github.com/aigarnetwork/aigar@v0.0.0-20191115204914-d59a6eb70f8e/core/rawdb/accessors_chain.go (about)

     1  //  Copyright 2018 The go-ethereum Authors
     2  //  Copyright 2019 The go-aigar Authors
     3  //  This file is part of the go-aigar library.
     4  //
     5  //  The go-aigar library is free software: you can redistribute it and/or modify
     6  //  it under the terms of the GNU Lesser General Public License as published by
     7  //  the Free Software Foundation, either version 3 of the License, or
     8  //  (at your option) any later version.
     9  //
    10  //  The go-aigar library is distributed in the hope that it will be useful,
    11  //  but WITHOUT ANY WARRANTY; without even the implied warranty of
    12  //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    13  //  GNU Lesser General Public License for more details.
    14  //
    15  //  You should have received a copy of the GNU Lesser General Public License
    16  //  along with the go-aigar library. If not, see <http://www.gnu.org/licenses/>.
    17  
    18  package rawdb
    19  
    20  import (
    21  	"bytes"
    22  	"encoding/binary"
    23  	"math/big"
    24  
    25  	"github.com/AigarNetwork/aigar/common"
    26  	"github.com/AigarNetwork/aigar/core/types"
    27  	"github.com/AigarNetwork/aigar/ethdb"
    28  	"github.com/AigarNetwork/aigar/log"
    29  	"github.com/AigarNetwork/aigar/params"
    30  	"github.com/AigarNetwork/aigar/rlp"
    31  )
    32  
    33  // ReadCanonicalHash retrieves the hash assigned to a canonical block number.
    34  func ReadCanonicalHash(db ethdb.Reader, number uint64) common.Hash {
    35  	data, _ := db.Ancient(freezerHashTable, number)
    36  	if len(data) == 0 {
    37  		data, _ = db.Get(headerHashKey(number))
    38  		// In the background freezer is moving data from leveldb to flatten files.
    39  		// So during the first check for ancient db, the data is not yet in there,
    40  		// but when we reach into leveldb, the data was already moved. That would
    41  		// result in a not found error.
    42  		if len(data) == 0 {
    43  			data, _ = db.Ancient(freezerHashTable, number)
    44  		}
    45  	}
    46  	if len(data) == 0 {
    47  		return common.Hash{}
    48  	}
    49  	return common.BytesToHash(data)
    50  }
    51  
    52  // WriteCanonicalHash stores the hash assigned to a canonical block number.
    53  func WriteCanonicalHash(db ethdb.KeyValueWriter, hash common.Hash, number uint64) {
    54  	if err := db.Put(headerHashKey(number), hash.Bytes()); err != nil {
    55  		log.Crit("Failed to store number to hash mapping", "err", err)
    56  	}
    57  }
    58  
    59  // DeleteCanonicalHash removes the number to hash canonical mapping.
    60  func DeleteCanonicalHash(db ethdb.KeyValueWriter, number uint64) {
    61  	if err := db.Delete(headerHashKey(number)); err != nil {
    62  		log.Crit("Failed to delete number to hash mapping", "err", err)
    63  	}
    64  }
    65  
    66  // ReadAllHashes retrieves all the hashes assigned to blocks at a certain heights,
    67  // both canonical and reorged forks included.
    68  func ReadAllHashes(db ethdb.Iteratee, number uint64) []common.Hash {
    69  	prefix := headerKeyPrefix(number)
    70  
    71  	hashes := make([]common.Hash, 0, 1)
    72  	it := db.NewIteratorWithPrefix(prefix)
    73  	defer it.Release()
    74  
    75  	for it.Next() {
    76  		if key := it.Key(); len(key) == len(prefix)+32 {
    77  			hashes = append(hashes, common.BytesToHash(key[len(key)-32:]))
    78  		}
    79  	}
    80  	return hashes
    81  }
    82  
    83  // ReadHeaderNumber returns the header number assigned to a hash.
    84  func ReadHeaderNumber(db ethdb.KeyValueReader, hash common.Hash) *uint64 {
    85  	data, _ := db.Get(headerNumberKey(hash))
    86  	if len(data) != 8 {
    87  		return nil
    88  	}
    89  	number := binary.BigEndian.Uint64(data)
    90  	return &number
    91  }
    92  
    93  // WriteHeaderNumber stores the hash->number mapping.
