Weights for pallet-bridge-grandpa (#815)

* Add benchmarking skeleton * Allow runtime to indicate concrete header type for benches * Set up skeleton for benchmark tests * Play around with mutating bench header * Create a working test for benchmarking * Add benches related to enacting authority set changes * Add bench for checking effect of prec-commits/vote ancestries * Use new `no_std` test utils in benchmarks * Support pallet instances in benchmarking * Use correct benchmarking instance macro * Add instance to runtime benchmark helper impl * Start using new justification creation API * Allow mock header's number to be specified * Set up benches with correct fork/depth parameters * Use new pallet name during runtime bench setup * Use correct `set_id` in tests * Limit number of forks as workaround to get tests passing * Use number of authorities which matches number of forks * Make sure test post-conditions are checked properly * Only read `CurrentAuthoritySet` from storage once * Add combined benchmark for `submit_finality_proof` * Add bench test * Introduce config bounds related to justification verification * Use config consts from pallet in benchmarking * Return data relevant to benchmarks from helper functions * Annotate `submit_finality_proof` with autogenerated weights * Return actual weight after call execution * Ignore Clippy warnings in bench template * Update benchmark template * Use `test-utils` to create test headers * Clarify that helper is only for messages benches * Add more documentation to benches * Update TODOs * Clarify return types in comment * Fix pallet name post-merge * Update NOTE to a TODO item * Indicate that Config params are max values, not actual values * Change Config validator count type to be `u32` * Return decoded justification instead of fields * Add missing trait bounds for tests * Correctly issue weight refund Thanks for spotting this Tomek! * Update comment * Add note about SESSION_LENGTH * Fix benchmarking code
2026-05-30 14:01:02 +00:00 · 2021-04-01 12:51:43 -04:00
parent 67cdca8aa4
commit 025a9cad59
12 changed files with 544 additions and 15 deletions
@@ -311,18 +311,34 @@ parameter_types! {
 	// Note that once this is hit the pallet will essentially throttle incoming requests down to one
 	// call per block.
 	pub const MaxRequests: u32 = 50;
+	pub const WestendSessionLength: bp_westend::BlockNumber = bp_westend::SESSION_LENGTH;
+	pub const RialtoSessionLength: bp_rialto::BlockNumber = bp_rialto::SESSION_LENGTH;
+
+	// TODO [#846]: Right now this will break benchmarking if it is greater than `u8::MAX`
+	pub const RialtoValidatorCount: u32 = 255;
+	pub const WestendValidatorCount: u32 = 255;
 }

 pub type RialtoGrandpaInstance = ();
 impl pallet_bridge_grandpa::Config for Runtime {
 	type BridgedChain = bp_rialto::Rialto;
 	type MaxRequests = MaxRequests;
+	type MaxBridgedSessionLength = RialtoSessionLength;
+	type MaxBridgedValidatorCount = RialtoValidatorCount;
+
+	// TODO [#391]: Use weights generated for the Millau runtime instead of Rialto ones.
+	type WeightInfo = pallet_bridge_grandpa::weights::RialtoWeight<Runtime>;
 }

 pub type WestendGrandpaInstance = pallet_bridge_grandpa::Instance1;
 impl pallet_bridge_grandpa::Config<WestendGrandpaInstance> for Runtime {
 	type BridgedChain = bp_westend::Westend;
 	type MaxRequests = MaxRequests;
+	type MaxBridgedSessionLength = WestendSessionLength;
+	type MaxBridgedValidatorCount = WestendValidatorCount;
+
+	// TODO [#391]: Use weights generated for the Millau runtime instead of Rialto ones.
+	type WeightInfo = pallet_bridge_grandpa::weights::RialtoWeight<Runtime>;
 }

 impl pallet_shift_session_manager::Config for Runtime {}
@@ -417,11 +417,18 @@ parameter_types! {
 	// Note that once this is hit the pallet will essentially throttle incoming requests down to one
 	// call per block.
 	pub const MaxRequests: u32 = 50;
+	pub const MillauSessionLength: bp_millau::BlockNumber = bp_millau::SESSION_LENGTH;
+
+	// TODO [#846]: Right now this will break benchmarking if it is greater than `u8::MAX`
+	pub const MillauValidatorCount: u32 = 255;
 }

 impl pallet_bridge_grandpa::Config for Runtime {
 	type BridgedChain = bp_millau::Millau;
 	type MaxRequests = MaxRequests;
+	type MaxBridgedSessionLength = MillauSessionLength;
+	type MaxBridgedValidatorCount = MillauValidatorCount;
+	type WeightInfo = pallet_bridge_grandpa::weights::RialtoWeight<Runtime>;
 }

