// NodeKey retrieves the currently configured private key of the node, checking
// first any manually set key, falling back to the one found in the configured
// data folder. If no key can be found, a new one is generated.
func (c *Config) NodeKey() *ecdsa.PrivateKey {
	// Use any specifically configured key
	if c.PrivateKey != nil {
		return c.PrivateKey
	}
	// Generate ephemeral key if no datadir is being used
	if c.DataDir == "" {
		key, err := crypto.GenerateKey()
		if err != nil {
			glog.Fatalf("Failed to generate ephemeral node key: %v", err)
		}
		return key
	}
	// Fall back to persistent key from the data directory
	keyfile := filepath.Join(c.DataDir, datadirPrivateKey)
	if key, err := crypto.LoadECDSA(keyfile); err == nil {
		return key
	}
	// No persistent key found, generate and store a new one
	key, err := crypto.GenerateKey()
	if err != nil {
		glog.Fatalf("Failed to generate node key: %v", err)
	}
	if err := crypto.SaveECDSA(keyfile, key); err != nil {
		glog.V(logger.Error).Infof("Failed to persist node key: %v", err)
	}
	return key
}

// insert injects a new head block into the current block chain. This method
// assumes that the block is indeed a true head. It will also reset the head
// header and the head fast sync block to this very same block if they are older
// or if they are on a different side chain.
//
// Note, this function assumes that the `mu` mutex is held!
func (bc *BlockChain) insert(block *types.Block) {
	// If the block is on a side chain or an unknown one, force other heads onto it too
	updateHeads := GetCanonicalHash(bc.chainDb, block.NumberU64()) != block.Hash()

	// Add the block to the canonical chain number scheme and mark as the head
	if err := WriteCanonicalHash(bc.chainDb, block.Hash(), block.NumberU64()); err != nil {
		glog.Fatalf("failed to insert block number: %v", err)
	}
	if err := WriteHeadBlockHash(bc.chainDb, block.Hash()); err != nil {
		glog.Fatalf("failed to insert head block hash: %v", err)
	}
	bc.currentBlock = block

	// If the block is better than out head or is on a different chain, force update heads
	if updateHeads {
		if err := WriteHeadHeaderHash(bc.chainDb, block.Hash()); err != nil {
			glog.Fatalf("failed to insert head header hash: %v", err)
		}
		bc.currentHeader = block.Header()

		if err := WriteHeadFastBlockHash(bc.chainDb, block.Hash()); err != nil {
			glog.Fatalf("failed to insert head fast block hash: %v", err)
		}
		bc.currentFastBlock = block
	}
}

// writeHeader writes a header into the local chain, given that its parent is
// already known. If the total difficulty of the newly inserted header becomes
// greater than the current known TD, the canonical chain is re-routed.
//
// Note: This method is not concurrent-safe with inserting blocks simultaneously
// into the chain, as side effects caused by reorganisations cannot be emulated
// without the real blocks. Hence, writing headers directly should only be done
// in two scenarios: pure-header mode of operation (light clients), or properly
// separated header/block phases (non-archive clients).
func (self *BlockChain) writeHeader(header *types.Header) error {
	self.wg.Add(1)
	defer self.wg.Done()

	// Calculate the total difficulty of the header
	ptd := self.GetTd(header.ParentHash)
	if ptd == nil {
		return ParentError(header.ParentHash)
	}

	localTd := self.GetTd(self.currentHeader.Hash())
	externTd := new(big.Int).Add(header.Difficulty, ptd)

	// Make sure no inconsistent state is leaked during insertion
	self.mu.Lock()
	defer self.mu.Unlock()

