Skeleton of the Router module (#1726)

The purpose of this commit is to establish a foundation of the router module, it paves the way for the implementation of other features.

polkadot/runtime/parachains/src/initializer.rs

@@ -27,7 +27,10 @@ use frame_support::{
 };
 use sp_runtime::traits::One;
 use codec::{Encode, Decode};
-use crate::{configuration::{self, HostConfiguration}, paras, scheduler, inclusion};
+use crate::{
+	configuration::{self, HostConfiguration},
+	paras, router, scheduler, inclusion,
+};
 
 /// Information about a session change that has just occurred.
 #[derive(Default, Clone)]
@@ -55,7 +58,12 @@ struct BufferedSessionChange<N> {
 }
 
 pub trait Trait:
-	frame_system::Trait + configuration::Trait + paras::Trait + scheduler::Trait + inclusion::Trait
+	frame_system::Trait
+	+ configuration::Trait
+	+ paras::Trait
+	+ scheduler::Trait
+	+ inclusion::Trait
+	+ router::Trait
 {
 	/// A randomness beacon.
 	type Randomness: Randomness<Self::Hash>;
@@ -114,10 +122,12 @@ decl_module! {
 			// - Scheduler
 			// - Inclusion
 			// - Validity
+			// - Router
 			let total_weight = configuration::Module::<T>::initializer_initialize(now) +
 				paras::Module::<T>::initializer_initialize(now) +
 				scheduler::Module::<T>::initializer_initialize(now) +
-				inclusion::Module::<T>::initializer_initialize(now);
+				inclusion::Module::<T>::initializer_initialize(now) +
+				router::Module::<T>::initializer_initialize(now);
 
 			HasInitialized::set(Some(()));
 
@@ -127,6 +137,7 @@ decl_module! {
 		fn on_finalize() {
 			// reverse initialization order.
 
+			router::Module::<T>::initializer_finalize();
 			inclusion::Module::<T>::initializer_finalize();
 			scheduler::Module::<T>::initializer_finalize();
 			paras::Module::<T>::initializer_finalize();
@@ -170,6 +181,7 @@ impl<T: Trait> Module<T> {
 		paras::Module::<T>::initializer_on_new_session(&notification);
 		scheduler::Module::<T>::initializer_on_new_session(&notification);
 		inclusion::Module::<T>::initializer_on_new_session(&notification);
+		router::Module::<T>::initializer_on_new_session(&notification);
 	}
 
 	/// Should be called when a new session occurs. Buffers the session notification to be applied

polkadot/runtime/parachains/src/lib.rs

@@ -20,7 +20,6 @@
 //! particular the `Initializer` module, as it is responsible for initializing the state
 //! of the other modules.
 
-
 #![cfg_attr(not(feature = "std"), no_std)]
 
 use sp_std::result;
@@ -33,6 +32,7 @@ pub mod inclusion;
 pub mod inclusion_inherent;
 pub mod initializer;
 pub mod paras;
+pub mod router;
 pub mod scheduler;
 pub mod validity;
 

polkadot/runtime/parachains/src/mock.rs

@@ -103,6 +103,8 @@ impl crate::configuration::Trait for Test { }
 
 impl crate::paras::Trait for Test { }
 
+impl crate::router::Trait for Test { }
+
 impl crate::scheduler::Trait for Test { }
 
 impl crate::inclusion::Trait for Test {
@@ -120,6 +122,11 @@ pub type Configuration = crate::configuration::Module<Test>;
 /// Mocked paras.
 pub type Paras = crate::paras::Module<Test>;
 
+/// Mocked router.
+// TODO: Will be used in the follow ups.
+#[allow(dead_code)]
+pub type Router = crate::router::Module<Test>;
+
 /// Mocked scheduler.
 pub type Scheduler = crate::scheduler::Module<Test>;
 

polkadot/runtime/parachains/src/router.rs

@@ -0,0 +1,80 @@
+// Copyright 2020 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot 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.
+
+// Polkadot 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! The router module is responsible for handling messaging.
+//!
+//! The core of the messaging is checking and processing messages sent out by the candidates,
+//! routing the messages at their destinations and informing the parachains about the incoming
+//! messages.
+
+use crate::{configuration, initializer};
+use sp_std::prelude::*;
+use frame_support::{decl_error, decl_module, decl_storage, weights::Weight};
+use primitives::v1::{Id as ParaId};
+
+pub trait Trait: frame_system::Trait + configuration::Trait {}
+
+decl_storage! {
+	trait Store for Module<T: Trait> as Router {
+		/// Paras that are to be cleaned up at the end of the session.
+		/// The entries are sorted ascending by the para id.
+		OutgoingParas: Vec<ParaId>;
+	}
+}
+
+decl_error! {
+	pub enum Error for Module<T: Trait> { }
+}
+
+decl_module! {
+	/// The router module.
+	pub struct Module<T: Trait> for enum Call where origin: <T as frame_system::Trait>::Origin {
+		type Error = Error<T>;
+	}
+}
+
+impl<T: Trait> Module<T> {
+	/// Block initialization logic, called by initializer.
+	pub(crate) fn initializer_initialize(_now: T::BlockNumber) -> Weight {
+		0
+	}
+
+	/// Block finalization logic, called by initializer.
+	pub(crate) fn initializer_finalize() {}
+
+	/// Called by the initializer to note that a new session has started.
+	pub(crate) fn initializer_on_new_session(
+		_notification: &initializer::SessionChangeNotification<T::BlockNumber>,
+	) {
+		let outgoing = OutgoingParas::take();
+		for _outgoing_para in outgoing {
+
+		}
+	}
+
+	/// Schedule a para to be cleaned up at the start of the next session.
+	pub fn schedule_para_cleanup(id: ParaId) {
+		OutgoingParas::mutate(|v| {
+			if let Err(i) = v.binary_search(&id) {
+				v.insert(i, id);
+			}
+		});
+	}
+}
+
+#[cfg(test)]
+mod tests {
+}