New slashing mechanism (#554)

* Slashing improvements

- unstake when balance too low
- unstake after N slashes according to val prefs
- don't early-terminate session/era unless unstaked
- offline grace period before punishment

* Fix warning

* Cleanups and ensure slash_count decays

* Bump authoring version and introduce needed authoring stub

* Rename

* Fix offline tracker

* Fix offline tracker

* Renames

* Add test

* Tests

* Tests.

polkadot/runtime/src/checked_block.rs

@@ -16,10 +16,10 @@
 
 //! Typesafe block interaction.
 
-use super::{Call, Block, TIMESTAMP_SET_POSITION, PARACHAINS_SET_POSITION, NOTE_OFFLINE_POSITION};
+use super::{Call, Block, TIMESTAMP_SET_POSITION, PARACHAINS_SET_POSITION, NOTE_MISSED_PROPOSAL_POSITION};
 use timestamp::Call as TimestampCall;
 use parachains::Call as ParachainsCall;
-use session::Call as SessionCall;
+use staking::Call as StakingCall;
 use primitives::parachain::CandidateReceipt;
 
 /// Provides a type-safe wrapper around a structurally valid block.
@@ -92,8 +92,8 @@ impl CheckedBlock {
 
 	/// Extract the noted offline validator indices (if any) from the block.
 	pub fn noted_offline(&self) -> &[u32] {
-		self.inner.extrinsics.get(NOTE_OFFLINE_POSITION as usize).and_then(|xt| match xt.extrinsic.function {
-			Call::Session(SessionCall::note_offline(ref x)) => Some(&x[..]),
+		self.inner.extrinsics.get(NOTE_MISSED_PROPOSAL_POSITION as usize).and_then(|xt| match xt.extrinsic.function {
+			Call::Staking(StakingCall::note_missed_proposal(ref x)) => Some(&x[..]),
 			_ => None,
 		}).unwrap_or(&[])
 	}

polkadot/runtime/src/lib.rs

@@ -86,7 +86,7 @@ pub const TIMESTAMP_SET_POSITION: u32 = 0;
 /// The position of the parachains set extrinsic.
 pub const PARACHAINS_SET_POSITION: u32 = 1;
 /// The position of the offline nodes noting extrinsic.
-pub const NOTE_OFFLINE_POSITION: u32 = 2;
+pub const NOTE_MISSED_PROPOSAL_POSITION: u32 = 2;
 
 /// The address format for describing accounts.
 pub type Address = staking::Address<Concrete>;
@@ -111,8 +111,8 @@ pub struct Concrete;
 pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: ver_str!("polkadot"),
 	impl_name: ver_str!("parity-polkadot"),
-	authoring_version: 1,
-	spec_version: 3,
+	authoring_version: 2,
+	spec_version: 4,
 	impl_version: 0,
 };
 
@@ -162,7 +162,7 @@ impl Convert<AccountId, SessionKey> for SessionKeyConversion {
 }
 
 impl session::Trait for Concrete {
-	const NOTE_OFFLINE_POSITION: u32 = NOTE_OFFLINE_POSITION;
+	const NOTE_MISSED_PROPOSAL_POSITION: u32 = NOTE_MISSED_PROPOSAL_POSITION;
 	type ConvertAccountIdToSessionKey = SessionKeyConversion;
 	type OnSessionChange = Staking;
 }

polkadot/runtime/src/parachains.rs

@@ -265,7 +265,7 @@ mod tests {
 		type Header = Header;
 	}
 	impl session::Trait for Test {
-		const NOTE_OFFLINE_POSITION: u32 = 1;
+		const NOTE_MISSED_PROPOSAL_POSITION: u32 = 1;
 		type ConvertAccountIdToSessionKey = Identity;
 		type OnSessionChange = ();
 	}

polkadot/runtime/src/utils.rs

@@ -21,7 +21,7 @@ use super::{Call, UncheckedExtrinsic, Extrinsic, Staking};
 use runtime_primitives::traits::{Checkable, AuxLookup};
 use timestamp::Call as TimestampCall;
 use parachains::Call as ParachainsCall;
-use session::Call as SessionCall;
+use staking::Call as StakingCall;
 
 /// Produces the list of inherent extrinsics.
 pub fn inherent_extrinsics(data: ::primitives::InherentData) -> Vec<UncheckedExtrinsic> {
@@ -41,7 +41,7 @@ pub fn inherent_extrinsics(data: ::primitives::InherentData) -> Vec<UncheckedExt
 
 	if !data.offline_indices.is_empty() {
 		inherent.push(make_inherent(
-			Call::Session(SessionCall::note_offline(data.offline_indices))
+			Call::Staking(StakingCall::note_missed_proposal(data.offline_indices))
 		));
 	}