chainHead: Add support for storage closest merkle descendant

bin/node/bench/Cargo.toml

@@ -33,7 +33,7 @@ sc-basic-authorship = { version = "0.10.0-dev", path = "../../../client/basic-au
 sp-inherents = { version = "4.0.0-dev", path = "../../../primitives/inherents" }
 sp-timestamp = { version = "4.0.0-dev", default-features = false, path = "../../../primitives/timestamp" }
 sp-tracing = { version = "10.0.0", path = "../../../primitives/tracing" }
-hash-db = "0.16.0"
+hash-db = { git = "https://github.com/paritytech/trie.git", branch = "lexnv/expose_merkle_value" }
 tempfile = "3.1.0"
 fs_extra = "1"
 rand = { version = "0.8.5", features = ["small_rng"] }

client/api/src/backend.rs

@@ -476,6 +476,21 @@ pub trait StorageProvider<Block: BlockT, B: Backend<Block>> {
 		child_info: &ChildInfo,
 		key: &StorageKey,
 	) -> sp_blockchain::Result<Option<Block::Hash>>;
+
+	/// Given a block's `Hash` and a key, return the closest merkle value.
+	fn closest_merkle_value(
+		&self,
+		hash: Block::Hash,
+		key: &StorageKey,
+	) -> sp_blockchain::Result<Option<Block::Hash>>;
+
+	/// Given a block's `Hash`, a key and a child storage key, return the closest merkle value.
+	fn child_closest_merkle_value(
+		&self,
+		hash: Block::Hash,
+		child_info: &ChildInfo,
+		key: &StorageKey,
+	) -> sp_blockchain::Result<Option<Block::Hash>>;
 }
 
 /// Client backend.

client/db/Cargo.toml

@@ -16,7 +16,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 codec = { package = "parity-scale-codec", version = "3.6.1", features = [
 	"derive",
 ] }
-hash-db = "0.16.0"
+hash-db = { git = "https://github.com/paritytech/trie.git", branch = "lexnv/expose_merkle_value" }
 kvdb = "0.13.0"
 kvdb-memorydb = "0.13.0"
 kvdb-rocksdb = { version = "0.19.0", optional = true }

client/db/src/bench.rs

@@ -383,6 +383,24 @@ impl<B: BlockT> StateBackend<HashingFor<B>> for BenchmarkingState<B> {
 			.child_storage_hash(child_info, key)
 	}
 
+	fn closest_merkle_value(&self, key: &[u8]) -> Result<Option<B::Hash>, Self::Error> {
+		self.add_read_key(None, key);
+		self.state.borrow().as_ref().ok_or_else(state_err)?.closest_merkle_value(key)
+	}
+
+	fn child_closest_merkle_value(
+		&self,
+		child_info: &ChildInfo,
+		key: &[u8],
+	) -> Result<Option<B::Hash>, Self::Error> {
+		self.add_read_key(None, key);
+		self.state
+			.borrow()
+			.as_ref()
+			.ok_or_else(state_err)?
+			.child_closest_merkle_value(child_info, key)
+	}
+
 	fn exists_storage(&self, key: &[u8]) -> Result<bool, Self::Error> {
 		self.add_read_key(None, key);
 		self.state.borrow().as_ref().ok_or_else(state_err)?.exists_storage(key)

client/db/src/lib.rs

@@ -215,6 +215,18 @@ impl<B: BlockT> StateBackend<HashingFor<B>> for RefTrackingState<B> {
 		self.state.child_storage_hash(child_info, key)
 	}
 
+	fn closest_merkle_value(&self, key: &[u8]) -> Result<Option<B::Hash>, Self::Error> {
+		self.state.closest_merkle_value(key)
+	}
+
+	fn child_closest_merkle_value(
+		&self,
+		child_info: &ChildInfo,
+		key: &[u8],
+	) -> Result<Option<B::Hash>, Self::Error> {
+		self.state.child_closest_merkle_value(child_info, key)
+	}
+
 	fn exists_storage(&self, key: &[u8]) -> Result<bool, Self::Error> {
 		self.state.exists_storage(key)
 	}

client/db/src/record_stats_state.rs

@@ -145,6 +145,18 @@ impl<S: StateBackend<HashingFor<B>>, B: BlockT> StateBackend<HashingFor<B>>
 		self.state.child_storage_hash(child_info, key)
 	}
 
+	fn closest_merkle_value(&self, key: &[u8]) -> Result<Option<B::Hash>, Self::Error> {
+		self.state.closest_merkle_value(key)
+	}
+
+	fn child_closest_merkle_value(
+		&self,
+		child_info: &ChildInfo,
+		key: &[u8],
+	) -> Result<Option<B::Hash>, Self::Error> {
+		self.state.child_closest_merkle_value(child_info, key)
+	}
+
 	fn exists_storage(&self, key: &[u8]) -> Result<bool, Self::Error> {
 		self.state.exists_storage(key)
 	}

client/rpc-spec-v2/src/chain_head/api.rs

@@ -119,4 +119,31 @@ pub trait ChainHeadApi<Hash> {
 	/// This method is unstable and subject to change in the future.
 	#[method(name = "chainHead_unstable_unpin", blocking)]
 	fn chain_head_unstable_unpin(&self, follow_subscription: String, hash: Hash) -> RpcResult<()>;
+
+	/// Resumes a storage fetch started with `chainHead_storage` after it has generated an
+	/// `operationWaitingForContinue` event.
+	///
+	/// # Unstable
+	///
+	/// This method is unstable and subject to change in the future.
+	#[method(name = "chainHead_unstable_continue", blocking)]
+	fn chain_head_unstable_continue(
+		&self,
+		follow_subscription: String,
+		operation_id: String,
+	) -> RpcResult<()>;
+
+	/// Stops an operation started with chainHead_unstable_body, chainHead_unstable_call, or
+	/// chainHead_unstable_storage. If the operation was still in progress, this interrupts it. If
+	/// the operation was already finished, this call has no effect.
+	///
+	/// # Unstable
+	///
+	/// This method is unstable and subject to change in the future.
+	#[method(name = "chainHead_unstable_stopOperation", blocking)]
+	fn chain_head_unstable_stop_operation(
+		&self,
+		follow_subscription: String,
+		operation_id: String,
+	) -> RpcResult<()>;
 }