feat(lib/babe): implement secondary slot block production (#2260)

implement secondary VRF slot block production and secondary plain slot block production

Author: kishansagathiya

dot/sync/chain_processor.go

@@ -103,15 +103,22 @@ func (s *chainProcessor) processReadyBlocks() {
 }
 
 // processBlockData processes the BlockData from a BlockResponse and
-// eturns the index of the last BlockData it handled on success,
+// returns the index of the last BlockData it handled on success,
 // or the index of the block data that errored on failure.
 func (s *chainProcessor) processBlockData(bd *types.BlockData) error {
 	if bd == nil {
 		return ErrNilBlockData
 	}
 
-	hasHeader, _ := s.blockState.HasHeader(bd.Hash)
-	hasBody, _ := s.blockState.HasBlockBody(bd.Hash)
+	hasHeader, err := s.blockState.HasHeader(bd.Hash)
+	if err != nil {
+		return fmt.Errorf("failed to check if block state has header for hash %s: %w", bd.Hash, err)
+	}
+	hasBody, err := s.blockState.HasBlockBody(bd.Hash)
+	if err != nil {
+		return fmt.Errorf("failed to check block state has body for hash %s: %w", bd.Hash, err)
+	}
+
 	if hasHeader && hasBody {
 		// TODO: fix this; sometimes when the node shuts down the "best block" isn't stored properly,
 		// so when the node restarts it has blocks higher than what it thinks is the best, causing it not to sync

dot/types/babe.go

@@ -10,6 +10,19 @@ import (
 // RandomnessLength is the length of the epoch randomness (32 bytes)
 const RandomnessLength = 32
 
+// AllowedSlots tells in what ways a slot can be claimed.
+type AllowedSlots byte
+
+// https://github.com/paritytech/substrate/blob/ded44948e2d5a398abcb4e342b0513cb690961bb/primitives/consensus/babe/src/lib.rs#L219-L226
+const (
+	// PrimarySlots only allows primary slots.
+	PrimarySlots AllowedSlots = iota
+	// PrimaryAndSecondaryPlainSlots allow primary and secondary plain slots.
+	PrimaryAndSecondaryPlainSlots
+	// PrimaryAndSecondaryVRFSlots allows primary and secondary VRF slots.
+	PrimaryAndSecondaryVRFSlots
+)
+
 // BabeConfiguration contains the genesis data for BABE
 //nolint:lll
 // see: https://github.com/paritytech/substrate/blob/426c26b8bddfcdbaf8d29f45b128e0864b57de1c/core/consensus/babe/primitives/src/lib.rs#L132

dot/types/babe_digest.go

@@ -5,6 +5,7 @@ package types
 
 import (
 	"errors"
+	"fmt"
 
 	"github.com/ChainSafe/gossamer/lib/crypto/sr25519"
 	"github.com/ChainSafe/gossamer/pkg/scale"
@@ -53,16 +54,7 @@ func NewBabePrimaryPreDigest(authorityIndex uint32,
 
 // ToPreRuntimeDigest returns the BabePrimaryPreDigest as a PreRuntimeDigest
 func (d *BabePrimaryPreDigest) ToPreRuntimeDigest() (*PreRuntimeDigest, error) {
-	digest := NewBabeDigest()
-	err := digest.Set(*d)
-	if err != nil {
-		return nil, err
-	}
-	enc, err := scale.Marshal(digest)
-	if err != nil {
-		return nil, err
-	}
-	return NewBABEPreRuntimeDigest(enc), nil
+	return toPreRuntimeDigest(*d)
 }
 
 // Index Returns VDT index
@@ -82,18 +74,9 @@ func NewBabeSecondaryPlainPreDigest(authorityIndex uint32, slotNumber uint64) *B
 	}
 }
 
-// ToPreRuntimeDigest returns the BabePrimaryPreDigest as a PreRuntimeDigest
+// ToPreRuntimeDigest returns the BabeSecondaryPlainPreDigest as a PreRuntimeDigest
 func (d *BabeSecondaryPlainPreDigest) ToPreRuntimeDigest() (*PreRuntimeDigest, error) {
-	digest := NewBabeDigest()
-	err := digest.Set(*d)
-	if err != nil {
-		return nil, err
-	}
-	enc, err := scale.Marshal(digest)
-	if err != nil {
-		return nil, err
-	}
-	return NewBABEPreRuntimeDigest(enc), nil
+	return toPreRuntimeDigest(*d)
 }
 
