// 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
}
// rpcOutputBlock converts the given block to the RPC output which depends on fullTx. If inclTx is true transactions are
// returned. When fullTx is true the returned block contains full transaction details, otherwise it will only contain
// transaction hashes.
func (s *PublicBlockChainAPI) rpcOutputBlock(b *types.Block, inclTx bool, fullTx bool) (map[string]interface{}, error) {
fields := map[string]interface{}{
"number": rpc.NewHexNumber(b.Number()),
"hash": b.Hash(),
"parentHash": b.ParentHash(),
"nonce": b.Header().Nonce,
"sha3Uncles": b.UncleHash(),
"logsBloom": b.Bloom(),
"stateRoot": b.Root(),
"miner": b.Coinbase(),
"difficulty": rpc.NewHexNumber(b.Difficulty()),
"totalDifficulty": rpc.NewHexNumber(s.bc.GetTd(b.Hash())),
"extraData": fmt.Sprintf("0x%x", b.Extra()),
"size": rpc.NewHexNumber(b.Size().Int64()),
"gasLimit": rpc.NewHexNumber(b.GasLimit()),
"gasUsed": rpc.NewHexNumber(b.GasUsed()),
"timestamp": rpc.NewHexNumber(b.Time()),
"transactionsRoot": b.TxHash(),
"receiptRoot": b.ReceiptHash(),
}
if inclTx {
formatTx := func(tx *types.Transaction) (interface{}, error) {
return tx.Hash(), nil
}
if fullTx {
formatTx = func(tx *types.Transaction) (interface{}, error) {
return newRPCTransaction(b, tx.Hash())
}
}
txs := b.Transactions()
transactions := make([]interface{}, len(txs))
var err error
for i, tx := range b.Transactions() {
if transactions[i], err = formatTx(tx); err != nil {
return nil, err
}
}
fields["transactions"] = transactions
}
uncles := b.Uncles()
uncleHashes := make([]common.Hash, len(uncles))
for i, uncle := range uncles {
uncleHashes[i] = uncle.Hash()
}
fields["uncles"] = uncleHashes
return fields, 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
}
