Decorate mpsc-notification-to-protocol with the protocol name (#3873)

Currently, all protocols use the same metric name for
`mpsc-notification-to-protocol` this is bad because we can't actually
tell which protocol might cause problems.

This patch proposes we derive the name of the metric from the protocol
name, so that we have separate metrics for each protocol and properly
detect which one is having problem processing its messages.

---------

Signed-off-by: Alexandru Gheorghe <alexandru.gheorghe@parity.io>

substrate/client/network/src/protocol/notifications/service/mod.rs

@@ -338,7 +338,8 @@ impl NotificationService for NotificationHandle {
 	// Clone [`NotificationService`]
 	fn clone(&mut self) -> Result<Box<dyn NotificationService>, ()> {
 		let mut subscribers = self.subscribers.lock();
-		let (event_tx, event_rx) = tracing_unbounded("mpsc-notification-to-protocol", 100_000);
+
+		let (event_tx, event_rx) = tracing_unbounded(self.rx.name(), 100_000);
 		subscribers.push(event_tx);
 
 		Ok(Box::new(NotificationHandle {
@@ -624,11 +625,24 @@ pub fn notification_service(
 	protocol: ProtocolName,
 ) -> (ProtocolHandlePair, Box<dyn NotificationService>) {
 	let (cmd_tx, cmd_rx) = mpsc::channel(COMMAND_QUEUE_SIZE);
-	let (event_tx, event_rx) = tracing_unbounded("mpsc-notification-to-protocol", 100_000);
+
+	let (event_tx, event_rx) =
+		tracing_unbounded(metric_label_for_protocol(&protocol).leak(), 100_000);
 	let subscribers = Arc::new(Mutex::new(vec![event_tx]));
 
 	(
 		ProtocolHandlePair::new(protocol.clone(), subscribers.clone(), cmd_rx),
 		Box::new(NotificationHandle::new(protocol.clone(), cmd_tx, event_rx, subscribers)),
 	)
 }
+
+// Decorates the mpsc-notification-to-protocol metric with the name of the protocol,
+// to be able to distiguish between different protocols in dashboards.
+fn metric_label_for_protocol(protocol: &ProtocolName) -> String {
+	let protocol_name = protocol.to_string();
+	let keys = protocol_name.split("/").collect::<Vec<_>>();
+	keys.iter()
+		.rev()
+		.take(2) // Last two tokens give the protocol name and version
+		.fold("mpsc-notification-to-protocol".into(), |acc, val| format!("{}-{}", acc, val))
+}

substrate/client/utils/src/mpsc.rs

@@ -86,7 +86,7 @@ pub fn tracing_unbounded<T>(
 		warning_fired: Arc::new(AtomicBool::new(false)),
 		creation_backtrace: Arc::new(Backtrace::force_capture()),
 	};
-	let receiver = TracingUnboundedReceiver { inner: r, name };
+	let receiver = TracingUnboundedReceiver { inner: r, name: name.into() };
 	(sender, receiver)
 }
 
@@ -157,6 +157,11 @@ impl<T> TracingUnboundedReceiver<T> {
 	pub fn len(&self) -> usize {
 		self.inner.len()
 	}
+
+	/// The name of this receiver
+	pub fn name(&self) -> &'static str {
+		self.name
+	}
 }
 
 impl<T> Drop for TracingUnboundedReceiver<T> {