Fix key collision for child trie (#4162)

* In progress, runtime io must switch to future proof root +
child_specific (unique id) + u32 type.

* Switch interface, sr-io seems ok, rpc could use similar interface to
sr-io, genesis json broken if there is child trie in existing encoding
genesis.

* test from previous implementation.

* fix proving test.

* Restore Keyspacedb from other branch, only apply to child trie.

* Removing unneeded child_info from child root (child info are stored
if things changed, otherwhise the root does not change).

* Switch rpc to use same format as ext: more future proof.

* use root from child info for trie backend essence.

* Breaking long lines.

* Update doc and clean pr a bit.

* fix error type

* Restore removed doc on merge and update sr-io doc.

* Switch child storage api to use directly unique id, if managed id
where to be put in place, the api will change at this time.

* Clean deprecated host interface from child.

* Removing assertion on child info (can fail depending on root
memoization).

* merging child info in the overlay when possible.

* child iteration by prefix using child_info.

* Using ChainInfo in frame support. ChainInfo gets redesign to avoid
buffers allocation on every calls.

* Add length of root to the data of child info.

* comments

* Encode compact.

* Remove child info with root.

* Fix try_update condition.

* Comment Ext child root caching.

* Replace tuples by struct with field

* remove StorageTuple alias.

* Fix doc tests, and remove StorageOverlay and ChildStorageOverlay
aliases.

substrate/client/src/client.rs

@@ -28,7 +28,7 @@ use hash_db::{Hasher, Prefix};
 use primitives::{
 	Blake2Hasher, H256, ChangesTrieConfiguration, convert_hash,
 	NeverNativeValue, ExecutionContext, NativeOrEncoded,
-	storage::{StorageKey, StorageData, well_known_keys},
+	storage::{StorageKey, StorageData, well_known_keys, ChildInfo},
 	traits::CodeExecutor,
 };
 use sc_telemetry::{telemetry, SUBSTRATE_INFO};
@@ -199,10 +199,10 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 		execution_extensions: ExecutionExtensions<Block>,
 	) -> sp_blockchain::Result<Self> {
 		if backend.blockchain().header(BlockId::Number(Zero::zero()))?.is_none() {
-			let (genesis_storage, children_genesis_storage) = build_genesis_storage.build_storage()?;
+			let genesis_storage = build_genesis_storage.build_storage()?;
 			let mut op = backend.begin_operation()?;
 			backend.begin_state_operation(&mut op, BlockId::Hash(Default::default()))?;
-			let state_root = op.reset_storage(genesis_storage, children_genesis_storage)?;
+			let state_root = op.reset_storage(genesis_storage)?;
 			let genesis_block = genesis::construct_genesis_block::<Block>(state_root.into());
 			info!("Initializing Genesis block/state (state: {}, header-hash: {})",
 				genesis_block.header().state_root(),
@@ -267,10 +267,11 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 		&self,
 		id: &BlockId<Block>,
 		child_storage_key: &StorageKey,
+		child_info: ChildInfo,
 		key_prefix: &StorageKey
 	) -> sp_blockchain::Result<Vec<StorageKey>> {
 		let keys = self.state_at(id)?
-			.child_keys(&child_storage_key.0, &key_prefix.0)
+			.child_keys(&child_storage_key.0, child_info, &key_prefix.0)
 			.into_iter()
 			.map(StorageKey)
 			.collect();
@@ -281,11 +282,13 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 	pub fn child_storage(
 		&self,
 		id: &BlockId<Block>,
-		child_storage_key: &StorageKey,
+		storage_key: &StorageKey,
+		child_info: ChildInfo,
 		key: &StorageKey
 	) -> sp_blockchain::Result<Option<StorageData>> {
 		Ok(self.state_at(id)?
-			.child_storage(&child_storage_key.0, &key.0).map_err(|e| sp_blockchain::Error::from_state(Box::new(e)))?
+			.child_storage(&storage_key.0, child_info, &key.0)
+			.map_err(|e| sp_blockchain::Error::from_state(Box::new(e)))?
 			.map(StorageData))
 	}
 
@@ -293,11 +296,13 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 	pub fn child_storage_hash(
 		&self,
 		id: &BlockId<Block>,
-		child_storage_key: &StorageKey,
+		storage_key: &StorageKey,
+		child_info: ChildInfo,
 		key: &StorageKey
 	) -> sp_blockchain::Result<Option<Block::Hash>> {
 		Ok(self.state_at(id)?
-			.child_storage_hash(&child_storage_key.0, &key.0).map_err(|e| sp_blockchain::Error::from_state(Box::new(e)))?
+			.child_storage_hash(&storage_key.0, child_info, &key.0)
+			.map_err(|e| sp_blockchain::Error::from_state(Box::new(e)))?
 		)
 	}
 
@@ -334,13 +339,14 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 		&self,
 		id: &BlockId<Block>,
 		storage_key: &[u8],
+		child_info: ChildInfo,
 		keys: I,
 	) -> sp_blockchain::Result<StorageProof> where
 		I: IntoIterator,
 		I::Item: AsRef<[u8]>,
 	{
 		self.state_at(id)
-			.and_then(|state| prove_child_read(state, storage_key, keys)
+			.and_then(|state| prove_child_read(state, storage_key, child_info, keys)
 				.map_err(Into::into))
 	}
 
@@ -1012,7 +1018,7 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 				overlay.commit_prospective();
 
 				let (top, children) = overlay.into_committed();
-				let children = children.map(|(sk, it)| (sk, it.collect())).collect();
+				let children = children.map(|(sk, it)| (sk, it.0.collect())).collect();
 				if import_headers.post().state_root() != &storage_update.1 {
 					return Err(sp_blockchain::Error::InvalidStateRoot);
 				}