Adapt RemoteExternalities and its related types to be used with generic hash parameters (#3953)

Closes  https://github.com/paritytech/polkadot-sdk/issues/3737

---------

Co-authored-by: command-bot <>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Bastian Köcher <git@kchr.de>

prdoc/pr_3953.prdoc

@@ -0,0 +1,19 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: Adapt RemoteExternalities and its related types to be used with generic hash parameters
+
+doc:
+  - audience: Node Dev
+    description: |
+      Modify `RemoteExternalities`, `Mode`, `OnlineConfig` and`Snapshot` to rely now on generic parameter, instead of `BlockT`.
+      Adjust in consequence their implementation to be compatible with types `Hash`, or if possible any generic.
+      Adapt Builder struct and implementation for these bounds.
+
+crates: 
+- name: frame-remote-externalities
+  bump: major
+- name: pallet-state-trie-migration
+  bump: patch
+- name: try-runtime-cli
+  bump: patch

substrate/frame/state-trie-migration/src/lib.rs

@@ -1698,8 +1698,10 @@ pub(crate) mod remote_tests {
 	///
 	/// This will print some very useful statistics, make sure [`crate::LOG_TARGET`] is enabled.
 	#[allow(dead_code)]
-	pub(crate) async fn run_with_limits<Runtime, Block>(limits: MigrationLimits, mode: Mode<Block>)
-	where
+	pub(crate) async fn run_with_limits<Runtime, Block>(
+		limits: MigrationLimits,
+		mode: Mode<Block::Hash>,
+	) where
 		Runtime: crate::Config<Hash = H256>,
 		Block: BlockT<Hash = H256> + DeserializeOwned,
 		Block::Header: serde::de::DeserializeOwned,

substrate/utils/frame/remote-externalities/src/lib.rs

@@ -36,7 +36,7 @@ use sp_core::{
 	},
 };
 use sp_runtime::{
-	traits::{Block as BlockT, HashingFor},
+	traits::{Block as BlockT, Hash, HashingFor},
 	StateVersion,
 };
 use sp_state_machine::TestExternalities;
@@ -63,21 +63,21 @@ const SNAPSHOT_VERSION: SnapshotVersion = Compact(3);
 
 /// The snapshot that we store on disk.
 #[derive(Decode, Encode)]
-struct Snapshot<B: BlockT> {
+struct Snapshot<H> {
 	snapshot_version: SnapshotVersion,
 	state_version: StateVersion,
-	block_hash: B::Hash,
+	block_hash: H,
 	// <Vec<Key, (Value, MemoryDbRefCount)>>
 	raw_storage: Vec<(Vec<u8>, (Vec<u8>, i32))>,
-	storage_root: B::Hash,
+	storage_root: H,
 }
 
-impl<B: BlockT> Snapshot<B> {
+impl<H: Decode> Snapshot<H> {
 	pub fn new(
 		state_version: StateVersion,
-		block_hash: B::Hash,
+		block_hash: H,
 		raw_storage: Vec<(Vec<u8>, (Vec<u8>, i32))>,
-		storage_root: B::Hash,
+		storage_root: H,
 	) -> Self {
 		Self {
 			snapshot_version: SNAPSHOT_VERSION,
@@ -88,7 +88,7 @@ impl<B: BlockT> Snapshot<B> {
 		}
 	}
 
-	fn load(path: &PathBuf) -> Result<Snapshot<B>, &'static str> {
+	fn load(path: &PathBuf) -> Result<Snapshot<H>, &'static str> {
 		let bytes = fs::read(path).map_err(|_| "fs::read failed.")?;
 		// The first item in the SCALE encoded struct bytes is the snapshot version. We decode and
 		// check that first, before proceeding to decode the rest of the snapshot.
@@ -105,21 +105,21 @@ impl<B: BlockT> Snapshot<B> {
 
 /// An externalities that acts exactly the same as [`sp_io::TestExternalities`] but has a few extra
 /// bits and pieces to it, and can be loaded remotely.
-pub struct RemoteExternalities<B: BlockT> {
+pub struct RemoteExternalities<H: Hash> {
 	/// The inner externalities.
-	pub inner_ext: TestExternalities<HashingFor<B>>,
-	/// The block hash it which we created this externality env.
-	pub block_hash: B::Hash,
+	pub inner_ext: TestExternalities<H>,
+	/// The block hash with which we created this externality env.
+	pub block_hash: H::Out,
 }
 
