func (self *Filter) getLogs(start, end uint64) (logs vm.Logs) {
	var block *types.Block

	for i := start; i <= end; i++ {
		hash := core.GetCanonicalHash(self.db, i)
		if hash != (common.Hash{}) {
			block = core.GetBlock(self.db, hash)
		} else { // block not found
			return logs
		}

		// Use bloom filtering to see if this block is interesting given the
		// current parameters
		if self.bloomFilter(block) {
			// Get the logs of the block
			var (
				receipts   = core.GetBlockReceipts(self.db, block.Hash())
				unfiltered vm.Logs
			)
			for _, receipt := range receipts {
				unfiltered = append(unfiltered, receipt.Logs...)
			}
			logs = append(logs, self.FilterLogs(unfiltered)...)
		}
	}

	return logs
}

// reportBlock reports the given block and error using the canonical block
// reporting tool. Reporting the block to the service is handled in a separate
// goroutine.
func reportBlock(block *types.Block, err error) {
	if glog.V(logger.Error) {
		glog.Errorf("Bad block #%v (%s)\n", block.Number(), block.Hash().Hex())
		glog.Errorf("    %v", err)
	}
	go ReportBlock(block, err)
}

// GenerateChain creates a chain of n blocks. The first block's
// parent will be the provided parent. db is used to store
// intermediate states and should contain the parent's state trie.
//
// The generator function is called with a new block generator for
// every block. Any transactions and uncles added to the generator
// become part of the block. If gen is nil, the blocks will be empty
// and their coinbase will be the zero address.
//
// Blocks created by GenerateChain do not contain valid proof of work
// values. Inserting them into BlockChain requires use of FakePow or
// a similar non-validating proof of work implementation.
func GenerateChain(parent *types.Block, db ethdb.Database, n int, gen func(int, *BlockGen)) ([]*types.Block, []types.Receipts) {
	blocks, receipts := make(types.Blocks, n), make([]types.Receipts, n)
	genblock := func(i int, h *types.Header, statedb *state.StateDB) (*types.Block, types.Receipts) {
		b := &BlockGen{parent: parent, i: i, chain: blocks, header: h, statedb: statedb}
		if gen != nil {
			gen(i, b)
		}
		AccumulateRewards(statedb, h, b.uncles)
		root, err := statedb.Commit()
		if err != nil {
			panic(fmt.Sprintf("state write error: %v", err))
		}
		h.Root = root
		return types.NewBlock(h, b.txs, b.uncles, b.receipts), b.receipts
	}
	for i := 0; i < n; i++ {
		statedb, err := state.New(parent.Root(), db)
		if err != nil {
			panic(err)
		}
		header := makeHeader(parent, statedb)
		block, receipt := genblock(i, header, statedb)
		blocks[i] = block
		receipts[i] = receipt
		parent = block
	}
	return blocks, receipts
}

func (self *Filter) bloomFilter(block *types.Block) bool {
	if len(self.addresses) > 0 {
		var included bool
		for _, addr := range self.addresses {
			if types.BloomLookup(block.Bloom(), addr) {
				included = true
				break
			}
		}

		if !included {
			return false
		}
	}

	for _, sub := range self.topics {
		var included bool
		for _, topic := range sub {
			if (topic == common.Hash{}) || types.BloomLookup(block.Bloom(), topic) {
				included = true
				break
			}
		}
		if !included {
			return false
		}
	}

	return true
}

// GetUnclesInChain retrieves all the uncles from a given block backwards until
// a specific distance is reached.
func (self *BlockChain) GetUnclesInChain(block *types.Block, length int) []*types.Header {
	uncles := []*types.Header{}
	for i := 0; block != nil && i < length; i++ {
		uncles = append(uncles, block.Uncles()...)
		block = self.GetBlock(block.ParentHash())
	}
	return uncles
}

// newRPCTransaction returns a transaction that will serialize to the RPC representation.
func newRPCTransaction(b *types.Block, txHash common.Hash) (*RPCTransaction, error) {
	for idx, tx := range b.Transactions() {
		if tx.Hash() == txHash {
			return newRPCTransactionFromBlockIndex(b, idx)
		}
	}

	return nil, nil
}

// CalcGasLimit computes the gas limit of the next block after parent.
// The result may be modified by the caller.
// This is miner strategy, not consensus protocol.
func CalcGasLimit(parent *types.Block) *big.Int {
	// contrib = (parentGasUsed * 3 / 2) / 1024
	contrib := new(big.Int).Mul(parent.GasUsed(), big.NewInt(3))
	contrib = contrib.Div(contrib, big.NewInt(2))
	contrib = contrib.Div(contrib, params.GasLimitBoundDivisor)

