Initial version of Call::decode dispatch. (#300)

* Initial version of call dispatch.

* cargo fmt --all

* Remove unused stuff.

* cargo fmt --all

* weight is part of msg + events

* should_fail_on_weight_mismatch

* plug into runtime

* cargo fmt --all

* fix benchmarks compilation?

* expected/actual values in events

* return actual weight from MessageDispatch::dispatch()

* MessageOrigin -> InstanceId + move bridge_account_id to bp-runtime

* fix benchmarks again

* cargo fmt --all

* clippy

Co-authored-by: Svyatoslav Nikolsky <svyatonik@gmail.com>

bridges/primitives/message-dispatch/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "bp-message-dispatch"
+description = "Primitives of bridge messages dispatch modules."
+version = "0.1.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
+license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
+
+[dependencies]
+bp-runtime = { path = "../runtime", default-features = false }
+codec = { package = "parity-scale-codec", version = "1.3.1", default-features = false }
+
+[features]
+default = ["std"]
+std = [
+	"bp-runtime/std",
+	"codec/std",
+]

bridges/primitives/message-dispatch/src/lib.rs

@@ -0,0 +1,40 @@
+// 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/>.
+
+//! A common interface for all Bridge Message Dispatch modules.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+#![warn(missing_docs)]
+
+use bp_runtime::InstanceId;
+
+/// Message dispatch weight.
+pub type Weight = u64;
+
+/// A generic trait to dispatch arbitrary messages delivered over the bridge.
+pub trait MessageDispatch<MessageId> {
+	/// A type of the message to be dispatched.
+	type Message: codec::Decode;
+
+	/// Dispatches the message internally.
+	///
+	/// `bridge` indicates instance of deployed bridge where the message came from.
+	///
+	/// `id` is a short unique if of the message.
+	///
+	/// Returns post-dispatch (actual) message weight.
+	fn dispatch(bridge: InstanceId, id: MessageId, message: Self::Message) -> Weight;
+}

bridges/primitives/runtime/Cargo.toml

@@ -6,6 +6,20 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"
 license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 
+[dependencies]
+codec = { package = "parity-scale-codec", version = "1.3.1", default-features = false }
+
+# Substrate Based Dependencies
+
+[dependencies.sp-io]
+version = "2.0.0-rc6"
+tag = 'v2.0.0-rc6'
+default-features = false
+git = "https://github.com/paritytech/substrate/"
+
 [features]
 default = ["std"]
-std = []
+std = [
+	"codec/std",
+	"sp-io/std",
+]

bridges/primitives/runtime/src/lib.rs

@@ -18,8 +18,29 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
+use codec::{Decode, Encode};
+use sp_io::hashing::blake2_256;
+
+/// Call-dispatch module prefix.
+pub const CALL_DISPATCH_MODULE_PREFIX: &[u8] = b"pallet-bridge/call-dispatch";
+
 /// Id of deployed module instance. We have a bunch of pallets that may be used in
 /// different bridges. E.g. message-lane pallet may be deployed twice in the same
 /// runtime to bridge ThisChain with Chain1 and Chain2. Sometimes we need to be able
 /// to identify deployed instance dynamically. This type is used for that.
 pub type InstanceId = [u8; 4];
+
+/// Returns id of account that acts as "system" account of given bridge instance.
+/// The `module_prefix` (arbitrary slice) may be used to generate module-level
+/// "system" account, so you could have separate "system" accounts for currency
+/// exchange, message dispatch and other modules.
+///
+/// The account is not supposed to actually exists on the chain, or to have any funds.
+/// It is only used to
+pub fn bridge_account_id<AccountId>(bridge: InstanceId, module_prefix: &[u8]) -> AccountId
+where
+	AccountId: Decode + Default,
+{
+	let entropy = (module_prefix, bridge).using_encoded(blake2_256);
+	AccountId::decode(&mut &entropy[..]).unwrap_or_default()
+}