    94  func WriteHeaderNumber(db ethdb.KeyValueWriter, hash common.Hash, number uint64) {
    95  	key := headerNumberKey(hash)
    96  	enc := encodeBlockNumber(number)
    97  	if err := db.Put(key, enc); err != nil {
    98  		log.Crit("Failed to store hash to number mapping", "err", err)
    99  	}
   100  }
   101  
   102  // DeleteHeaderNumber removes hash->number mapping.
   103  func DeleteHeaderNumber(db ethdb.KeyValueWriter, hash common.Hash) {
   104  	if err := db.Delete(headerNumberKey(hash)); err != nil {
   105  		log.Crit("Failed to delete hash to number mapping", "err", err)
   106  	}
   107  }
   108  
   109  // ReadHeadHeaderHash retrieves the hash of the current canonical head header.
   110  func ReadHeadHeaderHash(db ethdb.KeyValueReader) common.Hash {
   111  	data, _ := db.Get(headHeaderKey)
   112  	if len(data) == 0 {
   113  		return common.Hash{}
   114  	}
   115  	return common.BytesToHash(data)
   116  }
   117  
   118  // WriteHeadHeaderHash stores the hash of the current canonical head header.
   119  func WriteHeadHeaderHash(db ethdb.KeyValueWriter, hash common.Hash) {
   120  	if err := db.Put(headHeaderKey, hash.Bytes()); err != nil {
   121  		log.Crit("Failed to store last header's hash", "err", err)
   122  	}
   123  }
   124  
   125  // ReadHeadBlockHash retrieves the hash of the current canonical head block.
   126  func ReadHeadBlockHash(db ethdb.KeyValueReader) common.Hash {
   127  	data, _ := db.Get(headBlockKey)
   128  	if len(data) == 0 {
   129  		return common.Hash{}
   130  	}
   131  	return common.BytesToHash(data)
   132  }
   133  
   134  // WriteHeadBlockHash stores the head block's hash.
   135  func WriteHeadBlockHash(db ethdb.KeyValueWriter, hash common.Hash) {
   136  	if err := db.Put(headBlockKey, hash.Bytes()); err != nil {
   137  		log.Crit("Failed to store last block's hash", "err", err)
   138  	}
   139  }
   140  
   141  // ReadHeadFastBlockHash retrieves the hash of the current fast-sync head block.
   142  func ReadHeadFastBlockHash(db ethdb.KeyValueReader) common.Hash {
   143  	data, _ := db.Get(headFastBlockKey)
   144  	if len(data) == 0 {
   145  		return common.Hash{}
   146  	}
   147  	return common.BytesToHash(data)
   148  }
   149  
   150  // WriteHeadFastBlockHash stores the hash of the current fast-sync head block.
   151  func WriteHeadFastBlockHash(db ethdb.KeyValueWriter, hash common.Hash) {
   152  	if err := db.Put(headFastBlockKey, hash.Bytes()); err != nil {
   153  		log.Crit("Failed to store last fast block's hash", "err", err)
   154  	}
   155  }
   156  
   157  // ReadFastTrieProgress retrieves the number of tries nodes fast synced to allow
   158  // reporting correct numbers across restarts.
   159  func ReadFastTrieProgress(db ethdb.KeyValueReader) uint64 {
   160  	data, _ := db.Get(fastTrieProgressKey)
   161  	if len(data) == 0 {
   162  		return 0
   163  	}
   164  	return new(big.Int).SetBytes(data).Uint64()
   165  }
   166  
   167  // WriteFastTrieProgress stores the fast sync trie process counter to support
   168  // retrieving it across restarts.
   169  func WriteFastTrieProgress(db ethdb.KeyValueWriter, count uint64) {
   170  	if err := db.Put(fastTrieProgressKey, new(big.Int).SetUint64(count).Bytes()); err != nil {
   171  		log.Crit("Failed to store fast sync trie progress", "err", err)
   172  	}
   173  }
   174  
   175  // ReadHeaderRLP retrieves a block header in its raw RLP database encoding.
   176  func ReadHeaderRLP(db ethdb.Reader, hash common.Hash, number uint64) rlp.RawValue {
   177  	data, _ := db.Ancient(freezerHeaderTable, number)
   178  	if len(data) == 0 {
   179  		data, _ = db.Get(headerKey(number, hash))
   180  		// In the background freezer is moving data from leveldb to flatten files.
   181  		// So during the first check for ancient db, the data is not yet in there,
   182  		// but when we reach into leveldb, the data was already moved. That would
   183  		// result in a not found error.