 impl pallet_shift_session_manager::Config for Runtime {}
@@ -799,6 +806,7 @@ impl_runtime_apis! {
 			config: frame_benchmarking::BenchmarkConfig,
 		) -> Result<Vec<frame_benchmarking::BenchmarkBatch>, sp_runtime::RuntimeString> {
 			use frame_benchmarking::{Benchmarking, BenchmarkBatch, TrackedStorageKey, add_benchmark};
+
 			let whitelist: Vec<TrackedStorageKey> = vec![
 				// Block Number
 				hex_literal::hex!("26aa394eea5630e07c48ae0c9558cef702a5c1b19ab7a04f536c519aca4983ac").to_vec().into(),
@@ -945,6 +953,7 @@ impl_runtime_apis! {
 					>(
 						&lane_id,
 					).0;
+
 					let make_millau_header = |state_root| bp_millau::Header::new(
 						0,
 						Default::default(),
@@ -1005,7 +1014,6 @@ impl_runtime_apis! {
 				}
 			}

-			add_benchmark!(params, batches, pallet_bridge_eth_poa, BridgeKovan);
 			add_benchmark!(
 				params,
 				batches,
@@ -1018,6 +1026,7 @@ impl_runtime_apis! {
 				pallet_bridge_messages,
 				MessagesBench::<Runtime, WithMillauMessagesInstance>
 			);
+			add_benchmark!(params, batches, pallet_bridge_grandpa, BridgeMillauGrandpa);

 			if batches.is_empty() { return Err("Benchmark not found for this pallet.".into()) }
 			Ok(batches)
@@ -11,6 +11,7 @@ license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 codec = { package = "parity-scale-codec", version = "2.0.0", default-features = false }
 finality-grandpa = { version = "0.14.0", default-features = false }
 log = { version = "0.4.14", default-features = false }
+num-traits = { version = "0.2", default-features = false }
 serde = { version = "1.0", optional = true }

 # Bridge Dependencies
@@ -27,25 +28,33 @@ sp-runtime = { git = "https://github.com/paritytech/substrate", branch = "master
 sp-std = { git = "https://github.com/paritytech/substrate", branch = "master" , default-features = false }
 sp-trie = { git = "https://github.com/paritytech/substrate", branch = "master" , default-features = false }

+# Optional Benchmarking Dependencies
+bp-test-utils = { path = "../../primitives/test-utils", default-features = false, optional = true }
+frame-benchmarking = { git = "https://github.com/paritytech/substrate", branch = "master" , default-features = false, optional = true }
+
 [dev-dependencies]
-bp-test-utils = {path = "../../primitives/test-utils" }
 pallet-substrate-bridge = { path = "../../modules/substrate" }
 sp-io = { git = "https://github.com/paritytech/substrate", branch = "master" }

