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core: clarify code in forkchoice (#26257) 

refactoring without logic change
This commit is contained in:
setunapo 2022-11-28 18:07:25 +08:00 committed by GitHub
parent 1325fef102
commit 0dc9b01c11
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 18 additions and 13 deletions
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23
core/forkchoice.go
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@ -74,10 +74,10 @@ func NewForkChoice(chainReader ChainReader, preserve func(header *types.Header)
// In the td mode, the new head is chosen if the corresponding
// total difficulty is higher. In the extern mode, the trusted
// header is always selected as the head.
func (f *ForkChoice) ReorgNeeded(current *types.Header, header *types.Header) (bool, error) {
func (f *ForkChoice) ReorgNeeded(current *types.Header, extern *types.Header) (bool, error) {
var (
localTD = f.chain.GetTd(current.Hash(), current.Number.Uint64())
externTd = f.chain.GetTd(header.Hash(), header.Number.Uint64())
externTd = f.chain.GetTd(extern.Hash(), extern.Number.Uint64())
)
if localTD == nil || externTd == nil {
return false, errors.New("missing td")
@ -88,21 +88,26 @@ func (f *ForkChoice) ReorgNeeded(current *types.Header, header *types.Header) (b
if ttd := f.chain.Config().TerminalTotalDifficulty; ttd != nil && ttd.Cmp(externTd) <= 0 {
return true, nil
}
// If the total difficulty is higher than our known, add it to the canonical chain
if diff := externTd.Cmp(localTD); diff > 0 {
return true, nil
} else if diff < 0 {
return false, nil
}
// Local and external difficulty is identical.
// Second clause in the if statement reduces the vulnerability to selfish mining.
// Please refer to http://www.cs.cornell.edu/~ie53/publications/btcProcFC.pdf
reorg := externTd.Cmp(localTD) > 0
if !reorg && externTd.Cmp(localTD) == 0 {
number, headNumber := header.Number.Uint64(), current.Number.Uint64()
if number < headNumber {
reorg := false
externNum, localNum := extern.Number.Uint64(), current.Number.Uint64()
if externNum < localNum {
reorg = true
} else if number == headNumber {
} else if externNum == localNum {
var currentPreserve, externPreserve bool
if f.preserve != nil {
currentPreserve, externPreserve = f.preserve(current), f.preserve(header)
currentPreserve, externPreserve = f.preserve(current), f.preserve(extern)
}
reorg = !currentPreserve && (externPreserve || f.rand.Float64() < 0.5)
}
}
return reorg, nil
}