Decouples light-sync state from chain spec (#9491)

* Decouples light-sync state from chain spec

This decouples the light-sync state from chain spec. First, the
light-sync state currently only works with BABE+Grandpa, so not
all *Substrate* based chains can use this feature. The next problem was
also that this pulled the `sc-consensus-babe` and `sc-finality-grandpa`
crate into `sc-chain-spec`.

If a chain now wants to support the light-sync state, it needs to add
the `LightSyncStateExtension` to the chain spec as an extension. This is
documented in the crate level docs of `sc-sync-state-rpc`. If this
extension is not available, `SyncStateRpc` fails at initialization.

* Fix compilation for browser

* Fmt

substrate/client/chain-spec/src/chain_spec.rs

@@ -28,10 +28,7 @@ use sp_core::{
 	storage::{ChildInfo, Storage, StorageChild, StorageData, StorageKey},
 	Bytes,
 };
-use sp_runtime::{
-	traits::{Block as BlockT, NumberFor},
-	BuildStorage,
-};
+use sp_runtime::BuildStorage;
 use std::{borrow::Cow, collections::HashMap, fs::File, path::PathBuf, sync::Arc};
 
 enum GenesisSource<G> {
@@ -167,7 +164,6 @@ struct ClientSpec<E> {
 	consensus_engine: (),
 	#[serde(skip_serializing)]
 	genesis: serde::de::IgnoredAny,
-	light_sync_state: Option<SerializableLightSyncState>,
 	/// Mapping from `block_hash` to `wasm_code`.
 	///
 	/// The given `wasm_code` will be used to substitute the on-chain wasm code from the given
@@ -231,11 +227,16 @@ impl<G, E> ChainSpec<G, E> {
 		self.client_spec.boot_nodes.push(addr)
 	}
 
-	/// Returns a reference to defined chain spec extensions.
+	/// Returns a reference to the defined chain spec extensions.
 	pub fn extensions(&self) -> &E {
 		&self.client_spec.extensions
 	}
 
+	/// Returns a mutable reference to the defined chain spec extensions.
+	pub fn extensions_mut(&mut self) -> &mut E {
+		&mut self.client_spec.extensions
+	}
+
 	/// Create hardcoded spec.
 	pub fn from_genesis<F: Fn() -> G + 'static + Send + Sync>(
 		name: &str,
@@ -259,7 +260,6 @@ impl<G, E> ChainSpec<G, E> {
 			extensions,
 			consensus_engine: (),
 			genesis: Default::default(),
-			light_sync_state: None,
 			code_substitutes: HashMap::new(),
 		};
 
@@ -270,11 +270,6 @@ impl<G, E> ChainSpec<G, E> {
 	fn chain_type(&self) -> ChainType {
 		self.client_spec.chain_type.clone()
 	}
-
-	/// Hardcode infomation to allow light clients to sync quickly into the chain spec.
-	fn set_light_sync_state(&mut self, light_sync_state: SerializableLightSyncState) {
-		self.client_spec.light_sync_state = Some(light_sync_state);
-	}
 }
 
 impl<G, E: serde::de::DeserializeOwned> ChainSpec<G, E> {
@@ -379,6 +374,10 @@ where
 		ChainSpec::extensions(self) as &dyn GetExtension
 	}
 
+	fn extensions_mut(&mut self) -> &mut dyn GetExtension {
+		ChainSpec::extensions_mut(self) as &mut dyn GetExtension
+	}
+
 	fn as_json(&self, raw: bool) -> Result<String, String> {
 		ChainSpec::as_json(self, raw)
 	}
@@ -395,10 +394,6 @@ where
 		self.genesis = GenesisSource::Storage(storage);
 	}
 
-	fn set_light_sync_state(&mut self, light_sync_state: SerializableLightSyncState) {
-		ChainSpec::set_light_sync_state(self, light_sync_state)
-	}
-
 	fn code_substitutes(&self) -> std::collections::HashMap<String, Vec<u8>> {
 		self.client_spec
 			.code_substitutes
@@ -408,60 +403,6 @@ where
 	}
 }
 
