feat: compute pallet/storage prefix hash at compile time (#1539)

Since the hash rules of this part of the `pallet_prefix/storage_prefix`
are always fixed, we can put the runtime calculation into compile time.

---
polkadot address: 15ouFh2SHpGbHtDPsJ6cXQfes9Cx1gEFnJJsJVqPGzBSTudr

---------

Co-authored-by: Juan <juangirini@gmail.com>
Co-authored-by: command-bot <>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

substrate/frame/support/src/storage/generator/double_map.rs

@@ -33,7 +33,7 @@ use sp_std::prelude::*;
 ///
 /// Thus value for (key1, key2) is stored at:
 /// ```nocompile
-/// Twox128(module_prefix) ++ Twox128(storage_prefix) ++ Hasher1(encode(key1)) ++ Hasher2(encode(key2))
+/// Twox128(pallet_prefix) ++ Twox128(storage_prefix) ++ Hasher1(encode(key1)) ++ Hasher2(encode(key2))
 /// ```
 ///
 /// # Warning
@@ -53,18 +53,15 @@ pub trait StorageDoubleMap<K1: FullEncode, K2: FullEncode, V: FullCodec> {
 	/// Hasher for the second key.
 	type Hasher2: StorageHasher;
 
-	/// Module prefix. Used for generating final key.
-	fn module_prefix() -> &'static [u8];
+	/// Pallet prefix. Used for generating final key.
+	fn pallet_prefix() -> &'static [u8];
 
 	/// Storage prefix. Used for generating final key.
 	fn storage_prefix() -> &'static [u8];
 
-	/// The full prefix; just the hash of `module_prefix` concatenated to the hash of
+	/// The full prefix; just the hash of `pallet_prefix` concatenated to the hash of
 	/// `storage_prefix`.
-	fn prefix_hash() -> Vec<u8> {
-		let result = storage_prefix(Self::module_prefix(), Self::storage_prefix());
-		result.to_vec()
-	}
+	fn prefix_hash() -> [u8; 32];
 
 	/// Convert an optional value retrieved from storage to the type queried.
 	fn from_optional_value_to_query(v: Option<V>) -> Self::Query;
@@ -77,7 +74,7 @@ pub trait StorageDoubleMap<K1: FullEncode, K2: FullEncode, V: FullCodec> {
 	where
 		KArg1: EncodeLike<K1>,
 	{
-		let storage_prefix = storage_prefix(Self::module_prefix(), Self::storage_prefix());
+		let storage_prefix = storage_prefix(Self::pallet_prefix(), Self::storage_prefix());
 		let key_hashed = k1.using_encoded(Self::Hasher1::hash);
 
 		let mut final_key = Vec::with_capacity(storage_prefix.len() + key_hashed.as_ref().len());
@@ -94,7 +91,7 @@ pub trait StorageDoubleMap<K1: FullEncode, K2: FullEncode, V: FullCodec> {
 		KArg1: EncodeLike<K1>,
 		KArg2: EncodeLike<K2>,
 	{
-		let storage_prefix = storage_prefix(Self::module_prefix(), Self::storage_prefix());
+		let storage_prefix = storage_prefix(Self::pallet_prefix(), Self::storage_prefix());
 		let key1_hashed = k1.using_encoded(Self::Hasher1::hash);
 		let key2_hashed = k2.using_encoded(Self::Hasher2::hash);
 
@@ -334,7 +331,7 @@ where
 		key2: KeyArg2,
 	) -> Option<V> {
 		let old_key = {
-			let storage_prefix = storage_prefix(Self::module_prefix(), Self::storage_prefix());
+			let storage_prefix = storage_prefix(Self::pallet_prefix(), Self::storage_prefix());
 
 			let key1_hashed = key1.using_encoded(OldHasher1::hash);
 			let key2_hashed = key2.using_encoded(OldHasher2::hash);
@@ -419,7 +416,7 @@ where
 	}
 
 	fn iter() -> Self::Iterator {
-		let prefix = G::prefix_hash();
+		let prefix = G::prefix_hash().to_vec();
 		Self::Iterator {
 			prefix: prefix.clone(),
 			previous_key: prefix,
@@ -442,7 +439,7 @@ where
 	}
 
