Parachains pallet benchmarks (#1436)

* added parachains pallet benchmarks

* deduplicate insertion of bridged header

* pruning weight

* fixes

* fix compilation

bridges/bin/runtime-common/src/parachains_benchmarking.rs

@@ -0,0 +1,80 @@
+// 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/>.
+
+//! Everything required to run benchmarks of parachains finality module.
+
+#![cfg(feature = "runtime-benchmarks")]
+
+use crate::messages_benchmarking::{grow_trie, insert_header_to_grandpa_pallet};
+
+use bp_parachains::parachain_head_storage_key_at_source;
+use bp_polkadot_core::parachains::{ParaHead, ParaHeadsProof, ParaId};
+use bp_runtime::StorageProofSize;
+use codec::Encode;
+use frame_support::traits::Get;
+use pallet_bridge_parachains::{RelayBlockHash, RelayBlockHasher};
+use sp_std::prelude::*;
+use sp_trie::{record_all_keys, trie_types::TrieDBMutV1, LayoutV1, MemoryDB, Recorder, TrieMut};
+
+/// Prepare proof of messages for the `receive_messages_proof` call.
+///
+/// In addition to returning valid messages proof, environment is prepared to verify this message
+/// proof.
+pub fn prepare_parachain_heads_proof<R, PI>(
+	parachains: &[ParaId],
+	parachain_head_size: u32,
+	size: StorageProofSize,
+) -> (RelayBlockHash, ParaHeadsProof)
+where
+	R: pallet_bridge_parachains::Config<PI>
+		+ pallet_bridge_grandpa::Config<R::BridgesGrandpaPalletInstance>,
+	PI: 'static,
+	<R as pallet_bridge_grandpa::Config<R::BridgesGrandpaPalletInstance>>::BridgedChain:
+		bp_runtime::Chain<Hash = RelayBlockHash>,
+{
+	let parachain_head = ParaHead(vec![0u8; parachain_head_size as usize]);
+
+	// insert all heads to the trie
+	let mut storage_keys = Vec::with_capacity(parachains.len());
+	let mut state_root = Default::default();
+	let mut mdb = MemoryDB::default();
+	{
+		let mut trie = TrieDBMutV1::<RelayBlockHasher>::new(&mut mdb, &mut state_root);
+
+		// insert parachain heads
+		for parachain in parachains {
+			let storage_key =
+				parachain_head_storage_key_at_source(R::ParasPalletName::get(), *parachain);
+			trie.insert(&storage_key.0, &parachain_head.encode())
+				.map_err(|_| "TrieMut::insert has failed")
+				.expect("TrieMut::insert should not fail in benchmarks");
+			storage_keys.push(storage_key);
+		}
+	}
+	state_root = grow_trie(state_root, &mut mdb, size);
+
+	// generate heads storage proof
+	let mut proof_recorder = Recorder::<RelayBlockHash>::new();
+	record_all_keys::<LayoutV1<RelayBlockHasher>, _>(&mdb, &state_root, &mut proof_recorder)
+		.map_err(|_| "record_all_keys has failed")
+		.expect("record_all_keys should not fail in benchmarks");
+	let proof = proof_recorder.drain().into_iter().map(|n| n.data.to_vec()).collect();
+
+	let relay_block_hash =
+		insert_header_to_grandpa_pallet::<R, R::BridgesGrandpaPalletInstance>(state_root);
+
+	(relay_block_hash, ParaHeadsProof(proof))
+}