Relay DummyOrdered messages (paritytech#318)

* DummyOrdered relay: initial commit

* 1 ML file -> 3 files

* extracted generic message race loop

* uncommented race error procesing

* lane loop tests

* cargo fmt

* moved HeaderId to utils.rs

* restart lane loop on stall

* message delivery strategy tests

* removed obsolete code

* clippy

* Update relays/ethereum/src/message_lane_loop.rs

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* Update relays/ethereum/src/message_lane_loop.rs

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* added more races docs

* Update relays/ethereum/src/message_race_delivery.rs

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* update docs

* Update relays/ethereum/src/message_race_loop.rs

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* deal with TODOs

* removed docs

* docs

* cargo fmt --all

* Update relays/ethereum/src/message_race_loop.rs

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>
Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

bridges/relays/ethereum/src/ethereum_client.rs

@@ -21,8 +21,8 @@ use crate::ethereum_types::{
 use crate::rpc::{Ethereum, EthereumRpc};
 use crate::rpc_errors::{EthereumNodeError, RpcError};
 use crate::substrate_types::{GrandpaJustification, Hash as SubstrateHash, QueuedSubstrateHeader, SubstrateHeaderId};
-use crate::sync_types::{HeaderId, SubmittedHeaders};
-use crate::utils::MaybeConnectionError;
+use crate::sync_types::SubmittedHeaders;
+use crate::utils::{HeaderId, MaybeConnectionError};
 
 use async_trait::async_trait;
 use codec::{Decode, Encode};

bridges/relays/ethereum/src/ethereum_deploy_contract.rs

@@ -21,7 +21,7 @@ use crate::instances::BridgeInstance;
 use crate::rpc::SubstrateRpc;
 use crate::substrate_client::{SubstrateConnectionParams, SubstrateRpcClient};
 use crate::substrate_types::{Hash as SubstrateHash, Header as SubstrateHeader, SubstrateHeaderId};
-use crate::sync_types::HeaderId;
+use crate::utils::HeaderId;
 
 use codec::{Decode, Encode};
 use num_traits::Zero;

bridges/relays/ethereum/src/ethereum_exchange.rs

@@ -34,7 +34,7 @@ use crate::substrate_client::{
 	SubmitEthereumExchangeTransactionProof, SubstrateConnectionParams, SubstrateRpcClient, SubstrateSigningParams,
 };
 use crate::substrate_types::into_substrate_ethereum_receipt;
-use crate::sync_types::HeaderId;
+use crate::utils::HeaderId;
 
 use async_trait::async_trait;
 use bp_currency_exchange::MaybeLockFundsTransaction;

bridges/relays/ethereum/src/ethereum_types.rs

@@ -15,7 +15,8 @@
 // along with Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
 
 use crate::substrate_types::{into_substrate_ethereum_header, into_substrate_ethereum_receipts};
-use crate::sync_types::{HeaderId, HeadersSyncPipeline, QueuedHeader, SourceHeader};
+use crate::sync_types::{HeadersSyncPipeline, QueuedHeader, SourceHeader};
+use crate::utils::HeaderId;
 use codec::Encode;
 
 pub use web3::types::{Address, Bytes, CallRequest, H256, U128, U256, U64};

bridges/relays/ethereum/src/exchange.rs

@@ -54,7 +54,7 @@ pub trait SourceBlock {
 	type Transaction: SourceTransaction;
 
 	/// Return hash of the block.
-	fn id(&self) -> crate::sync_types::HeaderId<Self::Hash, Self::Number>;
+	fn id(&self) -> crate::utils::HeaderId<Self::Hash, Self::Number>;
 	/// Return block transactions iterator.
 	fn transactions(&self) -> Vec<Self::Transaction>;
 }
@@ -81,7 +81,7 @@ pub type TransactionOf<P> = <<P as TransactionProofPipeline>::Block as SourceBlo
 pub type TransactionHashOf<P> = <TransactionOf<P> as SourceTransaction>::Hash;
 