 	fn iter_keys() -> Self::FullKeyIterator {
-		let prefix = G::prefix_hash();
+		let prefix = G::prefix_hash().to_vec();
 		Self::FullKeyIterator {
 			prefix: prefix.clone(),
 			previous_key: prefix,
@@ -470,7 +467,7 @@ where
 	}
 
 	fn translate<O: Decode, F: FnMut(K1, K2, O) -> Option<V>>(mut f: F) {
-		let prefix = G::prefix_hash();
+		let prefix = G::prefix_hash().to_vec();
 		let mut previous_key = prefix.clone();
 		while let Some(next) =
 			sp_io::storage::next_key(&previous_key).filter(|n| n.starts_with(&prefix))
@@ -561,7 +558,7 @@ mod test_iterators {
 			type DoubleMap = self::frame_system::DoubleMap<Runtime>;
 
 			// All map iterator
-			let prefix = DoubleMap::prefix_hash();
+			let prefix = DoubleMap::prefix_hash().to_vec();
 
 			unhashed::put(&key_before_prefix(prefix.clone()), &1u64);
 			unhashed::put(&key_after_prefix(prefix.clone()), &1u64);
@@ -621,7 +618,7 @@ mod test_iterators {
 			assert_eq!(unhashed::get(&key_after_prefix(prefix.clone())), Some(1u64));
 
 			// Translate
-			let prefix = DoubleMap::prefix_hash();
+			let prefix = DoubleMap::prefix_hash().to_vec();
 
 			unhashed::put(&key_before_prefix(prefix.clone()), &1u64);
 			unhashed::put(&key_after_prefix(prefix.clone()), &1u64);

substrate/frame/support/src/storage/generator/map.rs

@@ -28,7 +28,7 @@ use sp_std::prelude::*;
 ///
 /// By default each key value is stored at:
 /// ```nocompile
-/// Twox128(module_prefix) ++ Twox128(storage_prefix) ++ Hasher(encode(key))
+/// Twox128(pallet_prefix) ++ Twox128(storage_prefix) ++ Hasher(encode(key))
 /// ```
 ///
 /// # Warning
@@ -42,18 +42,15 @@ pub trait StorageMap<K: FullEncode, V: FullCodec> {
 	/// Hasher. Used for generating final key.
 	type Hasher: StorageHasher;
 
-	/// Module prefix. Used for generating final key.
-	fn module_prefix() -> &'static [u8];
+	/// Pallet prefix. Used for generating final key.
+	fn pallet_prefix() -> &'static [u8];
 
 	/// Storage prefix. Used for generating final key.
 	fn storage_prefix() -> &'static [u8];
 
-	/// The full prefix; just the hash of `module_prefix` concatenated to the hash of
+	/// The full prefix; just the hash of `pallet_prefix` concatenated to the hash of
 	/// `storage_prefix`.
-	fn prefix_hash() -> Vec<u8> {
-		let result = storage_prefix(Self::module_prefix(), Self::storage_prefix());
-		result.to_vec()
-	}
+	fn prefix_hash() -> [u8; 32];
 
 	/// Convert an optional value retrieved from storage to the type queried.
 	fn from_optional_value_to_query(v: Option<V>) -> Self::Query;
@@ -66,7 +63,7 @@ pub trait StorageMap<K: FullEncode, V: FullCodec> {
 	where
 		KeyArg: EncodeLike<K>,
 	{
-		let storage_prefix = storage_prefix(Self::module_prefix(), Self::storage_prefix());
+		let storage_prefix = storage_prefix(Self::pallet_prefix(), Self::storage_prefix());
 		let key_hashed = key.using_encoded(Self::Hasher::hash);
 
 		let mut final_key = Vec::with_capacity(storage_prefix.len() + key_hashed.as_ref().len());
@@ -128,7 +125,7 @@ where
 