-/// Hardcoded infomation that allows light clients to sync quickly.
-pub struct LightSyncState<Block: BlockT> {
-	/// The header of the best finalized block.
-	pub finalized_block_header: <Block as BlockT>::Header,
-	/// The epoch changes tree for babe.
-	pub babe_epoch_changes: sc_consensus_epochs::EpochChangesFor<Block, sc_consensus_babe::Epoch>,
-	/// The babe weight of the finalized block.
-	pub babe_finalized_block_weight: sp_consensus_babe::BabeBlockWeight,
-	/// The authority set for grandpa.
-	pub grandpa_authority_set:
-		sc_finality_grandpa::AuthoritySet<<Block as BlockT>::Hash, NumberFor<Block>>,
-}
-
-impl<Block: BlockT> LightSyncState<Block> {
-	/// Convert into a `SerializableLightSyncState`.
-	pub fn to_serializable(&self) -> SerializableLightSyncState {
-		use codec::Encode;
-
-		SerializableLightSyncState {
-			finalized_block_header: StorageData(self.finalized_block_header.encode()),
-			babe_epoch_changes: StorageData(self.babe_epoch_changes.encode()),
-			babe_finalized_block_weight: self.babe_finalized_block_weight,
-			grandpa_authority_set: StorageData(self.grandpa_authority_set.encode()),
-		}
-	}
-
-	/// Convert from a `SerializableLightSyncState`.
-	pub fn from_serializable(
-		serialized: &SerializableLightSyncState,
-	) -> Result<Self, codec::Error> {
-		Ok(Self {
-			finalized_block_header: codec::Decode::decode(
-				&mut &serialized.finalized_block_header.0[..],
-			)?,
-			babe_epoch_changes: codec::Decode::decode(&mut &serialized.babe_epoch_changes.0[..])?,
-			babe_finalized_block_weight: serialized.babe_finalized_block_weight,
-			grandpa_authority_set: codec::Decode::decode(
-				&mut &serialized.grandpa_authority_set.0[..],
-			)?,
-		})
-	}
-}
-
-/// The serializable form of `LightSyncState`. Created using `LightSyncState::serialize`.
-#[derive(Serialize, Deserialize, Clone, Debug)]
-#[serde(rename_all = "camelCase")]
-#[serde(deny_unknown_fields)]
-pub struct SerializableLightSyncState {
-	finalized_block_header: StorageData,
-	babe_epoch_changes: StorageData,
-	babe_finalized_block_weight: sp_consensus_babe::BabeBlockWeight,
-	grandpa_authority_set: StorageData,
-}
-
 #[cfg(test)]
 mod tests {
 	use super::*;

substrate/client/chain-spec/src/extension.rs

@@ -126,8 +126,10 @@ pub trait Extension: Serialize + DeserializeOwned + Clone {
 
 	/// Get an extension of specific type.
 	fn get<T: 'static>(&self) -> Option<&T>;
-	/// Get an extension of specific type as refernce to `Any`
+	/// Get an extension of specific type as reference to `Any`.
 	fn get_any(&self, t: TypeId) -> &dyn Any;
+	/// Get an extension of specific type as mutable reference to `Any`.
+	fn get_any_mut(&mut self, t: TypeId) -> &mut dyn Any;
 
 	/// Get forkable extensions of specific type.
 	fn forks<BlockNumber, T>(&self) -> Option<Forks<BlockNumber, T>>
@@ -151,6 +153,9 @@ impl Extension for crate::NoExtension {
 	fn get_any(&self, _t: TypeId) -> &dyn Any {
 		self
 	}
+	fn get_any_mut(&mut self, _: TypeId) -> &mut dyn Any {
+		self
+	}
 }
 
 pub trait IsForks {
@@ -240,16 +245,26 @@ where
 	type Forks = Self;
 
 	fn get<T: 'static>(&self) -> Option<&T> {
-		match TypeId::of::<T>() {
-			x if x == TypeId::of::<E>() => <dyn Any>::downcast_ref(&self.base),
-			_ => self.base.get(),
+		if TypeId::of::<T>() == TypeId::of::<E>() {
+			<dyn Any>::downcast_ref(&self.base)
+		} else {
+			self.base.get()
 		}
 	}
 