   184  		if len(data) == 0 {
   185  			data, _ = db.Ancient(freezerHeaderTable, number)
   186  		}
   187  	}
   188  	return data
   189  }
   190  
   191  // HasHeader verifies the existence of a block header corresponding to the hash.
   192  func HasHeader(db ethdb.Reader, hash common.Hash, number uint64) bool {
   193  	if has, err := db.Ancient(freezerHashTable, number); err == nil && common.BytesToHash(has) == hash {
   194  		return true
   195  	}
   196  	if has, err := db.Has(headerKey(number, hash)); !has || err != nil {
   197  		return false
   198  	}
   199  	return true
   200  }
   201  
   202  // ReadHeader retrieves the block header corresponding to the hash.
   203  func ReadHeader(db ethdb.Reader, hash common.Hash, number uint64) *types.Header {
   204  	data := ReadHeaderRLP(db, hash, number)
   205  	if len(data) == 0 {
   206  		return nil
   207  	}
   208  	header := new(types.Header)
   209  	if err := rlp.Decode(bytes.NewReader(data), header); err != nil {
   210  		log.Error("Invalid block header RLP", "hash", hash, "err", err)
   211  		return nil
   212  	}
   213  	return header
   214  }
   215  
   216  // WriteHeader stores a block header into the database and also stores the hash-
   217  // to-number mapping.
   218  func WriteHeader(db ethdb.KeyValueWriter, header *types.Header) {
   219  	var (
   220  		hash   = header.Hash()
   221  		number = header.Number.Uint64()
   222  	)
   223  	// Write the hash -> number mapping
   224  	WriteHeaderNumber(db, hash, number)
   225  
   226  	// Write the encoded header
   227  	data, err := rlp.EncodeToBytes(header)
   228  	if err != nil {
   229  		log.Crit("Failed to RLP encode header", "err", err)
   230  	}
   231  	key := headerKey(number, hash)
   232  	if err := db.Put(key, data); err != nil {
   233  		log.Crit("Failed to store header", "err", err)
   234  	}
   235  }
   236  
   237  // DeleteHeader removes all block header data associated with a hash.
   238  func DeleteHeader(db ethdb.KeyValueWriter, hash common.Hash, number uint64) {
   239  	deleteHeaderWithoutNumber(db, hash, number)
   240  	if err := db.Delete(headerNumberKey(hash)); err != nil {
   241  		log.Crit("Failed to delete hash to number mapping", "err", err)
   242  	}
   243  }
   244  
   245  // deleteHeaderWithoutNumber removes only the block header but does not remove
   246  // the hash to number mapping.
   247  func deleteHeaderWithoutNumber(db ethdb.KeyValueWriter, hash common.Hash, number uint64) {
   248  	if err := db.Delete(headerKey(number, hash)); err != nil {
   249  		log.Crit("Failed to delete header", "err", err)
   250  	}
   251  }
   252  
   253  // ReadBodyRLP retrieves the block body (transactions and uncles) in RLP encoding.
   254  func ReadBodyRLP(db ethdb.Reader, hash common.Hash, number uint64) rlp.RawValue {
   255  	data, _ := db.Ancient(freezerBodiesTable, number)
   256  	if len(data) == 0 {
   257  		data, _ = db.Get(blockBodyKey(number, hash))
   258  		// In the background freezer is moving data from leveldb to flatten files.
   259  		// So during the first check for ancient db, the data is not yet in there,
   260  		// but when we reach into leveldb, the data was already moved. That would
   261  		// result in a not found error.
   262  		if len(data) == 0 {
   263  			data, _ = db.Ancient(freezerBodiesTable, number)
   264  		}
   265  	}
   266  	return data
   267  }
   268  
   269  // WriteBodyRLP stores an RLP encoded block body into the database.
   270  func WriteBodyRLP(db ethdb.KeyValueWriter, hash common.Hash, number uint64, rlp rlp.RawValue) {
   271  	if err := db.Put(blockBodyKey(number, hash), rlp); err != nil {
   272  		log.Crit("Failed to store block body", "err", err)
   273  	}
   274  }
   275  
   276  // HasBody verifies the existence of a block body corresponding to the hash.
   277  func HasBody(db ethdb.Reader, hash common.Hash, number uint64) bool {
   278  	if has, err := db.Ancient(freezerHashTable, number); err == nil && common.BytesToHash(has) == hash {
   279  		return true
   280  	}
   281  	if has, err := db.Has(blockBodyKey(number, hash)); !has || err != nil {
   282  		return false
   283  	}
   284  	return true
   285  }
   286  
   287  // ReadBody retrieves the block body corresponding to the hash.