 [features]
 default = ["std"]
 std = [
-	"bp-runtime/std",
 	"bp-header-chain/std",
+	"bp-runtime/std",
+	"bp-test-utils/std",
 	"codec/std",
 	"finality-grandpa/std",
 	"frame-support/std",
 	"frame-system/std",
 	"log/std",
+	"num-traits/std",
 	"serde",
 	"sp-finality-grandpa/std",
 	"sp-runtime/std",
 	"sp-std/std",
 	"sp-trie/std",
 ]
-runtime-benchmarks = []
+runtime-benchmarks = [
+	"bp-test-utils",
+	"frame-benchmarking",
+]
@@ -0,0 +1,264 @@
+// Copyright 2019-2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common 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.
+
+// Parity Bridges Common 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 Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Benchmarks for the GRANDPA Pallet.
+//!
+//! The main dispatchable for the GRANDPA pallet is `submit_finality_proof`, so these benchmarks are
+//! based around that. There are to main factors which affect finality proof verification:
+//!
+//! 1. The number of `votes-ancestries` in the justification
+//! 2. The number of `pre-commits` in the justification
+//!
+//! Vote ancestries are the headers between (`finality_target`, `head_of_chain`], where
+//! `header_of_chain` is a decendant of `finality_target`.
+//!
+//! Pre-commits are messages which are signed by validators at the head of the chain they think is
+//! the best.
+//!
+//! Consider the following:
+//!
+//!   / [B'] <- [C']
+//! [A] <- [B] <- [C]
+//!
+//! The common ancestor of both forks is block A, so this is what GRANDPA will finalize. In order to
+//! verify this we will have vote ancestries of [B, C, B', C'] and pre-commits [C, C'].
+//!
+//! Note that the worst case scenario here would be a justification where each validator has it's
+//! own fork which is `SESSION_LENGTH` blocks long.
+//!
+//! As far as benchmarking results go, the only benchmark that should be used in
+//! `pallet-bridge-grandpa` to annotate weights is the `submit_finality_proof` one. The others are
+//! looking at the effects of specific code paths and do not actually reflect the overall worst case
+//! scenario.
+
+use crate::*;
+
+use bp_test_utils::{
+	accounts, authority_list, make_justification_for_header, test_keyring, JustificationGeneratorParams, ALICE,
+	TEST_GRANDPA_ROUND, TEST_GRANDPA_SET_ID,
+};
+use frame_benchmarking::{benchmarks_instance_pallet, whitelisted_caller};
+use frame_support::traits::Get;
+use frame_system::RawOrigin;
+use num_traits::cast::AsPrimitive;
+use sp_finality_grandpa::AuthorityId;
+use sp_runtime::traits::{One, Zero};
+use sp_std::{vec, vec::Vec};
+
+benchmarks_instance_pallet! {
+	// This is the "gold standard" benchmark for this extrinsic, and it's what should be used to
+	// annotate the weight in the pallet.
+	//
+	// The other benchmarks related to `submit_finality_proof` are looking at the effect of specific
+	// parameters and are there mostly for seeing how specific codepaths behave.
+	submit_finality_proof {
+		let s in 1..T::MaxBridgedSessionLength::get().as_() as u32;
+		let p in 1..T::MaxBridgedValidatorCount::get();
+
+		let caller: T::AccountId = whitelisted_caller();
+
+		let authority_list = accounts(p as u8)
+			.iter()
+			.map(|id| (AuthorityId::from(*id), 1))
+			.collect::<Vec<_>>();
+
+		let init_data = InitializationData {
+			header: bp_test_utils::test_header(Zero::zero()),
+			authority_list,
+			set_id: TEST_GRANDPA_SET_ID,
+			is_halted: false,
+		};
+
+		initialize_bridge::<T, I>(init_data);
+		let header: BridgedHeader<T, I> = bp_test_utils::test_header(One::one());
+
+		let params = JustificationGeneratorParams {
+			header: header.clone(),
+			round: TEST_GRANDPA_ROUND,
+			set_id: TEST_GRANDPA_SET_ID,
+			authorities: accounts(p as u8).iter().map(|k| (*k, 1)).collect::<Vec<_>>(),
+			depth: s,
+			forks: p,
+		};
+
+		let justification = make_justification_for_header(params);
+
+	}: _(RawOrigin::Signed(caller), header, justification)
+	verify {
+		let header: BridgedHeader<T, I> = bp_test_utils::test_header(One::one());
+		let expected_hash = header.hash();
+
+		assert_eq!(<BestFinalized<T, I>>::get(), expected_hash);
+		assert!(<ImportedHeaders<T, I>>::contains_key(expected_hash));
+	}
+
+	// What we want to check here is the effect of vote ancestries on justification verification
+	// do this by varying the number of headers between `finality_target` and `header_of_chain`.
+	submit_finality_proof_on_single_fork {
+		let s in 1..T::MaxBridgedSessionLength::get().as_() as u32;
+
+		let caller: T::AccountId = whitelisted_caller();
+
+		let init_data = InitializationData {
+			header: bp_test_utils::test_header(Zero::zero()),
