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/rpc/src/state/mod.rs

@@ -95,6 +95,8 @@ pub trait StateBackend<B, E, Block: BlockT, RA>: Send + Sync + 'static
 		&self,
 		block: Option<Block::Hash>,
 		child_storage_key: StorageKey,
+		child_info: StorageKey,
+		child_type: u32,
 		prefix: StorageKey,
 	) -> FutureResult<Vec<StorageKey>>;
 
@@ -103,6 +105,8 @@ pub trait StateBackend<B, E, Block: BlockT, RA>: Send + Sync + 'static
 		&self,
 		block: Option<Block::Hash>,
 		child_storage_key: StorageKey,
+		child_info: StorageKey,
+		child_type: u32,
 		key: StorageKey,
 	) -> FutureResult<Option<StorageData>>;
 
@@ -111,6 +115,8 @@ pub trait StateBackend<B, E, Block: BlockT, RA>: Send + Sync + 'static
 		&self,
 		block: Option<Block::Hash>,
 		child_storage_key: StorageKey,
+		child_info: StorageKey,
+		child_type: u32,
 		key: StorageKey,
 	) -> FutureResult<Option<Block::Hash>>;
 
@@ -119,9 +125,11 @@ pub trait StateBackend<B, E, Block: BlockT, RA>: Send + Sync + 'static
 		&self,
 		block: Option<Block::Hash>,
 		child_storage_key: StorageKey,
+		child_info: StorageKey,
+		child_type: u32,
 		key: StorageKey,
 	) -> FutureResult<Option<u64>> {
-		Box::new(self.child_storage(block, child_storage_key, key)
+		Box::new(self.child_storage(block, child_storage_key, child_info, child_type, key)
 			.map(|x| x.map(|x| x.0.len() as u64)))
 	}
 
@@ -256,37 +264,45 @@ impl<B, E, Block, RA> StateApi<Block::Hash> for State<B, E, Block, RA>
 	fn child_storage(
 		&self,
 		child_storage_key: StorageKey,
+		child_info: StorageKey,
+		child_type: u32,
 		key: StorageKey,
 		block: Option<Block::Hash>
 	) -> FutureResult<Option<StorageData>> {
-		self.backend.child_storage(block, child_storage_key, key)
+		self.backend.child_storage(block, child_storage_key, child_info, child_type, key)
 	}
 
 	fn child_storage_keys(
 		&self,
 		child_storage_key: StorageKey,
+		child_info: StorageKey,
+		child_type: u32,
 		key_prefix: StorageKey,
 		block: Option<Block::Hash>
 	) -> FutureResult<Vec<StorageKey>> {
-		self.backend.child_storage_keys(block, child_storage_key, key_prefix)
+		self.backend.child_storage_keys(block, child_storage_key, child_info, child_type, key_prefix)
 	}
 
 	fn child_storage_hash(
 		&self,
 		child_storage_key: StorageKey,
+		child_info: StorageKey,
+		child_type: u32,
 		key: StorageKey,
 		block: Option<Block::Hash>
 	) -> FutureResult<Option<Block::Hash>> {
-		self.backend.child_storage_hash(block, child_storage_key, key)
+		self.backend.child_storage_hash(block, child_storage_key, child_info, child_type, key)
 	}
 
 	fn child_storage_size(
 		&self,
 		child_storage_key: StorageKey,
+		child_info: StorageKey,
+		child_type: u32,
 		key: StorageKey,
 		block: Option<Block::Hash>
 	) -> FutureResult<Option<u64>> {
-		self.backend.child_storage_size(block, child_storage_key, key)
+		self.backend.child_storage_size(block, child_storage_key, child_info, child_type, key)
 	}
 
 	fn metadata(&self, block: Option<Block::Hash>) -> FutureResult<Bytes> {
@@ -335,3 +351,9 @@ impl<B, E, Block, RA> StateApi<Block::Hash> for State<B, E, Block, RA>
 fn client_err(err: sp_blockchain::Error) -> Error {
 	Error::Client(Box::new(err))
 }
+
+const CHILD_RESOLUTION_ERROR: &str = "Unexpected child info and type";
+
+fn child_resolution_error() -> sp_blockchain::Error {
+	sp_blockchain::Error::Msg(CHILD_RESOLUTION_ERROR.to_string())
+}