Call pqPipelineFlush from PQsendFlushRequest

alvherre · alvherre · commit 1a5594b95762 · 2023-11-08T16:44:08.000+01:00
When PQsendFlushRequest() was added by commit 69cf1d5, we argued against adding a PQflush() call in it[1]. This is still the right decision: if the user wants a flush to occur, they can just call that. However, we failed to realize that the message bytes could still be given to the kernel for transmitting when this can be made without blocking. That's what pqPipelineFlush() does, and it is done for every single other message type sent by libpq, so do that. (When the socket is in blocking mode this may indeed block, but that's what all the other libpq message-sending routines do, too.) [1] https://www.postgresql.org/message-id/202106252352.5ca4byasfun5%40alvherre.pgsql Author: Jelte Fennema-Nio <postgres@jeltef.nl> Discussion: https://postgr.es/m/CAGECzQTxZRevRWkKodE-SnJk1Yfm4eKT+8E4Cyq3MJ9YKTnNew@mail.gmail.com
diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
@@ -3316,6 +3316,14 @@ PQsendFlushRequest(PGconn *conn)
 		return 0;
 	}
 
+	/*
+	 * Give the data a push (in pipeline mode, only if we're past the size
+	 * threshold).  In nonblock mode, don't complain if we're unable to send
+	 * it all; PQgetResult() will do any additional flushing needed.
+	 */
+	if (pqPipelineFlush(conn) < 0)
+		return 0;
+
 	return 1;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -3316,6 +3316,14 @@ PQsendFlushRequest(PGconn *conn)`
`3316`	`3316`	`return 0;`
`3317`	`3317`	`}`
`3318`	`3318`
	`3319`	`+ /*`
	`3320`	`+ * Give the data a push (in pipeline mode, only if we're past the size`
	`3321`	`+ * threshold). In nonblock mode, don't complain if we're unable to send`
	`3322`	`+ * it all; PQgetResult() will do any additional flushing needed.`
	`3323`	`+ */`
	`3324`	`+ if (pqPipelineFlush(conn) < 0)`
	`3325`	`+ return 0;`
	`3326`	`+`
`3319`	`3327`	`return 1;`
`3320`	`3328`	`}`
`3321`	`3329`