Node-side metrics for asynchronous backing (#6549)

* Add metrics for `prune_view_candidate_storage`

* Add metrics for `request_unblocked_collations`

* Fix docstring

* Couple fixes from review comments

node/core/prospective-parachains/src/lib.rs

@@ -1,4 +1,4 @@
-// Copyright 2022 Parity Technologies (UK) Ltd.
+// Copyright 2022-2023 Parity Technologies (UK) Ltd.
 // This file is part of Polkadot.
 
 // Polkadot is free software: you can redistribute it and/or modify
@@ -61,6 +61,9 @@ mod fragment_tree;
 #[cfg(test)]
 mod tests;
 
+mod metrics;
+use self::metrics::Metrics;
+
 const LOG_TARGET: &str = "parachain::prospective-parachains";
 
 struct RelayBlockViewData {
@@ -82,12 +85,14 @@ impl View {
 
 /// The prospective parachains subsystem.
 #[derive(Default)]
-pub struct ProspectiveParachainsSubsystem;
+pub struct ProspectiveParachainsSubsystem {
+	metrics: Metrics,
+}
 
 impl ProspectiveParachainsSubsystem {
 	/// Create a new instance of the `ProspectiveParachainsSubsystem`.
-	pub fn new() -> Self {
-		Self
+	pub fn new(metrics: Metrics) -> Self {
+		Self { metrics }
 	}
 }
 
@@ -98,7 +103,7 @@ where
 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		SpawnedSubsystem {
-			future: run(ctx)
+			future: run(ctx, self.metrics)
 				.map_err(|e| SubsystemError::with_origin("prospective-parachains", e))
 				.boxed(),
 			name: "prospective-parachains-subsystem",
@@ -107,23 +112,27 @@ where
 }
 
 #[overseer::contextbounds(ProspectiveParachains, prefix = self::overseer)]
-async fn run<Context>(mut ctx: Context) -> FatalResult<()> {
+async fn run<Context>(mut ctx: Context, metrics: Metrics) -> FatalResult<()> {
 	let mut view = View::new();
 	loop {
 		crate::error::log_error(
-			run_iteration(&mut ctx, &mut view).await,
+			run_iteration(&mut ctx, &mut view, &metrics).await,
 			"Encountered issue during run iteration",
 		)?;
 	}
 }
 
 #[overseer::contextbounds(ProspectiveParachains, prefix = self::overseer)]
-async fn run_iteration<Context>(ctx: &mut Context, view: &mut View) -> Result<()> {
+async fn run_iteration<Context>(
+	ctx: &mut Context,
+	view: &mut View,
+	metrics: &Metrics,
+) -> Result<()> {
 	loop {
 		match ctx.recv().await.map_err(FatalError::SubsystemReceive)? {
 			FromOrchestra::Signal(OverseerSignal::Conclude) => return Ok(()),
 			FromOrchestra::Signal(OverseerSignal::ActiveLeaves(update)) => {
-				handle_active_leaves_update(&mut *ctx, view, update).await?;
+				handle_active_leaves_update(&mut *ctx, view, update, metrics).await?;
 			},
 			FromOrchestra::Signal(OverseerSignal::BlockFinalized(..)) => {},
 			FromOrchestra::Communication { msg } => match msg {
@@ -155,6 +164,7 @@ async fn handle_active_leaves_update<Context>(
 	ctx: &mut Context,
 	view: &mut View,
 	update: ActiveLeavesUpdate,
+	metrics: &Metrics,
 ) -> JfyiErrorResult<()> {
 	// 1. clean up inactive leaves
 	// 2. determine all scheduled para at new block
@@ -245,13 +255,15 @@ async fn handle_active_leaves_update<Context>(
 
 	if !update.deactivated.is_empty() {
 		// This has potential to be a hotspot.
-		prune_view_candidate_storage(view);
+		prune_view_candidate_storage(view, metrics);
 	}
 
 	Ok(())
 }
 
-fn prune_view_candidate_storage(view: &mut View) {
+fn prune_view_candidate_storage(view: &mut View, metrics: &Metrics) {
+	metrics.time_prune_view_candidate_storage();
+
 	let active_leaves = &view.active_leaves;
 	view.candidate_storage.retain(|para_id, storage| {
 		let mut coverage = HashSet::new();
@@ -721,10 +733,3 @@ async fn fetch_block_info<Context>(
 		storage_root: header.state_root,
 	}))
 }
-
-#[derive(Clone)]
-struct MetricsInner;
-
-/// Prospective parachain metrics.
-#[derive(Default, Clone)]
-pub struct Metrics(Option<MetricsInner>);

