freeze on initialize per new session

Author: MrishoLukamba

polkadot/runtime/parachains/src/assigner_coretime/mod.rs

@@ -207,7 +207,7 @@ impl<N> From<Schedule<N>> for WorkState<N> {
 #[frame_support::pallet]
 pub mod pallet {
 	use super::*;
-
+	
 	#[pallet::pallet]
 	#[pallet::without_storage_info]
 	pub struct Pallet<T>(_);

polkadot/runtime/parachains/src/paras/mod.rs

@@ -129,6 +129,7 @@ use sp_runtime::{
 	traits::{AppVerify, One, Saturating},
 	DispatchResult, SaturatedConversion,
 };
+use crate::scheduler::common::Assignment;
 
 use serde::{Deserialize, Serialize};
 
@@ -244,6 +245,7 @@ impl ParaLifecycle {
 	pub fn is_transitioning(&self) -> bool {
 		!Self::is_stable(self)
 	}
+
 }
 
 impl<N: Ord + Copy + PartialEq> ParaPastCodeMeta<N> {
@@ -677,6 +679,8 @@ pub mod pallet {
 		/// The given validation code was rejected by the PVF pre-checking vote.
 		/// `code_hash` `para_id`
 		PvfCheckRejected(ValidationCodeHash, ParaId),
+		/// A paraId has been frozen
+		ParaIdFrozen(ParaId)
 	}
 
 	#[pallet::error]
@@ -871,6 +875,10 @@ pub mod pallet {
 	#[pallet::storage]
 	pub type CodeByHash<T: Config> = StorageMap<_, Identity, ValidationCodeHash, ValidationCode>;
 
+	/// Frozen parachain list
+	#[pallet::storage]
+	pub type FrozenParas<T: Config> = StorageValue<_,Vec<ParaId>,ValueQuery>;
+
 	#[pallet::genesis_config]
 	#[derive(DefaultNoBound)]
 	pub struct GenesisConfig<T: Config> {
@@ -1160,6 +1168,30 @@ pub mod pallet {
 			MostRecentContext::<T>::insert(&para, context);
 			Ok(())
 		}
+
+		#[pallet::call_index(9)]
+		#[pallet::weight(Weight::zero())]
+		pub fn freeze_parachain(origin: OriginFor<T>, para_id: ParaId) -> DispatchResult {
+			ensure_root(origin)?;
+			// clean any ongoing activies on the parablock
+			crate::scheduler::ClaimQueue::<T>::mutate(|cq|{
+				for assignments in cq.values_mut() {
+					assignments.retain(|&assignment| {
+						let assigned_para_id = match assignment {
+							Assignment::Bulk(id) => id,
+							Assignment::Pool { para_id, ..} => para_id
+						};
+						para_id != assigned_para_id
+					})
+				}
+			});
+			// TODO
+			FrozenParas::<T>::mutate(|paras|{
+				paras.push(para_id)
+			});
+			Self::deposit_event(Event::ParaIdFrozen(para_id));
+			Ok(())
+		}
 	}
 
 	#[pallet::validate_unsigned]

polkadot/runtime/parachains/src/scheduler.rs

@@ -398,9 +398,10 @@ impl<T: Config> Pallet<T> {
 	}
 
 	fn fill_claim_queue(core_idx: CoreIndex, n_lookahead: u32) {
+		
 		ClaimQueue::<T>::mutate(|la| {
 			let cq = la.entry(core_idx).or_default();
-
+			let frozen_paras = crate::paras::FrozenParas::<T>::get();
 			let mut n_lookahead_used = cq.len() as u32;
 
 			// If the claim queue used to be empty, we need to double the first assignment.
@@ -411,15 +412,31 @@ impl<T: Config> Pallet<T> {
 			if n_lookahead_used == 0 && n_lookahead > 1 {
 				if let Some(assignment) = T::AssignmentProvider::pop_assignment_for_core(core_idx) {
 					T::AssignmentProvider::assignment_duplicated(&assignment);
-					cq.push_back(assignment.clone());
-					cq.push_back(assignment);
-					n_lookahead_used += 2;
+					// check if the paraId is frozen
+					let para_id = match assignment {
+						Assignment::Bulk(id) => id,
+						Assignment::Pool { para_id, ..} => para_id
+					};
+
+					if !frozen_paras.contains(&para_id) {
+						cq.push_back(assignment.clone());
+						cq.push_back(assignment);
+						n_lookahead_used += 2;
+					}
+			
 				}
 			}
 
 			for _ in n_lookahead_used..n_lookahead {
 				if let Some(assignment) = T::AssignmentProvider::pop_assignment_for_core(core_idx) {
-					cq.push_back(assignment);
+					
+					let para_id = match assignment {
+						Assignment::Bulk(id) => id,
+						Assignment::Pool { para_id, ..} => para_id
+					};
+					if !frozen_paras.contains(&para_id) {
+						cq.push_back(assignment);
+					}
 				} else {
 					break
 				}