From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Wed, 20 Nov 2019 21:09:50 +0000 (-0500)
Subject: Fix: sessiond: don't wait for a rotation from a null chunk to finish
X-Git-Tag: v2.12.0-rc1~234
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=3b61d9ee2a0611e980fb2817d6dd5fa3c9c7be68;p=lttng-tools.git

Fix: sessiond: don't wait for a rotation from a null chunk to finish

The rotation completion checking does not handle waiting for the
completion of a rotation _from_ a NULL trace chunk. This is correct as
there is essentially nothing to check. Streams always rotate out of a
null trace chunk immediately as it means the stream had no output and
could not receive data.

Concretely, this happens when stopping a session, rotating, and
re-starting a session.

The fix consists in simply re-working the logic of the "rotate"
command to not launch a rotation completion check job and not put the
session in the "rotation ongoing" state.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 5a122d8d3..7c9477df9 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -4925,9 +4925,6 @@ int cmd_rotate_session(struct ltt_session *session,
 		cmd_ret = LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP;
 		goto end;
 	}
-
-	session->rotation_state = LTTNG_ROTATION_STATE_ONGOING;
-
 	if (session->active) {
 		new_trace_chunk = session_create_new_trace_chunk(session, NULL,
 				NULL, NULL);
@@ -4951,11 +4948,6 @@ int cmd_rotate_session(struct ltt_session *session,
 		goto error;
 	}
 
-	assert(chunk_being_archived);
-	chunk_status = lttng_trace_chunk_get_id(chunk_being_archived,
-			&ongoing_rotation_chunk_id);
-	assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
-
 	if (session->kernel_session) {
 		cmd_ret = kernel_rotate_session(session);
 		if (cmd_ret != LTTNG_OK) {
@@ -4971,6 +4963,26 @@ int cmd_rotate_session(struct ltt_session *session,
 		}
 	}
 
+	if (!session->active) {
+		session->rotated_after_last_stop = true;
+	}
+
+	if (!chunk_being_archived) {
+		DBG("Rotating session \"%s\" from a \"NULL\" trace chunk to a new trace chunk, skipping completion check",
+				session->name);
+		if (failed_to_rotate) {
+			cmd_ret = rotation_fail_code;
+			goto error;
+		}
+		cmd_ret = LTTNG_OK;
+		goto end;
+	}
+
+	session->rotation_state = LTTNG_ROTATION_STATE_ONGOING;
+	chunk_status = lttng_trace_chunk_get_id(chunk_being_archived,
+			&ongoing_rotation_chunk_id);
+	assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
+
 	ret = session_close_trace_chunk(session, chunk_being_archived,
 			quiet_rotation ?
 					NULL :
@@ -4995,10 +5007,6 @@ int cmd_rotate_session(struct ltt_session *session,
 		goto error;
 	}
 
-	if (!session->active) {
-		session->rotated_after_last_stop = true;
-	}
-
 	if (rotate_return) {
 		rotate_return->rotation_id = ongoing_rotation_chunk_id;
 	}