ChainSpec trait (#5185)

* ChainSpec trait

* Apply suggestions from code review

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Added docs

* Fixed build

* Fixed build

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

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

@@ -26,6 +26,7 @@ use sp_core::storage::{StorageKey, StorageData, ChildInfo, Storage, StorageChild
 use sp_runtime::BuildStorage;
 use serde_json as json;
 use crate::RuntimeGenesis;
+use crate::extension::GetExtension;
 use sc_network::Multiaddr;
 use sc_telemetry::TelemetryEndpoints;
 
@@ -269,9 +270,9 @@ impl<G, E: serde::de::DeserializeOwned> ChainSpec<G, E> {
 	}
 }
 
-impl<G: RuntimeGenesis, E: serde::Serialize> ChainSpec<G, E> {
+impl<G: RuntimeGenesis, E: serde::Serialize + Clone> ChainSpec<G, E> {
 	/// Dump to json string.
-	pub fn to_json(self, raw: bool) -> Result<String, String> {
+	pub fn as_json(&self, raw: bool) -> Result<String, String> {
 		#[derive(Serialize, Deserialize)]
 		struct Container<G, E> {
 			#[serde(flatten)]
@@ -306,7 +307,7 @@ impl<G: RuntimeGenesis, E: serde::Serialize> ChainSpec<G, E> {
 			(_, genesis) => genesis,
 		};
 		let container = Container {
-			client_spec: self.client_spec,
+			client_spec: self.client_spec.clone(),
 			genesis,
 		};
 		json::to_string_pretty(&container)
@@ -314,6 +315,52 @@ impl<G: RuntimeGenesis, E: serde::Serialize> ChainSpec<G, E> {
 	}
 }
 
+impl<G, E> crate::ChainSpec for ChainSpec<G, E>
+where
+	G: RuntimeGenesis,
+	E: GetExtension + serde::Serialize + Clone,
+{
+	fn boot_nodes(&self) -> &[String] {
+		ChainSpec::boot_nodes(self)
+	}
+
+	fn name(&self) -> &str {
+		ChainSpec::name(self)
+	}
+
+	fn id(&self) -> &str {
+		ChainSpec::id(self)
+	}
+
+	fn telemetry_endpoints(&self) -> &Option<TelemetryEndpoints> {
+		ChainSpec::telemetry_endpoints(self)
+	}
+
+	fn protocol_id(&self) -> Option<&str> {
+		ChainSpec::protocol_id(self)
+	}
+
+	fn properties(&self) -> Properties {
+		ChainSpec::properties(self)
+	}
+
+	fn add_boot_node(&mut self, addr: Multiaddr) {
+		ChainSpec::add_boot_node(self, addr)
+	}
+
+	fn extensions(&self) -> &dyn GetExtension {
+		ChainSpec::extensions(self) as &dyn GetExtension
+	}
+
+	fn as_json(&self, raw: bool) -> Result<String, String> {
+		ChainSpec::as_json(self, raw)
+	}
+
+	fn as_storage_builder(&self) -> &dyn BuildStorage {
+		self
+	}
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;
@@ -344,7 +391,7 @@ mod tests {
 			PathBuf::from("./res/chain_spec.json")
 		).unwrap();
 
-		assert_eq!(spec1.to_json(false), spec2.to_json(false));
+		assert_eq!(spec1.as_json(false), spec2.as_json(false));
 	}
 
 	#[derive(Debug, Serialize, Deserialize)]

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

@@ -17,6 +17,8 @@
 //! Chain Spec extensions helpers.
 
 use std::fmt::Debug;
+use std::any::{TypeId, Any};
+
 use std::collections::BTreeMap;
 
 use serde::{Serialize, Deserialize, de::DeserializeOwned};
@@ -120,6 +122,8 @@ 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`
+	fn get_any(&self, t: TypeId) -> &dyn Any;
 
 	/// Get forkable extensions of specific type.
 	fn forks<BlockNumber, T>(&self) -> Option<Forks<BlockNumber, T>> where
@@ -137,6 +141,7 @@ impl Extension for crate::NoExtension {
 	type Forks = Self;
 
 	fn get<T: 'static>(&self) -> Option<&T> { None }
+	fn get_any(&self, _t: TypeId) -> &dyn Any { self }
 }
 
 pub trait IsForks {
@@ -225,22 +230,25 @@ impl<B, E> Extension for Forks<B, E> where
 	type Forks = Self;
 
 	fn get<T: 'static>(&self) -> Option<&T> {
-		use std::any::{TypeId, Any};
-
 		match TypeId::of::<T>() {
 			x if x == TypeId::of::<E>() => Any::downcast_ref(&self.base),
 			_ => 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),
+		}
+	}
+
 	fn forks<BlockNumber, T>(&self) -> Option<Forks<BlockNumber, T>> where
 		BlockNumber: Ord + Clone + 'static,
 		T: Group + 'static,
 		<Self::Forks as IsForks>::Extension: Extension,
 		<<Self::Forks as IsForks>::Extension as Group>::Fork: Extension,
 	{
-		use std::any::{TypeId, Any};
-
 		if TypeId::of::<BlockNumber>() == TypeId::of::<B>() {
 			Any::downcast_ref(&self.for_type::<T>()?).cloned()
 		} else {
@@ -250,6 +258,24 @@ impl<B, E> Extension for Forks<B, E> where
 	}
 }
 