	// If the total difficulty is higher than our known, add it to the canonical chain
	// Second clause in the if statement reduces the vulnerability to selfish mining.
	// Please refer to http://www.cs.cornell.edu/~ie53/publications/btcProcFC.pdf
	if externTd.Cmp(localTd) > 0 || (externTd.Cmp(localTd) == 0 && mrand.Float64() < 0.5) {
		// Delete any canonical number assignments above the new head
		for i := header.Number.Uint64() + 1; GetCanonicalHash(self.chainDb, i) != (common.Hash{}); i++ {
			DeleteCanonicalHash(self.chainDb, i)
		}
		// Overwrite any stale canonical number assignments
		head := self.GetHeader(header.ParentHash)
		for GetCanonicalHash(self.chainDb, head.Number.Uint64()) != head.Hash() {
			WriteCanonicalHash(self.chainDb, head.Hash(), head.Number.Uint64())
			head = self.GetHeader(head.ParentHash)
		}
		// Extend the canonical chain with the new header
		if err := WriteCanonicalHash(self.chainDb, header.Hash(), header.Number.Uint64()); err != nil {
			glog.Fatalf("failed to insert header number: %v", err)
		}
		if err := WriteHeadHeaderHash(self.chainDb, header.Hash()); err != nil {
			glog.Fatalf("failed to insert head header hash: %v", err)
		}
		self.currentHeader = types.CopyHeader(header)
	}
	// Irrelevant of the canonical status, write the header itself to the database
	if err := WriteTd(self.chainDb, header.Hash(), externTd); err != nil {
		glog.Fatalf("failed to write header total difficulty: %v", err)
	}
	if err := WriteHeader(self.chainDb, header); err != nil {
		glog.Fatalf("filed to write header contents: %v", err)
	}
	return nil
}

// SetHead rewinds the local chain to a new head. Everything above the new head
// will be deleted and the new one set.
func (hc *HeaderChain) SetHead(head uint64, delFn DeleteCallback) {
	height := uint64(0)
	if hc.currentHeader != nil {
		height = hc.currentHeader.Number.Uint64()
	}

	for hc.currentHeader != nil && hc.currentHeader.Number.Uint64() > head {
		hash := hc.currentHeader.Hash()
		if delFn != nil {
			delFn(hash)
		}
		DeleteHeader(hc.chainDb, hash)
		DeleteTd(hc.chainDb, hash)
		hc.currentHeader = hc.GetHeader(hc.currentHeader.ParentHash)
	}
	// Roll back the canonical chain numbering
	for i := height; i > head; i-- {
		DeleteCanonicalHash(hc.chainDb, i)
	}
	// Clear out any stale content from the caches
	hc.headerCache.Purge()
	hc.tdCache.Purge()

	if hc.currentHeader == nil {
		hc.currentHeader = hc.genesisHeader
	}
	hc.currentHeaderHash = hc.currentHeader.Hash()

	if err := WriteHeadHeaderHash(hc.chainDb, hc.currentHeaderHash); err != nil {
		glog.Fatalf("failed to reset head header hash: %v", err)
	}
}

func (bc *ChainManager) setLastState() error {
	data, _ := bc.chainDb.Get([]byte("LastBlock"))
	if len(data) != 0 {
		block := bc.GetBlock(common.BytesToHash(data))
		if block != nil {
			bc.currentBlock = block
			bc.lastBlockHash = block.Hash()
		} else {
			glog.Infof("LastBlock (%x) not found. Recovering...\n", data)
			if bc.recover() {
				glog.Infof("Recover successful")
			} else {
				glog.Fatalf("Recover failed. Please report")
			}
		}
	} else {
		bc.Reset()
	}
	bc.td = bc.currentBlock.Td
	bc.currentGasLimit = CalcGasLimit(bc.currentBlock)

	if glog.V(logger.Info) {
		glog.Infof("Last block (#%v) %x TD=%v\n", bc.currentBlock.Number(), bc.currentBlock.Hash(), bc.td)
	}

	return nil
}

// WriteHeadFastBlockHash stores the fast head block's hash.
func WriteHeadFastBlockHash(db ethdb.Database, hash common.Hash) error {
	if err := db.Put(headFastKey, hash.Bytes()); err != nil {
		glog.Fatalf("failed to store last fast block's hash into database: %v", err)
		return err
	}
	return nil
}

// SetCurrentHeader sets the current head header of the canonical chain.
func (hc *HeaderChain) SetCurrentHeader(head *types.Header) {
	if err := WriteHeadHeaderHash(hc.chainDb, head.Hash()); err != nil {
		glog.Fatalf("failed to insert head header hash: %v", err)
	}
	hc.currentHeader = head
	hc.currentHeaderHash = head.Hash()
}

