subscriber: look at event parents to determine resource id (#114)

This PR changes the way poll and state update ops are associated
with resource by incorporating the feedback in tokio-rs/tokio#4072 (comment)
Instead of only looking at entered spans, we now use `Context::event_span`

Signed-off-by: Zahari Dichev <zaharidichev@gmail.com>

console-subscriber/src/lib.rs

@@ -413,8 +413,8 @@ where
             }
             // else unknown waker event... what to do? can't trace it from here...
         } else if self.poll_op_callsites.contains(event.metadata()) {
-            match ctx.current_span().id() {
-                Some(resource_id) if self.is_id_resource(resource_id, &ctx) => {
+            match ctx.event_span(event) {
+                Some(resource_span) if self.is_resource(resource_span.metadata()) => {
                     let mut poll_op_visitor = PollOpVisitor::default();
                     event.record(&mut poll_op_visitor);
                     if let Some((op_name, is_ready)) = poll_op_visitor.result() {
@@ -432,21 +432,28 @@ where
                             self.send(Event::PollOp {
                                 metadata,
                                 at,
-                                resource_id: resource_id.clone(),
+                                resource_id: resource_span.id(),
                                 op_name,
                                 async_op_id,
                                 task_id,
                                 is_ready,
                             });
+                        } else {
+                            eprintln!(
+                                "poll op event should be emitted in the context of an async op and task spans: {:?}",
+                                event
+                            )
                         }
-                        // else poll op event should be emitted in the context of an async op and task spans
                     }
                 }
-                _ => {} // poll op event should be emitted in the context of a resource span
+                _ => eprintln!(
+                    "poll op event should have a resource span parent: {:?}",
+                    event
+                ),
             }
         } else if self.state_update_callsites.contains(event.metadata()) {
-            match ctx.current_span().id() {
-                Some(resource_id) if self.is_id_resource(resource_id, &ctx) => {
+            match ctx.event_span(event) {
+                Some(resource_span) if self.is_resource(resource_span.metadata()) => {
                     let meta_id = event.metadata().into();
                     let mut state_update_visitor = StateUpdateVisitor::new(meta_id);
                     event.record(&mut state_update_visitor);
@@ -455,13 +462,13 @@ where
                         self.send(Event::StateUpdate {
                             metadata,
                             at,
-                            resource_id: resource_id.clone(),
+                            resource_id: resource_span.id(),
                             update,
                         });
                     }
                 }
                 _ => eprintln!(
-                    "state update event should be emitted in the context of a resource span: {:?}",
+                    "state update event should have a resource span parent: {:?}",
                     event
                 ),
             }