	// decay = parentGasLimit / 1024 -1
	decay := new(big.Int).Div(parent.GasLimit(), params.GasLimitBoundDivisor)
	decay.Sub(decay, big.NewInt(1))

	/*
		strategy: gasLimit of block-to-mine is set based on parent's
		gasUsed value.  if parentGasUsed > parentGasLimit * (2/3) then we
		increase it, otherwise lower it (or leave it unchanged if it's right
		at that usage) the amount increased/decreased depends on how far away
		from parentGasLimit * (2/3) parentGasUsed is.
	*/
	gl := new(big.Int).Sub(parent.GasLimit(), decay)
	gl = gl.Add(gl, contrib)
	gl.Set(common.BigMax(gl, params.MinGasLimit))

	// however, if we're now below the target (GenesisGasLimit) we increase the
	// limit as much as we can (parentGasLimit / 1024 -1)
	if gl.Cmp(params.GenesisGasLimit) < 0 {
		gl.Add(parent.GasLimit(), decay)
		gl.Set(common.BigMin(gl, params.GenesisGasLimit))
	}
	return gl
}

// newRPCTransaction returns a transaction that will serialize to the RPC representation.
func newRPCTransactionFromBlockIndex(b *types.Block, txIndex int) (*RPCTransaction, error) {
	if txIndex >= 0 && txIndex < len(b.Transactions()) {
		tx := b.Transactions()[txIndex]
		from, err := tx.From()
		if err != nil {
			return nil, err
		}

		return &RPCTransaction{
			BlockHash:        b.Hash(),
			BlockNumber:      rpc.NewHexNumber(b.Number()),
			From:             from,
			Gas:              rpc.NewHexNumber(tx.Gas()),
			GasPrice:         rpc.NewHexNumber(tx.GasPrice()),
			Hash:             tx.Hash(),
			Input:            fmt.Sprintf("0x%x", tx.Data()),
			Nonce:            rpc.NewHexNumber(tx.Nonce()),
			To:               tx.To(),
			TransactionIndex: rpc.NewHexNumber(txIndex),
			Value:            rpc.NewHexNumber(tx.Value()),
		}, nil
	}

	return nil, nil
}

// enqueue schedules a new future import operation, if the block to be imported
// has not yet been seen.
func (f *Fetcher) enqueue(peer string, block *types.Block) {
	hash := block.Hash()

	// Ensure the peer isn't DOSing us
	count := f.queues[peer] + 1
	if count > blockLimit {
		glog.V(logger.Debug).Infof("Peer %s: discarded block #%d [%x…], exceeded allowance (%d)", peer, block.NumberU64(), hash.Bytes()[:4], blockLimit)
		propBroadcastDOSMeter.Mark(1)
		f.forgetHash(hash)
		return
	}
	// Discard any past or too distant blocks
	if dist := int64(block.NumberU64()) - int64(f.chainHeight()); dist < -maxUncleDist || dist > maxQueueDist {
		glog.V(logger.Debug).Infof("Peer %s: discarded block #%d [%x…], distance %d", peer, block.NumberU64(), hash.Bytes()[:4], dist)
		propBroadcastDropMeter.Mark(1)
		f.forgetHash(hash)
		return
	}
	// Schedule the block for future importing
	if _, ok := f.queued[hash]; !ok {
		op := &inject{
			origin: peer,
			block:  block,
		}
		f.queues[peer] = count
		f.queued[hash] = op
		f.queue.Push(op, -float32(block.NumberU64()))
		if f.queueChangeHook != nil {
			f.queueChangeHook(op.block.Hash(), true)
		}
		if glog.V(logger.Debug) {
			glog.Infof("Peer %s: queued block #%d [%x…], total %v", peer, block.NumberU64(), hash.Bytes()[:4], f.queue.Size())
		}
	}
}

func (self *GasPriceOracle) processBlock(block *types.Block) {
	i := block.NumberU64()
	if i > self.lastProcessed {
		self.lastProcessed = i
	}

	lastBase := self.minPrice
	bpl := self.blocks[i-1]
	if bpl != nil {
		lastBase = bpl.baseGasPrice
	}
	if lastBase == nil {
		return
	}

	var corr int
	lp := self.lowestPrice(block)
	if lp == nil {
		return
	}

	if lastBase.Cmp(lp) < 0 {
		corr = self.eth.GpobaseStepUp
	} else {
		corr = -self.eth.GpobaseStepDown
	}

