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opinion_hasher.go
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opinion_hasher.go
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package opinionhash
import (
"github.com/spacemeshos/go-scale"
"github.com/spacemeshos/go-spacemesh/common/types"
"github.com/spacemeshos/go-spacemesh/hash"
)
var abstainSentinel = []byte{0}
// New returns new instance of the opinion hasher.
func New() *OpinionHasher {
hasher := hash.New()
return &OpinionHasher{enc: scale.NewEncoder(hasher), h: hasher}
}
// OpinionHasher is a utility for computing opinion hash.
type OpinionHasher struct {
enc *scale.Encoder
h hash.Hash
}
// WritePrevious aggregated hash.
func (h *OpinionHasher) WritePrevious(hash types.Hash32) {
_, err := h.h.Write(hash[:])
if err != nil {
panic("unexpected hash write failure: " + err.Error())
}
}
// WriteAbstain writes abstain sentinel as an opinion.
func (h *OpinionHasher) WriteAbstain() {
_, err := h.h.Write(abstainSentinel)
if err != nil {
panic("unexpected hash write failure: " + err.Error())
}
}
// WriteSupport writes id and height of the block.
func (h *OpinionHasher) WriteSupport(id types.BlockID, height uint64) {
_, err := scale.EncodeByteArray(h.enc, id[:])
if err != nil {
if err != nil {
panic("unexpected scale encode failure: " + err.Error())
}
}
_, err = scale.EncodeUint64(h.enc, height)
if err != nil {
panic("unexpected scale encode failure: " + err.Error())
}
}
// Sum appends hash sum to dst.
func (h *OpinionHasher) Sum(dst []byte) []byte {
return h.h.Sum(dst)
}
// Hash instantiates 32bytes and write hash.Sum to it.
func (h *OpinionHasher) Hash() (rst types.Hash32) {
h.Sum(rst[:0])
return rst
}
// Reset opinion hasher state.
func (h *OpinionHasher) Reset() {
h.h.Reset()
}