 	/// Enumerate all elements in the map.
 	fn iter() -> Self::Iterator {
-		let prefix = G::prefix_hash();
+		let prefix = G::prefix_hash().to_vec();
 		PrefixIterator {
 			prefix: prefix.clone(),
 			previous_key: prefix,
@@ -150,7 +147,7 @@ where
 
 	/// Enumerate all keys in the map.
 	fn iter_keys() -> Self::KeyIterator {
-		let prefix = G::prefix_hash();
+		let prefix = G::prefix_hash().to_vec();
 		KeyPrefixIterator {
 			prefix: prefix.clone(),
 			previous_key: prefix,
@@ -190,7 +187,7 @@ where
 		previous_key: Option<Vec<u8>>,
 		mut f: F,
 	) -> Option<Vec<u8>> {
-		let prefix = G::prefix_hash();
+		let prefix = G::prefix_hash().to_vec();
 		let previous_key = previous_key.unwrap_or_else(|| prefix.clone());
 
 		let current_key =
@@ -339,7 +336,7 @@ impl<K: FullEncode, V: FullCodec, G: StorageMap<K, V>> storage::StorageMap<K, V>
 
 	fn migrate_key<OldHasher: StorageHasher, KeyArg: EncodeLike<K>>(key: KeyArg) -> Option<V> {
 		let old_key = {
-			let storage_prefix = storage_prefix(Self::module_prefix(), Self::storage_prefix());
+			let storage_prefix = storage_prefix(Self::pallet_prefix(), Self::storage_prefix());
 			let key_hashed = key.using_encoded(OldHasher::hash);
 
 			let mut final_key =
@@ -398,7 +395,7 @@ mod test_iterators {
 			type Map = self::frame_system::Map<Runtime>;
 
 			// All map iterator
-			let prefix = Map::prefix_hash();
+			let prefix = Map::prefix_hash().to_vec();
 
 			unhashed::put(&key_before_prefix(prefix.clone()), &1u64);
 			unhashed::put(&key_after_prefix(prefix.clone()), &1u64);
@@ -420,7 +417,7 @@ mod test_iterators {
 			assert_eq!(unhashed::get(&key_after_prefix(prefix.clone())), Some(1u64));
 
 			// Translate
-			let prefix = Map::prefix_hash();
+			let prefix = Map::prefix_hash().to_vec();
 
 			unhashed::put(&key_before_prefix(prefix.clone()), &1u64);
 			unhashed::put(&key_after_prefix(prefix.clone()), &1u64);

substrate/frame/support/src/storage/generator/nmap.rs

@@ -61,18 +61,15 @@ pub trait StorageNMap<K: KeyGenerator, V: FullCodec> {
 	/// The type that get/take returns.
 	type Query;
 
-	/// Module prefix. Used for generating final key.
-	fn module_prefix() -> &'static [u8];
+	/// Pallet prefix. Used for generating final key.
+	fn pallet_prefix() -> &'static [u8];
 
 	/// Storage prefix. Used for generating final key.
 	fn storage_prefix() -> &'static [u8];
 
-	/// The full prefix; just the hash of `module_prefix` concatenated to the hash of
+	/// The full prefix; just the hash of `pallet_prefix` concatenated to the hash of
 	/// `storage_prefix`.
-	fn prefix_hash() -> Vec<u8> {
-		let result = storage_prefix(Self::module_prefix(), Self::storage_prefix());
-		result.to_vec()
-	}
+	fn prefix_hash() -> [u8; 32];
 
 	/// Convert an optional value retrieved from storage to the type queried.
 	fn from_optional_value_to_query(v: Option<V>) -> Self::Query;
@@ -85,7 +82,7 @@ pub trait StorageNMap<K: KeyGenerator, V: FullCodec> {
 	where
 		K: HasKeyPrefix<KP>,
 	{
-		let storage_prefix = storage_prefix(Self::module_prefix(), Self::storage_prefix());
+		let storage_prefix = storage_prefix(Self::pallet_prefix(), Self::storage_prefix());
 		let key_hashed = <K as HasKeyPrefix<KP>>::partial_key(key);
 