+			authority_list: authority_list(),
+			set_id: TEST_GRANDPA_SET_ID,
+			is_halted: false,
+		};
+
+		initialize_bridge::<T, I>(init_data);
+		let header: BridgedHeader<T, I> = bp_test_utils::test_header(One::one());
+
+		let params = JustificationGeneratorParams {
+			header: header.clone(),
+			round: TEST_GRANDPA_ROUND,
+			set_id: TEST_GRANDPA_SET_ID,
+			authorities: test_keyring(),
+			depth: s,
+			forks: 1,
+		};
+
+		let justification = make_justification_for_header(params);
+
+	}: submit_finality_proof(RawOrigin::Signed(caller), header, justification)
+	verify {
+		let header: BridgedHeader<T, I> = bp_test_utils::test_header(One::one());
+		let expected_hash = header.hash();
+
+		assert_eq!(<BestFinalized<T, I>>::get(), expected_hash);
+		assert!(<ImportedHeaders<T, I>>::contains_key(expected_hash));
+	}
+
+	// What we want to check here is the effect of many pre-commits on justification verification.
+	// We do this by creating many forks, whose head will be used as a signed pre-commit in the
+	// final justification.
+	submit_finality_proof_on_many_forks {
+		let p in 1..T::MaxBridgedValidatorCount::get();
+
+		let caller: T::AccountId = whitelisted_caller();
+
+		let authority_list = accounts(p as u8)
+			.iter()
+			.map(|id| (AuthorityId::from(*id), 1))
+			.collect::<Vec<_>>();
+
+		let init_data = InitializationData {
+			header: bp_test_utils::test_header(Zero::zero()),
+			authority_list,
+			set_id: TEST_GRANDPA_SET_ID,
+			is_halted: false,
+		};
+
+		initialize_bridge::<T, I>(init_data);
+		let header: BridgedHeader<T, I> = bp_test_utils::test_header(One::one());
+
+		let params = JustificationGeneratorParams {
+			header: header.clone(),
+			round: TEST_GRANDPA_ROUND,
+			set_id: TEST_GRANDPA_SET_ID,
+			authorities: accounts(p as u8).iter().map(|k| (*k, 1)).collect::<Vec<_>>(),
+			depth: 2,
+			forks: p,
+		};
+
+		let justification = make_justification_for_header(params);
+
+	}: submit_finality_proof(RawOrigin::Signed(caller), header, justification)
+	verify {
+		let header: BridgedHeader<T, I> = bp_test_utils::test_header(One::one());
+		let expected_hash = header.hash();
+
+		assert_eq!(<BestFinalized<T, I>>::get(), expected_hash);
+		assert!(<ImportedHeaders<T, I>>::contains_key(expected_hash));
+	}
+
+	// Here we want to find out the overheaded of looking through consensus digests found in a
+	// header. As the number of logs in a header grows, how much more work do we require to look
+	// through them?
+	//
+	// Note that this should be the same for looking through scheduled changes and forces changes,
+	// which is why we only have one benchmark for this.
+	find_scheduled_change {
+		// Not really sure what a good bound for this is.
+		let n in 1..1000;
+
+		let mut logs = vec![];
+		for i in 0..n {
+			// We chose a non-consensus log on purpose since that way we have to look through all
+			// the logs in the header
+			logs.push(sp_runtime::DigestItem::Other(vec![]));
+		}
+
+		let mut header: BridgedHeader<T, I> = bp_test_utils::test_header(Zero::zero());
+		let digest = header.digest_mut();
+		*digest = sp_runtime::Digest {
+			logs,
+		};
+
+	}: {
+		crate::find_scheduled_change(&header)
+	}
+
+	// What we want to check here is how long it takes to read and write the authority set tracked
+	// by the pallet as the number of authorities grows.
+	read_write_authority_sets {
+		// The current max target number of validators on Polkadot/Kusama
+		let n in 1..1000;
+
+		let mut authorities = vec![];
+		for i in 0..n {
+			authorities.push((ALICE, 1));
+		}
+
+		let authority_set = bp_header_chain::AuthoritySet {
+			authorities: authorities.iter().map(|(id, w)| (AuthorityId::from(*id), *w)).collect(),
+			set_id: 0
+		};
+
+		<CurrentAuthoritySet<T, I>>::put(&authority_set);
+
+	}: {
+		let authority_set = <CurrentAuthoritySet<T, I>>::get();
+		<CurrentAuthoritySet<T, I>>::put(&authority_set);
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use frame_support::assert_ok;
+
+	#[test]
+	fn finality_proof_is_valid() {
+		mock::run_test(|| {
+			assert_ok!(test_benchmark_submit_finality_proof::<mock::TestRuntime>());
+		});
+	}
+
+	#[test]
+	fn single_fork_finality_proof_is_valid() {
+		mock::run_test(|| {
+			assert_ok!(test_benchmark_submit_finality_proof_on_single_fork::<mock::TestRuntime>());
+		});
+	}
+
+	#[test]
+	fn multi_fork_finality_proof_is_valid() {
+		mock::run_test(|| {
+			assert_ok!(test_benchmark_submit_finality_proof_on_many_forks::<mock::TestRuntime>());
+		});
+	}
+}
@@ -36,12 +36,15 @@
 // Runtime-generated enums
 #![allow(clippy::large_enum_variant)]