 // Index Returns VDT index
@@ -119,5 +102,26 @@ func NewBabeSecondaryVRFPreDigest(authorityIndex uint32,
 	}
 }
 
+// ToPreRuntimeDigest returns the BabeSecondaryVRFPreDigest as a PreRuntimeDigest
+func (d *BabeSecondaryVRFPreDigest) ToPreRuntimeDigest() (*PreRuntimeDigest, error) {
+	return toPreRuntimeDigest(*d)
+}
+
 // Index Returns VDT index
 func (d BabeSecondaryVRFPreDigest) Index() uint { return 3 }
+
+// toPreRuntimeDigest returns the VaryingDataTypeValue as a PreRuntimeDigest
+func toPreRuntimeDigest(value scale.VaryingDataTypeValue) (*PreRuntimeDigest, error) {
+	digest := NewBabeDigest()
+	err := digest.Set(value)
+	if err != nil {
+		return nil, fmt.Errorf("cannot set varying data type value to babe digest: %w", err)
+	}
+
+	enc, err := scale.Marshal(digest)
+	if err != nil {
+		return nil, fmt.Errorf("cannot marshal babe digest: %w", err)
+	}
+
+	return NewBABEPreRuntimeDigest(enc), nil
+}

lib/babe/babe.go

@@ -386,6 +386,7 @@ func (b *Service) handleEpoch(epoch uint64) (next uint64, err error) {
 		// stop current epoch handler
 		cancel()
 	case err := <-errCh:
+		// TODO: errEpochPast is sent on this channel, but it doesnot get logged here
 		cleanup()
 		logger.Errorf("error from epochHandler: %s", err)
 	}
@@ -400,7 +401,10 @@ func (b *Service) handleEpoch(epoch uint64) (next uint64, err error) {
 	return next, nil
 }
 
-func (b *Service) handleSlot(epoch, slotNum uint64, authorityIndex uint32, proof *VrfOutputAndProof) error {
+func (b *Service) handleSlot(epoch, slotNum uint64,
+	authorityIndex uint32,
+	preRuntimeDigest *types.PreRuntimeDigest,
+) error {
 	parentHeader, err := b.blockState.BestBlockHeader()
 	if err != nil {
 		return err
@@ -442,7 +446,7 @@ func (b *Service) handleSlot(epoch, slotNum uint64, authorityIndex uint32, proof
 
 	rt.SetContextStorage(ts)
 
-	block, err := b.buildBlock(parent, currentSlot, rt, authorityIndex, proof)
+	block, err := b.buildBlock(parent, currentSlot, rt, authorityIndex, preRuntimeDigest)
 	if err != nil {
 		return err
 	}

lib/babe/build.go

@@ -26,13 +26,13 @@ const (
 
 // construct a block for this slot with the given parent
 func (b *Service) buildBlock(parent *types.Header, slot Slot, rt runtime.Instance,
-	authorityIndex uint32, proof *VrfOutputAndProof) (*types.Block, error) {
+	authorityIndex uint32, preRuntimeDigest *types.PreRuntimeDigest) (*types.Block, error) {
 	builder, err := NewBlockBuilder(
 		b.keypair,
 		b.transactionState,
 		b.blockState,
-		proof,
 		authorityIndex,
+		preRuntimeDigest,
 	)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create block builder: %w", err)
@@ -59,30 +59,31 @@ type BlockBuilder struct {
 	keypair               *sr25519.Keypair
 	transactionState      TransactionState
 	blockState            BlockState
-	proof                 *VrfOutputAndProof
 	currentAuthorityIndex uint32
+	preRuntimeDigest      *types.PreRuntimeDigest
 }
 
 // NewBlockBuilder creates a new block builder.
-func NewBlockBuilder(kp *sr25519.Keypair, ts TransactionState,
-	bs BlockState, proof *VrfOutputAndProof,
-	authidx uint32) (*BlockBuilder, error) {
+func NewBlockBuilder(
+	kp *sr25519.Keypair,
+	ts TransactionState,
+	bs BlockState,
+	authidx uint32,
+	preRuntimeDigest *types.PreRuntimeDigest,
+) (*BlockBuilder, error) {
 	if ts == nil {
 		return nil, ErrNilTransactionState
 	}
 	if bs == nil {
 		return nil, ErrNilBlockState
 	}
-	if proof == nil {
-		return nil, ErrNilVRFProof
-	}
 
