Fix committee assignment bugs (#1740)

* moved processiing logs to block chain service layer

* fix-committee-start-shard-bug

* typo

* fixed test

beacon-chain/core/epoch/epoch_processing.go

@@ -260,18 +260,18 @@ func ProcessPrevSlotShardSeed(state *pb.BeaconState) *pb.BeaconState {
 }
 
 // ProcessCurrSlotShardSeed sets the current shuffling information in the beacon state.
-//   Set state.current_shuffling_epoch = next_epoch
 //   Set state.current_shuffling_start_shard = (state.current_shuffling_start_shard +
 //     get_current_epoch_committee_count(state)) % SHARD_COUNT
+//   Set state.current_shuffling_epoch = next_epoch
 //   Set state.current_shuffling_seed = generate_seed(state, state.current_shuffling_epoch)
 func ProcessCurrSlotShardSeed(state *pb.BeaconState) (*pb.BeaconState, error) {
-	state.CurrentShufflingEpoch = helpers.NextEpoch(state)
 	state.CurrentShufflingStartShard = (state.CurrentShufflingStartShard +
 		helpers.CurrentEpochCommitteeCount(state)) % params.BeaconConfig().ShardCount
 	seed, err := helpers.GenerateSeed(state, state.CurrentShufflingEpoch)
 	if err != nil {
 		return nil, fmt.Errorf("could not update current shuffling seed: %v", err)
 	}
+	state.CurrentShufflingEpoch = helpers.NextEpoch(state)
 	state.CurrentShufflingSeedHash32 = seed[:]
 	return state, nil
 }

beacon-chain/core/helpers/committee.go

@@ -144,18 +144,22 @@ func NextEpochCommitteeCount(state *pb.BeaconState) uint64 {
 //        shuffling_epoch = state.previous_shuffling_epoch
 //        shuffling_start_shard = state.previous_shuffling_start_shard
 //    elif epoch == next_epoch:
-//        current_committees_per_epoch = get_current_epoch_committee_count(state)
-//        committees_per_epoch = get_next_epoch_committee_count(state)
-//        shuffling_epoch = next_epoch
 //
 //        epochs_since_last_registry_update = current_epoch - state.validator_registry_update_epoch
 //        if registry_change:
+//            committees_per_epoch = get_next_epoch_committee_count(state)
+//            shuffling_epoch = next_epoch
 //            seed = generate_seed(state, next_epoch)
+//            current_committees_per_epoch = get_current_epoch_committee_count(state)
 //            shuffling_start_shard = (state.current_epoch_start_shard + current_committees_per_epoch) % SHARD_COUNT
 //        elif epochs_since_last_registry_update > 1 and is_power_of_two(epochs_since_last_registry_update):
+//            committees_per_epoch = get_next_epoch_committee_count(state)
+//            shuffling_epoch = next_epoch
 //            seed = generate_seed(state, next_epoch)
 //            shuffling_start_shard = state.current_epoch_start_shard
 //        else:
+//            committees_per_epoch = get_current_epoch_committee_count(state)
+//            shuffling_epoch = state.current_shuffling_epoch
 //            seed = state.current_epoch_seed
 //            shuffling_start_shard = state.current_epoch_start_shard
 //
@@ -200,7 +204,7 @@ func CrosslinkCommitteesAtSlot(
 	}
 
 	if wantedEpoch == currentEpoch {
-		committeesPerEpoch = PrevEpochCommitteeCount(state)
+		committeesPerEpoch = CurrentEpochCommitteeCount(state)
 		seed = bytesutil.ToBytes32(state.CurrentShufflingSeedHash32)
 		shufflingEpoch = state.CurrentShufflingEpoch
 		shufflingStartShard = state.CurrentShufflingStartShard
@@ -210,13 +214,13 @@ func CrosslinkCommitteesAtSlot(
 		shufflingEpoch = state.PreviousShufflingEpoch
 		shufflingStartShard = state.PreviousShufflingStartShard
 	} else if wantedEpoch == nextEpoch {
-		currentCommitteesPerEpoch := CurrentEpochCommitteeCount(state)
-		committeesPerEpoch = NextEpochCommitteeCount(state)
-		shufflingEpoch = nextEpoch
 
 		epochsSinceLastRegistryUpdate := currentEpoch - state.ValidatorRegistryUpdateEpoch
 		if registryChange {
+			committeesPerEpoch = NextEpochCommitteeCount(state)
+			shufflingEpoch = nextEpoch
 			seed, err = GenerateSeed(state, nextEpoch)
+			currentCommitteesPerEpoch := CurrentEpochCommitteeCount(state)
 			if err != nil {
 				return nil, fmt.Errorf("could not generate seed: %v", err)
 			}
@@ -224,12 +228,16 @@ func CrosslinkCommitteesAtSlot(
 				params.BeaconConfig().ShardCount
 		} else if epochsSinceLastRegistryUpdate > 1 &&
 			mathutil.IsPowerOf2(epochsSinceLastRegistryUpdate) {
+			committeesPerEpoch = NextEpochCommitteeCount(state)
+			shufflingEpoch = nextEpoch
 			seed, err = GenerateSeed(state, nextEpoch)
 			if err != nil {
 				return nil, fmt.Errorf("could not generate seed: %v", err)
 			}
 			shufflingStartShard = state.CurrentShufflingStartShard
 		} else {
+			committeesPerEpoch = CurrentEpochCommitteeCount(state)
+			shufflingEpoch = state.CurrentShufflingEpoch
 			seed = bytesutil.ToBytes32(state.CurrentShufflingSeedHash32)
 			shufflingStartShard = state.CurrentShufflingStartShard
 		}

beacon-chain/core/helpers/committee_test.go

@@ -382,29 +382,29 @@ func TestNextEpochCommitteeAssignment_OK(t *testing.T) {
 	}{
 		{
 			index:      0,
-			slot:       params.BeaconConfig().GenesisSlot + 179,
+			slot:       params.BeaconConfig().GenesisSlot + 146,
-			committee:  []uint64{0, 100},
+			committee:  []uint64{105, 0},
-			shard:      51,
+			shard:      18,
 			isProposer: false,
 		},
 		{
 			index:      105,
-			slot:       params.BeaconConfig().GenesisSlot + 138,
+			slot:       params.BeaconConfig().GenesisSlot + 146,
-			committee:  []uint64{55, 105},
+			committee:  []uint64{105, 0},
-			shard:      10,
+			shard:      18,
-			isProposer: false,
+			isProposer: true,
 		},
 		{
 			index:      64,
-			slot:       params.BeaconConfig().GenesisSlot + 176,
+			slot:       params.BeaconConfig().GenesisSlot + 139,
-			committee:  []uint64{126, 64},
+			committee:  []uint64{64, 52},
-			shard:      48,
+			shard:      11,
 			isProposer: false,
 		},
 		{
 			index:      11,
 			slot:       params.BeaconConfig().GenesisSlot + 130,
-			committee:  []uint64{11, 14},
+			committee:  []uint64{11, 121},
 			shard:      2,
 			isProposer: true,
 		},