Storing multiple Justifications per block (#7640)

* primitives/runtime: initial changes on supporting multiple Justifications

* primitives/runtime: make Justifications strongly typed

* Encode/decode Justifications

* primitives/runtime: add Justification type

* backend: apply_finality and finalize_block takes a single Justification

* manual-seal: create engine id and let rpc take encoded justification

* backend: skeleton functions for appending justifications

* backend: initial implementation append_justification

Initial implementation of append_justification on the Backend trait, and also remove unused skeleton
functions for append_justificaton on Finaziler trait.
k

* backend: guard against duplicate consensus engine id

* client/db: add check for block finality

* client/api: add append_justification to in_mem db

* client/light: add no-op append_justification

* network: fix decode call for Justification

* network: only send a single Justification in BlockData

* network: minor comment update

* protocol: update field names to distinguish single justification

* client: further field renames to plural

* client: update function names to plural justifications

* client/db: upgrade existing database for new format

* network: remove dependency on grandpa crate

* db: fix check for finalized block

* grandpa: check for multiple grandpa justifications hwne importing

* backend: update Finalizer trait to take multiple Justifications

* db: remove debugging statements in migration code

* manual-seal: update note about engine id

* db: fix check for finalized block

* client: update variable name to reflect it is now plural

* grandpa: fix incorrect empty Justications in test

* primitives: make Justifications opaque to avoid being empty

* network: fix detecting empty Justification

* runtime: doc strings for Justifications functions

* runtime: add into_justifications

* primitives: check for duplicates in when adding to Justifications

* network/test: use real grandpa engine id in test

* client: fix reviewer comments

* primitives: rename Justifications::push to append

* backend: revert changes to Finalizer trait

* backend: revert mark_finalized

* backend: revert changes to finalize_block

* backend: revert finalized_blocks

* db: add a quick early return for performance

* client: minor reviewer comments

* service/test: use local ConsensusEngineId

* network: add link to issue for sending multiple Justifications

* Apply suggestions from code review

Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>

* Apply suggestions from code review

Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>

* network: tweaks to review suggestions

* network: revert change to BlockData for backwards compatibility

* Apply suggestion from code review

Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>

* Apply suggestions from code review

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

* primitives: update doc comment for Justifications

* client/db/upgrade: avoid grandpa crate dependency

* consensus: revert to single Justification for import_justification

* primitives: improve justifications docs

* style cleanups

* use and_then

* client: rename JUSTIFICATIONS db column

* network: revert to using FRNK in network-test

Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>
Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>
Co-authored-by: André Silva <andrerfosilva@gmail.com>

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

@@ -28,7 +28,7 @@
 
 use std::collections::HashMap;
 
-use sp_runtime::{Justification, traits::{Block as BlockT, Header as _, NumberFor}};
+use sp_runtime::{Justifications, traits::{Block as BlockT, Header as _, NumberFor}};
 
 use crate::{
 	error::Error as ConsensusError,
@@ -68,8 +68,8 @@ pub struct IncomingBlock<B: BlockT> {
 	pub header: Option<<B as BlockT>::Header>,
 	/// Block body if requested.
 	pub body: Option<Vec<<B as BlockT>::Extrinsic>>,
-	/// Justification if requested.
-	pub justification: Option<Justification>,
+	/// Justification(s) if requested.
+	pub justifications: Option<Justifications>,
 	/// The peer, we received this from
 	pub origin: Option<Origin>,
 	/// Allow importing the block skipping state verification if parent state is missing.
@@ -90,7 +90,7 @@ pub trait Verifier<B: BlockT>: Send + Sync {
 		&mut self,
 		origin: BlockOrigin,
 		header: B::Header,
-		justification: Option<Justification>,
+		justifications: Option<Justifications>,
 		body: Option<Vec<B::Extrinsic>>,
 	) -> Result<(BlockImportParams<B, ()>, Option<Vec<(CacheKeyId, Vec<u8>)>>), String>;
 }
@@ -102,13 +102,13 @@ pub trait Verifier<B: BlockT>: Send + Sync {
 pub trait ImportQueue<B: BlockT>: Send {
 	/// Import bunch of blocks.
 	fn import_blocks(&mut self, origin: BlockOrigin, blocks: Vec<IncomingBlock<B>>);
-	/// Import a block justification.
-	fn import_justification(
+	/// Import block justifications.
+	fn import_justifications(
 		&mut self,
 		who: Origin,
 		hash: B::Hash,
 		number: NumberFor<B>,
-		justification: Justification
+		justifications: Justifications
 	);
 	/// Polls for actions to perform on the network.
 	///
@@ -182,8 +182,8 @@ pub(crate) fn import_single_block_metered<B: BlockT, V: Verifier<B>, Transaction
 ) -> Result<BlockImportResult<NumberFor<B>>, BlockImportError> {
 	let peer = block.origin;
 
-	let (header, justification) = match (block.header, block.justification) {
-		(Some(header), justification) => (header, justification),
+	let (header, justifications) = match (block.header, block.justifications) {
+		(Some(header), justifications) => (header, justifications),
 		(None, _) => {
 			if let Some(ref peer) = peer {
 				debug!(target: "sync", "Header {} was not provided by {} ", block.hash, peer);
@@ -238,7 +238,7 @@ pub(crate) fn import_single_block_metered<B: BlockT, V: Verifier<B>, Transaction
 	}
 
 	let started = wasm_timer::Instant::now();
-	let (mut import_block, maybe_keys) = verifier.verify(block_origin, header, justification, block.body)
+	let (mut import_block, maybe_keys) = verifier.verify(block_origin, header, justifications, block.body)
 		.map_err(|msg| {
 			if let Some(ref peer) = peer {
 				trace!(target: "sync", "Verifying {}({}) from {} failed: {}", number, hash, peer, msg);