+use crate::weights::WeightInfo;
+
 use bp_header_chain::justification::GrandpaJustification;
 use bp_runtime::{BlockNumberOf, Chain, HashOf, HasherOf, HeaderOf};
 use codec::{Decode, Encode};
 use finality_grandpa::voter_set::VoterSet;
 use frame_support::ensure;
 use frame_system::{ensure_signed, RawOrigin};
+use num_traits::cast::AsPrimitive;
 #[cfg(feature = "std")]
 use serde::{Deserialize, Serialize};
 use sp_finality_grandpa::{ConsensusLog, GRANDPA_ENGINE_ID};
@@ -51,6 +54,12 @@ use sp_runtime::RuntimeDebug;
 #[cfg(test)]
 mod mock;

+/// Module containing weights for this pallet.
+pub mod weights;
+
+#[cfg(feature = "runtime-benchmarks")]
+pub mod benchmarking;
+
 // Re-export in crate namespace for `construct_runtime!`
 pub use pallet::*;

@@ -82,6 +91,30 @@ pub mod pallet {
 		/// until the request count has decreased.
 		#[pallet::constant]
 		type MaxRequests: Get<u32>;
+
+		/// The maximum length of a session on the bridged chain.
+		///
+		/// The pallet uses this to bound justification verification since justifications contain
+		/// ancestry proofs whose size is capped at `MaxBridgedSessionLength`.
+		#[pallet::constant]
+		type MaxBridgedSessionLength: Get<BridgedBlockNumber<Self, I>>;
+
+		/// The number of validators on the bridged chain.
+		///
+		/// The pallet uses this to bound justification verification since justifications may
+		/// contain up to `MaxBridgedValidatorCount` number of signed `pre-commit` messages which
+		/// need to be verified.
+		///
+		/// Note that `MaxBridgedValidatorCount` should *not* match the exact number of validators
+		/// on the bridged chain. Instead it should be a number which is greater than the actual
+		/// number of validators in order to provide some buffer room should the validator set
+		/// increase in size. If this number ends up being lower than the actual number of
+		/// validators on the bridged chain you risk stalling the bridge.
+		#[pallet::constant]
+		type MaxBridgedValidatorCount: Get<u32>;
+
+		/// Weights gathered through benchmarking.
+		type WeightInfo: WeightInfo;
 	}

 	#[pallet::pallet]
@@ -107,7 +140,10 @@ pub mod pallet {
 		///
 		/// If successful in verification, it will write the target header to the underlying storage
 		/// pallet.
-		#[pallet::weight(0)]
+		#[pallet::weight(T::WeightInfo::submit_finality_proof(
+			T::MaxBridgedSessionLength::get().as_() as u32,
+			T::MaxBridgedValidatorCount::get(),
+		))]
 		pub fn submit_finality_proof(
 			origin: OriginFor<T>,
 			finality_target: BridgedHeader<T, I>,
@@ -134,16 +170,26 @@ pub mod pallet {
 			// "travelling back in time" (which could be indicative of something bad, e.g a hard-fork).
 			ensure!(best_finalized.number() < number, <Error<T, I>>::OldHeader);

-			verify_justification::<T, I>(&justification, hash, *number)?;
+			let authority_set = <CurrentAuthoritySet<T, I>>::get();
+			let set_id = authority_set.set_id;
+			verify_justification::<T, I>(&justification, hash, *number, authority_set)?;

-			try_enact_authority_change::<T, I>(&finality_target)?;
+			let _enacted = try_enact_authority_change::<T, I>(&finality_target, set_id)?;
 			<BestFinalized<T, I>>::put(hash);
 			<ImportedHeaders<T, I>>::insert(hash, finality_target);
 			<RequestCount<T, I>>::mutate(|count| *count += 1);

 			log::info!(target: "runtime::bridge-grandpa", "Succesfully imported finalized header with hash {:?}!", hash);

-			Ok(().into())
+			// Note that the number of precommits is indicitive of the number of GRANDPA forks being
+			// voted on.
+			let precommits = justification.commit.precommits.len();
+
+			// This represents the average number of votes in a single fork since the weight formula
+			// uses that metric instead of the aggregated number of vote ancestries.
+			let votes = (justification.votes_ancestries.len() + precommits - 1) / precommits;
+
+			Ok(Some(T::WeightInfo::submit_finality_proof(votes as u32, precommits as u32)).into())
 		}