 		let mut final_key = Vec::with_capacity(storage_prefix.len() + key_hashed.len());
@@ -102,7 +99,7 @@ pub trait StorageNMap<K: KeyGenerator, V: FullCodec> {
 		KG: KeyGenerator,
 		KArg: EncodeLikeTuple<KG::KArg> + TupleToEncodedIter,
 	{
-		let storage_prefix = storage_prefix(Self::module_prefix(), Self::storage_prefix());
+		let storage_prefix = storage_prefix(Self::pallet_prefix(), Self::storage_prefix());
 		let key_hashed = KG::final_key(key);
 
 		let mut final_key = Vec::with_capacity(storage_prefix.len() + key_hashed.len());
@@ -299,7 +296,7 @@ where
 		KArg: EncodeLikeTuple<K::KArg> + TupleToEncodedIter,
 	{
 		let old_key = {
-			let storage_prefix = storage_prefix(Self::module_prefix(), Self::storage_prefix());
+			let storage_prefix = storage_prefix(Self::pallet_prefix(), Self::storage_prefix());
 			let key_hashed = K::migrate_key(&key, hash_fns);
 
 			let mut final_key = Vec::with_capacity(storage_prefix.len() + key_hashed.len());
@@ -386,11 +383,11 @@ impl<K: ReversibleKeyGenerator, V: FullCodec, G: StorageNMap<K, V>>
 	}
 
 	fn iter() -> Self::Iterator {
-		Self::iter_from(G::prefix_hash())
+		Self::iter_from(G::prefix_hash().to_vec())
 	}
 
 	fn iter_from(starting_raw_key: Vec<u8>) -> Self::Iterator {
-		let prefix = G::prefix_hash();
+		let prefix = G::prefix_hash().to_vec();
 		Self::Iterator {
 			prefix,
 			previous_key: starting_raw_key,
@@ -404,11 +401,11 @@ impl<K: ReversibleKeyGenerator, V: FullCodec, G: StorageNMap<K, V>>
 	}
 
 	fn iter_keys() -> Self::KeyIterator {
-		Self::iter_keys_from(G::prefix_hash())
+		Self::iter_keys_from(G::prefix_hash().to_vec())
 	}
 
 	fn iter_keys_from(starting_raw_key: Vec<u8>) -> Self::KeyIterator {
-		let prefix = G::prefix_hash();
+		let prefix = G::prefix_hash().to_vec();
 		Self::KeyIterator {
 			prefix,
 			previous_key: starting_raw_key,
@@ -427,7 +424,7 @@ impl<K: ReversibleKeyGenerator, V: FullCodec, G: StorageNMap<K, V>>
 	}
 
 	fn translate<O: Decode, F: FnMut(K::Key, O) -> Option<V>>(mut f: F) {
-		let prefix = G::prefix_hash();
+		let prefix = G::prefix_hash().to_vec();
 		let mut previous_key = prefix.clone();
 		while let Some(next) =
 			sp_io::storage::next_key(&previous_key).filter(|n| n.starts_with(&prefix))
@@ -537,7 +534,7 @@ mod test_iterators {
 			type NMap = self::frame_system::NMap<Runtime>;
 
 			// All map iterator
-			let prefix = NMap::prefix_hash();
+			let prefix = NMap::prefix_hash().to_vec();
 
 			unhashed::put(&key_before_prefix(prefix.clone()), &1u64);
 			unhashed::put(&key_after_prefix(prefix.clone()), &1u64);
@@ -594,7 +591,7 @@ mod test_iterators {
 			assert_eq!(unhashed::get(&key_after_prefix(prefix.clone())), Some(1u64));
 
 			// Translate
-			let prefix = NMap::prefix_hash();
+			let prefix = NMap::prefix_hash().to_vec();
 
 			unhashed::put(&key_before_prefix(prefix.clone()), &1u64);
 			unhashed::put(&key_after_prefix(prefix.clone()), &1u64);

substrate/frame/support/src/storage/generator/value.rs

@@ -25,14 +25,14 @@ use codec::{Decode, Encode, EncodeLike, FullCodec};
 ///
 /// By default value is stored at:
 /// ```nocompile
-/// Twox128(module_prefix) ++ Twox128(storage_prefix)
+/// Twox128(pallet_prefix) ++ Twox128(storage_prefix)
 /// ```
 pub trait StorageValue<T: FullCodec> {
 	/// The type that get/take returns.
 	type Query;
 
