+
+/*
+ * Handle the metadata requests from the UST consumer
+ *
+ * Return 0 on success else a negative value.
+ */
+int ust_consumer_metadata_request(struct consumer_socket *socket)
+{
+ int ret;
+ ssize_t ret_push;
+ struct lttcomm_metadata_request_msg request;
+ struct buffer_reg_uid *reg_uid;
+ struct ust_registry_session *ust_reg;
+ struct lttcomm_consumer_msg msg;
+
+ assert(socket);
+
+ rcu_read_lock();
+ pthread_mutex_lock(socket->lock);
+
+ health_code_update();
+
+ /* Wait for a metadata request */
+ ret = consumer_socket_recv(socket, &request, sizeof(request));
+ if (ret < 0) {
+ goto end;
+ }
+
+ DBG("Metadata request received for session %" PRIu64 ", key %" PRIu64,
+ request.session_id, request.key);
+
+ reg_uid = buffer_reg_uid_find(request.session_id,
+ request.bits_per_long, request.uid);
+ if (reg_uid) {
+ ust_reg = reg_uid->registry->reg.ust;
+ } else {
+ struct buffer_reg_pid *reg_pid =
+ buffer_reg_pid_find(request.session_id_per_pid);
+ if (!reg_pid) {
+ DBG("PID registry not found for session id %" PRIu64,
+ request.session_id_per_pid);
+
+ msg.cmd_type = LTTNG_ERR_UND;
+ (void) consumer_send_msg(socket, &msg);
+ /*
+ * This is possible since the session might have been destroyed
+ * during a consumer metadata request. So here, return gracefully
+ * because the destroy session will push the remaining metadata to
+ * the consumer.
+ */
+ ret = 0;
+ goto end;
+ }
+ ust_reg = reg_pid->registry->reg.ust;
+ }
+ assert(ust_reg);
+
+ ret_push = ust_app_push_metadata(ust_reg, socket, 1);
+ if (ret_push < 0) {
+ ERR("Pushing metadata");
+ ret = -1;
+ goto end;
+ }
+ DBG("UST Consumer metadata pushed successfully");
+ ret = 0;
+
+end:
+ pthread_mutex_unlock(socket->lock);
+ rcu_read_unlock();
+ return ret;
+}