 		/// Bootstrap the bridge pallet with an initial header and authority set from which to sync.
@@ -319,9 +365,14 @@ pub mod pallet {
 	///
 	/// This function does not support forced changes, or scheduled changes with delays
 	/// since these types of changes are indicitive of abnormal behaviour from GRANDPA.
+	///
+	/// Returned value will indicate if a change was enacted or not.
 	pub(crate) fn try_enact_authority_change<T: Config<I>, I: 'static>(
 		header: &BridgedHeader<T, I>,
-	) -> Result<(), sp_runtime::DispatchError> {
+		current_set_id: sp_finality_grandpa::SetId,
+	) -> Result<bool, sp_runtime::DispatchError> {
+		let mut change_enacted = false;
+
 		// We don't support forced changes - at that point governance intervention is required.
 		ensure!(
 			super::find_forced_change(header).is_none(),
@@ -332,7 +383,6 @@ pub mod pallet {
 			// GRANDPA only includes a `delay` for forced changes, so this isn't valid.
 			ensure!(change.delay == Zero::zero(), <Error<T, I>>::UnsupportedScheduledChange);

-			let current_set_id = <CurrentAuthoritySet<T, I>>::get().set_id;
 			// TODO [#788]: Stop manually increasing the `set_id` here.
 			let next_authorities = bp_header_chain::AuthoritySet {
 				authorities: change.next_authorities,
@@ -342,6 +392,7 @@ pub mod pallet {
 			// Since our header schedules a change and we know the delay is 0, it must also enact
 			// the change.
 			<CurrentAuthoritySet<T, I>>::put(&next_authorities);
+			change_enacted = true;

 			log::info!(
 				target: "runtime::bridge-grandpa",
@@ -352,20 +403,23 @@ pub mod pallet {
 			);
 		};

-		Ok(())
+		Ok(change_enacted)
 	}

 	/// Verify a GRANDPA justification (finality proof) for a given header.
 	///
 	/// Will use the GRANDPA current authorities known to the pallet.
+	///
+	/// If succesful it returns the decoded GRANDPA justification so we can refund any weight which
+	/// was overcharged in the initial call.
 	pub(crate) fn verify_justification<T: Config<I>, I: 'static>(
 		justification: &GrandpaJustification<BridgedHeader<T, I>>,
 		hash: BridgedBlockHash<T, I>,
 		number: BridgedBlockNumber<T, I>,
+		authority_set: bp_header_chain::AuthoritySet,
 	) -> Result<(), sp_runtime::DispatchError> {
 		use bp_header_chain::justification::verify_justification;

-		let authority_set = <CurrentAuthoritySet<T, I>>::get();
 		let voter_set = VoterSet::new(authority_set.authorities).ok_or(<Error<T, I>>::InvalidAuthoritySet)?;
 		let set_id = authority_set.set_id;

@@ -510,7 +564,7 @@ pub(crate) fn find_forced_change<H: HeaderT>(
 	header.digest().convert_first(|l| l.try_to(id).and_then(filter_log))
 }

-/// (Re)initialize bridge with given header for using it in external benchmarks.
+/// (Re)initialize bridge with given header for using it in `pallet-bridge-messages` benchmarks.
 #[cfg(feature = "runtime-benchmarks")]
 pub fn initialize_for_benchmarks<T: Config<I>, I: 'static>(header: BridgedHeader<T, I>) {
 	initialize_bridge::<T, I>(InitializationData {
@@ -80,11 +80,16 @@ impl frame_system::Config for TestRuntime {

 parameter_types! {
 	pub const MaxRequests: u32 = 2;
+	pub const SessionLength: u64 = 5;
+	pub const NumValidators: u32 = 5;
 }

 impl grandpa::Config for TestRuntime {
 	type BridgedChain = TestBridgedChain;
 	type MaxRequests = MaxRequests;
+	type MaxBridgedSessionLength = SessionLength;
+	type MaxBridgedValidatorCount = NumValidators;
+	type WeightInfo = ();
 }

