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Diffstat (limited to 'core/database_util.go')
| -rw-r--r-- | core/database_util.go | 652 |
1 files changed, 0 insertions, 652 deletions
diff --git a/core/database_util.go b/core/database_util.go deleted file mode 100644 index 8c4698985..000000000 --- a/core/database_util.go +++ /dev/null @@ -1,652 +0,0 @@ -// Copyright 2015 The go-ethereum Authors -// This file is part of the go-ethereum library. -// -// The go-ethereum library is free software: you can redistribute it and/or modify -// it under the terms of the GNU Lesser General Public License as published by -// the Free Software Foundation, either version 3 of the License, or -// (at your option) any later version. -// -// The go-ethereum library is distributed in the hope that it will be useful, -// but WITHOUT ANY WARRANTY; without even the implied warranty of -// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -// GNU Lesser General Public License for more details. -// -// You should have received a copy of the GNU Lesser General Public License -// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. - -package core - -import ( - "bytes" - "encoding/binary" - "encoding/json" - "errors" - "fmt" - "math/big" - - "github.com/ethereum/go-ethereum/common" - "github.com/ethereum/go-ethereum/core/types" - "github.com/ethereum/go-ethereum/ethdb" - "github.com/ethereum/go-ethereum/log" - "github.com/ethereum/go-ethereum/metrics" - "github.com/ethereum/go-ethereum/params" - "github.com/ethereum/go-ethereum/rlp" -) - -// DatabaseReader wraps the Get method of a backing data store. -type DatabaseReader interface { - Get(key []byte) (value []byte, err error) -} - -// DatabaseDeleter wraps the Delete method of a backing data store. -type DatabaseDeleter interface { - Delete(key []byte) error -} - -var ( - headHeaderKey = []byte("LastHeader") - headBlockKey = []byte("LastBlock") - headFastKey = []byte("LastFast") - trieSyncKey = []byte("TrieSync") - - // Data item prefixes (use single byte to avoid mixing data types, avoid `i`). - headerPrefix = []byte("h") // headerPrefix + num (uint64 big endian) + hash -> header - tdSuffix = []byte("t") // headerPrefix + num (uint64 big endian) + hash + tdSuffix -> td - numSuffix = []byte("n") // headerPrefix + num (uint64 big endian) + numSuffix -> hash - blockHashPrefix = []byte("H") // blockHashPrefix + hash -> num (uint64 big endian) - bodyPrefix = []byte("b") // bodyPrefix + num (uint64 big endian) + hash -> block body - blockReceiptsPrefix = []byte("r") // blockReceiptsPrefix + num (uint64 big endian) + hash -> block receipts - lookupPrefix = []byte("l") // lookupPrefix + hash -> transaction/receipt lookup metadata - bloomBitsPrefix = []byte("B") // bloomBitsPrefix + bit (uint16 big endian) + section (uint64 big endian) + hash -> bloom bits - - preimagePrefix = "secure-key-" // preimagePrefix + hash -> preimage - configPrefix = []byte("ethereum-config-") // config prefix for the db - - // Chain index prefixes (use `i` + single byte to avoid mixing data types). - BloomBitsIndexPrefix = []byte("iB") // BloomBitsIndexPrefix is the data table of a chain indexer to track its progress - - // used by old db, now only used for conversion - oldReceiptsPrefix = []byte("receipts-") - oldTxMetaSuffix = []byte{0x01} - - ErrChainConfigNotFound = errors.New("ChainConfig not found") // general config not found error - - preimageCounter = metrics.NewRegisteredCounter("db/preimage/total", nil) - preimageHitCounter = metrics.NewRegisteredCounter("db/preimage/hits", nil) -) - -// TxLookupEntry is a positional metadata to help looking up the data content of -// a transaction or receipt given only its hash. -type TxLookupEntry struct { - BlockHash common.Hash - BlockIndex uint64 - Index uint64 -} - -// encodeBlockNumber encodes a block number as big endian uint64 -func encodeBlockNumber(number uint64) []byte { - enc := make([]byte, 8) - binary.BigEndian.PutUint64(enc, number) - return enc -} - -// GetCanonicalHash retrieves a hash assigned to a