Introduce interface for relay chain interaction (#835)

cumulus/client/relay-chain-interface/src/lib.rs

@@ -0,0 +1,248 @@
+// Copyright 2021 Parity Technologies (UK) Ltd.
+// This file is part of Cumulus.
+
+// Cumulus 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.
+
+// Cumulus 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 Cumulus.  If not, see <http://www.gnu.org/licenses/>.
+
+use std::{collections::BTreeMap, sync::Arc};
+
+use cumulus_primitives_core::{
+	relay_chain::{
+		v1::{CommittedCandidateReceipt, OccupiedCoreAssumption, SessionIndex, ValidatorId},
+		Block as PBlock, BlockId, Hash as PHash, InboundHrmpMessage,
+	},
+	InboundDownwardMessage, ParaId, PersistedValidationData,
+};
+use polkadot_overseer::Handle as OverseerHandle;
+use sc_client_api::{blockchain::BlockStatus, StorageProof};
+
+use sp_api::ApiError;
+use sp_state_machine::StorageValue;
+
+use async_trait::async_trait;
+
+#[derive(Debug, derive_more::Display)]
+pub enum WaitError {
+	#[display(fmt = "Timeout while waiting for relay-chain block `{}` to be imported.", _0)]
+	Timeout(PHash),
+	#[display(
+		fmt = "Import listener closed while waiting for relay-chain block `{}` to be imported.",
+		_0
+	)]
+	ImportListenerClosed(PHash),
+	#[display(
+		fmt = "Blockchain returned an error while waiting for relay-chain block `{}` to be imported: {:?}",
+		_0,
+		_1
+	)]
+	BlockchainError(PHash, sp_blockchain::Error),
+}
+
+/// Trait that provides all necessary methods for interaction between collator and relay chain.
+#[async_trait]
+pub trait RelayChainInterface: Send + Sync {
+	/// Fetch a storage item by key.
+	fn get_storage_by_key(
+		&self,
+		block_id: &BlockId,
+		key: &[u8],
+	) -> Result<Option<StorageValue>, sp_blockchain::Error>;
+
+	/// Fetch a vector of current validators.
+	fn validators(&self, block_id: &BlockId) -> Result<Vec<ValidatorId>, ApiError>;
+
+	/// Get the status of a given block.
+	fn block_status(&self, block_id: BlockId) -> Result<BlockStatus, sp_blockchain::Error>;
+
+	/// Get the hash of the current best block.
+	fn best_block_hash(&self) -> PHash;
+
+	/// Returns the whole contents of the downward message queue for the parachain we are collating
+	/// for.
+	///
+	/// Returns `None` in case of an error.
+	fn retrieve_dmq_contents(
+		&self,
+		para_id: ParaId,
+		relay_parent: PHash,
+	) -> Option<Vec<InboundDownwardMessage>>;
+
+	/// Returns channels contents for each inbound HRMP channel addressed to the parachain we are
+	/// collating for.
+	///
+	/// Empty channels are also included.
+	fn retrieve_all_inbound_hrmp_channel_contents(
+		&self,
+		para_id: ParaId,
+		relay_parent: PHash,
+	) -> Option<BTreeMap<ParaId, Vec<InboundHrmpMessage>>>;
+
+	/// Yields the persisted validation data for the given `ParaId` along with an assumption that
+	/// should be used if the para currently occupies a core.
+	///
+	/// Returns `None` if either the para is not registered or the assumption is `Freed`
+	/// and the para already occupies a core.
+	fn persisted_validation_data(
+		&self,
+		block_id: &BlockId,
+		para_id: ParaId,
+		_: OccupiedCoreAssumption,
+	) -> Result<Option<PersistedValidationData>, ApiError>;
+
+	/// Get the receipt of a candidate pending availability. This returns `Some` for any paras
+	/// assigned to occupied cores in `availability_cores` and `None` otherwise.
+	fn candidate_pending_availability(
+		&self,
+		block_id: &BlockId,
+		para_id: ParaId,
+	) -> Result<Option<CommittedCandidateReceipt>, ApiError>;
+
+	/// Returns the session index expected at a child of the block.
+	fn session_index_for_child(&self, block_id: &BlockId) -> Result<SessionIndex, ApiError>;
+
+	/// Get a stream of import block notifications.
+	fn import_notification_stream(&self) -> sc_client_api::ImportNotifications<PBlock>;
+
+	/// Wait for a block with a given hash in the relay chain.
+	///
+	/// This method returns immediately on error or if the block is already
+	/// reported to be in chain. Otherwise, it waits for the block to arrive.
+	async fn wait_for_block(&self, hash: PHash) -> Result<(), WaitError>;
+
+	/// Get a stream of finality notifications.
