Unify error enums in substrate and ethereum clients with thiserror (#1094)

* Unify error enums in substrate and ethereum clients with `thiserror`

Related to https://github.com/paritytech/parity-bridges-common/issues/857

* Add license pre-amble

* rustfmt

* Fix spelling

bridges/relays/lib-substrate-relay/Cargo.toml

@@ -7,6 +7,7 @@ license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 
 [dependencies]
 anyhow = "1.0"
+thiserror = "1.0.26"
 async-std = "1.9.0"
 async-trait = "0.1.42"
 codec = { package = "parity-scale-codec", version = "2.2.0" }

bridges/relays/lib-substrate-relay/src/error.rs

@@ -0,0 +1,58 @@
+// 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/>.
+
+//! Relay errors.
+
+use relay_substrate_client as client;
+use sp_finality_grandpa::AuthorityList;
+use sp_runtime::traits::MaybeDisplay;
+use std::fmt::Debug;
+use thiserror::Error;
+
+/// Relay errors.
+#[derive(Error, Debug)]
+pub enum Error<Hash: Debug + MaybeDisplay, HeaderNumber: Debug + MaybeDisplay> {
+	/// Failed to submit signed extrinsic from to the target chain.
+	#[error("Failed to submit {0} transaction: {1:?}")]
+	SubmitTransaction(&'static str, client::Error),
+	/// Failed subscribe to justification stream of the source chain.
+	#[error("Failed to subscribe to {0} justifications: {1:?}")]
+	Subscribe(&'static str, client::Error),
+	/// Failed subscribe to read justification from the source chain (client error).
+	#[error("Failed to read {0} justification from the stream: {1}")]
+	ReadJustification(&'static str, client::Error),
+	/// Failed subscribe to read justification from the source chain (stream ended).
+	#[error("Failed to read {0} justification from the stream: stream has ended unexpectedly")]
+	ReadJustificationStreamEnded(&'static str),
+	/// Failed subscribe to decode justification from the source chain.
+	#[error("Failed to decode {0} justification: {1:?}")]
+	DecodeJustification(&'static str, codec::Error),
+	/// GRANDPA authorities read from the source chain are invalid.
+	#[error("Read invalid {0} authorities set: {1:?}")]
+	ReadInvalidAuthorities(&'static str, AuthorityList),
+	/// Failed to guess initial GRANDPA authorities at the given header of the source chain.
+	#[error("Failed to guess initial {0} GRANDPA authorities set id: checked all possible ids in range [0; {1}]")]
+	GuessInitialAuthorities(&'static str, HeaderNumber),
+	/// Failed to retrieve GRANDPA authorities at the given header from the source chain.
+	#[error("Failed to retrive {0} GRANDPA authorities set at header {1}: {2:?}")]
+	RetrieveAuthorities(&'static str, Hash, client::Error),
+	/// Failed to decode GRANDPA authorities at the given header of the source chain.
+	#[error("Failed to decode {0} GRANDPA authorities set at header {1}: {2:?}")]
+	DecodeAuthorities(&'static str, Hash, codec::Error),
+	/// Failed to retrieve header by the hash from the source chain.
+	#[error("Failed to retrieve {0} header with hash {1}: {:?}")]
+	RetrieveHeader(&'static str, Hash, client::Error),
+}

bridges/relays/lib-substrate-relay/src/headers_initialize.rs

@@ -21,6 +21,8 @@
 //! and authorities set from source to target chain. The headers sync starts
 //! with this header.
 
+use crate::error::Error;
+
 use bp_header_chain::{
 	find_grandpa_authorities_scheduled_change,
 	justification::{verify_justification, GrandpaJustification},
@@ -32,7 +34,7 @@ use num_traits::{One, Zero};
 use relay_substrate_client::{Chain, Client};
 use sp_core::Bytes;
 use sp_finality_grandpa::AuthorityList as GrandpaAuthoritiesSet;
-use sp_runtime::traits::Header as HeaderT;
+use sp_runtime::traits::{Header as HeaderT, Header};
 
 /// Submit headers-bridge initialization transaction.
 pub async fn initialize<SourceChain: Chain, TargetChain: Chain>(
@@ -77,7 +79,7 @@ async fn do_initialize<SourceChain: Chain, TargetChain: Chain>(
 	prepare_initialize_transaction: impl FnOnce(TargetChain::Index, InitializationData<SourceChain::Header>) -> Bytes
 		+ Send
 		+ 'static,
-) -> Result<TargetChain::Hash, String> {
+) -> Result<TargetChain::Hash, Error<SourceChain::Hash, <SourceChain::Header as Header>::Number>> {
 	let initialization_data = prepare_initialization_data(source_client).await?;
 	log::info!(
 		target: "bridge",
@@ -92,41 +94,40 @@ async fn do_initialize<SourceChain: Chain, TargetChain: Chain>(
 			prepare_initialize_transaction(transaction_nonce, initialization_data)
 		})
 		.await
-		.map_err(|err| format!("Failed to submit {} transaction: {:?}", TargetChain::NAME, err))?;
+		.map_err(|err| Error::SubmitTransaction(TargetChain::NAME, err))?;
 	Ok(initialization_tx_hash)
 }
 