canonical block number. -func GetCanonicalHash(db DatabaseReader, number uint64) common.Hash { - data, _ := db.Get(append(append(headerPrefix, encodeBlockNumber(number)...), numSuffix...)) - if len(data) == 0 { - return common.Hash{} - } - return common.BytesToHash(data) -} - -// missingNumber is returned by GetBlockNumber if no header with the -// given block hash has been stored in the database -const missingNumber = uint64(0xffffffffffffffff) - -// GetBlockNumber returns the block number assigned to a block hash -// if the corresponding header is present in the database -func GetBlockNumber(db DatabaseReader, hash common.Hash) uint64 { - data, _ := db.Get(append(blockHashPrefix, hash.Bytes()...)) - if len(data) != 8 { - return missingNumber - } - return binary.BigEndian.Uint64(data) -} - -// GetHeadHeaderHash retrieves the hash of the current canonical head block's -// header. The difference between this and GetHeadBlockHash is that whereas the -// last block hash is only updated upon a full block import, the last header -// hash is updated already at header import, allowing head tracking for the -// light synchronization mechanism. -func GetHeadHeaderHash(db DatabaseReader) common.Hash { - data, _ := db.Get(headHeaderKey) - if len(data) == 0 { - return common.Hash{} - } - return common.BytesToHash(data) -} - -// GetHeadBlockHash retrieves the hash of the current canonical head block. -func GetHeadBlockHash(db DatabaseReader) common.Hash { - data, _ := db.Get(headBlockKey) - if len(data) == 0 { - return common.Hash{} - } - return common.BytesToHash(data) -} - -// GetHeadFastBlockHash retrieves the hash of the current canonical head block during -// fast synchronization. The difference between this and GetHeadBlockHash is that -// whereas the last block hash is only updated upon a full block import, the last -// fast hash is updated when importing pre-processed blocks. -func GetHeadFastBlockHash(db DatabaseReader) common.Hash { - data, _ := db.Get(headFastKey) - if len(data) == 0 { - return common.Hash{} - } - return common.BytesToHash(data) -} - -// GetTrieSyncProgress retrieves the number of tries nodes fast synced to allow -// reportinc correct numbers across restarts. -func GetTrieSyncProgress(db DatabaseReader) uint64 { - data, _ := db.Get(trieSyncKey) - if len(data) == 0 { - return 0 - } - return new(big.Int).SetBytes(data).Uint64() -} - -// GetHeaderRLP retrieves a block header in its raw RLP database encoding, or nil -// if the header's not found. -func GetHeaderRLP(db DatabaseReader, hash common.Hash, number uint64) rlp.RawValue { - data, _ := db.Get(headerKey(hash, number)) - return data -} - -// GetHeader retrieves the block header corresponding to the hash, nil if none -// found. -func GetHeader(db DatabaseReader, hash common.Hash, number uint64) *types.Header { - data := GetHeaderRLP(db, hash, number) - if len(data) == 0 { - return nil - } - header := new(types.Header) - if err := rlp.Decode(bytes.NewReader(data), header); err != nil { - log.Error("Invalid block header RLP", "hash", hash, "err", err) - return nil - } - return header -} - -// GetBodyRLP retrieves the block body (transactions and uncles) in RLP encoding. -func GetBodyRLP(db DatabaseReader, hash common.Hash, number uint64) rlp.RawValue { - data, _ := db.Get(blockBodyKey(hash, number)) - return data -} - -func headerKey(hash common.Hash, number uint64) []byte { - return append(append(headerPrefix, encodeBlockNumber(number)...), hash.Bytes()...) -} - -func blockBodyKey(hash common.Hash, number uint64) []byte { - return append(append(bodyPrefix, encodeBlockNumber(number)...), hash.Bytes()...) -} - -// GetBody retrieves the block body (transactons, uncles) corresponding to the -// hash, nil if none found. -func GetBody(db DatabaseReader, hash common.Hash, number uint64) *types.Body { - data := GetBodyRLP(db, hash, number) - if len(data) == 0 { - return nil - } - body := new(types.Body) - if err := rlp.Decode(bytes.NewReader(data), body); err != nil { - log.Error("Invalid block body