consensus/parlia: modify the offset

consensus/parlia/parlia.go

@@ -742,8 +742,8 @@ func (p *Parlia) snapshot(chain consensus.ChainHeaderReader, number uint64, hash
  // If we're at the genesis, snapshot the initial state. Alternatively if we have
  // piled up more headers than allowed to be reorged (chain reinit from a freezer),
  // consider the checkpoint trusted and snapshot it.
- // even BEP-341 enabled, an offset `p.config.Epoch/2` can ensure getting the right validators.
- if number == 0 || (number%p.config.Epoch == p.config.Epoch/2 && (len(headers) > int(params.FullImmutabilityThreshold))) {
+ // An offset `p.config.Epoch - 1` can ensure getting the right validators.
+ if number == 0 || ((number+1)%p.config.Epoch == 0 && (len(headers) > int(params.FullImmutabilityThreshold))) {
  var (
  checkpoint *types.Header
  blockHash common.Hash
@@ -754,7 +754,7 @@ func (p *Parlia) snapshot(chain consensus.ChainHeaderReader, number uint64, hash
  blockHash = checkpoint.Hash()
  }
  } else {
- checkpoint = chain.GetHeaderByNumber(number - p.config.Epoch/2)
+ checkpoint = chain.GetHeaderByNumber(number + 1 - p.config.Epoch)
  blockHeader := chain.GetHeaderByNumber(number)
  if blockHeader != nil {
  blockHash = blockHeader.Hash()