 /// Prepare initialization data for the GRANDPA verifier pallet.
 async fn prepare_initialization_data<SourceChain: Chain>(
 	source_client: Client<SourceChain>,
-) -> Result<InitializationData<SourceChain::Header>, String> {
+) -> Result<
+	InitializationData<SourceChain::Header>,
+	Error<SourceChain::Hash, <SourceChain::Header as Header>::Number>,
+> {
 	// In ideal world we just need to get best finalized header and then to read GRANDPA authorities
 	// set (`pallet_grandpa::CurrentSetId` + `GrandpaApi::grandpa_authorities()`) at this header.
 	//
 	// But now there are problems with this approach - `CurrentSetId` may return invalid value. So
 	// here we're waiting for the next justification, read the authorities set and then try to
 	// figure out the set id with bruteforce.
-	let justifications = source_client.subscribe_justifications().await.map_err(|err| {
-		format!("Failed to subscribe to {} justifications: {:?}", SourceChain::NAME, err)
-	})?;
-
+	let justifications = source_client
+		.subscribe_justifications()
+		.await
+		.map_err(|err| Error::Subscribe(SourceChain::NAME, err))?;
 	// Read next justification - the header that it finalizes will be used as initial header.
 	let justification = justifications
 		.next()
 		.await
-		.map_err(|err| err.to_string())
+		.map_err(|e| Error::ReadJustification(SourceChain::NAME, e))
 		.and_then(|justification| {
-			justification.ok_or_else(|| "stream has ended unexpectedly".into())
-		})
-		.map_err(|err| {
-			format!("Failed to read {} justification from the stream: {}", SourceChain::NAME, err,)
+			justification.ok_or_else(|| Error::ReadJustificationStreamEnded(SourceChain::NAME))
 		})?;
 
 	// Read initial header.
 	let justification: GrandpaJustification<SourceChain::Header> =
-		Decode::decode(&mut &justification.0[..]).map_err(|err| {
-			format!("Failed to decode {} justification: {:?}", SourceChain::NAME, err)
-		})?;
+		Decode::decode(&mut &justification.0[..])
+			.map_err(|err| Error::DecodeJustification(SourceChain::NAME, err))?;
 
 	let (initial_header_hash, initial_header_number) =
 		(justification.commit.target_hash, justification.commit.target_number);
@@ -174,11 +175,7 @@ async fn prepare_initialization_data<SourceChain: Chain>(
 	let mut min_possible_block_number = SourceChain::BlockNumber::zero();
 	let authorities_for_verification = VoterSet::new(authorities_for_verification.clone())
 		.ok_or_else(|| {
-			format!(
-				"Read invalid {} authorities set: {:?}",
-				SourceChain::NAME,
-				authorities_for_verification,
-			)
+			Error::ReadInvalidAuthorities(SourceChain::NAME, authorities_for_verification)
 		})?;
 	loop {
 		log::trace!(
@@ -205,12 +202,7 @@ async fn prepare_initialization_data<SourceChain: Chain>(
 			// there can't be more authorities set changes than headers => if we have reached
 			// `initial_block_number` and still have not found correct value of
 			// `initial_authorities_set_id`, then something else is broken => fail
-			return Err(format!(
-				"Failed to guess initial {} GRANDPA authorities set id: checked all\
-			possible ids in range [0; {}]",
-				SourceChain::NAME,
-				initial_header_number
-			))
+			return Err(Error::GuessInitialAuthorities(SourceChain::NAME, initial_header_number))
 		}
 	}
 
@@ -230,37 +222,24 @@ async fn prepare_initialization_data<SourceChain: Chain>(
 async fn source_header<SourceChain: Chain>(
 	source_client: &Client<SourceChain>,
 	header_hash: SourceChain::Hash,
-) -> Result<SourceChain::Header, String> {
-	source_client.header_by_hash(header_hash).await.map_err(|err| {
-		format!(
-			"Failed to retrive {} header with hash {}: {:?}",
-			SourceChain::NAME,
-			header_hash,
-			err,
-		)
-	})
+) -> Result<SourceChain::Header, Error<SourceChain::Hash, <SourceChain::Header as Header>::Number>>
+{
+	source_client
+		.header_by_hash(header_hash)
+		.await
+		.map_err(|err| Error::RetrieveHeader(SourceChain::NAME, header_hash, err))
 }
 
 /// Read GRANDPA authorities set at given header.
 async fn source_authorities_set<SourceChain: Chain>(
 	source_client: &Client<SourceChain>,
 	header_hash: SourceChain::Hash,
-) -> Result<GrandpaAuthoritiesSet, String> {
-	let raw_authorities_set =
-		source_client.grandpa_authorities_set(header_hash).await.map_err(|err| {
-			format!(
-				"Failed to retrive {} GRANDPA authorities set at header {}: {:?}",
-				SourceChain::NAME,
-				header_hash,
-				err,
-			)
-		})?;
-	GrandpaAuthoritiesSet::decode(&mut &raw_authorities_set[..]).map_err(|err| {
-		format!(
-			"Failed to decode {} GRANDPA authorities set at header {}: {:?}",
-			SourceChain::NAME,
-			header_hash,
-			err,
-		)
-	})
+) -> Result<GrandpaAuthoritiesSet, Error<SourceChain::Hash, <SourceChain::Header as Header>::Number>>
+{
+	let raw_authorities_set = source_client
+		.grandpa_authorities_set(header_hash)
+		.await
+		.map_err(|err| Error::RetrieveAuthorities(SourceChain::NAME, header_hash, err))?;
+	GrandpaAuthoritiesSet::decode(&mut &raw_authorities_set[..])
+		.map_err(|err| Error::DecodeAuthorities(SourceChain::NAME, header_hash, err))
 }

bridges/relays/lib-substrate-relay/src/lib.rs

@@ -19,6 +19,7 @@
 #![warn(missing_docs)]
 
 pub mod conversion_rate_update;
+pub mod error;
 pub mod finality_pipeline;
 pub mod finality_target;
 pub mod headers_initialize;