 	bb := &BlockBuilder{
 		keypair:               kp,
 		transactionState:      ts,
 		blockState:            bs,
-		proof:                 proof,
 		currentAuthorityIndex: authidx,
+		preRuntimeDigest:      preRuntimeDigest,
 	}
 
 	return bb, nil
@@ -91,18 +92,10 @@ func NewBlockBuilder(kp *sr25519.Keypair, ts TransactionState,
 func (b *BlockBuilder) buildBlock(parent *types.Header, slot Slot, rt runtime.Instance) (*types.Block, error) {
 	logger.Tracef("build block with parent %s and slot: %s", parent, slot)
 
-	// create pre-digest
-	preDigest, err := b.buildBlockPreDigest(slot)
-	if err != nil {
-		return nil, err
-	}
-
-	logger.Trace("built pre-digest")
-
 	// create new block header
 	number := big.NewInt(0).Add(parent.Number, big.NewInt(1))
 	digest := types.NewDigest()
-	err = digest.Add(*preDigest)
+	err := digest.Add(*b.preRuntimeDigest)
 	if err != nil {
 		return nil, err
 	}
@@ -120,7 +113,7 @@ func (b *BlockBuilder) buildBlock(parent *types.Header, slot Slot, rt runtime.In
 	logger.Trace("initialised block")
 
 	// add block inherents
-	inherents, err := b.buildBlockInherents(slot, rt)
+	inherents, err := buildBlockInherents(slot, rt)
 	if err != nil {
 		return nil, fmt.Errorf("cannot build inherents: %s", err)
 	}
@@ -191,37 +184,6 @@ func (b *BlockBuilder) buildBlockSeal(header *types.Header) (*types.SealDigest,
 	}, nil
 }
 
-// buildBlockPreDigest creates the pre-digest for the slot.
-// the pre-digest consists of the ConsensusEngineID and the encoded BABE header for the slot.
-func (b *BlockBuilder) buildBlockPreDigest(slot Slot) (*types.PreRuntimeDigest, error) {
-	babeHeader := types.NewBabeDigest()
-	data := b.buildBlockBABEPrimaryPreDigest(slot)
-	if err := babeHeader.Set(*data); err != nil {
-		return nil, fmt.Errorf("cannot set babe header: %w", err)
-	}
-
-	encBABEPrimaryPreDigest, err := scale.Marshal(babeHeader)
-	if err != nil {
-		return nil, err
-	}
-
-	return &types.PreRuntimeDigest{
-		ConsensusEngineID: types.BabeEngineID,
-		Data:              encBABEPrimaryPreDigest,
-	}, nil
-}
-
-// buildBlockBABEPrimaryPreDigest creates the BABE header for the slot.
-// the BABE header includes the proof of authorship right for this slot.
-func (b *BlockBuilder) buildBlockBABEPrimaryPreDigest(slot Slot) *types.BabePrimaryPreDigest {
-	return types.NewBabePrimaryPreDigest(
-		b.currentAuthorityIndex,
-		slot.number,
-		b.proof.output,
-		b.proof.proof,
-	)
-}
-
 // buildBlockExtrinsics applies extrinsics to the block. it returns an array of included extrinsics.
 // for each extrinsic in queue, add it to the block, until the slot ends or the block is full.
 // if any extrinsic fails, it returns an empty array and an error.
@@ -276,7 +238,7 @@ func (b *BlockBuilder) buildBlockExtrinsics(slot Slot, rt runtime.Instance) []*t
 	return included
 }
 
-func (b *BlockBuilder) buildBlockInherents(slot Slot, rt runtime.Instance) ([][]byte, error) {
+func buildBlockInherents(slot Slot, rt runtime.Instance) ([][]byte, error) {
 	// Setup inherents: add timstap0
 	idata := types.NewInherentsData()
 	timestamp := uint64(time.Now().UnixMilli())

lib/babe/build_integration_test.go

@@ -41,15 +41,15 @@ func TestSeal(t *testing.T) {
 	babeService.epochHandler, err = babeService.initiateAndGetEpochHandler(0)
 	require.NoError(t, err)
 
