frostfs-contract/common/vote.go

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package common
import (
"github.com/nspcc-dev/neo-go/pkg/interop"
"github.com/nspcc-dev/neo-go/pkg/interop/binary"
"github.com/nspcc-dev/neo-go/pkg/interop/crypto"
"github.com/nspcc-dev/neo-go/pkg/interop/native/ledger"
"github.com/nspcc-dev/neo-go/pkg/interop/storage"
"github.com/nspcc-dev/neo-go/pkg/interop/util"
)
type Ballot struct {
// ID of the voting decision.
ID []byte
// Public keys of already voted inner ring nodes.
Voters []interop.PublicKey
// Height of block with the last vote.
Height int
}
const voteKey = "ballots"
const blockDiff = 20 // change base on performance evaluation
func InitVote(ctx storage.Context) {
SetSerialized(ctx, voteKey, []Ballot{})
}
// Vote adds ballot for the decision with specific 'id' and returns amount
// on unique voters for that decision.
func Vote(ctx storage.Context, id, from []byte) int {
var (
newCandidates []Ballot
candidates = getBallots(ctx)
found = -1
blockHeight = ledger.CurrentIndex()
)
for i := 0; i < len(candidates); i++ {
cnd := candidates[i]
if blockHeight-cnd.Height > blockDiff {
continue
}
if BytesEqual(cnd.ID, id) {
voters := cnd.Voters
for j := range voters {
if BytesEqual(voters[j], from) {
return len(voters)
}
}
voters = append(voters, from)
cnd = Ballot{ID: id, Voters: voters, Height: blockHeight}
found = len(voters)
}
newCandidates = append(newCandidates, cnd)
}
if found < 0 {
voters := []interop.PublicKey{from}
newCandidates = append(newCandidates, Ballot{
ID: id,
Voters: voters,
Height: blockHeight})
found = 1
}
SetSerialized(ctx, voteKey, newCandidates)
return found
}
// RemoveVotes clears ballots of the decision that has been accepted by
// inner ring nodes.
func RemoveVotes(ctx storage.Context, id []byte) {
var (
newCandidates []Ballot
candidates = getBallots(ctx)
)
for i := 0; i < len(candidates); i++ {
cnd := candidates[i]
if !BytesEqual(cnd.ID, id) {
newCandidates = append(newCandidates, cnd)
}
}
SetSerialized(ctx, voteKey, newCandidates)
}
// getBallots returns deserialized slice of vote ballots.
func getBallots(ctx storage.Context) []Ballot {
data := storage.Get(ctx, voteKey)
if data != nil {
return binary.Deserialize(data.([]byte)).([]Ballot)
}
return []Ballot{}
}
// BytesEqual compares two slice of bytes by wrapping them into strings,
// which is necessary with new util.Equal interop behaviour, see neo-go#1176.
func BytesEqual(a []byte, b []byte) bool {
return util.Equals(string(a), string(b))
}
func InvokeID(args []interface{}, prefix []byte) []byte {
for i := range args {
arg := args[i].([]byte)
prefix = append(prefix, arg...)
}
return crypto.SHA256(prefix)
}