Implement change trie for child trie. (#3122)

* Initial implementation, some redundancy is awkward and there is
some useless computation (but there is a pending pr for that).
Next are tests.

* Minimal tests and fix extend child.

* implement iterator for change child trie.

* prune child trie.

* Fix pruning test.

* bump spec version.

* Avoid empty child trie (could also be checked before)

* tabs.

* Fix child digest overriding each others.

* Restore doc deleted on merge.

* Check correct child value on extrinsics build.

* Revert runtime version update.

substrate/core/network/src/chain.rs

@@ -64,6 +64,7 @@ pub trait Client<Block: BlockT>: Send + Sync {
 		last: Block::Hash,
 		min: Block::Hash,
 		max: Block::Hash,
+		storage_key: Option<&StorageKey>,
 		key: &StorageKey
 	) -> Result<ChangesProof<Block::Header>, Error>;
 
@@ -136,9 +137,10 @@ impl<B, E, Block, RA> Client<Block> for SubstrateClient<B, E, Block, RA> where
 		last: Block::Hash,
 		min: Block::Hash,
 		max: Block::Hash,
-		key: &StorageKey
+		storage_key: Option<&StorageKey>,
+		key: &StorageKey,
 	) -> Result<ChangesProof<Block::Header>, Error> {
-		(self as &SubstrateClient<B, E, Block, RA>).key_changes_proof(first, last, min, max, key)
+		(self as &SubstrateClient<B, E, Block, RA>).key_changes_proof(first, last, min, max, storage_key, key)
 	}
 
 	fn is_descendent_of(&self, base: &Block::Hash, block: &Block::Hash) -> Result<bool, Error> {

substrate/core/network/src/protocol.rs

@@ -226,7 +226,8 @@ impl<'a, B: BlockT> LightDispatchNetwork<B> for LightDispatchIn<'a, B> {
 		last: <B as BlockT>::Hash,
 		min: <B as BlockT>::Hash,
 		max: <B as BlockT>::Hash,
-		key: Vec<u8>
+		storage_key: Option<Vec<u8>>,
+		key: Vec<u8>,
 	) {
 		let message = message::generic::Message::RemoteChangesRequest(message::RemoteChangesRequest {
 			id,
@@ -234,6 +235,7 @@ impl<'a, B: BlockT> LightDispatchNetwork<B> for LightDispatchIn<'a, B> {
 			last,
 			min,
 			max,
+			storage_key,
 			key,
 		});
 
@@ -1385,24 +1387,34 @@ impl<B: BlockT, S: NetworkSpecialization<B>, H: ExHashT> Protocol<B, S, H> {
 		trace!(target: "sync", "Remote changes proof request {} from {} for key {} ({}..{})",
 			request.id,
 			who,
-			request.key.to_hex::<String>(),
+			if let Some(sk) = request.storage_key.as_ref() {
+				format!("{} : {}", sk.to_hex::<String>(), request.key.to_hex::<String>())
+			} else {
+				request.key.to_hex::<String>()
+			},
 			request.first,
 			request.last
 		);
+		let storage_key = request.storage_key.map(|sk| StorageKey(sk));
 		let key = StorageKey(request.key);
 		let proof = match self.context_data.chain.key_changes_proof(
 			request.first,
 			request.last,
 			request.min,
 			request.max,
-			&key
+			storage_key.as_ref(),
+			&key,
 		) {
 			Ok(proof) => proof,
 			Err(error) => {
 				trace!(target: "sync", "Remote changes proof request {} from {} for key {} ({}..{}) failed with: {}",
 					request.id,
 					who,
-					key.0.to_hex::<String>(),
+					if let Some(sk) = storage_key {
+						format!("{} : {}", sk.0.to_hex::<String>(), key.0.to_hex::<String>())
+					} else {
+						key.0.to_hex::<String>()
+					},
 					request.first,
 					request.last,
 					error

substrate/core/network/src/protocol/light_dispatch.rs

@@ -84,7 +84,8 @@ pub trait LightDispatchNetwork<B: BlockT> {
 		last: <B as BlockT>::Hash,
 		min: <B as BlockT>::Hash,
 		max: <B as BlockT>::Hash,
-		key: Vec<u8>
+		storage_key: Option<Vec<u8>>,
+		key: Vec<u8>,
 	);
 
 	/// Send to `who` a body request.
@@ -629,6 +630,7 @@ impl<Block: BlockT> Request<Block> {
 					data.last_block.1.clone(),
 					data.tries_roots.1.clone(),
 					data.max_block.1.clone(),
+					data.storage_key.clone(),
 					data.key.clone(),
 				),
 			RequestData::RemoteBody(ref data, _) =>
@@ -785,7 +787,7 @@ pub mod tests {
 			_: Vec<u8>) {}
 		fn send_call_request(&mut self, _: &PeerId, _: RequestId, _: <B as BlockT>::Hash, _: String, _: Vec<u8>) {}
 		fn send_changes_request(&mut self, _: &PeerId, _: RequestId, _: <B as BlockT>::Hash, _: <B as BlockT>::Hash,
-			_: <B as BlockT>::Hash, _: <B as BlockT>::Hash, _: Vec<u8>) {}
+			_: <B as BlockT>::Hash, _: <B as BlockT>::Hash, _: Option<Vec<u8>>, _: Vec<u8>) {}
 		fn send_body_request(&mut self, _: &PeerId, _: RequestId, _: BlockAttributes, _: FromBlock<<B as BlockT>::Hash,
 			<<B as BlockT>::Header as HeaderT>::Number>, _: Option<B::Hash>, _: Direction, _: Option<u32>) {}
 	}
@@ -1063,6 +1065,7 @@ pub mod tests {
 			max_block: (100, Default::default()),
 			tries_roots: (1, Default::default(), vec![]),
 			key: vec![],
+			storage_key: None,
 			retry_count: None,
 		}, tx));
 

substrate/core/network/src/protocol/message.rs

@@ -334,6 +334,8 @@ pub mod generic {
 		pub min: H,
 		/// Hash of the last block that we can use when querying changes.
 		pub max: H,
+		/// Storage child node key which changes are requested.
+		pub storage_key: Option<Vec<u8>>,
 		/// Storage key which changes are requested.
 		pub key: Vec<u8>,
 	}