src.ctf.lttng-live: don't try to detach after socket error

Background
==========
The message iterator `_finalize()` method typically needs to detach from
the live session (LTTNG_VIEWER_DETACH_SESSION) so that the relay daemon
can free up the associated resources.

Issue
=====
In the case we encounter a socket error during the `_next()` method,
we don't want a component to try to send a detach command to the relay
during the `_iter_finalize()` method as this will surely lead to another
error. The annoying thing is that this other error would pollute the
error cause stack that lead to the first error.

Solution
========
Close the socket when we encounter an error and check in the
`lttng_live_detach_session` function if the socket it valid before
sending a _DETACH_SESSION command.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: Ic56e72013e78e4c5ef3343034b0e6f216599be6a
Reviewed-on: https://review.lttng.org/c/babeltrace/+/2357
Reviewed-by: Simon Marchi <simon.marchi@efficios.com>

diff --git a/src/plugins/ctf/lttng-live/viewer-connection.c b/src/plugins/ctf/lttng-live/viewer-connection.c
index 4139546611fd20a865cd8ba676fd8478706f003d..4f29cda8723a45344cc8a552c7d1998d5465595e 100644 (file)
--- a/src/plugins/ctf/lttng-live/viewer-connection.c
+++ b/src/plugins/ctf/lttng-live/viewer-connection.c
@@ -110,6 +110,24 @@ enum ctf_msg_iter_medium_status viewer_status_to_ctf_msg_iter_medium_status(
        }
 }
 
+static inline
+void viewer_connection_close_socket(
+               struct live_viewer_connection *viewer_connection)
+{
+       bt_self_component_class *self_comp_class =
+               viewer_connection->self_comp_class;
+       bt_self_component *self_comp =
+               viewer_connection->self_comp;
+       int ret = bt_socket_close(viewer_connection->control_sock);
+       if (ret == -1) {
+               BT_COMP_OR_COMP_CLASS_LOGW_ERRNO(
+                       self_comp, self_comp_class,
+                       "Error closing viewer connection socket: ", ".");
+       }
+
+       viewer_connection->control_sock = BT_INVALID_SOCKET;
+}
+
 /*
  * This function receives a message from the Relay daemon.
  * If it received the entire message, it returns _OK,
@@ -157,12 +175,14 @@ enum lttng_live_viewer_status lttng_live_recv(
                                }
                        } else {
                                /*
-                                * For any other types of socket error, returng
-                                * an error.
+                                * For any other types of socket error, close
+                                * the socket and return an error.
                                 */
                                LTTNG_LIVE_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE_ERRNO(
                                        self_comp, self_comp_class,
                                        "Error receiving from Relay", ".");
+
+                               viewer_connection_close_socket(viewer_connection);
                                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                                goto end;
                        }
@@ -172,10 +192,12 @@ enum lttng_live_viewer_status lttng_live_recv(
                         * connection was orderly shutdown from the other peer.
                         * If that happens when we are trying to receive
                         * a message from it, it means something when wrong.
+                        * Close the socket and return an error.
                         */
-                       status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                        BT_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp,
                                self_comp_class, "Remote side has closed connection");
+                       viewer_connection_close_socket(viewer_connection);
+                       status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                        goto end;
                }
 
@@ -236,11 +258,14 @@ enum lttng_live_viewer_status lttng_live_send(
                                }
                        } else {
                                /*
-                                * The send() call returned an error.
+                                * For any other types of socket error, close
+                                * the socket and return an error.
                                 */
                                LTTNG_LIVE_COMP_OR_COMP_CLASS_LOGE_APPEND_CAUSE_ERRNO(
                                        self_comp, self_comp_class,
                                        "Error sending to Relay", ".");
+
+                               viewer_connection_close_socket(viewer_connection);
                                status = LTTNG_LIVE_VIEWER_STATUS_ERROR;
                                goto end;
                        }
@@ -1150,7 +1175,12 @@ enum lttng_live_viewer_status lttng_live_detach_session(
        const size_t cmd_buf_len = sizeof(cmd) + sizeof(rq);
        char cmd_buf[cmd_buf_len];
 
-       if (!session->attached) {
+       /*
+        * The session might already be detached and the viewer socket might
+        * already been closed. This happens when calling this function when
+        * tearing down the graph after an error.
+        */
+       if (!session->attached || viewer_connection->control_sock == BT_INVALID_SOCKET) {
                return 0;
        }