// WriteCanonicalHash stores the canonical hash for the given block number.
func WriteCanonicalHash(db ethdb.Database, hash common.Hash, number uint64) error {
	key := append(blockNumPrefix, big.NewInt(int64(number)).Bytes()...)
	if err := db.Put(key, hash.Bytes()); err != nil {
		glog.Fatalf("failed to store number to hash mapping into database: %v", err)
		return err
	}
	return nil
}

// writeHeader writes a header into the local chain, given that its parent is
// already known. If the total difficulty of the newly inserted header becomes
// greater than the current known TD, the canonical chain is re-routed.
//
// Note: This method is not concurrent-safe with inserting blocks simultaneously
// into the chain, as side effects caused by reorganisations cannot be emulated
// without the real blocks. Hence, writing headers directly should only be done
// in two scenarios: pure-header mode of operation (light clients), or properly
// separated header/block phases (non-archive clients).
func (self *BlockChain) writeHeader(header *types.Header) error {
	self.wg.Add(1)
	defer self.wg.Done()

	// Calculate the total difficulty of the header
	ptd := self.GetTd(header.ParentHash)
	if ptd == nil {
		return ParentError(header.ParentHash)
	}
	td := new(big.Int).Add(header.Difficulty, ptd)

	// Make sure no inconsistent state is leaked during insertion
	self.mu.Lock()
	defer self.mu.Unlock()

	// If the total difficulty is higher than our known, add it to the canonical chain
	if td.Cmp(self.GetTd(self.currentHeader.Hash())) > 0 {
		// Delete any canonical number assignments above the new head
		for i := header.Number.Uint64() + 1; GetCanonicalHash(self.chainDb, i) != (common.Hash{}); i++ {
			DeleteCanonicalHash(self.chainDb, i)
		}
		// Overwrite any stale canonical number assignments
		head := self.GetHeader(header.ParentHash)
		for GetCanonicalHash(self.chainDb, head.Number.Uint64()) != head.Hash() {
			WriteCanonicalHash(self.chainDb, head.Hash(), head.Number.Uint64())
			head = self.GetHeader(head.ParentHash)
		}
		// Extend the canonical chain with the new header
		if err := WriteCanonicalHash(self.chainDb, header.Hash(), header.Number.Uint64()); err != nil {
			glog.Fatalf("failed to insert header number: %v", err)
		}
		if err := WriteHeadHeaderHash(self.chainDb, header.Hash()); err != nil {
			glog.Fatalf("failed to insert head header hash: %v", err)
		}
		self.currentHeader = types.CopyHeader(header)
	}
	// Irrelevant of the canonical status, write the header itself to the database
	if err := WriteTd(self.chainDb, header.Hash(), td); err != nil {
		glog.Fatalf("failed to write header total difficulty: %v", err)
	}
	if err := WriteHeader(self.chainDb, header); err != nil {
		glog.Fatalf("filed to write header contents: %v", err)
	}
	return nil
}

// WriteBlock writes the block to the chain.
func (self *BlockChain) WriteBlock(block *types.Block) (status writeStatus, err error) {
	self.wg.Add(1)
	defer self.wg.Done()

	// Calculate the total difficulty of the block
	ptd := self.GetTd(block.ParentHash())
	if ptd == nil {
		return NonStatTy, ParentError(block.ParentHash())
	}

	localTd := self.GetTd(self.currentBlock.Hash())
	externTd := new(big.Int).Add(block.Difficulty(), ptd)

	// Make sure no inconsistent state is leaked during insertion
	self.mu.Lock()
	defer self.mu.Unlock()

