internal/ethapi: make GetFinalizedHeader monotonically increasing (#2655)

eth/api_backend.go

@@ -441,14 +441,14 @@ func (b *EthAPIBackend) Engine() consensus.Engine {
 	return b.eth.engine
 }
 
-func (b *EthAPIBackend) CurrentTurnLength() (turnLength uint8, err error) {
+func (b *EthAPIBackend) CurrentValidators() ([]common.Address, error) {
 	if p, ok := b.eth.engine.(*parlia.Parlia); ok {
 		service := p.APIs(b.Chain())[0].Service
 		currentHead := rpc.LatestBlockNumber
-		return service.(*parlia.API).GetTurnLength(&currentHead)
+		return service.(*parlia.API).GetValidators(&currentHead)
 	}
 
-	return 1, nil
+	return []common.Address{}, errors.New("not supported")
 }
 
 func (b *EthAPIBackend) CurrentHeader() *types.Header {

internal/ethapi/api.go

@@ -862,54 +862,72 @@ func (s *BlockChainAPI) Health() bool {
 	return true
 }
 
-// GetFinalizedHeader returns the requested finalized block header.
+func (s *BlockChainAPI) getFinalizedNumber(ctx context.Context, verifiedValidatorNum int64) (int64, error) {
-//   - probabilisticFinalized should be in range [2,21],
+	parliaConfig := s.b.ChainConfig().Parlia
-//     then the block header with number `max(fastFinalized, latest-probabilisticFinalized)` is returned
+	if parliaConfig == nil {
-func (s *BlockChainAPI) GetFinalizedHeader(ctx context.Context, probabilisticFinalized int64) (map[string]interface{}, error) {
+		return 0, fmt.Errorf("only parlia engine supported")
-	if probabilisticFinalized < 2 || probabilisticFinalized > 21 {
-		return nil, fmt.Errorf("%d out of range [2,21]", probabilisticFinalized)
 	}
 
-	currentTurnLength, err := s.b.CurrentTurnLength()
+	curValidators, err := s.b.CurrentValidators()
 	if err != nil { // impossible
-		return nil, err
+		return 0, err
 	}
+	valLen := int64(len(curValidators))
+	if verifiedValidatorNum < 1 || verifiedValidatorNum > valLen {
+		return 0, fmt.Errorf("%d out of range [1,%d]", verifiedValidatorNum, valLen)
+	}
+
 	fastFinalizedHeader, err := s.b.HeaderByNumber(ctx, rpc.FinalizedBlockNumber)
 	if err != nil { // impossible
-		return nil, err
+		return 0, err
 	}
+
 	latestHeader, err := s.b.HeaderByNumber(ctx, rpc.LatestBlockNumber)
+	if err != nil { // impossible
+		return 0, err
+	}
+	lastHeader := latestHeader
+	confirmedValSet := make(map[common.Address]struct{}, valLen)
+	confirmedValSet[lastHeader.Coinbase] = struct{}{}
+	for count := 1; int64(len(confirmedValSet)) < verifiedValidatorNum && count <= int(parliaConfig.Epoch) && lastHeader.Number.Int64() > max(fastFinalizedHeader.Number.Int64(), 1); count++ {
+		lastHeader, err = s.b.HeaderByHash(ctx, lastHeader.ParentHash)
+		if err != nil { // impossible
+			return 0, err
+		}
+		confirmedValSet[lastHeader.Coinbase] = struct{}{}
+	}
+
+	finalizedBlockNumber := max(fastFinalizedHeader.Number.Int64(), lastHeader.Number.Int64())
+	log.Debug("getFinalizedNumber", "LatestBlockNumber", latestHeader.Number.Int64(), "fastFinalizedHeight", fastFinalizedHeader.Number.Int64(),
+		"lastHeader", lastHeader.Number.Int64(), "finalizedBlockNumber", finalizedBlockNumber, "len(confirmedValSet)", len(confirmedValSet))
+
+	return finalizedBlockNumber, nil
+}
+
+// GetFinalizedHeader returns the finalized block header based on the specified parameters.
+//   - `verifiedValidatorNum` must be within the range [1, len(currentValidators)].
+//   - The function calculates `probabilisticFinalizedHeight` as the highest height of the block verified by `verifiedValidatorNum` validators,
+//     it then returns the block header with a height equal to `max(fastFinalizedHeight, probabilisticFinalizedHeight)`.
+//   - The height of the returned block header is guaranteed to be monotonically increasing.
+func (s *BlockChainAPI) GetFinalizedHeader(ctx context.Context, verifiedValidatorNum int64) (map[string]interface{}, error) {
+	finalizedBlockNumber, err := s.getFinalizedNumber(ctx, verifiedValidatorNum)
 	if err != nil { // impossible
 		return nil, err
 	}
-	finalizedBlockNumber := max(fastFinalizedHeader.Number.Int64(), latestHeader.Number.Int64()-probabilisticFinalized*int64(currentTurnLength))
-
 	return s.GetHeaderByNumber(ctx, rpc.BlockNumber(finalizedBlockNumber))
 }
 
