From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed, 18 May 2016 18:04:13 +0000 (-0400)
Subject: Fix: ust-consumer: flush empty packets on snapshot channel
X-Git-Tag: v2.7.3~22
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=de3fb857f034c208c135a10a3cdec2dfe43fbda6;p=lttng-tools.git

Fix: ust-consumer: flush empty packets on snapshot channel

Snapshot operation on a non-stopped stream should use a "final" flush to
ensure empty packets are flushed, so we gather timestamps at the moment
where the snapshot is taken. This is important for streams that have a
low amount of activity, which might be on an empty packet when the
snapshot is triggered.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c
index 4709b1955..0c8123969 100644
--- a/src/common/ust-consumer/ust-consumer.c
+++ b/src/common/ust-consumer/ust-consumer.c
@@ -1110,7 +1110,13 @@ static int snapshot_channel(uint64_t key, char *path, uint64_t relayd_id,
 			}
 		}
 
-		ustctl_flush_buffer(stream->ustream, 1);
+		/*
+		 * If tracing is active, we want to perform a "full" buffer flush.
+		 * Else, if quiescent, it has already been done by the prior stop.
+		 */
+		if (!stream->quiescent) {
+			ustctl_flush_buffer(stream->ustream, 0);
+		}
 
 		ret = lttng_ustconsumer_take_snapshot(stream);
 		if (ret < 0) {