change: Append block producer to log on block finalization

Signed-off-by: Nikolaos Dymitriadis <[email protected]>

toolkit/pallets/block-production-log/src/lib.rs

@@ -35,6 +35,10 @@ pub mod pallet {
 	#[pallet::unbounded]
 	pub type Log<T: Config> = StorageValue<_, Vec<(Slot, T::BlockProducerId)>, ValueQuery>;
 
+	/// Temporary storage of the current block's producer, to be appended to the log on block finalization.
+	#[pallet::storage]
+	pub type CurrentProducer<T: Config> = StorageValue<_, T::BlockProducerId, OptionQuery>;
+
 	/// This storage is used to prevent calling `append` multiple times for the same block or for past blocks.
 	#[pallet::storage]
 	pub type LatestBlock<T: Config> = StorageValue<_, BlockNumberFor<T>, OptionQuery>;
@@ -70,7 +74,7 @@ pub mod pallet {
 
 	#[pallet::call]
 	impl<T: Config> Pallet<T> {
-		/// Appends an entry to the log. Log has to be ordered by slots and writing the same slot twice is forbidden.
+		/// Schedules an entry to be appended to the log. Log has to be ordered by slots and writing the same slot twice is forbidden.
 		#[pallet::call_index(0)]
 		#[pallet::weight((T::WeightInfo::append(), DispatchClass::Mandatory))]
 		pub fn append(
@@ -86,7 +90,19 @@ pub mod pallet {
 			}?;
 			LatestBlock::<T>::put(current_block);
 
-			Ok(Log::<T>::append((T::current_slot(), block_producer_id)))
+			Ok(CurrentProducer::<T>::put(block_producer_id))
+		}
+	}
+
+	#[pallet::hooks]
+	impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {
+		fn on_finalize(block: BlockNumberFor<T>) {
+			let block_producer_id =
+				CurrentProducer::<T>::take().expect("Author is set before on_finalize; qed");
+
+			log::info!("👷 Block {block:?} producer is {block_producer_id:?}");
+
+			Log::<T>::append((T::current_slot(), block_producer_id))
 		}
 	}
 
@@ -96,5 +112,15 @@ pub mod pallet {
 			Log::<T>::put(to_retain);
 			to_return
 		}
+
+		pub fn peek_prefix<'a>(slot: Slot) -> impl Iterator<Item = (Slot, T::BlockProducerId)> {
+			Log::<T>::get().into_iter().filter(move |(s, _)| s <= &slot)
+		}
+
+		pub fn drop_prefix<'a>(slot: Slot) {
+			let entries_left: Vec<_> =
+				Log::<T>::get().into_iter().filter(move |(s, _)| s > &slot).collect();
+			Log::<T>::put(entries_left);
+		}
 	}
 }

toolkit/pallets/block-production-log/src/test.rs

@@ -1,5 +1,8 @@
 use super::*;
-use frame_support::{assert_err, assert_ok, traits::UnfilteredDispatchable};
+use frame_support::{
+	assert_err, assert_ok,
+	traits::{Hooks, UnfilteredDispatchable},
+};
 use mock::*;
 use sp_consensus_slots::Slot;
 
@@ -15,6 +18,13 @@ fn first_append_should_succeed() {
 		let call = Call::<Test>::append { block_producer_id: make_id(1) };
 		assert_ok!(call.dispatch_bypass_filter(RuntimeOrigin::none()));
 
+		assert_eq!(CurrentProducer::<Test>::get(), Some(make_id(1)));
+
+		// Log should not be appended to until block finalization
+		assert!(Log::<Test>::get().is_empty());
+
+		Pallet::<Test>::on_finalize(System::block_number());
+
 		assert_eq!(Log::<Test>::get().to_vec(), vec![(Slot::from(1001000), make_id(1))]);
 	})
 }
@@ -29,6 +39,10 @@ fn append_to_end_of_log() {
 		let call = Call::<Test>::append { block_producer_id: make_id(2) };
 		assert_ok!(call.dispatch_bypass_filter(RuntimeOrigin::none()));
 		assert_eq!(LatestBlock::<Test>::get(), Some(1001));
+		assert_eq!(CurrentProducer::<Test>::get(), Some(make_id(2)));
+
+		Pallet::<Test>::on_finalize(System::block_number());
+
 		assert_eq!(
 			Log::<Test>::get().to_vec(),
 			vec![(Slot::from(100), make_id(1)), (Slot::from(1001000), make_id(2))]