Fix: relayd: live: some listed sessions are not attacheable

The list sessions command currently returns sessions that do not
have a current trace chunk. This can be caused by the session
either being destroyed or being so young that it hasn't had a
trace chunk created against it yet.

In both cases, such sessions would not be attacheable in their
current condition. This fix omits them from from the listing
to reduce the number of failures at the "attach session" and
"attach stream" step.

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

diff --git a/src/bin/lttng-relayd/live.c b/src/bin/lttng-relayd/live.c
index 74c28a45784a1962aa9c068a63cccf9461f5a600..8c4f501aa3446afd5b5cb5d7e72e42bf82dd2d11 100644 (file)
--- a/src/bin/lttng-relayd/live.c
+++ b/src/bin/lttng-relayd/live.c
@@ -831,9 +831,18 @@ int viewer_list_sessions(struct relay_connection *conn)
 
                health_code_update();
 
+               pthread_mutex_lock(&session->lock);
                if (session->connection_closed) {
                        /* Skip closed session */
-                       continue;
+                       goto next_session;
+               }
+               if (!session->current_trace_chunk) {
+                       /*
+                        * Skip un-attachable session. It is either
+                        * being destroyed or has not had a trace
+                        * chunk created against it yet.
+                        */
+                       goto next_session;
                }
 
                if (count >= buf_count) {
@@ -844,7 +853,7 @@ int viewer_list_sessions(struct relay_connection *conn)
                                new_buf_count * sizeof(*send_session_buf));
                        if (!newbuf) {
                                ret = -1;
-                               break;
+                               goto break_loop;
                        }
                        send_session_buf = newbuf;
                        buf_count = new_buf_count;
@@ -854,12 +863,12 @@ int viewer_list_sessions(struct relay_connection *conn)
                                session->session_name,
                                sizeof(send_session->session_name))) {
                        ret = -1;
-                       break;
+                       goto break_loop;
                }
                if (lttng_strncpy(send_session->hostname, session->hostname,
                                sizeof(send_session->hostname))) {
                        ret = -1;
-                       break;
+                       goto break_loop;
                }
                send_session->id = htobe64(session->id);
                send_session->live_timer = htobe32(session->live_timer);
@@ -870,6 +879,12 @@ int viewer_list_sessions(struct relay_connection *conn)
                }
                send_session->streams = htobe32(session->stream_count);
                count++;
+       next_session:
+               pthread_mutex_unlock(&session->lock);
+               continue;
+       break_loop:
+               pthread_mutex_unlock(&session->lock);
+               break;
        }
        rcu_read_unlock();
        if (ret < 0) {