-impl<B: BlockT> Deref for RemoteExternalities<B> {
-	type Target = TestExternalities<HashingFor<B>>;
+impl<H: Hash> Deref for RemoteExternalities<H> {
+	type Target = TestExternalities<H>;
 	fn deref(&self) -> &Self::Target {
 		&self.inner_ext
 	}
 }
 
-impl<B: BlockT> DerefMut for RemoteExternalities<B> {
+impl<H: Hash> DerefMut for RemoteExternalities<H> {
 	fn deref_mut(&mut self) -> &mut Self::Target {
 		&mut self.inner_ext
 	}
@@ -127,16 +127,16 @@ impl<B: BlockT> DerefMut for RemoteExternalities<B> {
 
 /// The execution mode.
 #[derive(Clone)]
-pub enum Mode<B: BlockT> {
+pub enum Mode<H> {
 	/// Online. Potentially writes to a snapshot file.
-	Online(OnlineConfig<B>),
+	Online(OnlineConfig<H>),
 	/// Offline. Uses a state snapshot file and needs not any client config.
 	Offline(OfflineConfig),
 	/// Prefer using a snapshot file if it exists, else use a remote server.
-	OfflineOrElseOnline(OfflineConfig, OnlineConfig<B>),
+	OfflineOrElseOnline(OfflineConfig, OnlineConfig<H>),
 }
 
-impl<B: BlockT> Default for Mode<B> {
+impl<H> Default for Mode<H> {
 	fn default() -> Self {
 		Mode::Online(OnlineConfig::default())
 	}
@@ -221,10 +221,10 @@ impl From<HttpClient> for Transport {
 ///
 /// A state snapshot config may be present and will be written to in that case.
 #[derive(Clone)]
-pub struct OnlineConfig<B: BlockT> {
+pub struct OnlineConfig<H> {
 	/// The block hash at which to get the runtime state. Will be latest finalized head if not
 	/// provided.
-	pub at: Option<B::Hash>,
+	pub at: Option<H>,
 	/// An optional state snapshot file to WRITE to, not for reading. Not written if set to `None`.
 	pub state_snapshot: Option<SnapshotConfig>,
 	/// The pallets to scrape. These values are hashed and added to `hashed_prefix`.
@@ -240,7 +240,7 @@ pub struct OnlineConfig<B: BlockT> {
 	pub hashed_keys: Vec<Vec<u8>>,
 }
 
-impl<B: BlockT> OnlineConfig<B> {
+impl<H: Clone> OnlineConfig<H> {
 	/// Return rpc (http) client reference.
 	fn rpc_client(&self) -> &HttpClient {
 		self.transport
@@ -248,12 +248,12 @@ impl<B: BlockT> OnlineConfig<B> {
 			.expect("http client must have been initialized by now; qed.")
 	}
 
-	fn at_expected(&self) -> B::Hash {
-		self.at.expect("block at must be initialized; qed")
+	fn at_expected(&self) -> H {
+		self.at.clone().expect("block at must be initialized; qed")
 	}
 }
 
-impl<B: BlockT> Default for OnlineConfig<B> {
+impl<H> Default for OnlineConfig<H> {
 	fn default() -> Self {
 		Self {
 			transport: Transport::from(DEFAULT_HTTP_ENDPOINT.to_owned()),
@@ -267,7 +267,7 @@ impl<B: BlockT> Default for OnlineConfig<B> {
 	}
 }
 
-impl<B: BlockT> From<String> for OnlineConfig<B> {
+impl<H> From<String> for OnlineConfig<H> {
 	fn from(t: String) -> Self {
 		Self { transport: t.into(), ..Default::default() }
 	}
@@ -307,7 +307,7 @@ pub struct Builder<B: BlockT> {
 	/// The keys that will be excluded from the final externality. The *hashed* key must be given.
 	hashed_blacklist: Vec<Vec<u8>>,
 	/// Connectivity mode, online or offline.
-	mode: Mode<B>,
+	mode: Mode<B::Hash>,
 	/// If provided, overwrite the state version with this. Otherwise, the state_version of the
 	/// remote node is used. All cache files also store their state version.
 	///
@@ -328,7 +328,7 @@ impl<B: BlockT> Default for Builder<B> {
 
