in src/trace/trace_context.rs [362:385]
fn create_common_span(
&mut self,
operation_name: &str,
remote_peer: &str,
span_type: SpanType,
parent_span_id: i32,
) -> Span {
if self.next_span_id() == 0 {
panic!("entry span must be existed.");
}
let span = Span::new_obj(
self.inc_next_span_id(),
parent_span_id,
operation_name.to_string(),
remote_peer.to_string(),
span_type,
SpanLayer::Unknown,
false,
);
let uid = self.push_active_span(&span);
Span::new(uid, span, self.wg.clone(), self.span_stack.clone())
}