 	fn get_any(&self, t: TypeId) -> &dyn Any {
-		match t {
-			x if x == TypeId::of::<E>() => &self.base,
-			_ => self.base.get_any(t),
+		if t == TypeId::of::<E>() {
+			&self.base
+		} else {
+			self.base.get_any(t)
+		}
+	}
+
+	fn get_any_mut(&mut self, t: TypeId) -> &mut dyn Any {
+		if t == TypeId::of::<E>() {
+			&mut self.base
+		} else {
+			self.base.get_any_mut(t)
 		}
 	}
 
@@ -273,20 +288,31 @@ where
 pub trait GetExtension {
 	/// Get an extension of specific type.
 	fn get_any(&self, t: TypeId) -> &dyn Any;
+
+	/// Get an extension of specific type with mutable access.
+	fn get_any_mut(&mut self, t: TypeId) -> &mut dyn Any;
 }
 
 impl<E: Extension> GetExtension for E {
 	fn get_any(&self, t: TypeId) -> &dyn Any {
 		Extension::get_any(self, t)
 	}
+
+	fn get_any_mut(&mut self, t: TypeId) -> &mut dyn Any {
+		Extension::get_any_mut(self, t)
+	}
 }
 
-/// Helper function that queries an extension by type from `GetExtension`
-/// trait object.
+/// Helper function that queries an extension by type from `GetExtension` trait object.
 pub fn get_extension<T: 'static>(e: &dyn GetExtension) -> Option<&T> {
 	<dyn Any>::downcast_ref(GetExtension::get_any(e, TypeId::of::<T>()))
 }
 
+/// Helper function that queries an extension by type from `GetExtension` trait object.
+pub fn get_extension_mut<T: 'static>(e: &mut dyn GetExtension) -> Option<&mut T> {
+	<dyn Any>::downcast_mut(GetExtension::get_any_mut(e, TypeId::of::<T>()))
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;

substrate/client/chain-spec/src/lib.rs

@@ -110,10 +110,10 @@
 mod chain_spec;
 mod extension;
 
-pub use chain_spec::{
-	ChainSpec as GenericChainSpec, LightSyncState, NoExtension, SerializableLightSyncState,
+pub use chain_spec::{ChainSpec as GenericChainSpec, NoExtension};
+pub use extension::{
+	get_extension, get_extension_mut, Extension, Fork, Forks, GetExtension, Group,
 };
-pub use extension::{get_extension, Extension, Fork, Forks, GetExtension, Group};
 pub use sc_chain_spec_derive::{ChainSpecExtension, ChainSpecGroup};
 
 use sc_network::config::MultiaddrWithPeerId;
@@ -169,8 +169,10 @@ pub trait ChainSpec: BuildStorage + Send + Sync {
 	///
 	/// Returns an empty JSON object if 'properties' not defined in config
 	fn properties(&self) -> Properties;
-	/// Returns a reference to defined chain spec extensions.
+	/// Returns a reference to the defined chain spec extensions.
 	fn extensions(&self) -> &dyn GetExtension;
+	/// Returns a mutable reference to the defined chain spec extensions.
+	fn extensions_mut(&mut self) -> &mut dyn GetExtension;
 	/// Add a bootnode to the list.
 	fn add_boot_node(&mut self, addr: MultiaddrWithPeerId);
 	/// Return spec as JSON.
@@ -183,8 +185,6 @@ pub trait ChainSpec: BuildStorage + Send + Sync {
 	///
 	/// This will be used as storage at genesis.
 	fn set_storage(&mut self, storage: Storage);
-	/// Hardcode infomation to allow light clients to sync quickly into the chain spec.
-	fn set_light_sync_state(&mut self, light_sync_state: SerializableLightSyncState);
 	/// Returns code substitutes that should be used for the on chain wasm.
 	fn code_substitutes(&self) -> std::collections::HashMap<String, Vec<u8>>;
 }