src.ctf.lttng-live: add comments and debug statements

[babeltrace.git] / src / plugins / ctf / lttng-live / lttng-live.cpp

diff --git a/src/plugins/ctf/lttng-live/lttng-live.cpp b/src/plugins/ctf/lttng-live/lttng-live.cpp
index 344fbe27c17441fa88b4b94403f9cc48b3cb2c70..e87de8d47aa18660ceb3540e46b1cfaeef4198f1 100644 (file)
--- a/src/plugins/ctf/lttng-live/lttng-live.cpp
+++ b/src/plugins/ctf/lttng-live/lttng-live.cpp
@@ -481,15 +481,42 @@ lttng_live_get_session(struct lttng_live_msg_iter *lttng_live_msg_iter,
         }
     }
 
-    BT_COMP_LOGD("Updating all streams and metadata for session: "
+    BT_COMP_LOGD("Updating all data streams: "
                  "session-id=%" PRIu64 ", session-name=\"%s\"",
                  session->id, session->session_name->str);
 
     status = lttng_live_session_get_new_streams(session, lttng_live_msg_iter->self_msg_iter);
-    if (status != LTTNG_LIVE_ITERATOR_STATUS_OK && status != LTTNG_LIVE_ITERATOR_STATUS_END) {
+    switch (status) {
+    case LTTNG_LIVE_ITERATOR_STATUS_OK:
+        break;
+    case LTTNG_LIVE_ITERATOR_STATUS_END:
+        /*
+                * We received a `_END` from the `_get_new_streams()` function,
+                * which means no more data will ever be received from the data
+                * streams of this session. But it's possible that the metadata
+                * is incomplete.
+                * The live protocol guarantees that we receive all the
+                * metadata needed before we receive data streams needing it.
+                * But it's possible to receive metadata NOT needed by
+                * data streams after the session was closed. For example, this
+                * could happen if a new event is registered and the session is
+                * stopped before any tracepoint for that event is actually
+                * fired.
+                */
+        BT_COMP_LOGD(
+            "Updating streams returned _END status. Override status to _OK in order fetch any remaining metadata:"
+            "session-id=%" PRIu64 ", session-name=\"%s\"",
+            session->id, session->session_name->str);
+        status = LTTNG_LIVE_ITERATOR_STATUS_OK;
+        break;
+    default:
         goto end;
     }
 
+    BT_COMP_LOGD("Updating metadata stream for session: "
+                 "session-id=%" PRIu64 ", session-name=\"%s\"",
+                 session->id, session->session_name->str);
+
     trace_idx = 0;
     while (trace_idx < session->traces->len) {
         struct lttng_live_trace *trace =
@@ -607,9 +634,12 @@ lttng_live_iterator_handle_new_streams_and_metadata(struct lttng_live_msg_iter *
         status = lttng_live_get_session(lttng_live_msg_iter, session);
         switch (status) {
         case LTTNG_LIVE_ITERATOR_STATUS_OK:
-            break;
         case LTTNG_LIVE_ITERATOR_STATUS_END:
-            status = LTTNG_LIVE_ITERATOR_STATUS_OK;
+            /*
+             * A session returned `_END`. Other sessions may still
+             * be active so we override the status and continue
+             * looping if needed.
+             */
             break;
         default:
             goto end;
@@ -1799,8 +1829,8 @@ lttng_live_msg_iter_init(bt_self_message_iterator *self_msg_it,
 
     lttng_live_msg_iter = lttng_live_msg_iter_create(lttng_live, self_msg_it);
     if (!lttng_live_msg_iter) {
-        status = BT_MESSAGE_ITERATOR_CLASS_INITIALIZE_METHOD_STATUS_MEMORY_ERROR;
         BT_COMP_LOGE_APPEND_CAUSE(self_comp, "Failed to create lttng_live_msg_iter");
+        status = BT_MESSAGE_ITERATOR_CLASS_INITIALIZE_METHOD_STATUS_MEMORY_ERROR;
         goto error;
     }
 
@@ -1817,6 +1847,8 @@ lttng_live_msg_iter_init(bt_self_message_iterator *self_msg_it,
              */
             BT_COMP_LOGE_APPEND_CAUSE(self_comp, "Interrupted while creating viewer connection");
         }
+
+        status = BT_MESSAGE_ITERATOR_CLASS_INITIALIZE_METHOD_STATUS_ERROR;
         goto error;
     }
 
@@ -1831,6 +1863,8 @@ lttng_live_msg_iter_init(bt_self_message_iterator *self_msg_it,
              */
             BT_COMP_LOGE_APPEND_CAUSE(self_comp, "Interrupted when creating viewer session");
         }
+
+        status = BT_MESSAGE_ITERATOR_CLASS_INITIALIZE_METHOD_STATUS_ERROR;
         goto error;
     }
 
@@ -1850,6 +1884,7 @@ lttng_live_msg_iter_init(bt_self_message_iterator *self_msg_it,
                 "component parameter: url =\"%s\"",
                 SESS_NOT_FOUND_ACTION_PARAM, SESS_NOT_FOUND_ACTION_FAIL_STR,
                 lttng_live->params.url->str);
+            status = BT_MESSAGE_ITERATOR_CLASS_INITIALIZE_METHOD_STATUS_ERROR;
             goto error;
         case SESSION_NOT_FOUND_ACTION_END:
             BT_COMP_LOGI(
@@ -1869,7 +1904,6 @@ lttng_live_msg_iter_init(bt_self_message_iterator *self_msg_it,
     goto end;
 
 error:
-    status = BT_MESSAGE_ITERATOR_CLASS_INITIALIZE_METHOD_STATUS_ERROR;
     lttng_live_msg_iter_destroy(lttng_live_msg_iter);
 end:
     return status;