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promoter.go
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promoter.go
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package promoter
import (
"github.com/iotaledger/iota.go/account"
"github.com/iotaledger/iota.go/account/event"
"github.com/iotaledger/iota.go/account/store"
"github.com/iotaledger/iota.go/account/timesrc"
"github.com/iotaledger/iota.go/account/util"
"github.com/iotaledger/iota.go/api"
"github.com/iotaledger/iota.go/bundle"
"github.com/iotaledger/iota.go/transaction"
. "github.com/iotaledger/iota.go/trinary"
"github.com/pkg/errors"
"strings"
"time"
)
var ErrUnableToPromote = errors.New("unable to promote")
var ErrUnableToReattach = errors.New("unable to reattach")
// own emitted events
const (
// emitted when a promotion occurred
EventPromotion event.Event = 200
// emitted when a reattachment occurred
EventReattachment event.Event = 201
)
// PromotionReattachmentEvent is emitted when a promotion or reattachment happened.
type PromotionReattachmentEvent struct {
// The tail tx hash of the first bundle broadcasted to the network.
OriginTailTxHash Hash `json:"original_tail_tx_hash"`
// The bundle hash of the promoted/reattached bundle.
BundleHash Hash `json:"bundle_hash"`
// The tail tx hash of the promotion transaction.
PromotionTailTxHash Hash `json:"promotion_tail_tx_hash"`
// The tail tx hash of the reattached bundle.
ReattachmentTailTxHash Hash `json:"reattachment_tail_tx_hash"`
}
// NewPromoter creates a new Promoter. If the interval is set to 0, the Promoter will only
// promote/reattach through PromoteReattach().
func NewPromoter(setts *account.Settings, interval time.Duration) *Promoter {
if setts.EventMachine == nil {
setts.EventMachine = &event.DiscardEventMachine{}
}
promoter := &Promoter{
interval: interval, setts: setts,
tailCache: make(map[string]*transaction.Transaction),
}
promoter.syncTimer = util.NewSyncIntervalTimer(interval, promoter.promote, func(err error) {
promoter.setts.EventMachine.Emit(err, event.EventError)
})
return promoter
}
// Promoter is an account plugin which takes care of trying to get pending transfers
// to get confirmed by issuing promotion transactions and creating reattachments.
// The Promoter will only run one promotion/reattachment task at any given time.
type Promoter struct {
interval time.Duration
setts *account.Settings
acc account.Account
tailCache map[string]*transaction.Transaction
syncTimer *util.SyncIntervalTimer
}
func (p *Promoter) Name() string {
return "promoter-reattacher"
}
func (p *Promoter) Start(acc account.Account) error {
p.acc = acc
go p.syncTimer.Start()
return nil
}
func (p *Promoter) Shutdown() error {
p.syncTimer.Stop()
return nil
}
// PromoteReattach awaits the current promotion/reattachment task to finish (in case it's ongoing),
// pauses the task, executes a manual task, resumes the repeated task and then returns.
// PromoteReattach will block infinitely if called after the account has been shutdown.
func (p *Promoter) PromoteReattach() error {
p.syncTimer.Pause()
err := p.promote()
p.syncTimer.Resume()
return err
}
const approxAboveMaxDepthMinutes = 5
func aboveMaxDepth(timesource timesrc.TimeSource, ts time.Time) (bool, error) {
currentTime, err := timesource.Time()
if err != nil {
return false, err
}
return currentTime.Sub(ts).Minutes() < approxAboveMaxDepthMinutes, nil
}
const maxDepth = 15
const referenceTooOldMsg = "reference transaction is too old"
var emptySeed = strings.Repeat("9", 81)
var ErrUnpromotableTail = errors.New("tail is unpromoteable")
func (p *Promoter) promote() error {
pendingTransfers, err := p.setts.Store.GetPendingTransfers(p.acc.ID())
if err != nil {
return err
}
if len(pendingTransfers) == 0 {
return nil
}
send := func(preparedBundle []Trytes, tips *api.TransactionsToApprove) (Hash, error) {
readyBundle, err := p.setts.API.AttachToTangle(tips.TrunkTransaction, tips.BranchTransaction, p.setts.MWM, preparedBundle)
if err != nil {
return "", errors.Wrap(err, "performing PoW for promote/reattach cycle bundle failed")
}
readyBundle, err = p.setts.API.StoreAndBroadcast(readyBundle)
if err != nil {
return "", errors.Wrap(err, "unable to store/broadcast bundle in promote/reattach cycle")
}
tailTx, err := transaction.AsTransactionObject(readyBundle[0])
if err != nil {
return "", err
