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/in_mem.rs

@@ -25,7 +25,7 @@ use primitives::offchain::storage::{
 };
 use sp_runtime::generic::{BlockId, DigestItem};
 use sp_runtime::traits::{Block as BlockT, Header as HeaderT, Zero, NumberFor};
-use sp_runtime::{Justification, StorageOverlay, ChildrenStorageOverlay};
+use sp_runtime::{Justification, Storage};
 use state_machine::backend::{Backend as StateBackend, InMemory};
 use state_machine::{self, InMemoryChangesTrieStorage, ChangesTrieAnchorBlockId, ChangesTrieTransaction};
 use hash_db::{Hasher, Prefix};
@@ -505,15 +505,15 @@ where
 		Ok(())
 	}
 
-	fn reset_storage(&mut self, top: StorageOverlay, children: ChildrenStorageOverlay) -> sp_blockchain::Result<H::Out> {
-		check_genesis_storage(&top, &children)?;
+	fn reset_storage(&mut self, storage: Storage) -> sp_blockchain::Result<H::Out> {
+		check_genesis_storage(&storage)?;
 
-		let child_delta = children.into_iter()
-			.map(|(storage_key, child_overlay)|
-				(storage_key, child_overlay.into_iter().map(|(k, v)| (k, Some(v)))));
+		let child_delta = storage.children.into_iter()
+			.map(|(storage_key, child_content)|
+				(storage_key, child_content.data.into_iter().map(|(k, v)| (k, Some(v))), child_content.child_info));
 
 		let (root, transaction) = self.old_state.full_storage_root(
-			top.into_iter().map(|(k, v)| (k, Some(v))),
+			storage.top.into_iter().map(|(k, v)| (k, Some(v))),
 			child_delta
 		);
 
@@ -796,12 +796,12 @@ impl<Block, H> state_machine::ChangesTrieStorage<H, NumberFor<Block>> for Change
 }
 
 /// Check that genesis storage is valid.
-pub fn check_genesis_storage(top: &StorageOverlay, children: &ChildrenStorageOverlay) -> sp_blockchain::Result<()> {
-	if top.iter().any(|(k, _)| well_known_keys::is_child_storage_key(k)) {
+pub fn check_genesis_storage(storage: &Storage) -> sp_blockchain::Result<()> {
+	if storage.top.iter().any(|(k, _)| well_known_keys::is_child_storage_key(k)) {
 		return Err(sp_blockchain::Error::GenesisInvalid.into());
 	}
 
-	if children.keys().any(|child_key| !well_known_keys::is_child_storage_key(&child_key)) {
+	if storage.children.keys().any(|child_key| !well_known_keys::is_child_storage_key(&child_key)) {
 		return Err(sp_blockchain::Error::GenesisInvalid.into());
 	}