 #[derive(Debug)]
@@ -0,0 +1,141 @@
+// Copyright 2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common 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.
+
+// Parity Bridges Common 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 Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Autogenerated weights for pallet_bridge_grandpa
+//!
+//! THIS FILE WAS AUTO-GENERATED USING THE SUBSTRATE BENCHMARK CLI VERSION 3.0.0
+//! DATE: 2021-03-26, STEPS: [50, ], REPEAT: 20
+//! LOW RANGE: [], HIGH RANGE: []
+//! EXECUTION: Some(Wasm), WASM-EXECUTION: Compiled
+//! CHAIN: Some("dev"), DB CACHE: 128
+
+// Executed Command:
+// ./target/release/rialto-bridge-node
+// benchmark
+// --chain
+// dev
+// --execution
+// wasm
+// --extrinsic
+// *
+// --pallet
+// pallet_bridge_grandpa
+// --wasm-execution
+// compiled
+// --steps
+// 50
+// --repeat
+// 20
+// --template
+// ./.maintain/rialto-weight-template.hbs
+// --output
+// ./grandpa-template.txt
+// --raw
+
+#![allow(clippy::all)]
+#![allow(unused_parens)]
+#![allow(unused_imports)]
+
+use frame_support::{
+	traits::Get,
+	weights::{constants::RocksDbWeight, Weight},
+};
+use sp_std::marker::PhantomData;
+
+/// Weight functions needed for pallet_bridge_grandpa.
+pub trait WeightInfo {
+	fn submit_finality_proof(s: u32, p: u32) -> Weight;
+	fn submit_finality_proof_on_single_fork(s: u32) -> Weight;
+	fn submit_finality_proof_on_many_forks(p: u32) -> Weight;
+	fn find_scheduled_change(n: u32) -> Weight;
+	fn read_write_authority_sets(n: u32) -> Weight;
+	fn write_authority_sets(n: u32) -> Weight;
+}
+
+/// Weights for pallet_bridge_grandpa using the Rialto node and recommended hardware.
+pub struct RialtoWeight<T>(PhantomData<T>);
+impl<T: frame_system::Config> WeightInfo for RialtoWeight<T> {
+	fn submit_finality_proof(s: u32, p: u32) -> Weight {
+		(0 as Weight)
+			.saturating_add((3_248_661_000 as Weight).saturating_mul(s as Weight))
+			.saturating_add((776_552_000 as Weight).saturating_mul(p as Weight))
+			.saturating_add(T::DbWeight::get().reads(5 as Weight))
+			.saturating_add(T::DbWeight::get().writes(3 as Weight))
+	}
+	fn submit_finality_proof_on_single_fork(s: u32) -> Weight {
+		(189_213_000 as Weight)
+			.saturating_add((12_937_000 as Weight).saturating_mul(s as Weight))
+			.saturating_add(T::DbWeight::get().reads(5 as Weight))
+			.saturating_add(T::DbWeight::get().writes(3 as Weight))
+	}
+	fn submit_finality_proof_on_many_forks(p: u32) -> Weight {
+		(0 as Weight)
+			.saturating_add((138_751_000 as Weight).saturating_mul(p as Weight))
+			.saturating_add(T::DbWeight::get().reads(5 as Weight))
+			.saturating_add(T::DbWeight::get().writes(3 as Weight))
+	}
+	fn find_scheduled_change(n: u32) -> Weight {
+		(301_000 as Weight).saturating_add((10_000 as Weight).saturating_mul(n as Weight))
+	}
+	fn read_write_authority_sets(n: u32) -> Weight {
+		(6_787_000 as Weight)
+			.saturating_add((247_000 as Weight).saturating_mul(n as Weight))
+			.saturating_add(T::DbWeight::get().reads(1 as Weight))
+			.saturating_add(T::DbWeight::get().writes(1 as Weight))
+	}
+	fn write_authority_sets(n: u32) -> Weight {
+		(3_383_000 as Weight)
+			.saturating_add((99_000 as Weight).saturating_mul(n as Weight))
+			.saturating_add(T::DbWeight::get().writes(1 as Weight))
+	}
+}
+
+// For backwards compatibility and tests
+impl WeightInfo for () {
+	fn submit_finality_proof(s: u32, p: u32) -> Weight {
+		(0 as Weight)
+			.saturating_add((3_248_661_000 as Weight).saturating_mul(s as Weight))
+			.saturating_add((776_552_000 as Weight).saturating_mul(p as Weight))
+			.saturating_add(RocksDbWeight::get().reads(5 as Weight))
+			.saturating_add(RocksDbWeight::get().writes(3 as Weight))
+	}
+	fn submit_finality_proof_on_single_fork(s: u32) -> Weight {
+		(189_213_000 as Weight)
+			.saturating_add((12_937_000 as Weight).saturating_mul(s as Weight))
+			.saturating_add(RocksDbWeight::get().reads(5 as Weight))
+			.saturating_add(RocksDbWeight::get().writes(3 as Weight))
+	}
+	fn submit_finality_proof_on_many_forks(p: u32) -> Weight {
+		(0 as Weight)
+			.saturating_add((138_751_000 as Weight).saturating_mul(p as Weight))
+			.saturating_add(RocksDbWeight::get().reads(5 as Weight))
+			.saturating_add(RocksDbWeight::get().writes(3 as Weight))
+	}
+	fn find_scheduled_change(n: u32) -> Weight {
+		(301_000 as Weight).saturating_add((10_000 as Weight).saturating_mul(n as Weight))
+	}
+	fn read_write_authority_sets(n: u32) -> Weight {
+		(6_787_000 as Weight)
+			.saturating_add((247_000 as Weight).saturating_mul(n as Weight))
+			.saturating_add(RocksDbWeight::get().reads(1 as Weight))
+			.saturating_add(RocksDbWeight::get().writes(1 as Weight))
+	}
+	fn write_authority_sets(n: u32) -> Weight {
+		(3_383_000 as Weight)
+			.saturating_add((99_000 as Weight).saturating_mul(n as Weight))
+			.saturating_add(RocksDbWeight::get().writes(1 as Weight))
+	}
+}
@@ -95,7 +95,11 @@ pub const ADDITIONAL_MESSAGE_BYTE_DELIVERY_WEIGHT: Weight = 25_000;
 /// runtime upgrades.
 pub const MAX_SINGLE_MESSAGE_DELIVERY_CONFIRMATION_TX_WEIGHT: Weight = 2_000_000_000;