}
return tailTx.Hash, nil
}
promote := func(tailTx Hash) (Hash, error) {
depth := p.setts.Depth
for {
tips, err := p.setts.API.GetTransactionsToApprove(depth, tailTx)
if err != nil {
if err.Error() == referenceTooOldMsg {
depth++
if depth > maxDepth {
return "", ErrUnpromotableTail
}
continue
}
return "", err
}
pTransfers := bundle.Transfers{bundle.EmptyTransfer}
preparedBundle, err := p.setts.API.PrepareTransfers(emptySeed, pTransfers, api.PrepareTransfersOptions{})
if err != nil {
return "", errors.Wrap(err, "unable to prepare promotion bundle")
}
return send(preparedBundle, tips)
}
}
reattach := func(essenceBndl bundle.Bundle) (Hash, error) {
tips, err := p.setts.API.GetTransactionsToApprove(p.setts.Depth)
if err != nil {
return "", errors.Wrapf(err, "unable to GTTA for reattachment in promote/reattach cycle (bundle %s)", essenceBndl[0].Bundle)
}
essenceTrytes, err := transaction.TransactionsToTrytes(essenceBndl)
if err != nil {
return "", err
}
// reverse order of the trytes as PoW needs them from high to low index
for left, right := 0, len(essenceTrytes)-1; left < right; left, right = left+1, right-1 {
essenceTrytes[left], essenceTrytes[right] = essenceTrytes[right], essenceTrytes[left]
}
return send(essenceTrytes, tips)
}
storeTailTxHash := func(key string, tailTxHash string, msg string) error {
if err := p.setts.Store.AddTailHash(p.acc.ID(), key, tailTxHash); err != nil {
if err == store.ErrPendingTransferNotFound {
// might have been removed by polling goroutine
return nil
}
return errors.Wrap(err, msg)
}
return nil
}
tailsSet := map[string]struct{}{}
for key, pendingTransfer := range pendingTransfers {
// search for a tail transaction which is consistent and above max depth
var tailToPromote string
// go in reverse order to start from the most recent tails.
// we iterate over all tails even if a promotable tail was found in between
// in order to build the set of tail tx hashes, which is later used
// to clean up the cache from confirmed transactions.
for i := len(pendingTransfer.Tails) - 1; i >= 0; i-- {
tailTx := pendingTransfer.Tails[i]
// add tail to set for cleanup of cache
tailsSet[tailTx] = struct{}{}
if tailToPromote != "" {
continue
}
tx, isCached := p.tailCache[tailTx]
if !isCached {
consistent, _, err := p.setts.API.CheckConsistency(tailTx)
if err != nil {
continue
}
if !consistent {
continue
}
txTrytes, err := p.setts.API.GetTrytes(tailTx)
if err != nil {
continue
}
tx, err = transaction.AsTransactionObject(txTrytes[0])
if err != nil {
continue
}
p.tailCache[tailTx] = tx
}
if above, err := aboveMaxDepth(p.setts.TimeSource, time.Unix(int64(tx.Timestamp), 0)); !above || err != nil {
continue
}
tailToPromote = tailTx
}
// promote as tail was found
if len(tailToPromote) > 0 {
promoteTailTxHash, err := promote(tailToPromote)
if err != nil {
return errors.Wrap(ErrUnableToPromote, err.Error())
}
// only load bundle once promotion was successful
bndl, err := store.PendingTransferToBundle(pendingTransfer)
if err != nil {
return errors.Wrapf(err, "unable to translate pending transfer to bundle for reattachment")
}
p.setts.EventMachine.Emit(&PromotionReattachmentEvent{
BundleHash: bndl[0].Bundle,
PromotionTailTxHash: promoteTailTxHash,
OriginTailTxHash: key,
}, EventPromotion)
continue
}
// load bundle as we need to reattach
bndl, err := store.PendingTransferToBundle(pendingTransfer)
if err != nil {
return errors.Wrapf(err, "unable to translate pending transfer to bundle for reattachment")
}
// reattach
reattachTailTxHash, err := reattach(bndl)
if err != nil {
return errors.Wrap(ErrUnableToReattach, err.Error())
}
p.setts.EventMachine.Emit(&PromotionReattachmentEvent{
BundleHash: bndl[0].Bundle,
OriginTailTxHash: key,
ReattachmentTailTxHash: reattachTailTxHash,
}, EventReattachment)
if err := storeTailTxHash(key, reattachTailTxHash, "unable to store reattachment tx tail hash"); err != nil {
return err
}
promoteTailTxHash, err := promote(reattachTailTxHash)
if err != nil {
return errors.Wrap(ErrUnableToPromote, err.Error())
}
p.setts.EventMachine.Emit(&PromotionReattachmentEvent{
BundleHash: bndl[0].Bundle,
OriginTailTxHash: key,
PromotionTailTxHash: promoteTailTxHash,
}, EventPromotion)
}
// clear cache
for cachedTailTx := range p.tailCache {
if _, has := tailsSet[cachedTailTx]; !has {
delete(p.tailCache, cachedTailTx)
}
}
return nil
}