Child trie api changes BREAKING (#4857)

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

substrate/frame/contracts/src/account_db.rs

@@ -128,7 +128,7 @@ impl<T: Trait> AccountDb<T> for DirectAccountDb {
 		trie_id: Option<&TrieId>,
 		location: &StorageKey
 	) -> Option<Vec<u8>> {
-		trie_id.and_then(|id| child::get_raw(id, crate::trie_unique_id(&id[..]), &blake2_256(location)))
+		trie_id.and_then(|id| child::get_raw(&crate::child_trie_info(&id[..]), &blake2_256(location)))
 	}
 	fn get_code_hash(&self, account: &T::AccountId) -> Option<CodeHash<T>> {
 		<ContractInfoOf<T>>::get(account).and_then(|i| i.as_alive().map(|i| i.code_hash))
@@ -167,13 +167,13 @@ impl<T: Trait> AccountDb<T> for DirectAccountDb {
 					(false, Some(info), _) => info,
 					// Existing contract is being removed.
 					(true, Some(info), None) => {
-						child::kill_storage(&info.trie_id, info.child_trie_unique_id());
+						child::kill_storage(&info.child_trie_info());
 						<ContractInfoOf<T>>::remove(&address);
 						continue;
 					}
 					// Existing contract is being replaced by a new one.
 					(true, Some(info), Some(code_hash)) => {
-						child::kill_storage(&info.trie_id, info.child_trie_unique_id());
+						child::kill_storage(&info.child_trie_info());
 						AliveContractInfo::<T> {
 							code_hash,
 							storage_size: T::StorageSizeOffset::get(),
@@ -212,17 +212,16 @@ impl<T: Trait> AccountDb<T> for DirectAccountDb {
 
 				for (k, v) in changed.storage.into_iter() {
 					if let Some(value) = child::get_raw(
-						&new_info.trie_id[..],
-						new_info.child_trie_unique_id(),
+						&new_info.child_trie_info(),
 						&blake2_256(&k),
 					) {
 						new_info.storage_size -= value.len() as u32;
 					}
 					if let Some(value) = v {
 						new_info.storage_size += value.len() as u32;
-						child::put_raw(&new_info.trie_id[..], new_info.child_trie_unique_id(), &blake2_256(&k), &value[..]);
+						child::put_raw(&new_info.child_trie_info(), &blake2_256(&k), &value[..]);
 					} else {
-						child::kill(&new_info.trie_id[..], new_info.child_trie_unique_id(), &blake2_256(&k));
+						child::kill(&new_info.child_trie_info(), &blake2_256(&k));
 					}
 				}
 

substrate/frame/contracts/src/lib.rs

@@ -125,12 +125,11 @@ use sp_runtime::{
 use frame_support::dispatch::{DispatchResult, Dispatchable};
 use frame_support::weights::{SimpleDispatchInfo, MINIMUM_WEIGHT};
 use frame_support::{
-	Parameter, decl_module, decl_event, decl_storage, decl_error, storage::child,
-	parameter_types, IsSubType,
+	Parameter, decl_module, decl_event, decl_storage, decl_error,
+	parameter_types, IsSubType, storage::child::{self, ChildInfo},
 };
 use frame_support::traits::{OnUnbalanced, Currency, Get, Time, Randomness};
 use frame_system::{self as system, ensure_signed, RawOrigin, ensure_root};
-use sp_core::storage::well_known_keys::CHILD_STORAGE_KEY_PREFIX;
 use pallet_contracts_primitives::{RentProjection, ContractAccessError};
 
 pub type CodeHash<T> = <T as frame_system::Trait>::Hash;
@@ -229,15 +228,14 @@ pub struct RawAliveContractInfo<CodeHash, Balance, BlockNumber> {
 
 impl<CodeHash, Balance, BlockNumber> RawAliveContractInfo<CodeHash, Balance, BlockNumber> {
 	/// Associated child trie unique id is built from the hash part of the trie id.
-	pub fn child_trie_unique_id(&self) -> child::ChildInfo {
-		trie_unique_id(&self.trie_id[..])
+	pub fn child_trie_info(&self) -> ChildInfo {
+		child_trie_info(&self.trie_id[..])
 	}
 }
 