-	/// Module prefix. Used for generating final key.
-	fn module_prefix() -> &'static [u8];
+	/// Pallet prefix. Used for generating final key.
+	fn pallet_prefix() -> &'static [u8];
 
 	/// Storage prefix. Used for generating final key.
 	fn storage_prefix() -> &'static [u8];
@@ -44,9 +44,7 @@ pub trait StorageValue<T: FullCodec> {
 	fn from_query_to_optional_value(v: Self::Query) -> Option<T>;
 
 	/// Generate the full key used in top storage.
-	fn storage_value_final_key() -> [u8; 32] {
-		crate::storage::storage_prefix(Self::module_prefix(), Self::storage_prefix())
-	}
+	fn storage_value_final_key() -> [u8; 32];
 }
 
 impl<T: FullCodec, G: StorageValue<T>> storage::StorageValue<T> for G {
@@ -97,10 +95,6 @@ impl<T: FullCodec, G: StorageValue<T>> storage::StorageValue<T> for G {
 		}
 	}
 
-	fn kill() {
-		unhashed::kill(&Self::storage_value_final_key())
-	}
-
 	fn mutate<R, F: FnOnce(&mut G::Query) -> R>(f: F) -> R {
 		Self::try_mutate(|v| Ok::<R, Never>(f(v))).expect("`Never` can not be constructed; qed")
 	}
@@ -142,6 +136,10 @@ impl<T: FullCodec, G: StorageValue<T>> storage::StorageValue<T> for G {
 		ret
 	}
 
+	fn kill() {
+		unhashed::kill(&Self::storage_value_final_key())
+	}
+
 	fn take() -> G::Query {
 		let key = Self::storage_value_final_key();
 		let value = unhashed::get(&key);

substrate/frame/support/src/storage/mod.rs

@@ -191,7 +191,7 @@ pub trait StorageList<V: FullCodec> {
 
 	/// Append a single element.
 	///
-	/// Should not be called repeatedly; use `append_many` instead.  
+	/// Should not be called repeatedly; use `append_many` instead.
 	/// Worst case linear `O(len)` with `len` being the number if elements in the list.
 	fn append_one<EncodeLikeValue>(item: EncodeLikeValue)
 	where
@@ -202,7 +202,7 @@ pub trait StorageList<V: FullCodec> {
 
 	/// Append many elements.
 	///
-	/// Should not be called repeatedly; use `appender` instead.  
+	/// Should not be called repeatedly; use `appender` instead.
 	/// Worst case linear `O(len + items.count())` with `len` beings the number if elements in the
 	/// list.
 	fn append_many<EncodeLikeValue, I>(items: I)
@@ -1273,15 +1273,15 @@ impl<T> Iterator for ChildTriePrefixIterator<T> {
 
 /// Trait for storage types that store all its value after a unique prefix.
 pub trait StoragePrefixedContainer {
-	/// Module prefix. Used for generating final key.
-	fn module_prefix() -> &'static [u8];
+	/// Pallet prefix. Used for generating final key.
+	fn pallet_prefix() -> &'static [u8];
 
 	/// Storage prefix. Used for generating final key.
 	fn storage_prefix() -> &'static [u8];
 
 	/// Final full prefix that prefixes all keys.
 	fn final_prefix() -> [u8; 32] {
-		crate::storage::storage_prefix(Self::module_prefix(), Self::storage_prefix())
+		crate::storage::storage_prefix(Self::pallet_prefix(), Self::storage_prefix())
 	}
 }
 