RLP", "hash", hash, "err", err) - return nil - } - return body -} - -// GetTd retrieves a block's total difficulty corresponding to the hash, nil if -// none found. -func GetTd(db DatabaseReader, hash common.Hash, number uint64) *big.Int { - data, _ := db.Get(append(append(append(headerPrefix, encodeBlockNumber(number)...), hash[:]...), tdSuffix...)) - if len(data) == 0 { - return nil - } - td := new(big.Int) - if err := rlp.Decode(bytes.NewReader(data), td); err != nil { - log.Error("Invalid block total difficulty RLP", "hash", hash, "err", err) - return nil - } - return td -} - -// GetBlock retrieves an entire block corresponding to the hash, assembling it -// back from the stored header and body. If either the header or body could not -// be retrieved nil is returned. -// -// Note, due to concurrent download of header and block body the header and thus -// canonical hash can be stored in the database but the body data not (yet). -func GetBlock(db DatabaseReader, hash common.Hash, number uint64) *types.Block { - // Retrieve the block header and body contents - header := GetHeader(db, hash, number) - if header == nil { - return nil - } - body := GetBody(db, hash, number) - if body == nil { - return nil - } - // Reassemble the block and return - return types.NewBlockWithHeader(header).WithBody(body.Transactions, body.Uncles) -} - -// GetBlockReceipts retrieves the receipts generated by the transactions included -// in a block given by its hash. -func GetBlockReceipts(db DatabaseReader, hash common.Hash, number uint64) types.Receipts { - data, _ := db.Get(append(append(blockReceiptsPrefix, encodeBlockNumber(number)...), hash[:]...)) - if len(data) == 0 { - return nil - } - storageReceipts := []*types.ReceiptForStorage{} - if err := rlp.DecodeBytes(data, &storageReceipts); err != nil { - log.Error("Invalid receipt array RLP", "hash", hash, "err", err) - return nil - } - receipts := make(types.Receipts, len(storageReceipts)) - for i, receipt := range storageReceipts { - receipts[i] = (*types.Receipt)(receipt) - } - return receipts -} - -// GetTxLookupEntry retrieves the positional metadata associated with a transaction -// hash to allow retrieving the transaction or receipt by hash. -func GetTxLookupEntry(db DatabaseReader, hash common.Hash) (common.Hash, uint64, uint64) { - // Load the positional metadata from disk and bail if it fails - data, _ := db.Get(append(lookupPrefix, hash.Bytes()...)) - if len(data) == 0 { - return common.Hash{}, 0, 0 - } - // Parse and return the contents of the lookup entry - var entry TxLookupEntry - if err := rlp.DecodeBytes(data, &entry); err != nil { - log.Error("Invalid lookup entry RLP", "hash", hash, "err", err) - return common.Hash{}, 0, 0 - } - return entry.BlockHash, entry.BlockIndex, entry.Index -} - -// GetTransaction retrieves a specific transaction from the database, along with -// its added positional metadata. -func GetTransaction(db DatabaseReader, hash common.Hash) (*types.Transaction, common.Hash, uint64, uint64) { - // Retrieve the lookup metadata and resolve the transaction from the body - blockHash, blockNumber, txIndex := GetTxLookupEntry(db, hash) - - if blockHash != (common.Hash{}) { - body := GetBody(db, blockHash, blockNumber) - if body == nil || len(body.Transactions) <= int(txIndex) { - log.Error("Transaction referenced missing", "number", blockNumber, "hash", blockHash, "index", txIndex) - return nil, common.Hash{}, 0, 0 - } - return body.Transactions[txIndex], blockHash, blockNumber, txIndex - } - // Old transaction representation, load the transaction and it's metadata separately - data, _ := db.Get(hash.Bytes()) - if len(data) == 0 { - return nil, common.Hash{}, 0, 0 - } - var tx types.Transaction - if err := rlp.DecodeBytes(data, &tx); err != nil { - return nil, common.Hash{}, 0, 0 - } - // Retrieve the blockchain positional metadata - data, _ = db.Get(append(hash.Bytes(), oldTxMetaSuffix...)) - if len(data) == 0 { - return nil, common.Hash{}, 0, 0 - } - var entry TxLookupEntry - if err := rlp.DecodeBytes(data, &entry); err != nil { - return nil, common.Hash{}, 0, 0 - } - return &tx, entry.BlockHash, entry.BlockIndex, entry.Index -} - -// GetReceipt retrieves a specific transaction receipt from the database, along with -// its added positional metadata. -func GetReceipt(db DatabaseReader, hash common.Hash) (*types.Receipt, common.Hash, uint64, uint64) { - // Retrieve the lookup metadata and resolve the receipt from the receipts - blockHash, blockNumber, receiptIndex := GetTxLookupEntry(db, hash) - - if blockHash != (common.Hash{}) { - receipts := GetBlockReceipts(db, blockHash, blockNumber) - if len(receipts) <= int(receiptIndex) { - log.Error("Receipt refereced missing", "number", blockNumber, "hash", blockHash, "index", receiptIndex) - return nil, common.Hash{}, 0, 0 - } - return receipts[receiptIndex], blockHash, blockNumber, receiptIndex - } - // Old receipt representation, load the receipt and set an unknown metadata - data, _ := db.Get(append(oldReceiptsPrefix, hash[:]...)) - if len(data) == 0 { - return nil, common.Hash{}, 0, 0 - } - var receipt types.ReceiptForStorage - err := rlp.DecodeBytes(data, &receipt) - if err != nil { - log.Error("Invalid receipt RLP", "hash", hash, "err", err) - } - return (*types.Receipt)(&receipt), common.Hash{}, 0, 0 -} - -// GetBloomBits retrieves the compressed bloom bit vector belonging to the given -// section and bit index from the. -func GetBloomBits(db DatabaseReader, bit uint, section uint64, head common.Hash) ([]byte, error) { - key := append(append(bloomBitsPrefix, make([]byte, 10)...), head.Bytes()...) - - binary.BigEndian.PutUint16(key[1:], uint16(bit)) - binary.BigEndian.PutUint64(key[3:], section) - - return db.Get(key) -} - -// WriteCanonicalHash stores the canonical hash for the given block number. -func WriteCanonicalHash(db ethdb.Putter, hash common.Hash, number uint64) error { - key := append(append(headerPrefix, encodeBlockNumber(number)...), numSuffix...) - if err := db.Put(key, hash.Bytes()); err != nil { - log.Crit("Failed to store number to hash mapping", "err", err) - } - return nil -} - -// WriteHeadHeaderHash stores the head header's hash. -func WriteHeadHeaderHash(db ethdb.Putter, hash common.Hash) error { - if err := db.Put(headHeaderKey, hash.Bytes()); err != nil { - log.Crit("Failed to store last header's hash", "err", err) - } - return nil -} - -// WriteHeadBlockHash stores the head block's hash. -func WriteHeadBlockHash(db ethdb.Putter, hash common.Hash) error { - if err := db.Put(headBlockKey, hash.Bytes()); err != nil { - log.Crit("Failed to store last block's hash", "err", err) - } - return nil -} - -// WriteHeadFastBlockHash stores the fast head block's hash. -func WriteHeadFastBlockHash(db ethdb.Putter, hash common.Hash) error { - if err := db.Put(headFastKey, hash.Bytes()); err != nil { - log.Crit("Failed to store last fast block's hash", "err", err) - } - return nil -} - -// WriteTrieSyncProgress stores the fast sync trie process counter to support -// retrieving it across restarts. -func WriteTrieSyncProgress(db ethdb.Putter, count uint64) error { - if err := db.Put(trieSyncKey, new(big.Int).SetUint64(count).Bytes()); err != nil { - log.Crit("Failed to store fast sync trie progress", "err", err) - } - return nil -} - -// WriteHeader serializes a block header into the database. -func WriteHeader(db ethdb.Putter, header *types.Header) error { - data, err := rlp.EncodeToBytes(header) - if err != nil { - return err - } - hash := header.Hash().Bytes() - num := header.Number.Uint64() - encNum := encodeBlockNumber(num) - key := append(blockHashPrefix, hash...) - if err := db.Put(key, encNum); err != nil { - log.Crit("Failed to store hash to number mapping", "err", err) - } - key = append(append(headerPrefix, encNum...), hash...) - if err := db.Put(key, data); err != nil { - log.Crit("Failed to store header", "err", err) - } - return nil -} - -// WriteBody serializes the body of a block into the database. -func WriteBody(db ethdb.Putter, hash common.Hash, number uint64, body *types.Body) error { - data, err := rlp.EncodeToBytes(body) - if err != nil { - return err - } - return WriteBodyRLP(db, hash, number, data) -} - -// WriteBodyRLP writes a serialized body of a block into the database. -func WriteBodyRLP(db ethdb.Putter, hash common.Hash, number uint64, rlp rlp.RawValue) error { - key := append(append(bodyPrefix, encodeBlockNumber(number)...), hash.Bytes()...) - if err := db.Put(key, rlp); err != nil { - log.Crit("Failed to store block body", "err", err) - } - return nil -} - -// WriteTd serializes the total difficulty of a block into the database. -func WriteTd(db ethdb.Putter, hash common.Hash, number uint64, td *big.Int) error { - data, err := rlp.EncodeToBytes(td) - if err != nil { - return err - } - key := append(append(append(headerPrefix, encodeBlockNumber(number)...), hash.Bytes()...), tdSuffix...) - if err := db.Put(key, data); err != nil { - log.Crit("Failed to store block total difficulty", "err", err) - } - return nil -} - -// WriteBlock serializes a block into the database, header and body separately. -func WriteBlock(db ethdb.Putter, block *types.Block) error { - // Store the body first to retain database consistency - if err := WriteBody(db, block.Hash(), block.NumberU64(), block.Body()); err != nil { - return err - } - // Store the header too, signaling full block ownership - if err := WriteHeader(db, block.Header()); err != nil { - return err - } - return nil -} - -// WriteBlockReceipts stores all the transaction receipts belonging to a block -// as a single receipt slice. This is used during chain reorganisations for -// rescheduling dropped transactions. -func WriteBlockReceipts(db ethdb.Putter, hash common.Hash, number uint64, receipts types.Receipts) error { - // Convert the receipts into their storage form and serialize them - storageReceipts := make([]*types.ReceiptForStorage, len(receipts)) - for i, receipt := range receipts { - storageReceipts[i] = (*types.ReceiptForStorage)(receipt) - } - bytes, err := rlp.EncodeToBytes(storageReceipts) - if err != nil { - return err - } - // Store the flattened receipt slice - key := append(append(blockReceiptsPrefix, encodeBlockNumber(number)...), hash.Bytes()...) - if err := db.Put(key, bytes); err != nil { - log.Crit("Failed to store block receipts", "err", err) - } - return nil -} - -// WriteTxLookupEntries stores a positional metadata for every transaction from -// a block, enabling hash based transaction and receipt lookups. -func WriteTxLookupEntries(db ethdb.Putter, block *types.Block) error { - // Iterate over each transaction and encode its metadata - for i, tx := range block.Transactions() { - entry := TxLookupEntry{ - BlockHash: block.Hash(), - BlockIndex: block.NumberU64(), - Index: uint64(i), - } - data, err := rlp.EncodeToBytes(entry) - if err != nil { - return err - } - if err := db.Put(append(lookupPrefix, tx.Hash().Bytes()...), data); err != nil { - return err - } - } - return nil -} - -// WriteBloomBits writes the compressed bloom bits vector belonging to the given -// section and bit index. -func WriteBloomBits(db ethdb.Putter, bit uint, section uint64, head common.Hash, bits []byte) { - key := append(append(bloomBitsPrefix, make([]byte, 10)...), head.Bytes()...) - - binary.BigEndian.PutUint16(key[1:], uint16(bit)) - binary.BigEndian.PutUint64(key[3:], section) - - if err := db.Put(key, bits); err != nil { - log.Crit("Failed to store bloom bits", "err", err) - } -} - -// DeleteCanonicalHash removes the number to hash canonical mapping. -func DeleteCanonicalHash(db DatabaseDeleter, number uint64) { - db.Delete(append(append(headerPrefix, encodeBlockNumber(number)...), numSuffix...)) -} - -// DeleteHeader removes all block header data associated with a hash. -func DeleteHeader(db DatabaseDeleter, hash common.Hash, number uint64) { - db.Delete(append(blockHashPrefix, hash.Bytes()...)) - db.Delete(append(append(headerPrefix, encodeBlockNumber(number)...), hash.Bytes()...)) -} - -// DeleteBody removes all block body data associated with a hash. -func DeleteBody(db DatabaseDeleter, hash