Ensure per_epoch processing always runs.

Previously, it was running _after_ a state transition, not before it
with the slot processing.

beacon_node/beacon_chain/src/block_production.rs

@@ -4,7 +4,7 @@ use bls::Signature;
 use log::debug;
 use slot_clock::TestingSlotClockError;
 use types::{
-    beacon_state::CommitteesError,
+    beacon_state::SlotProcessingError,
     readers::{BeaconBlockReader, BeaconStateReader},
     BeaconBlock, BeaconBlockBody, BeaconState, Eth1Data, Hash256,
 };
@@ -14,7 +14,7 @@ pub enum Error {
     DBError(String),
     StateTransitionError(TransitionError),
     PresentSlotIsNone,
-    CommitteesError(CommitteesError),
+    SlotProcessingError(SlotProcessingError),
 }
 
 impl<T, U> BeaconChain<T, U>
@@ -116,8 +116,8 @@ impl From<TestingSlotClockError> for Error {
     }
 }
 
-impl From<CommitteesError> for Error {
-    fn from(e: CommitteesError) -> Error {
-        Error::CommitteesError(e)
+impl From<SlotProcessingError> for Error {
+    fn from(e: SlotProcessingError) -> Error {
+        Error::SlotProcessingError(e)
     }
 }

beacon_node/beacon_chain/src/canonical_head.rs

@@ -1,11 +1,11 @@
 use crate::{BeaconChain, CheckPoint, ClientDB, SlotClock};
 use std::sync::RwLockReadGuard;
-use types::{beacon_state::CommitteesError, BeaconBlock, BeaconState, Hash256};
+use types::{beacon_state::SlotProcessingError, BeaconBlock, BeaconState, Hash256};
 
 #[derive(Debug, PartialEq)]
 pub enum Error {
     PastSlot,
-    CommitteesError(CommitteesError),
+    SlotProcessingError(SlotProcessingError),
 }
 
 impl<T, U> BeaconChain<T, U>
@@ -64,8 +64,8 @@ where
     }
 }
 
-impl From<CommitteesError> for Error {
-    fn from(e: CommitteesError) -> Error {
-        Error::CommitteesError(e)
+impl From<SlotProcessingError> for Error {
+    fn from(e: SlotProcessingError) -> Error {
+        Error::SlotProcessingError(e)
     }
 }

beacon_node/beacon_chain/src/state_transition.rs

@@ -5,7 +5,7 @@ use log::debug;
 use slot_clock::{SystemTimeSlotClockError, TestingSlotClockError};
 use ssz::{ssz_encode, TreeHash};
 use types::{
-    beacon_state::{AttestationValidationError, CommitteesError, EpochProcessingError},
+    beacon_state::{AttestationValidationError, CommitteesError, SlotProcessingError},
     readers::BeaconBlockReader,
     BeaconBlock, BeaconState, Exit, Fork, Hash256, PendingAttestation,
 };
@@ -52,7 +52,7 @@ pub enum Error {
     BadCustodyResponses,
     SlotClockError(SystemTimeSlotClockError),
     CommitteesError(CommitteesError),
-    EpochProcessingError(EpochProcessingError),
+    SlotProcessingError(SlotProcessingError),
 }
 
 impl<T, U> BeaconChain<T, U>
@@ -309,10 +309,6 @@ where
             Error::BadCustodyResponses
         );
 
-        if state.slot % self.spec.epoch_length == 0 {
-            state.per_epoch_processing(&self.spec)?;
-        }
-
         debug!("State transition complete.");
 
         Ok(state)
@@ -367,8 +363,8 @@ impl From<CommitteesError> for Error {
     }
 }
 
-impl From<EpochProcessingError> for Error {
-    fn from(e: EpochProcessingError) -> Error {
-        Error::EpochProcessingError(e)
+impl From<SlotProcessingError> for Error {
+    fn from(e: SlotProcessingError) -> Error {
+        Error::SlotProcessingError(e)
     }
 }

eth2/types/src/beacon_state/mod.rs

@@ -22,6 +22,7 @@ pub use self::attestation_participants::Error as AttestationParticipantsError;
 pub use self::attestation_validation::Error as AttestationValidationError;
 pub use self::committees::Error as CommitteesError;
 pub use self::epoch_processing::Error as EpochProcessingError;
+pub use self::slot_processing::Error as SlotProcessingError;
 
 // Custody will not be added to the specs until Phase 1 (Sharding Phase) so dummy class used.
 type CustodyChallenge = usize;

eth2/types/src/beacon_state/slot_processing.rs

@@ -1,11 +1,21 @@
-use crate::{beacon_state::CommitteesError, BeaconState, ChainSpec, Hash256};
+use crate::{
+    beacon_state::{CommitteesError, EpochProcessingError},
+    BeaconState, ChainSpec, Hash256,
+};
+use log::debug;
+
+#[derive(Debug, PartialEq)]
+pub enum Error {
+    CommitteesError(CommitteesError),
+    EpochProcessingError(EpochProcessingError),
+}
 
 impl BeaconState {
     pub fn per_slot_processing(
         &mut self,
         previous_block_root: Hash256,
         spec: &ChainSpec,
-    ) -> Result<(), CommitteesError> {
+    ) -> Result<(), Error> {
         self.slot += 1;
 
         let block_proposer = self.get_beacon_proposer_index(self.slot, spec)?;
@@ -22,6 +32,10 @@ impl BeaconState {
             let root = merkle_root(&self.latest_block_roots[..]);
             self.batched_block_roots.push(root);
         }
+
+        if self.slot % spec.epoch_length == 0 {
+            self.per_epoch_processing(spec)?;
+        }
         Ok(())
     }
 
@@ -45,3 +59,15 @@ impl BeaconState {
 fn merkle_root(_input: &[Hash256]) -> Hash256 {
     Hash256::zero()
 }
+
+impl From<CommitteesError> for Error {
+    fn from(e: CommitteesError) -> Error {
+        Error::CommitteesError(e)
+    }
+}
+
+impl From<EpochProcessingError> for Error {
+    fn from(e: EpochProcessingError) -> Error {
+        Error::EpochProcessingError(e)
+    }
+}