   288  func ReadBody(db ethdb.Reader, hash common.Hash, number uint64) *types.Body {
   289  	data := ReadBodyRLP(db, hash, number)
   290  	if len(data) == 0 {
   291  		return nil
   292  	}
   293  	body := new(types.Body)
   294  	if err := rlp.Decode(bytes.NewReader(data), body); err != nil {
   295  		log.Error("Invalid block body RLP", "hash", hash, "err", err)
   296  		return nil
   297  	}
   298  	return body
   299  }
   300  
   301  // WriteBody stores a block body into the database.
   302  func WriteBody(db ethdb.KeyValueWriter, hash common.Hash, number uint64, body *types.Body) {
   303  	data, err := rlp.EncodeToBytes(body)
   304  	if err != nil {
   305  		log.Crit("Failed to RLP encode body", "err", err)
   306  	}
   307  	WriteBodyRLP(db, hash, number, data)
   308  }
   309  
   310  // DeleteBody removes all block body data associated with a hash.
   311  func DeleteBody(db ethdb.KeyValueWriter, hash common.Hash, number uint64) {
   312  	if err := db.Delete(blockBodyKey(number, hash)); err != nil {
   313  		log.Crit("Failed to delete block body", "err", err)
   314  	}
   315  }
   316  
   317  // ReadTdRLP retrieves a block's total difficulty corresponding to the hash in RLP encoding.
   318  func ReadTdRLP(db ethdb.Reader, hash common.Hash, number uint64) rlp.RawValue {
   319  	data, _ := db.Ancient(freezerDifficultyTable, number)
   320  	if len(data) == 0 {
   321  		data, _ = db.Get(headerTDKey(number, hash))
   322  		// In the background freezer is moving data from leveldb to flatten files.
   323  		// So during the first check for ancient db, the data is not yet in there,
   324  		// but when we reach into leveldb, the data was already moved. That would
   325  		// result in a not found error.
   326  		if len(data) == 0 {
   327  			data, _ = db.Ancient(freezerDifficultyTable, number)
   328  		}
   329  	}
   330  	return data
   331  }
   332  
   333  // ReadTd retrieves a block's total difficulty corresponding to the hash.
   334  func ReadTd(db ethdb.Reader, hash common.Hash, number uint64) *big.Int {
   335  	data := ReadTdRLP(db, hash, number)
   336  	if len(data) == 0 {
   337  		return nil
   338  	}
   339  	td := new(big.Int)
   340  	if err := rlp.Decode(bytes.NewReader(data), td); err != nil {
   341  		log.Error("Invalid block total difficulty RLP", "hash", hash, "err", err)
   342  		return nil
   343  	}
   344  	return td
   345  }
   346  
   347  // WriteTd stores the total difficulty of a block into the database.
   348  func WriteTd(db ethdb.KeyValueWriter, hash common.Hash, number uint64, td *big.Int) {
   349  	data, err := rlp.EncodeToBytes(td)
   350  	if err != nil {
   351  		log.Crit("Failed to RLP encode block total difficulty", "err", err)
   352  	}
   353  	if err := db.Put(headerTDKey(number, hash), data); err != nil {
   354  		log.Crit("Failed to store block total difficulty", "err", err)
   355  	}
   356  }
   357  
   358  // DeleteTd removes all block total difficulty data associated with a hash.
   359  func DeleteTd(db ethdb.KeyValueWriter, hash common.Hash, number uint64) {
   360  	if err := db.Delete(headerTDKey(number, hash)); err != nil {
   361  		log.Crit("Failed to delete block total difficulty", "err", err)
   362  	}
   363  }
   364  
   365  // HasReceipts verifies the existence of all the transaction receipts belonging
   366  // to a block.
   367  func HasReceipts(db ethdb.Reader, hash common.Hash, number uint64) bool {
   368  	if has, err := db.Ancient(freezerHashTable, number); err == nil && common.BytesToHash(has) == hash {
   369  		return true
   370  	}
   371  	if has, err := db.Has(blockReceiptsKey(number, hash)); !has || err != nil {
   372  		return false
   373  	}
   374  	return true
   375  }
   376  
   377  // ReadReceiptsRLP retrieves all the transaction receipts belonging to a block in RLP encoding.