 // Mode methods
 impl<B: BlockT> Builder<B> {
-	fn as_online(&self) -> &OnlineConfig<B> {
+	fn as_online(&self) -> &OnlineConfig<B::Hash> {
 		match &self.mode {
 			Mode::Online(config) => config,
 			Mode::OfflineOrElseOnline(_, config) => config,
@@ -336,7 +336,7 @@ impl<B: BlockT> Builder<B> {
 		}
 	}
 
-	fn as_online_mut(&mut self) -> &mut OnlineConfig<B> {
+	fn as_online_mut(&mut self) -> &mut OnlineConfig<B::Hash> {
 		match &mut self.mode {
 			Mode::Online(config) => config,
 			Mode::OfflineOrElseOnline(_, config) => config,
@@ -1055,7 +1055,7 @@ where
 		// If we need to save a snapshot, save the raw storage and root hash to the snapshot.
 		if let Some(path) = self.as_online().state_snapshot.clone().map(|c| c.path) {
 			let (raw_storage, storage_root) = pending_ext.into_raw_snapshot();
-			let snapshot = Snapshot::<B>::new(
+			let snapshot = Snapshot::<B::Hash>::new(
 				state_version,
 				self.as_online()
 					.at
@@ -1083,7 +1083,7 @@ where
 		Ok(pending_ext)
 	}
 
-	async fn do_load_remote(&mut self) -> Result<RemoteExternalities<B>, &'static str> {
+	async fn do_load_remote(&mut self) -> Result<RemoteExternalities<HashingFor<B>>, &'static str> {
 		self.init_remote_client().await?;
 		let block_hash = self.as_online().at_expected();
 		let inner_ext = self.load_remote_and_maybe_save().await?;
@@ -1093,12 +1093,12 @@ where
 	fn do_load_offline(
 		&mut self,
 		config: OfflineConfig,
-	) -> Result<RemoteExternalities<B>, &'static str> {
+	) -> Result<RemoteExternalities<HashingFor<B>>, &'static str> {
 		let mut sp = Spinner::with_timer(Spinners::Dots, "Loading snapshot...".into());
 		let start = Instant::now();
 		info!(target: LOG_TARGET, "Loading snapshot from {:?}", &config.state_snapshot.path);
 		let Snapshot { snapshot_version: _, block_hash, state_version, raw_storage, storage_root } =
-			Snapshot::<B>::load(&config.state_snapshot.path)?;
+			Snapshot::<B::Hash>::load(&config.state_snapshot.path)?;
 
 		let inner_ext = TestExternalities::from_raw_snapshot(
 			raw_storage,
@@ -1110,7 +1110,9 @@ where
 		Ok(RemoteExternalities { inner_ext, block_hash })
 	}
 
-	pub(crate) async fn pre_build(mut self) -> Result<RemoteExternalities<B>, &'static str> {
+	pub(crate) async fn pre_build(
+		mut self,
+	) -> Result<RemoteExternalities<HashingFor<B>>, &'static str> {
 		let mut ext = match self.mode.clone() {
 			Mode::Offline(config) => self.do_load_offline(config)?,
 			Mode::Online(_) => self.do_load_remote().await?,
@@ -1175,7 +1177,7 @@ where
 	}
 
 	/// Configure a state snapshot to be used.
-	pub fn mode(mut self, mode: Mode<B>) -> Self {
+	pub fn mode(mut self, mode: Mode<B::Hash>) -> Self {
 		self.mode = mode;
 		self
 	}
@@ -1186,7 +1188,7 @@ where
 		self
 	}
 
-	pub async fn build(self) -> Result<RemoteExternalities<B>, &'static str> {
+	pub async fn build(self) -> Result<RemoteExternalities<HashingFor<B>>, &'static str> {
 		let mut ext = self.pre_build().await?;
 		ext.commit_all().unwrap();
 

substrate/utils/frame/try-runtime/cli/src/lib.rs

@@ -288,7 +288,7 @@ impl State {
 		executor: &WasmExecutor<HostFns>,
 		state_snapshot: Option<SnapshotConfig>,
 		try_runtime_check: bool,
-	) -> sc_cli::Result<RemoteExternalities<Block>>
+	) -> sc_cli::Result<RemoteExternalities<HashingFor<Block>>>
 	where
 		Block::Header: DeserializeOwned,
 		<Block::Hash as FromStr>::Err: Debug,