Add more prometheus metrics to network::Protocol. (#5145)

substrate/client/network/src/protocol/sync/extra_requests.rs

@@ -53,6 +53,15 @@ pub(crate) struct ExtraRequests<B: BlockT> {
 	request_type_name: &'static str,
 }
 
+#[derive(Debug)]
+pub(crate) struct Metrics {
+	pub(crate) pending_requests: u32,
+	pub(crate) active_requests: u32,
+	pub(crate) importing_requests: u32,
+	pub(crate) failed_requests: u32,
+	_priv: ()
+}
+
 impl<B: BlockT> ExtraRequests<B> {
 	pub(crate) fn new(request_type_name: &'static str) -> Self {
 		ExtraRequests {
@@ -240,6 +249,18 @@ impl<B: BlockT> ExtraRequests<B> {
 	pub(crate) fn pending_requests(&self) -> impl Iterator<Item = &ExtraRequest<B>> {
 		self.pending_requests.iter()
 	}
+
+	/// Get some key metrics.
+	pub(crate) fn metrics(&self) -> Metrics {
+		use std::convert::TryInto;
+		Metrics {
+			pending_requests: self.pending_requests.len().try_into().unwrap_or(std::u32::MAX),
+			active_requests: self.active_requests.len().try_into().unwrap_or(std::u32::MAX),
+			failed_requests: self.failed_requests.len().try_into().unwrap_or(std::u32::MAX),
+			importing_requests: self.importing_requests.len().try_into().unwrap_or(std::u32::MAX),
+			_priv: ()
+		}
+	}
 }
 
 /// Matches peers with pending extra requests.