+/// A subset if the `Extension` trait that only allows for quering extensions.
+pub trait GetExtension {
+	/// Get an extension of specific type.
+	fn get_any(&self, t: TypeId) -> &dyn Any;
+}
+
+impl <E: Extension> GetExtension for E {
+	fn get_any(&self, t: TypeId) -> &dyn Any {
+		Extension::get_any(self, t)
+	}
+}
+
+/// Helper function that queries an extension by type from `GetExtension`
+/// trait object.
+pub fn get_extension<T: 'static>(e: &dyn GetExtension) -> Option<&T> {
+	Any::downcast_ref(GetExtension::get_any(e, TypeId::of::<T>()))
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;

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

@@ -30,14 +30,14 @@
 //! ```rust
 //! use std::collections::HashMap;
 //! use serde::{Serialize, Deserialize};
-//! use sc_chain_spec::{ChainSpec, ChainSpecExtension};
+//! use sc_chain_spec::{GenericChainSpec, ChainSpecExtension};
 //!
 //! #[derive(Clone, Debug, Serialize, Deserialize, ChainSpecExtension)]
 //! pub struct MyExtension {
 //!		pub known_blocks: HashMap<u64, String>,
 //! }
 //!
-//! pub type MyChainSpec<G> = ChainSpec<G, MyExtension>;
+//! pub type MyChainSpec<G> = GenericChainSpec<G, MyExtension>;
 //! ```
 //!
 //! Some parameters may require different values depending on the
@@ -49,7 +49,7 @@
 //!
 //! ```rust
 //! use serde::{Serialize, Deserialize};
-//! use sc_chain_spec::{Forks, ChainSpec, ChainSpecGroup, ChainSpecExtension};
+//! use sc_chain_spec::{Forks, ChainSpecGroup, ChainSpecExtension, GenericChainSpec};
 //!
 //! #[derive(Clone, Debug, Serialize, Deserialize, ChainSpecGroup)]
 //! pub struct ClientParams {
@@ -71,10 +71,10 @@
 //! pub type BlockNumber = u64;
 //!
 //! /// A chain spec supporting forkable `ClientParams`.
-//! pub type MyChainSpec1<G> = ChainSpec<G, Forks<BlockNumber, ClientParams>>;
+//! pub type MyChainSpec1<G> = GenericChainSpec<G, Forks<BlockNumber, ClientParams>>;
 //!
 //! /// A chain spec supporting forkable `Extension`.
-//! pub type MyChainSpec2<G> = ChainSpec<G, Forks<BlockNumber, Extension>>;
+//! pub type MyChainSpec2<G> = GenericChainSpec<G, Forks<BlockNumber, Extension>>;
 //! ```
 //!
 //! It's also possible to have a set of parameters that is allowed to change
@@ -84,7 +84,7 @@
 //!
 //! ```rust
 //! use serde::{Serialize, Deserialize};
-//! use sc_chain_spec::{Forks, ChainSpec, ChainSpecGroup, ChainSpecExtension};
+//! use sc_chain_spec::{Forks, GenericChainSpec, ChainSpecGroup, ChainSpecExtension};
 //!
 //! #[derive(Clone, Debug, Serialize, Deserialize, ChainSpecGroup)]
 //! pub struct ClientParams {
@@ -104,20 +104,48 @@
 //!		pub pool: Forks<u64, PoolParams>,
 //! }
 //!
-//! pub type MyChainSpec<G> = ChainSpec<G, Extension>;
+//! pub type MyChainSpec<G> = GenericChainSpec<G, Extension>;
 //! ```
 
 
 mod chain_spec;
 mod extension;
 
-pub use chain_spec::{ChainSpec, Properties, NoExtension};
-pub use extension::{Group, Fork, Forks, Extension};
+pub use chain_spec::{ChainSpec as GenericChainSpec, Properties, NoExtension};
+pub use extension::{Group, Fork, Forks, Extension, GetExtension, get_extension};
 pub use sc_chain_spec_derive::{ChainSpecExtension, ChainSpecGroup};
 
 use serde::{Serialize, de::DeserializeOwned};
 use sp_runtime::BuildStorage;
+use sc_network::Multiaddr;
+use sc_telemetry::TelemetryEndpoints;
 
 /// A set of traits for the runtime genesis config.
 pub trait RuntimeGenesis: Serialize + DeserializeOwned + BuildStorage {}
 impl<T: Serialize + DeserializeOwned + BuildStorage> RuntimeGenesis for T {}
+
+/// Common interface to `GenericChainSpec`
+pub trait ChainSpec: BuildStorage {
+	/// Spec name.
+	fn name(&self) -> &str;
+	/// Spec id.
+	fn id(&self) -> &str;
+	/// A list of bootnode addresses.
+	fn boot_nodes(&self) -> &[String];
+	/// Telemetry endpoints (if any)
+	fn telemetry_endpoints(&self) -> &Option<TelemetryEndpoints>;
+	/// Network protocol id.
+	fn protocol_id(&self) -> Option<&str>;
+	/// Additional loosly-typed properties of the chain.
+	///
+	/// Returns an empty JSON object if 'properties' not defined in config
+	fn properties(&self) -> Properties;
+	/// Returns a reference to defined chain spec extensions.
+	fn extensions(&self) -> &dyn GetExtension;
+	/// Add a bootnode to the list.
+	fn add_boot_node(&mut self, addr: Multiaddr);
+	/// Return spec as JSON.
+	fn as_json(&self, raw: bool) -> Result<String, String>;
+	/// Return StorageBuilder for this spec.
+	fn as_storage_builder(&self) -> &dyn BuildStorage;
+}