Fix grumbles from previous GRANDPA PR (#880)

* implement grandpa client

* consensus gossip with arbitrary topics

* defer GRANDPA messages until referenced blocks imported

* set up communication for voter in a transparent way

* instantiate GRANDPA voter

* keep last round state on disk

* switch back to crates.io finality-grandpa

* update cargo.lock

* use new `collect_garbage` API

* update sync test framework and make public

* test that observers can observe

* fix warning

* use more idiomatic predicate for collecting garbage in gossip

* kill spaces

* fix date

* fatal error when unable to complete

* rename run_voter to run_grandpa

* switch back to crates.io

substrate/Cargo.lock

@@ -602,7 +602,7 @@ dependencies = [
 
 [[package]]
 name = "finality-grandpa"
-version = "0.1.3"
+version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "futures 0.1.24 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2951,7 +2951,7 @@ dependencies = [
 name = "substrate-finality-grandpa"
 version = "0.1.0"
 dependencies = [
- "finality-grandpa 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "finality-grandpa 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures 0.1.24 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "parity-codec 2.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -4148,7 +4148,7 @@ dependencies = [
 "checksum failure_derive 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "946d0e98a50d9831f5d589038d2ca7f8f455b1c21028c0db0e84116a12696426"
 "checksum fake-simd 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "e88a8acf291dafb59c2d96e8f59828f3838bb1a70398823ade51a84de6a6deed"
 "checksum fdlimit 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "b1ee15a7050e5580b3712877157068ea713b245b080ff302ae2ca973cfcd9baa"
-"checksum finality-grandpa 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "7c9a8a25e71e4a11a1a5ef36a9ad09b4ae8c4e0bcf27a900137899ac678b01b0"
+"checksum finality-grandpa 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "20d8cf871510f0d57630e75f9e65f87cba29581ccab1f78666d8b2e422d0baa6"
 "checksum fixed-hash 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "0d5ec8112f00ea8a483e04748a85522184418fd1cf02890b626d8fc28683f7de"
 "checksum fnv 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)" = "2fad85553e09a6f881f739c29f0b00b0f01357c743266d478b68951ce23285f3"
 "checksum foreign-types 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f6f339eb8adc052cd2ca78910fda869aefa38d22d5cb648e6485e4d3fc06f3b1"

substrate/core/finality-grandpa/Cargo.toml

@@ -13,7 +13,7 @@ log = "0.4"
 tokio = "0.1.7"
 
 [dependencies.finality-grandpa]
-version = "0.1.3"
+version = "0.2.0"
 features = ["derive-codec"]
 
 [dev-dependencies]

substrate/core/finality-grandpa/src/lib.rs

@@ -82,6 +82,8 @@ pub enum Error {
 	Network(String),
 	/// A blockchain error.
 	Blockchain(String),
+	/// Could not complete a round on disk.
+	CouldNotCompleteRound(::client::error::Error),
 	/// A timer failed to fire.
 	Timer(::tokio::timer::Error),
 }
@@ -498,20 +500,27 @@ impl<B, E, Block: BlockT, N> voter::Environment<Block::Hash> for Environment<B,
 		}
 	}
 
-	fn completed(&self, round: u64, state: RoundState<Block::Hash>) {
+	fn completed(&self, round: u64, state: RoundState<Block::Hash>) -> Result<(), Self::Error> {
 		let encoded_state = (round, state).encode();
 		if let Err(e) = self.inner.backend()
 			.insert_aux(&[(LAST_COMPLETED_KEY, &encoded_state[..])], &[])
 		{
-			warn!(target: "afg", "Error bookkeeping last completed round in DB: {:?}", e);
+			warn!(target: "afg", "Shutting down voter due to error bookkeeping last completed round in DB: {:?}", e);
+			Err(Error::CouldNotCompleteRound(e))
+		} else {
+			Ok(())
 		}
 	}
 
-	fn finalize_block(&self, hash: Block::Hash, number: u32) {
+	fn finalize_block(&self, hash: Block::Hash, number: u32) -> Result<(), Self::Error> {
 		// TODO: don't unconditionally notify.
 		if let Err(e) = self.inner.finalize_block(BlockId::Hash(hash), true) {
 			warn!(target: "afg", "Error applying finality to block {:?}: {:?}", (hash, number), e);
 		}
+
+		// we return without error in all cases because not being able to finalize is
+		// non-fatal.
+		Ok(())
 	}
 
 	fn prevote_equivocation(
@@ -534,7 +543,7 @@ impl<B, E, Block: BlockT, N> voter::Environment<Block::Hash> for Environment<B,
 }
 
 /// Run a GRANDPA voter as a task. The returned future should be executed in a tokio runtime.
-pub fn run_voter<B, E, Block: BlockT, N>(
+pub fn run_grandpa<B, E, Block: BlockT, N>(
 	config: Config,
 	client: Arc<Client<B, E, Block>>,
 	voters: HashMap<AuthorityId, usize>,
@@ -679,7 +688,7 @@ mod tests {
 					.take_while(|n| Ok(n.header.number() < &20))
 					.for_each(move |_| Ok(()))
 			);
-			let voter = run_voter(
+			let voter = run_grandpa(
 				Config {
 					gossip_duration: TEST_GOSSIP_DURATION,
 					voters: voters.clone(),
@@ -738,7 +747,7 @@ mod tests {
 					.take_while(|n| Ok(n.header.number() < &20))
 					.for_each(move |_| Ok(()))
 			);
-			let voter = run_voter(
+			let voter = run_grandpa(
 				Config {
 					gossip_duration: TEST_GOSSIP_DURATION,
 					voters: voters.keys().cloned().collect(),