node/core/prospective-parachains/src/metrics.rs

@@ -0,0 +1,52 @@
+// Copyright 2023 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use polkadot_node_subsystem_util::metrics::{self, prometheus};
+
+#[derive(Clone)]
+pub(crate) struct MetricsInner {
+	pub(crate) prune_view_candidate_storage: prometheus::Histogram,
+}
+
+/// Candidate backing metrics.
+#[derive(Default, Clone)]
+pub struct Metrics(pub(crate) Option<MetricsInner>);
+
+impl Metrics {
+	/// Provide a timer for handling `prune_view_candidate_storage` which observes on drop.
+	pub fn time_prune_view_candidate_storage(
+		&self,
+	) -> Option<metrics::prometheus::prometheus::HistogramTimer> {
+		self.0
+			.as_ref()
+			.map(|metrics| metrics.prune_view_candidate_storage.start_timer())
+	}
+}
+
+impl metrics::Metrics for Metrics {
+	fn try_register(registry: &prometheus::Registry) -> Result<Self, prometheus::PrometheusError> {
+		let metrics = MetricsInner {
+			prune_view_candidate_storage: prometheus::register(
+				prometheus::Histogram::with_opts(prometheus::HistogramOpts::new(
+					"polkadot_parachain_prospective_parachains_prune_view_candidate_storage",
+					"Time spent within `prospective_parachains::prune_view_candidate_storage`",
+				))?,
+				registry,
+			)?,
+		};
+		Ok(Metrics(Some(metrics)))
+	}
+}

node/network/collator-protocol/src/validator_side/metrics.rs

@@ -1,4 +1,4 @@
-// Copyright 2017-2022 Parity Technologies (UK) Ltd.
+// Copyright 2017-2023 Parity Technologies (UK) Ltd.
 // This file is part of Polkadot.
 
 // Polkadot is free software: you can redistribute it and/or modify
@@ -56,6 +56,15 @@ impl Metrics {
 	) -> Option<metrics::prometheus::prometheus::HistogramTimer> {
 		self.0.as_ref().map(|metrics| metrics.collation_request_duration.start_timer())
 	}
+
+	/// Provide a timer for `request_unblocked_collations` which observes on drop.
+	pub fn time_request_unblocked_collations(
+		&self,
+	) -> Option<metrics::prometheus::prometheus::HistogramTimer> {
+		self.0
+			.as_ref()
+			.map(|metrics| metrics.request_unblocked_collations.start_timer())
+	}
 }
 
 #[derive(Clone)]
@@ -65,6 +74,7 @@ struct MetricsInner {
 	handle_collation_request_result: prometheus::Histogram,
 	collator_peer_count: prometheus::Gauge<prometheus::U64>,
 	collation_request_duration: prometheus::Histogram,
+	request_unblocked_collations: prometheus::Histogram,
 }
 
 impl metrics::Metrics for Metrics {
@@ -116,6 +126,15 @@ impl metrics::Metrics for Metrics {
 				)?,
 				registry,
 			)?,
+			request_unblocked_collations: prometheus::register(
+				prometheus::Histogram::with_opts(
+					prometheus::HistogramOpts::new(
+						"polkadot_parachain_collator_protocol_validator_request_unblocked_collations",
+						"Time spent within `collator_protocol_validator::request_unblocked_collations`",
+					)
+				)?,
+				registry,
+			)?,
 		};
 
 		Ok(Metrics(Some(metrics)))

node/network/collator-protocol/src/validator_side/mod.rs

@@ -1,4 +1,4 @@
-// Copyright 2020 Parity Technologies (UK) Ltd.
+// Copyright 2020-2023 Parity Technologies (UK) Ltd.
 // This file is part of Polkadot.
 
 // Polkadot is free software: you can redistribute it and/or modify
@@ -979,6 +979,8 @@ where
 	Sender: CollatorProtocolSenderTrait,
 	I: IntoIterator<Item = ((ParaId, Hash), Vec<BlockedAdvertisement>)>,
 {
+	let _timer = state.metrics.time_request_unblocked_collations();
+
 	for (key, mut value) in blocked {
 		let (para_id, para_head) = key;
 		let blocked = std::mem::take(&mut value);

node/service/src/overseer.rs

@@ -1,4 +1,4 @@
-// Copyright 2017-2020 Parity Technologies (UK) Ltd.
+// Copyright 2017-2023 Parity Technologies (UK) Ltd.
 // This file is part of Polkadot.
 
 // Polkadot is free software: you can redistribute it and/or modify
@@ -322,7 +322,7 @@ where
 			Metrics::register(registry)?,
 		))
 		.chain_selection(ChainSelectionSubsystem::new(chain_selection_config, parachains_db))
-		.prospective_parachains(ProspectiveParachainsSubsystem::new())
+		.prospective_parachains(ProspectiveParachainsSubsystem::new(Metrics::register(registry)?))
 		.leaves(Vec::from_iter(
 			leaves
 				.into_iter()