@@ -1289,18 +1289,18 @@ pub trait StoragePrefixedContainer {
 ///
 /// By default the final prefix is:
 /// ```nocompile
-/// Twox128(module_prefix) ++ Twox128(storage_prefix)
+/// Twox128(pallet_prefix) ++ Twox128(storage_prefix)
 /// ```
 pub trait StoragePrefixedMap<Value: FullCodec> {
-	/// Module prefix. Used for generating final key.
-	fn module_prefix() -> &'static [u8]; // TODO move to StoragePrefixedContainer
+	/// Pallet prefix. Used for generating final key.
+	fn pallet_prefix() -> &'static [u8]; // TODO move to StoragePrefixedContainer
 
 	/// Storage prefix. Used for generating final key.
 	fn storage_prefix() -> &'static [u8];
 
 	/// Final full prefix that prefixes all keys.
 	fn final_prefix() -> [u8; 32] {
-		crate::storage::storage_prefix(Self::module_prefix(), Self::storage_prefix())
+		crate::storage::storage_prefix(Self::pallet_prefix(), Self::storage_prefix())
 	}
 
 	/// Remove all values in the overlay and up to `limit` in the backend.
@@ -1624,7 +1624,7 @@ mod test {
 		TestExternalities::default().execute_with(|| {
 			struct MyStorage;
 			impl StoragePrefixedMap<u64> for MyStorage {
-				fn module_prefix() -> &'static [u8] {
+				fn pallet_prefix() -> &'static [u8] {
 					b"MyModule"
 				}
 
@@ -1701,7 +1701,7 @@ mod test {
 			impl generator::StorageValue<Digest> for Storage {
 				type Query = Digest;
 
-				fn module_prefix() -> &'static [u8] {
+				fn pallet_prefix() -> &'static [u8] {
 					b"MyModule"
 				}
 
@@ -1716,6 +1716,10 @@ mod test {
 				fn from_query_to_optional_value(v: Self::Query) -> Option<Digest> {
 					Some(v)
 				}
+
+				fn storage_value_final_key() -> [u8; 32] {
+					storage_prefix(Self::pallet_prefix(), Self::storage_prefix())
+				}
 			}
 
 			Storage::append(DigestItem::Other(Vec::new()));
@@ -1736,7 +1740,7 @@ mod test {
 				type Query = u64;
 				type Hasher = Twox64Concat;
 
-				fn module_prefix() -> &'static [u8] {
+				fn pallet_prefix() -> &'static [u8] {
 					b"MyModule"
 				}
 
@@ -1744,6 +1748,10 @@ mod test {
 					b"MyStorageMap"
 				}
 
+				fn prefix_hash() -> [u8; 32] {
+					storage_prefix(Self::pallet_prefix(), Self::storage_prefix())
+				}
+
 				fn from_optional_value_to_query(v: Option<u64>) -> Self::Query {
 					v.unwrap_or_default()
 				}

substrate/frame/support/src/storage/types/counted_map.rs

@@ -107,7 +107,7 @@ where
 	/// The prefix used to generate the key of the map.
 	pub fn map_storage_final_prefix() -> Vec<u8> {
 		use crate::storage::generator::StorageMap;
-		<Self as MapWrapper>::Map::prefix_hash()
+		<Self as MapWrapper>::Map::prefix_hash().to_vec()
 	}
 
 	/// Get the storage key used to fetch a value corresponding to a specific key.

substrate/frame/support/src/storage/types/counted_nmap.rs

@@ -104,7 +104,7 @@ where
 	/// The prefix used to generate the key of the map.
 	pub fn map_storage_final_prefix() -> Vec<u8> {
 		use crate::storage::generator::StorageNMap;
-		<Self as MapWrapper>::Map::prefix_hash()
+		<Self as MapWrapper>::Map::prefix_hash().to_vec()
 	}
 
 	/// Get the storage key used to fetch a value corresponding to a specific key.

