Add prometheus metrics for block authorship (paritytech#10316)

* Add prom metric  to basic authorship

* Add proposer_block_proposal_time

* +nightly-2021-10-29 fmt

* Use saturating_duration_since, not elasped

* Update client/basic-authorship/src/basic_authorship.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update client/basic-authorship/src/basic_authorship.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* +nightly-2021-10-29 fmt

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

client/basic-authorship/src/basic_authorship.rs

@@ -346,10 +346,23 @@ where
 		block_size_limit: Option<usize>,
 	) -> Result<Proposal<Block, backend::TransactionFor<B, Block>, PR::Proof>, sp_blockchain::Error>
 	{
+		let propose_with_start = time::Instant::now();
 		let mut block_builder =
 			self.client.new_block_at(&self.parent_id, inherent_digests, PR::ENABLED)?;
 
-		for inherent in block_builder.create_inherents(inherent_data)? {
+		let create_inherents_start = time::Instant::now();
+		let inherents = block_builder.create_inherents(inherent_data)?;
+		let create_inherents_end = time::Instant::now();
+
+		self.metrics.report(|metrics| {
+			metrics.create_inherents_time.observe(
+				create_inherents_end
+					.saturating_duration_since(create_inherents_start)
+					.as_secs_f64(),
+			);
+		});
+
+		for inherent in inherents {
 			match block_builder.push(inherent) {
 				Err(ApplyExtrinsicFailed(Validity(e))) if e.exhausted_resources() => {
 					warn!("⚠️  Dropping non-mandatory inherent from overweight block.")
@@ -529,6 +542,14 @@ where
 
 		let proof =
 			PR::into_proof(proof).map_err(|e| sp_blockchain::Error::Application(Box::new(e)))?;
+
+		let propose_with_end = time::Instant::now();
+		self.metrics.report(|metrics| {
+			metrics.create_block_proposal_time.observe(
+				propose_with_end.saturating_duration_since(propose_with_start).as_secs_f64(),
+			);
+		});
+
 		Ok(Proposal { block, proof, storage_changes })
 	}
 }

client/proposer-metrics/src/lib.rs

@@ -47,6 +47,8 @@ impl MetricsLink {
 pub struct Metrics {
 	pub block_constructed: Histogram,
 	pub number_of_transactions: Gauge<U64>,
+	pub create_inherents_time: Histogram,
+	pub create_block_proposal_time: Histogram,
 }
 
 impl Metrics {
@@ -66,6 +68,20 @@ impl Metrics {
 				)?,
 				registry,
 			)?,
+			create_inherents_time: register(
+				Histogram::with_opts(HistogramOpts::new(
+					"proposer_create_inherents_time",
+					"Histogram of time taken to execute create inherents",
+				))?,
+				registry,
+			)?,
+			create_block_proposal_time: register(
+				Histogram::with_opts(HistogramOpts::new(
+					"proposer_block_proposal_time",
+					"Histogram of time taken to construct a block and prepare it for proposal",
+				))?,
+				registry,
+			)?,
 		})
 	}
 }