, we're done */
+			if (results == numqueries)
+				break;
+
+			continue;
+		}
+
+		/* anything else is unexpected */
+		pg_fatal("got unexpected %s\n", PQresStatus(PQresultStatus(res)));
+	}
+
+	fprintf(stderr, "ok\n");
+}
+
 /*
  * When an operation in a pipeline fails the rest of the pipeline is flushed. We
  * still have to get results for each pipeline item, but the item will just be
@@ -1237,6 +1326,7 @@ print_test_list(void)
 {
 	printf("disallowed_in_pipeline\n");
 	printf("multi_pipelines\n");
+	printf("nosync\n");
 	printf("pipeline_abort\n");
 	printf("pipelined_insert\n");
 	printf("prepared\n");
@@ -1334,6 +1424,8 @@ main(int argc, char **argv)
 		test_disallowed_in_pipeline(conn);
 	else if (strcmp(testname, "multi_pipelines") == 0)
 		test_multi_pipelines(conn);
+	else if (strcmp(testname, "nosync") == 0)
+		test_nosync(conn);
 	else if (strcmp(testname, "pipeline_abort") == 0)
 		test_pipeline_abort(conn);
 	else if (strcmp(testname, "pipelined_insert") == 0)
-- 
2.30.2