	crand := int64(corr * (900 + rand.Intn(201)))
	newBase := new(big.Int).Mul(lastBase, big.NewInt(1000000+crand))
	newBase.Div(newBase, big.NewInt(1000000))

	if newBase.Cmp(self.minBase) < 0 {
		newBase = self.minBase
	}

	bpi := self.blocks[i]
	if bpi == nil {
		bpi = &blockPriceInfo{}
		self.blocks[i] = bpi
	}
	bpi.baseGasPrice = newBase
	self.lastBaseMutex.Lock()
	self.lastBase = newBase
	self.lastBaseMutex.Unlock()

	glog.V(logger.Detail).Infof("Processed block #%v, base price is %v\n", block.NumberU64(), newBase.Int64())
}

// insert spawns a new goroutine to run a block insertion into the chain. If the
// block's number is at the same height as the current import phase, if updates
// the phase states accordingly.
func (f *Fetcher) insert(peer string, block *types.Block) {
	hash := block.Hash()

	// Run the import on a new thread
	glog.V(logger.Debug).Infof("Peer %s: importing block #%d [%x…]", peer, block.NumberU64(), hash[:4])
	go func() {
		defer func() { f.done <- hash }()

		// If the parent's unknown, abort insertion
		parent := f.getBlock(block.ParentHash())
		if parent == nil {
			glog.V(logger.Debug).Infof("Peer %s: parent []%x] of block #%d [%x…] unknown", block.ParentHash().Bytes()[:4], peer, block.NumberU64(), hash[:4])
			return
		}
		// Quickly validate the header and propagate the block if it passes
		switch err := f.validateBlock(block, parent); err {
		case nil:
			// All ok, quickly propagate to our peers
			propBroadcastOutTimer.UpdateSince(block.ReceivedAt)
			go f.broadcastBlock(block, true)

		case core.BlockFutureErr:
			// Weird future block, don't fail, but neither propagate

		default:
			// Something went very wrong, drop the peer
			glog.V(logger.Debug).Infof("Peer %s: block #%d [%x…] verification failed: %v", peer, block.NumberU64(), hash[:4], err)
			f.dropPeer(peer)
			return
		}
		// Run the actual import and log any issues
		if _, err := f.insertChain(types.Blocks{block}); err != nil {
			glog.V(logger.Warn).Infof("Peer %s: block #%d [%x…] import failed: %v", peer, block.NumberU64(), hash[:4], err)
			return
		}
		// If import succeeded, broadcast the block
		propAnnounceOutTimer.UpdateSince(block.ReceivedAt)
		go f.broadcastBlock(block, false)

		// Invoke the testing hook if needed
		if f.importedHook != nil {
			f.importedHook(block)
		}
	}()
}

func makeHeader(parent *types.Block, state *state.StateDB) *types.Header {
	var time *big.Int
	if parent.Time() == nil {
		time = big.NewInt(10)
	} else {
		time = new(big.Int).Add(parent.Time(), big.NewInt(10)) // block time is fixed at 10 seconds
	}
	return &types.Header{
		Root:       state.IntermediateRoot(),
		ParentHash: parent.Hash(),
		Coinbase:   parent.Coinbase(),
		Difficulty: CalcDifficulty(time.Uint64(), new(big.Int).Sub(time, big.NewInt(10)).Uint64(), parent.Number(), parent.Difficulty()),
		GasLimit:   CalcGasLimit(parent),
		GasUsed:    new(big.Int),
		Number:     new(big.Int).Add(parent.Number(), common.Big1),
		Time:       time,
	}
}

// WriteBlock serializes a block into the database, header and body separately.
func WriteBlock(db ethdb.Database, block *types.Block) error {
	// Store the body first to retain database consistency
	if err := WriteBody(db, block.Hash(), &types.Body{block.Transactions(), block.Uncles()}); err != nil {
		return err
	}
	// Store the header too, signaling full block ownership
	if err := WriteHeader(db, block.Header()); err != nil {
		return err
	}
	return nil
}