   378  func ReadReceiptsRLP(db ethdb.Reader, hash common.Hash, number uint64) rlp.RawValue {
   379  	data, _ := db.Ancient(freezerReceiptTable, number)
   380  	if len(data) == 0 {
   381  		data, _ = db.Get(blockReceiptsKey(number, hash))
   382  		// In the background freezer is moving data from leveldb to flatten files.
   383  		// So during the first check for ancient db, the data is not yet in there,
   384  		// but when we reach into leveldb, the data was already moved. That would
   385  		// result in a not found error.
   386  		if len(data) == 0 {
   387  			data, _ = db.Ancient(freezerReceiptTable, number)
   388  		}
   389  	}
   390  	return data
   391  }
   392  
   393  // ReadRawReceipts retrieves all the transaction receipts belonging to a block.
   394  // The receipt metadata fields are not guaranteed to be populated, so they
   395  // should not be used. Use ReadReceipts instead if the metadata is needed.
   396  func ReadRawReceipts(db ethdb.Reader, hash common.Hash, number uint64) types.Receipts {
   397  	// Retrieve the flattened receipt slice
   398  	data := ReadReceiptsRLP(db, hash, number)
   399  	if len(data) == 0 {
   400  		return nil
   401  	}
   402  	// Convert the receipts from their storage form to their internal representation
   403  	storageReceipts := []*types.ReceiptForStorage{}
   404  	if err := rlp.DecodeBytes(data, &storageReceipts); err != nil {
   405  		log.Error("Invalid receipt array RLP", "hash", hash, "err", err)
   406  		return nil
   407  	}
   408  	receipts := make(types.Receipts, len(storageReceipts))
   409  	for i, storageReceipt := range storageReceipts {
   410  		receipts[i] = (*types.Receipt)(storageReceipt)
   411  	}
   412  	return receipts
   413  }
   414  
   415  // ReadReceipts retrieves all the transaction receipts belonging to a block, including
   416  // its correspoinding metadata fields. If it is unable to populate these metadata
   417  // fields then nil is returned.
   418  //
   419  // The current implementation populates these metadata fields by reading the receipts'
   420  // corresponding block body, so if the block body is not found it will return nil even
   421  // if the receipt itself is stored.
   422  func ReadReceipts(db ethdb.Reader, hash common.Hash, number uint64, config *params.ChainConfig) types.Receipts {
   423  	// We're deriving many fields from the block body, retrieve beside the receipt
   424  	receipts := ReadRawReceipts(db, hash, number)
   425  	if receipts == nil {
   426  		return nil
   427  	}
   428  	body := ReadBody(db, hash, number)
   429  	if body == nil {
   430  		log.Error("Missing body but have receipt", "hash", hash, "number", number)
   431  		return nil
   432  	}
   433  	if err := receipts.DeriveFields(config, hash, number, body.Transactions); err != nil {
   434  		log.Error("Failed to derive block receipts fields", "hash", hash, "number", number, "err", err)
   435  		return nil
   436  	}
   437  	return receipts
   438  }
   439  
   440  // WriteReceipts stores all the transaction receipts belonging to a block.
   441  func WriteReceipts(db ethdb.KeyValueWriter, hash common.Hash, number uint64, receipts types.Receipts) {
   442  	// Convert the receipts into their storage form and serialize them
   443  	storageReceipts := make([]*types.ReceiptForStorage, len(receipts))
   444  	for i, receipt := range receipts {
   445  		storageReceipts[i] = (*types.ReceiptForStorage)(receipt)
   446  	}
   447  	bytes, err := rlp.EncodeToBytes(storageReceipts)
   448  	if err != nil {
   449  		log.Crit("Failed to encode block receipts", "err", err)
   450  	}
   451  	// Store the flattened receipt slice
   452  	if err := db.Put(blockReceiptsKey(number, hash), bytes); err != nil {
   453  		log.Crit("Failed to store block receipts", "err", err)
   454  	}
   455  }
   456  
   457  // DeleteReceipts removes all receipt data associated with a block hash.
   458  func DeleteReceipts(db ethdb.KeyValueWriter, hash common.Hash, number uint64) {
   459  	if err := db.Delete(blockReceiptsKey(number, hash)); err != nil {
   460  		log.Crit("Failed to delete block receipts", "err", err)
   461  	}
   462  }
   463  
   464  // ReadBlock retrieves an entire block corresponding to the hash, assembling it
   465  // back from the stored header and body. If either the header or body could not
   466  // be retrieved nil is returned.
   467  //
   468  // Note, due to concurrent download of header and block body the header and thus
   469  // canonical hash can be stored in the database but the body data not (yet).