substrate/frame/support/src/storage/types/double_map.rs

@@ -117,12 +117,17 @@ where
 	type Query = QueryKind::Query;
 	type Hasher1 = Hasher1;
 	type Hasher2 = Hasher2;
-	fn module_prefix() -> &'static [u8] {
+	fn pallet_prefix() -> &'static [u8] {
 		Prefix::pallet_prefix().as_bytes()
 	}
+
 	fn storage_prefix() -> &'static [u8] {
 		Prefix::STORAGE_PREFIX.as_bytes()
 	}
+	fn prefix_hash() -> [u8; 32] {
+		Prefix::prefix_hash()
+	}
+
 	fn from_optional_value_to_query(v: Option<Value>) -> Self::Query {
 		QueryKind::from_optional_value_to_query(v)
 	}
@@ -145,8 +150,8 @@ where
 	OnEmpty: Get<QueryKind::Query> + 'static,
 	MaxValues: Get<Option<u32>>,
 {
-	fn module_prefix() -> &'static [u8] {
-		<Self as crate::storage::generator::StorageDoubleMap<Key1, Key2, Value>>::module_prefix()
+	fn pallet_prefix() -> &'static [u8] {
+		<Self as crate::storage::generator::StorageDoubleMap<Key1, Key2, Value>>::pallet_prefix()
 	}
 	fn storage_prefix() -> &'static [u8] {
 		<Self as crate::storage::generator::StorageDoubleMap<Key1, Key2, Value>>::storage_prefix()
@@ -691,7 +696,7 @@ where
 {
 	fn storage_info() -> Vec<StorageInfo> {
 		vec![StorageInfo {
-			pallet_name: Self::module_prefix().to_vec(),
+			pallet_name: Self::pallet_prefix().to_vec(),
 			storage_name: Self::storage_prefix().to_vec(),
 			prefix: Self::final_prefix().to_vec(),
 			max_values: MaxValues::get(),
@@ -722,7 +727,7 @@ where
 {
 	fn partial_storage_info() -> Vec<StorageInfo> {
 		vec![StorageInfo {
-			pallet_name: Self::module_prefix().to_vec(),
+			pallet_name: Self::pallet_prefix().to_vec(),
 			storage_name: Self::storage_prefix().to_vec(),
 			prefix: Self::final_prefix().to_vec(),
 			max_values: MaxValues::get(),

substrate/frame/support/src/storage/types/map.rs

@@ -83,12 +83,15 @@ where
 {
 	type Query = QueryKind::Query;
 	type Hasher = Hasher;
-	fn module_prefix() -> &'static [u8] {
+	fn pallet_prefix() -> &'static [u8] {
 		Prefix::pallet_prefix().as_bytes()
 	}
 	fn storage_prefix() -> &'static [u8] {
 		Prefix::STORAGE_PREFIX.as_bytes()
 	}
+	fn prefix_hash() -> [u8; 32] {
+		Prefix::prefix_hash()
+	}
 	fn from_optional_value_to_query(v: Option<Value>) -> Self::Query {
 		QueryKind::from_optional_value_to_query(v)
 	}
@@ -108,8 +111,8 @@ where
 	OnEmpty: Get<QueryKind::Query> + 'static,
 	MaxValues: Get<Option<u32>>,
 {
-	fn module_prefix() -> &'static [u8] {
-		<Self as crate::storage::generator::StorageMap<Key, Value>>::module_prefix()
+	fn pallet_prefix() -> &'static [u8] {
+		<Self as crate::storage::generator::StorageMap<Key, Value>>::pallet_prefix()
 	}
 	fn storage_prefix() -> &'static [u8] {
 		<Self as crate::storage::generator::StorageMap<Key, Value>>::storage_prefix()
@@ -469,7 +472,7 @@ where
 {
 	fn storage_info() -> Vec<StorageInfo> {
 		vec![StorageInfo {
-			pallet_name: Self::module_prefix().to_vec(),
+			pallet_name: Self::pallet_prefix().to_vec(),
 			storage_name: Self::storage_prefix().to_vec(),
 			prefix: Self::final_prefix().to_vec(),
 			max_values: MaxValues::get(),
@@ -497,7 +500,7 @@ where
 {
 	fn partial_storage_info() -> Vec<StorageInfo> {
 		vec![StorageInfo {
-			pallet_name: Self::module_prefix().to_vec(),
+			pallet_name: Self::pallet_prefix().to_vec(),
 			storage_name: Self::storage_prefix().to_vec(),
 			prefix: Self::final_prefix().to_vec(),
 			max_values: MaxValues::get(),