 /// Associated child trie unique id is built from the hash part of the trie id.
-pub(crate) fn trie_unique_id(trie_id: &[u8]) -> child::ChildInfo {
-	let start = CHILD_STORAGE_KEY_PREFIX.len() + b"default:".len();
-	child::ChildInfo::new_default(&trie_id[start ..])
+pub(crate) fn child_trie_info(trie_id: &[u8]) -> ChildInfo {
+	ChildInfo::new_default(trie_id)
 }
 
 pub type TombstoneContractInfo<T> =
@@ -270,10 +268,6 @@ pub trait TrieIdGenerator<AccountId> {
 	///
 	/// The implementation must ensure every new trie id is unique: two consecutive calls with the
 	/// same parameter needs to return different trie id values.
-	///
-	/// Also, the implementation is responsible for ensuring that `TrieId` starts with
-	/// `:child_storage:`.
-	/// TODO: We want to change this, see https://github.com/paritytech/substrate/issues/2325
 	fn trie_id(account_id: &AccountId) -> TrieId;
 }
 
@@ -297,13 +291,7 @@ where
 		let mut buf = Vec::new();
 		buf.extend_from_slice(account_id.as_ref());
 		buf.extend_from_slice(&new_seed.to_le_bytes()[..]);
-
-		// TODO: see https://github.com/paritytech/substrate/issues/2325
-		CHILD_STORAGE_KEY_PREFIX.iter()
-			.chain(b"default:")
-			.chain(T::Hashing::hash(&buf[..]).as_ref().iter())
-			.cloned()
-			.collect()
+		T::Hashing::hash(&buf[..]).as_ref().into()
 	}
 }
 
@@ -824,13 +812,11 @@ impl<T: Trait> Module<T> {
 		let key_values_taken = delta.iter()
 			.filter_map(|key| {
 				child::get_raw(
-					&origin_contract.trie_id,
-					origin_contract.child_trie_unique_id(),
+					&origin_contract.child_trie_info(),
 					&blake2_256(key),
 				).map(|value| {
 					child::kill(
-						&origin_contract.trie_id,
-						origin_contract.child_trie_unique_id(),
+						&origin_contract.child_trie_info(),
 						&blake2_256(key),
 					);
 
@@ -842,8 +828,8 @@ impl<T: Trait> Module<T> {
 		let tombstone = <TombstoneContractInfo<T>>::new(
 			// This operation is cheap enough because last_write (delta not included)
 			// is not this block as it has been checked earlier.
-			&child::child_root(
-				&origin_contract.trie_id,
+			&child::root(
+				&origin_contract.child_trie_info(),
 			)[..],
 			code_hash,
 		);
@@ -851,8 +837,7 @@ impl<T: Trait> Module<T> {
 		if tombstone != dest_tombstone {
 			for (key, value) in key_values_taken {
 				child::put_raw(
-					&origin_contract.trie_id,
-					origin_contract.child_trie_unique_id(),
+					&origin_contract.child_trie_info(),
 					&blake2_256(key),
 					&value,
 				);

substrate/frame/contracts/src/rent.rs

@@ -223,8 +223,7 @@ fn enact_verdict<T: Trait>(
 		Verdict::Kill => {
 			<ContractInfoOf<T>>::remove(account);
 			child::kill_storage(
-				&alive_contract_info.trie_id,
-				alive_contract_info.child_trie_unique_id(),
+				&alive_contract_info.child_trie_info(),
 			);
 			<Module<T>>::deposit_event(RawEvent::Evicted(account.clone(), false));
 			None
@@ -235,7 +234,9 @@ fn enact_verdict<T: Trait>(
 			}
 
 			// Note: this operation is heavy.
-			let child_storage_root = child::child_root(&alive_contract_info.trie_id);
+			let child_storage_root = child::root(
+				&alive_contract_info.child_trie_info(),
+			);
 
 			let tombstone = <TombstoneContractInfo<T>>::new(
 				&child_storage_root[..],
@@ -245,8 +246,7 @@ fn enact_verdict<T: Trait>(
 			<ContractInfoOf<T>>::insert(account, &tombstone_info);
 
 			child::kill_storage(
-				&alive_contract_info.trie_id,
-				alive_contract_info.child_trie_unique_id(),
+				&alive_contract_info.child_trie_info(),
 			);
 
 			<Module<T>>::deposit_event(RawEvent::Evicted(account.clone(), true));

substrate/frame/contracts/src/tests.rs

@@ -200,10 +200,7 @@ impl TrieIdGenerator<u64> for DummyTrieIdGenerator {
 			*v
 		});
 
-		// TODO: see https://github.com/paritytech/substrate/issues/2325
 		let mut res = vec![];
-		res.extend_from_slice(well_known_keys::CHILD_STORAGE_KEY_PREFIX);
-		res.extend_from_slice(b"default:");
 		res.extend_from_slice(&new_seed.to_le_bytes());
 		res.extend_from_slice(&account_id.to_le_bytes());
 		res