use a Event Cache to replace vec Events in deposit_event

srml/contract/src/tests.rs

@@ -341,6 +341,7 @@ fn instantiate_and_call_and_deposit_event() {
 				vec![],
 			);
 
+			System::flush_events();
 			assert_eq!(System::events(), vec![
 				EventRecord {
 					phase: Phase::ApplyExtrinsic(0),
@@ -416,6 +417,7 @@ fn dispatch_call() {
 
 			// Let's keep this assert even though it's redundant. If you ever need to update the
 			// wasm source this test will fail and will show you the actual hash.
+			System::flush_events();
 			assert_eq!(System::events(), vec![
 				EventRecord {
 					phase: Phase::ApplyExtrinsic(0),
@@ -443,6 +445,7 @@ fn dispatch_call() {
 				vec![],
 			));
 
+			System::flush_events();
 			assert_eq!(System::events(), vec![
 				EventRecord {
 					phase: Phase::ApplyExtrinsic(0),

srml/council/src/motions.rs

@@ -231,6 +231,7 @@ mod tests {
 			assert_eq!(CouncilMotions::proposal_of(&hash), Some(proposal));
 			assert_eq!(CouncilMotions::voting(&hash), Some((0, 3, vec![1], Vec::<u64>::new())));
 
+			System::flush_events();
 			assert_eq!(System::events(), vec![
 				EventRecord {
 					phase: Phase::ApplyExtrinsic(0),
@@ -284,6 +285,7 @@ mod tests {
 			assert_eq!(CouncilMotions::voting(&hash), Some((0, 2, Vec::<u64>::new(), vec![1])));
 			assert_noop!(CouncilMotions::vote(Origin::signed(1), hash.clone(), 0, false), "duplicate vote ignored");
 
+			System::flush_events();
 			assert_eq!(System::events(), vec![
 				EventRecord {
 					phase: Phase::ApplyExtrinsic(0),
@@ -306,6 +308,7 @@ mod tests {
 			assert_ok!(CouncilMotions::propose(Origin::signed(1), 3, Box::new(proposal.clone())));
 			assert_ok!(CouncilMotions::vote(Origin::signed(2), hash.clone(), 0, false));
 
+			System::flush_events();
 			assert_eq!(System::events(), vec![
 				EventRecord {
 					phase: Phase::ApplyExtrinsic(0),
@@ -332,6 +335,7 @@ mod tests {
 			assert_ok!(CouncilMotions::propose(Origin::signed(1), 2, Box::new(proposal.clone())));
 			assert_ok!(CouncilMotions::vote(Origin::signed(2), hash.clone(), 0, true));
 
+			System::flush_events();
 			assert_eq!(System::events(), vec![
 				EventRecord {
 					phase: Phase::ApplyExtrinsic(0),

srml/system/src/lib.rs

@@ -180,9 +180,11 @@ decl_module! {
 		pub fn deposit_event(event: T::Event) {
 			let extrinsic_index = Self::extrinsic_index();
 			let phase = extrinsic_index.map_or(Phase::Finalization, |c| Phase::ApplyExtrinsic(c));
-			let mut events = Self::events();
-			events.push(EventRecord { phase, event });
-			<Events<T>>::put(events);
+
+			EventsCacheCount::<T>::mutate(|index| {
+				EventsCache::<T>::insert(*index, EventRecord { phase, event });
+				*index += 1;
+			});
 		}
 	}
 }
@@ -306,6 +308,10 @@ decl_storage! {
 		Digest get(digest): T::Digest;
 		/// Events deposited for the current block.
 		Events get(events): Vec<EventRecord<T::Event>>;
+		/// Events map cache for the current block. related to issue 2223 https://github.com/paritytech/substrate/issues/2223
+		EventsCache: map u32 => Option<EventRecord<T::Event>>;
+		/// Events map cache index
+		EventsCacheCount: u32 = 0;
 	}
 	add_extra_genesis {
 		config(changes_trie_config): Option<ChangesTrieConfiguration>;
@@ -389,6 +395,8 @@ impl<T: Trait> Module<T> {
 		<ExtrinsicsRoot<T>>::put(txs_root);
 		<RandomSeed<T>>::put(Self::calculate_random());
 		<Events<T>>::kill();
+
+		<EventsCacheCount<T>>::kill();
 	}
 
 	/// Remove temporary "environment" entries in storage.
@@ -413,10 +421,24 @@ impl<T: Trait> Module<T> {
 		}
 
 		// <Events<T>> stays to be inspected by the client.
+		// flush all event cache into `Events`, related to issue 2223 https://github.com/paritytech/substrate/issues/2223
+		Self::flush_events();
 
 		<T::Header as traits::Header>::new(number, extrinsics_root, storage_root, parent_hash, digest)
 	}
 
+	pub fn flush_events() {
+		let mut events = Self::events();
+		for i in 0..EventsCacheCount::<T>::get() {
+			if let Some(e) = EventsCache::<T>::get(i) {
+				events.push(e);
+			}
+			EventsCache::<T>::remove(i);
+		}
+		EventsCacheCount::<T>::kill();
+		<Events<T>>::put(events);
+	}
+
 	/// Deposits a log and ensures it matches the blocks log data.
 	pub fn deposit_log(item: <T::Digest as traits::Digest>::Item) {
 		let mut l = <Digest<T>>::get();