-// GetFinalizedBlock returns the requested finalized block.
+// GetFinalizedBlock returns the finalized block based on the specified parameters.
-//   - probabilisticFinalized should be in range [2,21],
+//   - `verifiedValidatorNum` must be within the range [1, len(currentValidators)].
-//     then the block with number `max(fastFinalized, latest-probabilisticFinalized)` is returned
+//   - The function calculates `probabilisticFinalizedHeight` as the highest height of the block verified by `verifiedValidatorNum` validators,
-//   - When fullTx is true all transactions in the block are returned, otherwise
+//     it then returns the block with a height equal to `max(fastFinalizedHeight, probabilisticFinalizedHeight)`.
-//     only the transaction hash is returned.
+//   - If `fullTx` is true, the block includes all transactions; otherwise, only transaction hashes are included.
-func (s *BlockChainAPI) GetFinalizedBlock(ctx context.Context, probabilisticFinalized int64, fullTx bool) (map[string]interface{}, error) {
+//   - The height of the returned block is guaranteed to be monotonically increasing.
-	if probabilisticFinalized < 2 || probabilisticFinalized > 21 {
+func (s *BlockChainAPI) GetFinalizedBlock(ctx context.Context, verifiedValidatorNum int64, fullTx bool) (map[string]interface{}, error) {
-		return nil, fmt.Errorf("%d out of range [2,21]", probabilisticFinalized)
+	finalizedBlockNumber, err := s.getFinalizedNumber(ctx, verifiedValidatorNum)
-	}
-
-	currentTurnLength, err := s.b.CurrentTurnLength()
 	if err != nil { // impossible
 		return nil, err
 	}
-	fastFinalizedHeader, err := s.b.HeaderByNumber(ctx, rpc.FinalizedBlockNumber)
-	if err != nil { // impossible
-		return nil, err
-	}
-	latestHeader, err := s.b.HeaderByNumber(ctx, rpc.LatestBlockNumber)
-	if err != nil { // impossible
-		return nil, err
-	}
-	finalizedBlockNumber := max(fastFinalizedHeader.Number.Int64(), latestHeader.Number.Int64()-probabilisticFinalized*int64(currentTurnLength))
 
 	return s.GetBlockByNumber(ctx, rpc.BlockNumber(finalizedBlockNumber), fullTx)
 }

internal/ethapi/api_test.go

@@ -633,7 +633,7 @@ func (b testBackend) SubscribeNewTxsEvent(events chan<- core.NewTxsEvent) event.
 }
 func (b testBackend) ChainConfig() *params.ChainConfig             { return b.chain.Config() }
 func (b testBackend) Engine() consensus.Engine                     { return b.chain.Engine() }
-func (b testBackend) CurrentTurnLength() (uint8, error) { return 1, nil }
+func (b testBackend) CurrentValidators() ([]common.Address, error) { return []common.Address{}, nil }
 func (b testBackend) GetLogs(ctx context.Context, blockHash common.Hash, number uint64) ([][]*types.Log, error) {
 	panic("implement me")
 }

internal/ethapi/backend.go

@@ -89,8 +89,8 @@ type Backend interface {
 
 	ChainConfig() *params.ChainConfig
 	Engine() consensus.Engine
-	// CurrentTurnLength return the turnLength at the latest block
+	// CurrentValidators return the list of validator at the latest block
-	CurrentTurnLength() (uint8, error)
+	CurrentValidators() ([]common.Address, error)
 
 	// This is copied from filters.Backend
 	// eth/filters needs to be initialized from this backend type, so methods needed by

internal/ethapi/transaction_args_test.go

@@ -416,7 +416,7 @@ func (b *backendMock) SubscribeRemovedLogsEvent(ch chan<- core.RemovedLogsEvent)
 
 func (b *backendMock) Engine() consensus.Engine { return nil }
 
-func (b *backendMock) CurrentTurnLength() (uint8, error) { return 1, nil }
+func (b *backendMock) CurrentValidators() ([]common.Address, error) { return []common.Address{}, nil }
 
 func (b *backendMock) MevRunning() bool                       { return false }
 func (b *backendMock) HasBuilder(builder common.Address) bool { return false }