-/// The length of a session (how often authorities change) on Millau measured in of number of blocks.
+/// The target length of a session (how often authorities change) on Millau measured in of number of
+/// blocks.
+///
+/// Note that since this is a target sessions may change before/after this time depending on network
+/// conditions.
 pub const SESSION_LENGTH: BlockNumber = 5 * time_units::MINUTES;

 /// Re-export `time_units` to make usage easier.
@@ -86,7 +86,11 @@ pub const ADDITIONAL_MESSAGE_BYTE_DELIVERY_WEIGHT: Weight = 25_000;
 /// runtime upgrades.
 pub const MAX_SINGLE_MESSAGE_DELIVERY_CONFIRMATION_TX_WEIGHT: Weight = 2_000_000_000;

-/// The length of a session (how often authorities change) on Rialto measured in of number of blocks.
+/// The target length of a session (how often authorities change) on Rialto measured in of number of
+/// blocks.
+///
+/// Note that since this is a target sessions may change before/after this time depending on network
+/// conditions.
 pub const SESSION_LENGTH: BlockNumber = 4;

 /// Re-export `time_units` to make usage easier.
@@ -69,6 +69,13 @@ pub const FROM_WESTEND_LATEST_CONFIRMED_NONCE_METHOD: &str = "FromWestendInbound
 /// Name of the `FromWestendInboundLaneApi::unrewarded_relayers_state` runtime method.
 pub const FROM_WESTEND_UNREWARDED_RELAYERS_STATE: &str = "FromWestendInboundLaneApi_unrewarded_relayers_state";

+/// The target length of a session (how often authorities change) on Westend measured in of number of
+/// blocks.
+///
+/// Note that since this is a target sessions may change before/after this time depending on network
+/// conditions.
+pub const SESSION_LENGTH: BlockNumber = 10 * time_units::MINUTES;
+
 sp_api::decl_runtime_apis! {
 	/// API for querying information about the finalized Westend headers.
 	///
@@ -136,6 +136,21 @@ pub const MAX_UNREWARDED_RELAYER_ENTRIES_AT_INBOUND_LANE: MessageNonce = 128;
 /// Maximal number of unconfirmed messages at inbound lane.
 pub const MAX_UNCONFIRMED_MESSAGES_AT_INBOUND_LANE: MessageNonce = 8192;

+/// Re-export `time_units` to make usage easier.
+pub use time_units::*;
+
+/// Human readable time units defined in terms of number of blocks.
+pub mod time_units {
+	use super::BlockNumber;
+
+	pub const MILLISECS_PER_BLOCK: u64 = 6000;
+	pub const SLOT_DURATION: u64 = MILLISECS_PER_BLOCK;
+
+	pub const MINUTES: BlockNumber = 60_000 / (MILLISECS_PER_BLOCK as BlockNumber);
+	pub const HOURS: BlockNumber = MINUTES * 60;
+	pub const DAYS: BlockNumber = HOURS * 24;
+}
+
 /// Block number type used in Polkadot-like chains.
 pub type BlockNumber = u32;

@@ -21,6 +21,7 @@ use finality_grandpa::voter_set::VoterSet;
 use sp_application_crypto::Public;
 use sp_finality_grandpa::{AuthorityId, AuthorityList, AuthorityWeight};
 use sp_runtime::RuntimeDebug;
+use sp_std::prelude::*;

 /// Set of test accounts with friendly names.
 pub const ALICE: Account = Account(0);