 /// Header id.
-pub type HeaderId<P> = crate::sync_types::HeaderId<BlockHashOf<P>, BlockNumberOf<P>>;
+pub type HeaderId<P> = crate::utils::HeaderId<BlockHashOf<P>, BlockNumberOf<P>>;
 
 /// Source client API.
 #[async_trait]
@@ -443,7 +443,7 @@ async fn wait_header_finalized<P: TransactionProofPipeline>(
 #[cfg(test)]
 pub(crate) mod tests {
 	use super::*;
-	use crate::sync_types::HeaderId;
+	use crate::utils::HeaderId;
 
 	use parking_lot::Mutex;
 	use std::{

bridges/relays/ethereum/src/headers.rs

@@ -14,7 +14,9 @@
 // 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/>.
 
-use crate::sync_types::{HeaderId, HeaderIdOf, HeaderStatus, HeadersSyncPipeline, QueuedHeader, SourceHeader};
+use crate::sync_types::{HeaderIdOf, HeaderStatus, HeadersSyncPipeline, QueuedHeader, SourceHeader};
+use crate::utils::HeaderId;
+
 use linked_hash_map::LinkedHashMap;
 use num_traits::{One, Zero};
 use std::{
@@ -777,7 +779,7 @@ fn queued_incomplete_header<Id: Clone + Eq + std::hash::Hash, T>(
 pub(crate) mod tests {
 	use super::*;
 	use crate::ethereum_types::{EthereumHeaderId, EthereumHeadersSyncPipeline, Header, H256};
-	use crate::sync_types::{HeaderId, QueuedHeader};
+	use crate::sync_types::QueuedHeader;
 
 	pub(crate) fn header(number: u64) -> QueuedHeader<EthereumHeadersSyncPipeline> {
 		QueuedHeader::new(Header {

bridges/relays/ethereum/src/main.rs

@@ -27,6 +27,10 @@ mod exchange_loop;
 mod exchange_loop_metrics;
 mod headers;
 mod instances;
+mod message_lane;
+mod message_lane_loop;
+mod message_race_delivery;
+mod message_race_loop;
 mod metrics;
 mod rpc;
 mod rpc_errors;

bridges/relays/ethereum/src/message_lane.rs

@@ -0,0 +1,55 @@
+// Copyright 2019-2020 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/>.
+
+//! One-way message lane types. Within single one-way lane we have three 'races' where we try to:
+//!
+//! 1) relay new messages from source to target node;
+//! 2) relay proof-of-receiving from target to source node;
+//! 3) relay proof-of-processing from target no source node.
+
+use crate::utils::HeaderId;
+
+use std::fmt::Debug;
+
+/// One-way message lane.
+pub trait MessageLane {
+	/// Name of the messages source.
+	const SOURCE_NAME: &'static str;
+	/// Name of the messages target.
+	const TARGET_NAME: &'static str;
+
+	/// Message nonce type.
+	type MessageNonce: Clone + Copy + Debug + Default + From<u32> + Ord + std::ops::Add<Output = Self::MessageNonce>;
+
+	/// Messages proof.
+	type MessagesProof: Clone;
+
+	/// Number of the source header.
+	type SourceHeaderNumber: Clone + Debug + Default + Ord + PartialEq;
+	/// Hash of the source header.
+	type SourceHeaderHash: Clone + Debug + Default + PartialEq;
+
+	/// Number of the target header.
+	type TargetHeaderNumber: Clone + Debug + Default + Ord + PartialEq;
+	/// Hash of the target header.
+	type TargetHeaderHash: Clone + Debug + Default + PartialEq;
+}
+
+/// Source header id within given one-way message lane.
+pub type SourceHeaderIdOf<P> = HeaderId<<P as MessageLane>::SourceHeaderHash, <P as MessageLane>::SourceHeaderNumber>;
+
+/// Target header id within given one-way message lane.
+pub type TargetHeaderIdOf<P> = HeaderId<<P as MessageLane>::TargetHeaderHash, <P as MessageLane>::TargetHeaderNumber>;