Move authorities interface from Core to consensus (#1412)

* Move authorities interface from Core to consensus

f

* notify all caches of block insert + create with up-to-date best_fin

* merged authorities_are_cached from light_grandpa_import2

* Add ProvideCache trait

* Create helper function for 'get_cache'

* Fix some formatting

* Bump impl version

* Resolve wasm conflicts

* Apply review comments

* Use try_for_each

* Move authorities interface from Core to consensus

f

* notify all caches of block insert + create with up-to-date best_fin

* merged authorities_are_cached from light_grandpa_import2

* Add ProvideCache trait

* Create helper function for 'get_cache'

* Fix some formatting

* Bump impl version

* Resolve wasm conflicts

* Apply review comments

* Use try_for_each

* Move authorities interface from Core to consensus

f

* notify all caches of block insert + create with up-to-date best_fin

* merged authorities_are_cached from light_grandpa_import2

* Add ProvideCache trait

* Create helper function for 'get_cache'

* Fix some formatting

* Bump impl version

* Resolve wasm conflicts

* Apply review comments

* Use try_for_each

* Increment impl_version

* Update lib.rs

substrate/core/consensus/common/src/block_import.rs

@@ -16,9 +16,10 @@
 
 //! Block import helpers.
 
-use runtime_primitives::traits::{AuthorityIdFor, Block as BlockT, DigestItemFor, Header as HeaderT, NumberFor};
+use runtime_primitives::traits::{Block as BlockT, DigestItemFor, Header as HeaderT, NumberFor};
 use runtime_primitives::Justification;
 use std::borrow::Cow;
+use std::collections::HashMap;
 
 /// Block import result.
 #[derive(Debug, PartialEq, Eq)]
@@ -175,11 +176,13 @@ pub trait BlockImport<B: BlockT> {
 		parent_hash: B::Hash,
 	) -> Result<ImportResult, Self::Error>;
 
-	/// Import a Block alongside the new authorities valid from this block forward
+	/// Import a block.
+	///
+	/// Cached data can be accessed through the blockchain cache.
 	fn import_block(
 		&self,
 		block: ImportBlock<B>,
-		new_authorities: Option<Vec<AuthorityIdFor<B>>>,
+		cache: HashMap<Vec<u8>, Vec<u8>>,
 	) -> Result<ImportResult, Self::Error>;
 }
 

substrate/core/consensus/common/src/error.rs

@@ -58,6 +58,12 @@ error_chain! {
 			display("Message signature {:?} by {:?} is invalid.", s, a),
 		}
 
+		/// Invalid authorities set received from the runtime.
+		InvalidAuthoritiesSet {
+			description("authorities set is invalid"),
+			display("Current state of blockchain has invalid authorities set"),
+		}
+
 		/// Account is not an authority.
 		InvalidAuthority(a: Public) {
 			description("Message sender is not a valid authority"),

substrate/core/consensus/common/src/import_queue.rs

@@ -28,6 +28,7 @@ use crate::block_import::{
 	BlockImport, BlockOrigin, ImportBlock, ImportedAux, ImportResult, JustificationImport,
 };
 use crossbeam_channel::{self as channel, Receiver, Sender};
+use parity_codec::Encode;
 
 use std::sync::Arc;
 use std::thread;
@@ -38,6 +39,7 @@ use runtime_primitives::traits::{
 use runtime_primitives::Justification;
 
 use crate::error::Error as ConsensusError;
+use parity_codec::alloc::collections::hash_map::HashMap;
 
 /// Shared block import struct used by the queue.
 pub type SharedBlockImport<B> = Arc<dyn BlockImport<B, Error = ConsensusError> + Send + Sync>;
@@ -566,7 +568,12 @@ pub fn import_single_block<B: BlockT, V: Verifier<B>>(
 			BlockImportError::VerificationFailed(peer.clone(), msg)
 		})?;
 
-	import_error(import_handle.import_block(import_block, new_authorities))
+	let mut cache = HashMap::new();
+	if let Some(authorities) = new_authorities {
+		cache.insert(crate::well_known_cache_keys::AUTHORITIES.to_vec(), authorities.encode());
+	}
+
+	import_error(import_handle.import_block(import_block, cache))
 }
 
 #[cfg(test)]

substrate/core/consensus/common/src/lib.rs

@@ -53,7 +53,9 @@ pub use block_import::{
 
 /// Trait for getting the authorities at a given block.
 pub trait Authorities<B: Block> {
-	type Error: ::std::error::Error + Send + 'static;	/// Get the authorities at the given block.
+	type Error: std::error::Error + Send + 'static;
+
+	/// Get the authorities at the given block.
 	fn authorities(&self, at: &BlockId<B>) -> Result<Vec<AuthorityIdFor<B>>, Self::Error>;
 }
 
@@ -115,3 +117,9 @@ impl<T: SyncOracle> SyncOracle for Arc<T> {
 		T::is_offline(&*self)
 	}
 }
+
+/// A list of all well known keys in the cache.
+pub mod well_known_cache_keys {
+	/// A list of authorities.
+	pub const AUTHORITIES: &'static [u8] = b"auth";
+}