	// If the total difficulty is higher than our known, add it to the canonical chain
	// Second clause in the if statement reduces the vulnerability to selfish mining.
	// Please refer to http://www.cs.cornell.edu/~ie53/publications/btcProcFC.pdf
	if externTd.Cmp(localTd) > 0 || (externTd.Cmp(localTd) == 0 && mrand.Float64() < 0.5) {
		// Reorganize the chain if the parent is not the head block
		if block.ParentHash() != self.currentBlock.Hash() {
			if err := self.reorg(self.currentBlock, block); err != nil {
				return NonStatTy, err
			}
		}
		// Insert the block as the new head of the chain
		self.insert(block)
		status = CanonStatTy
	} else {
		status = SideStatTy
	}
	// Irrelevant of the canonical status, write the block itself to the database
	if err := WriteTd(self.chainDb, block.Hash(), externTd); err != nil {
		glog.Fatalf("failed to write block total difficulty: %v", err)
	}
	if err := WriteBlock(self.chainDb, block); err != nil {
		glog.Fatalf("filed to write block contents: %v", err)
	}
	self.futureBlocks.Remove(block.Hash())

	return
}

// ResetWithGenesisBlock purges the entire blockchain, restoring it to the
// specified genesis state.
func (bc *BlockChain) ResetWithGenesisBlock(genesis *types.Block) {
	// Dump the entire block chain and purge the caches
	bc.SetHead(0)

	bc.mu.Lock()
	defer bc.mu.Unlock()

	// Prepare the genesis block and reinitialise the chain
	if err := WriteTd(bc.chainDb, genesis.Hash(), genesis.Difficulty()); err != nil {
		glog.Fatalf("failed to write genesis block TD: %v", err)
	}
	if err := WriteBlock(bc.chainDb, genesis); err != nil {
		glog.Fatalf("failed to write genesis block: %v", err)
	}
	bc.genesisBlock = genesis
	bc.insert(bc.genesisBlock)
	bc.currentBlock = bc.genesisBlock
	bc.currentHeader = bc.genesisBlock.Header()
	bc.currentFastBlock = bc.genesisBlock
}

// WriteBlock writes the block to the chain.
func (self *BlockChain) WriteBlock(block *types.Block) (status writeStatus, err error) {
	self.wg.Add(1)
	defer self.wg.Done()

	// Calculate the total difficulty of the block
	ptd := self.GetTd(block.ParentHash())
	if ptd == nil {
		return NonStatTy, ParentError(block.ParentHash())
	}
	td := new(big.Int).Add(block.Difficulty(), ptd)

	// Make sure no inconsistent state is leaked during insertion
	self.mu.Lock()
	defer self.mu.Unlock()

	// If the total difficulty is higher than our known, add it to the canonical chain
	if td.Cmp(self.GetTd(self.currentBlock.Hash())) > 0 {
		// Reorganize the chain if the parent is not the head block
		if block.ParentHash() != self.currentBlock.Hash() {
			if err := self.reorg(self.currentBlock, block); err != nil {
				return NonStatTy, err
			}
		}
		// Insert the block as the new head of the chain
		self.insert(block)
		status = CanonStatTy
	} else {
		status = SideStatTy
	}
	// Irrelevant of the canonical status, write the block itself to the database
	if err := WriteTd(self.chainDb, block.Hash(), td); err != nil {
		glog.Fatalf("failed to write block total difficulty: %v", err)
	}
	if err := WriteBlock(self.chainDb, block); err != nil {
		glog.Fatalf("filed to write block contents: %v", err)
	}
	self.futureBlocks.Remove(block.Hash())

	return
}

// WriteTd serializes the total difficulty of a block into the database.
func WriteTd(db ethdb.Database, hash common.Hash, td *big.Int) error {
	data, err := rlp.EncodeToBytes(td)
	if err != nil {
		return err
	}
	key := append(append(blockPrefix, hash.Bytes()...), tdSuffix...)
	if err := db.Put(key, data); err != nil {
		glog.Fatalf("failed to store block total difficulty into database: %v", err)
		return err
	}
	glog.V(logger.Debug).Infof("stored block total difficulty [%x…]: %v", hash.Bytes()[:4], td)
	return nil
}

// WriteBody serializes the body of a block into the database.
func WriteBody(db ethdb.Database, hash common.Hash, body *types.Body) error {
	data, err := rlp.EncodeToBytes(body)
	if err != nil {
		return err
	}
	key := append(append(blockPrefix, hash.Bytes()...), bodySuffix...)
	if err := db.Put(key, data); err != nil {
		glog.Fatalf("failed to store block body into database: %v", err)
		return err
	}
	glog.V(logger.Debug).Infof("stored block body [%x…]", hash.Bytes()[:4])
	return nil
}