// 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
}

// returns the lowers possible price with which a tx was or could have been included
func (self *GasPriceOracle) lowestPrice(block *types.Block) *big.Int {
	gasUsed := big.NewInt(0)

	receipts := core.GetBlockReceipts(self.eth.ChainDb(), block.Hash())
	if len(receipts) > 0 {
		if cgu := receipts[len(receipts)-1].CumulativeGasUsed; cgu != nil {
			gasUsed = receipts[len(receipts)-1].CumulativeGasUsed
		}
	}

	if new(big.Int).Mul(gasUsed, big.NewInt(100)).Cmp(new(big.Int).Mul(block.GasLimit(),
		big.NewInt(int64(self.eth.GpoFullBlockRatio)))) < 0 {
		// block is not full, could have posted a tx with MinGasPrice
		return big.NewInt(0)
	}

	txs := block.Transactions()
	if len(txs) == 0 {
		return big.NewInt(0)
	}
	// block is full, find smallest gasPrice
	minPrice := txs[0].GasPrice()
	for i := 1; i < len(txs); i++ {
		price := txs[i].GasPrice()
		if price.Cmp(minPrice) < 0 {
			minPrice = price
		}
	}
	return minPrice
}

// Process processes the state changes according to the Ethereum rules by running
// the transaction messages using the statedb and applying any rewards to both
// the processor (coinbase) and any included uncles.
//
// Process returns the receipts and logs accumulated during the process and
// returns the amount of gas that was used in the process. If any of the
// transactions failed to execute due to insufficient gas it will return an error.
func (p *StateProcessor) Process(block *types.Block, statedb *state.StateDB) (types.Receipts, vm.Logs, *big.Int, error) {
	var (
		receipts     types.Receipts
		totalUsedGas = big.NewInt(0)
		err          error
		header       = block.Header()
		allLogs      vm.Logs
		gp           = new(GasPool).AddGas(block.GasLimit())
	)

	for i, tx := range block.Transactions() {
		statedb.StartRecord(tx.Hash(), block.Hash(), i)

		receipt, logs, _, err := ApplyTransaction(p.bc, gp, statedb, header, tx, totalUsedGas)
		if err != nil {
			return nil, nil, totalUsedGas, err
		}
		receipts = append(receipts, receipt)
		allLogs = append(allLogs, logs...)
	}
	AccumulateRewards(statedb, header, block.Uncles())

	return receipts, allLogs, totalUsedGas, err
}

// makeCurrent creates a new environment for the current cycle.
func (self *worker) makeCurrent(parent *types.Block, header *types.Header) error {
	state, err := state.New(parent.Root(), self.eth.ChainDb())
	if err != nil {
		return err
	}
	work := &Work{
		state:     state,
		ancestors: set.New(),
		family:    set.New(),
		uncles:    set.New(),
		header:    header,
		createdAt: time.Now(),
	}

	// when 08 is processed ancestors contain 07 (quick block)
	for _, ancestor := range self.chain.GetBlocksFromHash(parent.Hash(), 7) {
		for _, uncle := range ancestor.Uncles() {
			work.family.Add(uncle.Hash())
		}
		work.family.Add(ancestor.Hash())
		work.ancestors.Add(ancestor.Hash())
	}
	accounts, _ := self.eth.AccountManager().Accounts()

	// Keep track of transactions which return errors so they can be removed
	work.remove = set.New()
	work.tcount = 0
	work.ignoredTransactors = set.New()
	work.lowGasTransactors = set.New()
	work.ownedAccounts = accountAddressesSet(accounts)
	if self.current != nil {
		work.localMinedBlocks = self.current.localMinedBlocks
	}
	self.current = work
	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
}

// ValidateState validates the various changes that happen after a state
// transition, such as amount of used gas, the receipt roots and the state root
// itself. ValidateState returns a database batch if the validation was a succes
// otherwise nil and an error is returned.
func (v *BlockValidator) ValidateState(block, parent *types.Block, statedb *state.StateDB, receipts types.Receipts, usedGas *big.Int) (err error) {
	header := block.Header()
	if block.GasUsed().Cmp(usedGas) != 0 {
		return ValidationError(fmt.Sprintf("gas used error (%v / %v)", block.GasUsed(), usedGas))
	}
	// Validate the received block's bloom with the one derived from the generated receipts.
	// For valid blocks this should always validate to true.
	rbloom := types.CreateBloom(receipts)
	if rbloom != header.Bloom {
		return fmt.Errorf("unable to replicate block's bloom=%x", rbloom)
	}
	// Tre receipt Trie's root (R = (Tr [[H1, R1], ... [Hn, R1]]))
	receiptSha := types.DeriveSha(receipts)
	if receiptSha != header.ReceiptHash {
		return fmt.Errorf("invalid receipt root hash. received=%x calculated=%x", header.ReceiptHash, receiptSha)
	}
	// Validate the state root against the received state root and throw
	// an error if they don't match.
	if root := statedb.IntermediateRoot(); header.Root != root {
		return fmt.Errorf("invalid merkle root: header=%x computed=%x", header.Root, root)
	}
	return nil
}

// 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
	}
}