common.Hash, number uint64) { - db.Delete(append(append(bodyPrefix, encodeBlockNumber(number)...), hash.Bytes()...)) -} - -// DeleteTd removes all block total difficulty data associated with a hash. -func DeleteTd(db DatabaseDeleter, hash common.Hash, number uint64) { - db.Delete(append(append(append(headerPrefix, encodeBlockNumber(number)...), hash.Bytes()...), tdSuffix...)) -} - -// DeleteBlock removes all block data associated with a hash. -func DeleteBlock(db DatabaseDeleter, hash common.Hash, number uint64) { - DeleteBlockReceipts(db, hash, number) - DeleteHeader(db, hash, number) - DeleteBody(db, hash, number) - DeleteTd(db, hash, number) -} - -// DeleteBlockReceipts removes all receipt data associated with a block hash. -func DeleteBlockReceipts(db DatabaseDeleter, hash common.Hash, number uint64) { - db.Delete(append(append(blockReceiptsPrefix, encodeBlockNumber(number)...), hash.Bytes()...)) -} - -// DeleteTxLookupEntry removes all transaction data associated with a hash. -func DeleteTxLookupEntry(db DatabaseDeleter, hash common.Hash) { - db.Delete(append(lookupPrefix, hash.Bytes()...)) -} - -// PreimageTable returns a Database instance with the key prefix for preimage entries. -func PreimageTable(db ethdb.Database) ethdb.Database { - return ethdb.NewTable(db, preimagePrefix) -} - -// WritePreimages writes the provided set of preimages to the database. `number` is the -// current block number, and is used for debug messages only. -func WritePreimages(db ethdb.Database, number uint64, preimages map[common.Hash][]byte) error { - table := PreimageTable(db) - batch := table.NewBatch() - hitCount := 0 - for hash, preimage := range preimages { - if _, err := table.Get(hash.Bytes()); err != nil { - batch.Put(hash.Bytes(), preimage) - hitCount++ - } - } - preimageCounter.Inc(int64(len(preimages))) - preimageHitCounter.Inc(int64(hitCount)) - if hitCount > 0 { - if err := batch.Write(); err != nil { - return fmt.Errorf("preimage write fail for block %d: %v", number, err) - } - } - return nil -} - -// GetBlockChainVersion reads the version number from db. -func GetBlockChainVersion(db DatabaseReader) int { - var vsn uint - enc, _ := db.Get([]byte("BlockchainVersion")) - rlp.DecodeBytes(enc, &vsn) - return int(vsn) -} - -// WriteBlockChainVersion writes vsn as the version number to db. -func WriteBlockChainVersion(db ethdb.Putter, vsn int) { - enc, _ := rlp.EncodeToBytes(uint(vsn)) - db.Put([]byte("BlockchainVersion"), enc) -} - -// WriteChainConfig writes the chain config settings to the database. -func WriteChainConfig(db ethdb.Putter, hash common.Hash, cfg *params.ChainConfig) error { - // short circuit and ignore if nil config. GetChainConfig - // will return a default. - if cfg == nil { - return nil - } - - jsonChainConfig, err := json.Marshal(cfg) - if err != nil { - return err - } - - return db.Put(append(configPrefix, hash[:]...), jsonChainConfig) -} - -// GetChainConfig will fetch the network settings based on the given hash. -func GetChainConfig(db DatabaseReader, hash common.Hash) (*params.ChainConfig, error) { - jsonChainConfig, _ := db.Get(append(configPrefix, hash[:]...)) - if len(jsonChainConfig) == 0 { - return nil, ErrChainConfigNotFound - } - - var config params.ChainConfig - if err := json.Unmarshal(jsonChainConfig, &config); err != nil { - return nil, err - } - - return &config, nil -} - -// FindCommonAncestor returns the last common ancestor of two block headers -func FindCommonAncestor(db DatabaseReader, a, b *types.Header) *types.Header { - for bn := b.Number.Uint64(); a.Number.Uint64() > bn; { - a = GetHeader(db, a.ParentHash, a.Number.Uint64()-1) - if a == nil { - return nil - } - } - for an := a.Number.Uint64(); an < b.Number.Uint64(); { - b = GetHeader(db, b.ParentHash, b.Number.Uint64()-1) - if b == nil { - return nil - } - } - for a.Hash() != b.Hash() { - a = GetHeader(db, a.ParentHash, a.Number.Uint64()-1) - if a == nil { - return nil - } - b = GetHeader(db, b.ParentHash, b.Number.Uint64()-1) - if b == nil { - return nil - } - } - return a -} |