Fix: src.ctf.lttng-live: session closed before any metadata is received

Issue
=====
When stress-testing the LTTng-UST clear feature over an entire night I
witnessed 6 instances of Babeltrace infinite loop.

Using the GNU Debugger, Babeltrace was found to be endlessly issuing the
`LTTNG_VIEWER_GET_NEW_STREAMS` command to the Relay daemon to which the
Relay Daemon endlessly replied `LTTNG_VIEWER_NEW_STREAMS_HUP`.

This is caused by the fact that the session was closed before we
received any metadata and the lttng-live component class keeps trying to
ask for new streams before requesting the metadata.

Fix
===
If the session is marked as closed return a `_STATUS_END` to stop
considering this session.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I9c18d03cef1b61d1c02b7d608720bf5750a348c4
Reviewed-on: https://review.lttng.org/c/babeltrace/+/6827

diff --git a/src/plugins/ctf/lttng-live/metadata.cpp b/src/plugins/ctf/lttng-live/metadata.cpp
index d49ce76fc143a0889640798d9f1405412d7c6847..775396ee7d9cd2266dc4863f1758101bd3047c1d 100644 (file)
--- a/src/plugins/ctf/lttng-live/metadata.cpp
+++ b/src/plugins/ctf/lttng-live/metadata.cpp
@@ -114,7 +114,14 @@ enum lttng_live_iterator_status lttng_live_metadata_update(struct lttng_live_tra
 
     /* No metadata stream yet. */
     if (!metadata) {
-        if (session->new_streams_needed) {
+        if (session->closed) {
+            /*
+             * The session is closed AND we never received any
+             * metadata this indicates that we will never receive
+             * any metadata.
+             */
+            status = LTTNG_LIVE_ITERATOR_STATUS_END;
+        } else if (session->new_streams_needed) {
             status = LTTNG_LIVE_ITERATOR_STATUS_AGAIN;
         } else {
             session->new_streams_needed = true;