+	fn finality_notification_stream(&self) -> sc_client_api::FinalityNotifications<PBlock>;
+
+	/// Get a stream of storage change notifications.
+	fn storage_changes_notification_stream(
+		&self,
+		filter_keys: Option<&[sc_client_api::StorageKey]>,
+		child_filter_keys: Option<
+			&[(sc_client_api::StorageKey, Option<Vec<sc_client_api::StorageKey>>)],
+		>,
+	) -> sc_client_api::blockchain::Result<sc_client_api::StorageEventStream<PHash>>;
+
+	/// Whether the synchronization service is undergoing major sync.
+	/// Returns true if so.
+	fn is_major_syncing(&self) -> bool;
+
+	/// Get a handle to the overseer.
+	fn overseer_handle(&self) -> Option<OverseerHandle>;
+
+	/// Generate a storage read proof.
+	fn prove_read(
+		&self,
+		block_id: &BlockId,
+		relevant_keys: &Vec<Vec<u8>>,
+	) -> Result<Option<StorageProof>, Box<dyn sp_state_machine::Error>>;
+}
+
+#[async_trait]
+impl<T> RelayChainInterface for Arc<T>
+where
+	T: RelayChainInterface + ?Sized,
+{
+	fn retrieve_dmq_contents(
+		&self,
+		para_id: ParaId,
+		relay_parent: PHash,
+	) -> Option<Vec<InboundDownwardMessage>> {
+		(**self).retrieve_dmq_contents(para_id, relay_parent)
+	}
+
+	fn retrieve_all_inbound_hrmp_channel_contents(
+		&self,
+		para_id: ParaId,
+		relay_parent: PHash,
+	) -> Option<BTreeMap<ParaId, Vec<InboundHrmpMessage>>> {
+		(**self).retrieve_all_inbound_hrmp_channel_contents(para_id, relay_parent)
+	}
+
+	fn persisted_validation_data(
+		&self,
+		block_id: &BlockId,
+		para_id: ParaId,
+		occupied_core_assumption: OccupiedCoreAssumption,
+	) -> Result<Option<PersistedValidationData>, ApiError> {
+		(**self).persisted_validation_data(block_id, para_id, occupied_core_assumption)
+	}
+
+	fn candidate_pending_availability(
+		&self,
+		block_id: &BlockId,
+		para_id: ParaId,
+	) -> Result<Option<CommittedCandidateReceipt>, ApiError> {
+		(**self).candidate_pending_availability(block_id, para_id)
+	}
+
+	fn session_index_for_child(&self, block_id: &BlockId) -> Result<SessionIndex, ApiError> {
+		(**self).session_index_for_child(block_id)
+	}
+
+	fn validators(&self, block_id: &BlockId) -> Result<Vec<ValidatorId>, ApiError> {
+		(**self).validators(block_id)
+	}
+
+	fn import_notification_stream(&self) -> sc_client_api::ImportNotifications<PBlock> {
+		(**self).import_notification_stream()
+	}
+
+	fn finality_notification_stream(&self) -> sc_client_api::FinalityNotifications<PBlock> {
+		(**self).finality_notification_stream()
+	}
+
+	fn storage_changes_notification_stream(
+		&self,
+		filter_keys: Option<&[sc_client_api::StorageKey]>,
+		child_filter_keys: Option<
+			&[(sc_client_api::StorageKey, Option<Vec<sc_client_api::StorageKey>>)],
+		>,
+	) -> sc_client_api::blockchain::Result<sc_client_api::StorageEventStream<PHash>> {
+		(**self).storage_changes_notification_stream(filter_keys, child_filter_keys)
+	}
+
+	fn best_block_hash(&self) -> PHash {
+		(**self).best_block_hash()
+	}
+
+	fn block_status(&self, block_id: BlockId) -> Result<BlockStatus, sp_blockchain::Error> {
+		(**self).block_status(block_id)
+	}
+
+	fn is_major_syncing(&self) -> bool {
+		(**self).is_major_syncing()
+	}
+
+	fn overseer_handle(&self) -> Option<OverseerHandle> {
+		(**self).overseer_handle()
+	}
+
+	fn get_storage_by_key(
+		&self,
+		block_id: &BlockId,
+		key: &[u8],
+	) -> Result<Option<StorageValue>, sp_blockchain::Error> {
+		(**self).get_storage_by_key(block_id, key)
+	}
+
+	fn prove_read(
+		&self,
+		block_id: &BlockId,
+		relevant_keys: &Vec<Vec<u8>>,
+	) -> Result<Option<StorageProof>, Box<dyn sp_state_machine::Error>> {
+		(**self).prove_read(block_id, relevant_keys)
+	}
+
+	async fn wait_for_block(&self, hash: PHash) -> Result<(), WaitError> {
+		(**self).wait_for_block(hash).await
+	}
+}