   470  func ReadBlock(db ethdb.Reader, hash common.Hash, number uint64) *types.Block {
   471  	header := ReadHeader(db, hash, number)
   472  	if header == nil {
   473  		return nil
   474  	}
   475  	body := ReadBody(db, hash, number)
   476  	if body == nil {
   477  		return nil
   478  	}
   479  	return types.NewBlockWithHeader(header).WithBody(body.Transactions, body.Uncles)
   480  }
   481  
   482  // WriteBlock serializes a block into the database, header and body separately.
   483  func WriteBlock(db ethdb.KeyValueWriter, block *types.Block) {
   484  	WriteBody(db, block.Hash(), block.NumberU64(), block.Body())
   485  	WriteHeader(db, block.Header())
   486  }
   487  
   488  // WriteAncientBlock writes entire block data into ancient store and returns the total written size.
   489  func WriteAncientBlock(db ethdb.AncientWriter, block *types.Block, receipts types.Receipts, td *big.Int) int {
   490  	// Encode all block components to RLP format.
   491  	headerBlob, err := rlp.EncodeToBytes(block.Header())
   492  	if err != nil {
   493  		log.Crit("Failed to RLP encode block header", "err", err)
   494  	}
   495  	bodyBlob, err := rlp.EncodeToBytes(block.Body())
   496  	if err != nil {
   497  		log.Crit("Failed to RLP encode body", "err", err)
   498  	}
   499  	storageReceipts := make([]*types.ReceiptForStorage, len(receipts))
   500  	for i, receipt := range receipts {
   501  		storageReceipts[i] = (*types.ReceiptForStorage)(receipt)
   502  	}
   503  	receiptBlob, err := rlp.EncodeToBytes(storageReceipts)
   504  	if err != nil {
   505  		log.Crit("Failed to RLP encode block receipts", "err", err)
   506  	}
   507  	tdBlob, err := rlp.EncodeToBytes(td)
   508  	if err != nil {
   509  		log.Crit("Failed to RLP encode block total difficulty", "err", err)
   510  	}
   511  	// Write all blob to flatten files.
   512  	err = db.AppendAncient(block.NumberU64(), block.Hash().Bytes(), headerBlob, bodyBlob, receiptBlob, tdBlob)
   513  	if err != nil {
   514  		log.Crit("Failed to write block data to ancient store", "err", err)
   515  	}
   516  	return len(headerBlob) + len(bodyBlob) + len(receiptBlob) + len(tdBlob) + common.HashLength
   517  }
   518  
   519  // DeleteBlock removes all block data associated with a hash.
   520  func DeleteBlock(db ethdb.KeyValueWriter, hash common.Hash, number uint64) {
   521  	DeleteReceipts(db, hash, number)
   522  	DeleteHeader(db, hash, number)
   523  	DeleteBody(db, hash, number)
   524  	DeleteTd(db, hash, number)
   525  }
   526  
   527  // DeleteBlockWithoutNumber removes all block data associated with a hash, except
   528  // the hash to number mapping.
   529  func DeleteBlockWithoutNumber(db ethdb.KeyValueWriter, hash common.Hash, number uint64) {
   530  	DeleteReceipts(db, hash, number)
   531  	deleteHeaderWithoutNumber(db, hash, number)
   532  	DeleteBody(db, hash, number)
   533  	DeleteTd(db, hash, number)
   534  }
   535  
   536  // FindCommonAncestor returns the last common ancestor of two block headers
   537  func FindCommonAncestor(db ethdb.Reader, a, b *types.Header) *types.Header {
   538  	for bn := b.Number.Uint64(); a.Number.Uint64() > bn; {
   539  		a = ReadHeader(db, a.ParentHash, a.Number.Uint64()-1)
   540  		if a == nil {
   541  			return nil
   542  		}
   543  	}
   544  	for an := a.Number.Uint64(); an < b.Number.Uint64(); {
   545  		b = ReadHeader(db, b.ParentHash, b.Number.Uint64()-1)
   546  		if b == nil {
   547  			return nil
   548  		}
   549  	}
   550  	for a.Hash() != b.Hash() {
   551  		a = ReadHeader(db, a.ParentHash, a.Number.Uint64()-1)
   552  		if a == nil {
   553  			return nil
   554  		}
   555  		b = ReadHeader(db, b.ParentHash, b.Number.Uint64()-1)
   556  		if b == nil {
   557  			return nil
   558  		}
   559  	}
   560  	return a
   561  }