// WriteHeader serializes a block header into the database.
func WriteHeader(db ethdb.Database, header *types.Header) error {
	data, err := rlp.EncodeToBytes(header)
	if err != nil {
		return err
	}
	key := append(append(blockPrefix, header.Hash().Bytes()...), headerSuffix...)
	if err := db.Put(key, data); err != nil {
		glog.Fatalf("failed to store header into database: %v", err)
		return err
	}
	glog.V(logger.Debug).Infof("stored header #%v [%x…]", header.Number, header.Hash().Bytes()[:4])
	return nil
}

// sync databases every minute. If flushing fails we exit immediatly. The system
// may not continue under any circumstances.
func (s *Expanse) syncDatabases() {
	ticker := time.NewTicker(1 * time.Minute)
done:
	for {
		select {
		case <-ticker.C:
			// don't change the order of database flushes
			if err := s.dappDb.Flush(); err != nil {
				glog.Fatalf("fatal error: flush dappDb: %v (Restart your node. We are aware of this issue)\n", err)
			}
			if err := s.chainDb.Flush(); err != nil {
				glog.Fatalf("fatal error: flush chainDb: %v (Restart your node. We are aware of this issue)\n", err)
			}
		case <-s.shutdownChan:
			break done
		}
	}

	s.chainDb.Close()
	s.dappDb.Close()

	close(s.databasesClosed)
}

// 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.Database, hash common.Hash, 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
	if err := db.Put(append(blockReceiptsPrefix, hash.Bytes()...), bytes); err != nil {
		glog.Fatalf("failed to store block receipts into database: %v", err)
		return err
	}
	glog.V(logger.Debug).Infof("stored block receipts [%x…]", hash.Bytes()[:4])
	return nil
}

// WriteReceipts stores a batch of transaction receipts into the database.
func WriteReceipts(db ethdb.Database, receipts types.Receipts) error {
	batch := db.NewBatch()

	// Iterate over all the receipts and queue them for database injection
	for _, receipt := range receipts {
		storageReceipt := (*types.ReceiptForStorage)(receipt)
		data, err := rlp.EncodeToBytes(storageReceipt)
		if err != nil {
			return err
		}
		if err := batch.Put(append(receiptsPrefix, receipt.TxHash.Bytes()...), data); err != nil {
			return err
		}
	}
	// Write the scheduled data into the database
	if err := batch.Write(); err != nil {
		glog.Fatalf("failed to store receipts into database: %v", err)
		return err
	}
	return nil
}

// WriteTransactions stores the transactions associated with a specific block
// into the given database. Beside writing the transaction, the function also
// stores a metadata entry along with the transaction, detailing the position
// of this within the blockchain.
func WriteTransactions(db ethdb.Database, block *types.Block) error {
	batch := db.NewBatch()

	// Iterate over each transaction and encode it with its metadata
	for i, tx := range block.Transactions() {
		// Encode and queue up the transaction for storage
		data, err := rlp.EncodeToBytes(tx)
		if err != nil {
			return err
		}
		if err := batch.Put(tx.Hash().Bytes(), data); err != nil {
			return err
		}
		// Encode and queue up the transaction metadata for storage
		meta := struct {
			BlockHash  common.Hash
			BlockIndex uint64
			Index      uint64
		}{
			BlockHash:  block.Hash(),
			BlockIndex: block.NumberU64(),
			Index:      uint64(i),
		}
		data, err = rlp.EncodeToBytes(meta)
		if err != nil {
			return err
		}
		if err := batch.Put(append(tx.Hash().Bytes(), txMetaSuffix...), data); err != nil {
			return err
		}
	}
	// Write the scheduled data into the database
	if err := batch.Write(); err != nil {
		glog.Fatalf("failed to store transactions into database: %v", err)
		return err
	}
	return nil
}

