115 lines
3.6 KiB
Go
115 lines
3.6 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of go-ethereum.
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//
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// go-ethereum is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// go-ethereum is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
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package core
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import (
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"bytes"
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"math/big"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/core/types"
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"github.com/ethereum/go-ethereum/logger"
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"github.com/ethereum/go-ethereum/logger/glog"
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"github.com/ethereum/go-ethereum/params"
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"github.com/ethereum/go-ethereum/rlp"
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)
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// CalcDifficulty is the difficulty adjustment algorithm. It returns
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// the difficulty that a new block b should have when created at time
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// given the parent block's time and difficulty.
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func CalcDifficulty(time int64, parentTime int64, parentDiff *big.Int) *big.Int {
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diff := new(big.Int)
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adjust := new(big.Int).Div(parentDiff, params.DifficultyBoundDivisor)
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if big.NewInt(time-parentTime).Cmp(params.DurationLimit) < 0 {
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diff.Add(parentDiff, adjust)
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} else {
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diff.Sub(parentDiff, adjust)
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}
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if diff.Cmp(params.MinimumDifficulty) < 0 {
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return params.MinimumDifficulty
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}
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return diff
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}
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// CalcTD computes the total difficulty of block.
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func CalcTD(block, parent *types.Block) *big.Int {
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if parent == nil {
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return block.Difficulty()
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}
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d := block.Difficulty()
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d.Add(d, parent.Td)
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return d
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}
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// CalcGasLimit computes the gas limit of the next block after parent.
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// The result may be modified by the caller.
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func CalcGasLimit(parent *types.Block) *big.Int {
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decay := new(big.Int).Div(parent.GasLimit(), params.GasLimitBoundDivisor)
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contrib := new(big.Int).Mul(parent.GasUsed(), big.NewInt(3))
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contrib = contrib.Div(contrib, big.NewInt(2))
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contrib = contrib.Div(contrib, params.GasLimitBoundDivisor)
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gl := new(big.Int).Sub(parent.GasLimit(), decay)
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gl = gl.Add(gl, contrib)
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gl = gl.Add(gl, big.NewInt(1))
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gl.Set(common.BigMax(gl, params.MinGasLimit))
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if gl.Cmp(params.GenesisGasLimit) < 0 {
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gl.Add(parent.GasLimit(), decay)
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gl.Set(common.BigMin(gl, params.GenesisGasLimit))
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}
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return gl
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}
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// GetBlockByHash returns the block corresponding to the hash or nil if not found
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func GetBlockByHash(db common.Database, hash common.Hash) *types.Block {
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data, _ := db.Get(append(blockHashPre, hash[:]...))
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if len(data) == 0 {
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return nil
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}
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var block types.StorageBlock
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if err := rlp.Decode(bytes.NewReader(data), &block); err != nil {
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glog.V(logger.Error).Infof("invalid block RLP for hash %x: %v", hash, err)
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return nil
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}
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return (*types.Block)(&block)
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}
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// GetBlockByHash returns the canonical block by number or nil if not found
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func GetBlockByNumber(db common.Database, number uint64) *types.Block {
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key, _ := db.Get(append(blockNumPre, big.NewInt(int64(number)).Bytes()...))
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if len(key) == 0 {
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return nil
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}
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return GetBlockByHash(db, common.BytesToHash(key))
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}
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// WriteHead force writes the current head
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func WriteHead(db common.Database, block *types.Block) error {
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key := append(blockNumPre, block.Number().Bytes()...)
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err := db.Put(key, block.Hash().Bytes())
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if err != nil {
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return err
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}
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err = db.Put([]byte("LastBlock"), block.Hash().Bytes())
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if err != nil {
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return err
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}
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return nil
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}
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