substrate/frame/support/src/storage/types/nmap.rs

@@ -72,12 +72,15 @@ where
 	MaxValues: Get<Option<u32>>,
 {
 	type Query = QueryKind::Query;
-	fn module_prefix() -> &'static [u8] {
+	fn pallet_prefix() -> &'static [u8] {
 		Prefix::pallet_prefix().as_bytes()
 	}
 	fn storage_prefix() -> &'static [u8] {
 		Prefix::STORAGE_PREFIX.as_bytes()
 	}
+	fn prefix_hash() -> [u8; 32] {
+		Prefix::prefix_hash()
+	}
 	fn from_optional_value_to_query(v: Option<Value>) -> Self::Query {
 		QueryKind::from_optional_value_to_query(v)
 	}
@@ -96,8 +99,8 @@ where
 	OnEmpty: Get<QueryKind::Query> + 'static,
 	MaxValues: Get<Option<u32>>,
 {
-	fn module_prefix() -> &'static [u8] {
-		<Self as crate::storage::generator::StorageNMap<Key, Value>>::module_prefix()
+	fn pallet_prefix() -> &'static [u8] {
+		<Self as crate::storage::generator::StorageNMap<Key, Value>>::pallet_prefix()
 	}
 	fn storage_prefix() -> &'static [u8] {
 		<Self as crate::storage::generator::StorageNMap<Key, Value>>::storage_prefix()
@@ -581,7 +584,7 @@ where
 {
 	fn storage_info() -> Vec<StorageInfo> {
 		vec![StorageInfo {
-			pallet_name: Self::module_prefix().to_vec(),
+			pallet_name: Self::pallet_prefix().to_vec(),
 			storage_name: Self::storage_prefix().to_vec(),
 			prefix: Self::final_prefix().to_vec(),
 			max_values: MaxValues::get(),
@@ -607,7 +610,7 @@ where
 {
 	fn partial_storage_info() -> Vec<StorageInfo> {
 		vec![StorageInfo {
-			pallet_name: Self::module_prefix().to_vec(),
+			pallet_name: Self::pallet_prefix().to_vec(),
 			storage_name: Self::storage_prefix().to_vec(),
 			prefix: Self::final_prefix().to_vec(),
 			max_values: MaxValues::get(),

substrate/frame/support/src/storage/types/value.rs

@@ -49,7 +49,7 @@ where
 	OnEmpty: crate::traits::Get<QueryKind::Query> + 'static,
 {
 	type Query = QueryKind::Query;
-	fn module_prefix() -> &'static [u8] {
+	fn pallet_prefix() -> &'static [u8] {
 		Prefix::pallet_prefix().as_bytes()
 	}
 	fn storage_prefix() -> &'static [u8] {
@@ -61,6 +61,9 @@ where
 	fn from_query_to_optional_value(v: Self::Query) -> Option<Value> {
 		QueryKind::from_query_to_optional_value(v)
 	}
+	fn storage_value_final_key() -> [u8; 32] {
+		Prefix::prefix_hash()
+	}
 }
 
 impl<Prefix, Value, QueryKind, OnEmpty> StorageValue<Prefix, Value, QueryKind, OnEmpty>
@@ -251,7 +254,7 @@ where
 {
 	fn storage_info() -> Vec<StorageInfo> {
 		vec![StorageInfo {
-			pallet_name: Self::module_prefix().to_vec(),
+			pallet_name: Self::pallet_prefix().to_vec(),
 			storage_name: Self::storage_prefix().to_vec(),
 			prefix: Self::hashed_key().to_vec(),
 			max_values: Some(1),
@@ -271,7 +274,7 @@ where
 {
 	fn partial_storage_info() -> Vec<StorageInfo> {
 		vec![StorageInfo {
-			pallet_name: Self::module_prefix().to_vec(),
+			pallet_name: Self::pallet_prefix().to_vec(),
 			storage_name: Self::storage_prefix().to_vec(),
 			prefix: Self::hashed_key().to_vec(),
 			max_values: Some(1),