fix: dot/network: improve syncing at head

dot/core/interface.go

@@ -39,8 +39,6 @@ type BlockState interface {
 	GetBlockByHash(common.Hash) (*types.Block, error)
 	GenesisHash() common.Hash
 	GetSlotForBlock(common.Hash) (uint64, error)
-	HighestBlockHash() common.Hash
-	HighestBlockNumber() *big.Int
 	GetFinalizedHeader(uint64, uint64) (*types.Header, error)
 	GetFinalizedHash(uint64, uint64) (common.Hash, error)
 	SetFinalizedHash(common.Hash, uint64, uint64) error

dot/core/test_helpers.go

@@ -253,8 +253,8 @@ func (s *mockSyncer) HandleBlockAnnounce(msg *network.BlockAnnounceMessage) erro
 	return nil
 }
 
-func (s *mockSyncer) ProcessBlockData(_ []*types.BlockData) error {
-	return nil
+func (s *mockSyncer) ProcessBlockData(_ []*types.BlockData) (int, error) {
+	return 0, nil
 }
 
 func (s *mockSyncer) IsSynced() bool {

dot/network/state.go

@@ -29,6 +29,7 @@ type BlockState interface {
 	BestBlockNumber() (*big.Int, error)
 	GenesisHash() common.Hash
 	HasBlockBody(common.Hash) (bool, error)
+	GetFinalizedHeader(round, setID uint64) (*types.Header, error)
 }
 
 // Syncer is implemented by the syncing service
@@ -37,7 +38,7 @@ type Syncer interface {
 	CreateBlockResponse(*BlockRequestMessage) (*BlockResponseMessage, error)
 
 	// ProcessBlockData is called to process BlockData received in a BlockResponseMessage
-	ProcessBlockData(data []*types.BlockData) error
+	ProcessBlockData(data []*types.BlockData) (int, error)
 
 	// HandleBlockAnnounce is called upon receipt of a BlockAnnounceMessage to process it.
 	// If a request needs to be sent to the peer to retrieve the full block, this function will return it.

dot/network/state_test.go

@@ -71,3 +71,7 @@ func (mbs *MockBlockState) BestBlockNumber() (*big.Int, error) {
 func (mbs *MockBlockState) HasBlockBody(common.Hash) (bool, error) {
 	return false, nil
 }
+
+func (mbs *MockBlockState) GetFinalizedHeader(_, _ uint64) (*types.Header, error) {
+	return mbs.BestBlockHeader()
+}