//.........这里部分代码省略.........
			if !self.HasHeader(block.Hash()) {
				errs[index] = fmt.Errorf("containing header #%d [%x…] unknown", block.Number(), block.Hash().Bytes()[:4])
				atomic.AddInt32(&failed, 1)
				return
			}
			// Skip if the entire data is already known
			if self.HasBlock(block.Hash()) {
				atomic.AddInt32(&stats.ignored, 1)
				continue
			}
			// Compute all the non-consensus fields of the receipts
			transactions, logIndex := block.Transactions(), uint(0)
			for j := 0; j < len(receipts); j++ {
				// The transaction hash can be retrieved from the transaction itself
				receipts[j].TxHash = transactions[j].Hash()

				// The contract address can be derived from the transaction itself
				if MessageCreatesContract(transactions[j]) {
					from, _ := transactions[j].From()
					receipts[j].ContractAddress = crypto.CreateAddress(from, transactions[j].Nonce())
				}
				// The used gas can be calculated based on previous receipts
				if j == 0 {
					receipts[j].GasUsed = new(big.Int).Set(receipts[j].CumulativeGasUsed)
				} else {
					receipts[j].GasUsed = new(big.Int).Sub(receipts[j].CumulativeGasUsed, receipts[j-1].CumulativeGasUsed)
				}
				// The derived log fields can simply be set from the block and transaction
				for k := 0; k < len(receipts[j].Logs); k++ {
					receipts[j].Logs[k].BlockNumber = block.NumberU64()
					receipts[j].Logs[k].BlockHash = block.Hash()
					receipts[j].Logs[k].TxHash = receipts[j].TxHash
					receipts[j].Logs[k].TxIndex = uint(j)
					receipts[j].Logs[k].Index = logIndex
					logIndex++
				}
			}
			// Write all the data out into the database
			if err := WriteBody(self.chainDb, block.Hash(), &types.Body{block.Transactions(), block.Uncles()}); err != nil {
				errs[index] = fmt.Errorf("failed to write block body: %v", err)
				atomic.AddInt32(&failed, 1)
				glog.Fatal(errs[index])
				return
			}
			if err := WriteBlockReceipts(self.chainDb, block.Hash(), receipts); err != nil {
				errs[index] = fmt.Errorf("failed to write block receipts: %v", err)
				atomic.AddInt32(&failed, 1)
				glog.Fatal(errs[index])
				return
			}
			if err := WriteMipmapBloom(self.chainDb, block.NumberU64(), receipts); err != nil {
				errs[index] = fmt.Errorf("failed to write log blooms: %v", err)
				atomic.AddInt32(&failed, 1)
				glog.Fatal(errs[index])
				return
			}
			atomic.AddInt32(&stats.processed, 1)
		}
	}
	// Start as many worker threads as goroutines allowed
	pending := new(sync.WaitGroup)
	for i := 0; i < runtime.GOMAXPROCS(0); i++ {
		pending.Add(1)
		go func(id int) {
			defer pending.Done()
			process(id)
		}(i)
	}
	pending.Wait()

	// If anything failed, report
	if failed > 0 {
		for i, err := range errs {
			if err != nil {
				return i, err
			}
		}
	}
	if atomic.LoadInt32(&self.procInterrupt) == 1 {
		glog.V(logger.Debug).Infoln("premature abort during receipt chain processing")
		return 0, nil
	}
	// Update the head fast sync block if better
	self.mu.Lock()
	head := blockChain[len(errs)-1]
	if self.GetTd(self.currentFastBlock.Hash()).Cmp(self.GetTd(head.Hash())) < 0 {
		if err := WriteHeadFastBlockHash(self.chainDb, head.Hash()); err != nil {
			glog.Fatalf("failed to update head fast block hash: %v", err)
		}
		self.currentFastBlock = head
	}
	self.mu.Unlock()

	// Report some public statistics so the user has a clue what's going on
	first, last := blockChain[0], blockChain[len(blockChain)-1]
	glog.V(logger.Info).Infof("imported %d receipt(s) (%d ignored) in %v. #%d [%x… / %x…]", stats.processed, stats.ignored,
		time.Since(start), last.Number(), first.Hash().Bytes()[:4], last.Hash().Bytes()[:4])

	return 0, nil
}