-	authoringSlots := getAuthoringSlots(babeService.epochHandler.slotToProof)
+	authoringSlots := getAuthoringSlots(babeService.epochHandler.slotToPreRuntimeDigest)
 	require.NotEmpty(t, authoringSlots)
 
 	builder, _ := NewBlockBuilder(
 		babeService.keypair,
 		babeService.transactionState,
 		babeService.blockState,
-		babeService.epochHandler.slotToProof[authoringSlots[0]],
 		babeService.epochHandler.epochData.authorityIndex,
+		babeService.epochHandler.slotToPreRuntimeDigest[authoringSlots[0]],
 	)
 
 	zeroHash, err := common.HexToHash("0x00")
@@ -92,10 +92,10 @@ func createTestBlock(t *testing.T, babeService *Service, parent *types.Header,
 	rt, err := babeService.blockState.GetRuntime(nil)
 	require.NoError(t, err)
 
-	outAndProof, err := babeService.runLottery(slotNumber, epoch, epochData)
+	preRuntimeDigest, err := claimSlot(epoch, slotNumber, epochData, babeService.keypair)
 	require.NoError(t, err)
 
-	block, err := babeService.buildBlock(parent, slot, rt, epochData.authorityIndex, outAndProof)
+	block, err := babeService.buildBlock(parent, slot, rt, epochData.authorityIndex, preRuntimeDigest)
 	require.NoError(t, err)
 
 	babeService.blockState.StoreRuntime(block.Header.Hash(), rt)
@@ -154,14 +154,6 @@ func TestApplyExtrinsic(t *testing.T) {
 	babeService := createTestService(t, cfg)
 	const authorityIndex = 0
 
-	builder, _ := NewBlockBuilder(
-		babeService.keypair,
-		babeService.transactionState,
-		babeService.blockState,
-		&VrfOutputAndProof{},
-		authorityIndex,
-	)
-
 	duration, err := time.ParseDuration("1s")
 	require.NoError(t, err)
 
@@ -177,8 +169,13 @@ func TestApplyExtrinsic(t *testing.T) {
 		duration: duration,
 		number:   2,
 	}
+	testVRFOutputAndProof := &VrfOutputAndProof{}
 
-	preDigest2, err := builder.buildBlockPreDigest(slot2)
+	preDigest2, err := types.NewBabePrimaryPreDigest(
+		authorityIndex, slot2.number,
+		testVRFOutputAndProof.output,
+		testVRFOutputAndProof.proof,
+	).ToPreRuntimeDigest()
 	require.NoError(t, err)
 
 	parentHash := babeService.blockState.GenesisHash()
@@ -190,7 +187,11 @@ func TestApplyExtrinsic(t *testing.T) {
 	require.NoError(t, err)
 	rt.SetContextStorage(ts)
 
-	preDigest, err := builder.buildBlockPreDigest(slot)
+	preDigest, err := types.NewBabePrimaryPreDigest(
+		authorityIndex, slot.number,
+		testVRFOutputAndProof.output,
+		testVRFOutputAndProof.proof,
+	).ToPreRuntimeDigest()
 	require.NoError(t, err)
 
 	digest := types.NewDigest()
@@ -204,7 +205,7 @@ func TestApplyExtrinsic(t *testing.T) {
 	err = rt.InitializeBlock(header)
 	require.NoError(t, err)
 
-	_, err = builder.buildBlockInherents(slot, rt)
+	_, err = buildBlockInherents(slot, rt)
 	require.NoError(t, err)
 
 	header1, err := rt.FinalizeBlock()
@@ -223,7 +224,7 @@ func TestApplyExtrinsic(t *testing.T) {
 	err = rt.InitializeBlock(header2)
 	require.NoError(t, err)
 
-	_, err = builder.buildBlockInherents(slot, rt)
+	_, err = buildBlockInherents(slot, rt)
 	require.NoError(t, err)
 
 	res, err := rt.ApplyExtrinsic(extBytes)
@@ -381,7 +382,7 @@ func TestBuildBlock_failing(t *testing.T) {
 	require.NoError(t, err)
 
 	const authorityIndex uint32 = 0
-	_, err = babeService.buildBlock(parentHeader, slot, rt, authorityIndex, &VrfOutputAndProof{})
+	_, err = babeService.buildBlock(parentHeader, slot, rt, authorityIndex, &types.PreRuntimeDigest{})
 	require.NotNil(t, err)
 	require.Equal(t, "cannot build extrinsics: error applying extrinsic: Apply error, type: Payment",
 		err.Error(), "Did not receive expected error text")