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services: improve Notary service locking #4093

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cf564da
services: untie verifyIncompleteWitnesses from Notary service
AnnaShaleva Nov 21, 2025
b09687c
services: improve Notary service locking
AnnaShaleva Nov 21, 2025
bdf2c2b
notary: move finalized tx processing to a separate method
AnnaShaleva Nov 26, 2025
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116 changes: 67 additions & 49 deletions pkg/services/notary/notary.go
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,8 @@ type (
// started is a status bool to protect from double start/shutdown.
started atomic.Bool

// reqMtx protects requests list.
// reqMtx protects the request list from concurrent requests addition/removal.
// Use per-request locks instead of this one to perform request-changing operations.
reqMtx sync.RWMutex
// requests represents a map of main transactions which needs to be completed
// with the associated fallback transactions grouped by the main transaction hash
Expand Down Expand Up @@ -89,6 +90,7 @@ const defaultTxChannelCapacity = 100
type (
// request represents Notary service request.
request struct {
lock sync.RWMutex
// isSent indicates whether the main transaction was successfully sent to the network.
isSent bool
main *transaction.Transaction
Expand Down Expand Up @@ -117,7 +119,8 @@ type (
)

// isMainCompleted denotes whether all signatures for the main transaction were collected.
func (r request) isMainCompleted() bool {
// The caller must hold the request RLock.
func (r *request) isMainCompleted() bool {
if r.witnessInfo == nil {
return false
}
Expand Down Expand Up @@ -246,20 +249,22 @@ func (n *Notary) OnNewRequest(payload *payload.P2PNotaryRequest) {

nvbFallback := payload.FallbackTransaction.GetAttributes(transaction.NotValidBeforeT)[0].Value.(*transaction.NotValidBefore).Height
nKeys := payload.MainTransaction.GetAttributes(transaction.NotaryAssistedT)[0].Value.(*transaction.NotaryAssisted).NKeys
newInfo, validationErr := n.verifyIncompleteWitnesses(payload.MainTransaction, nKeys)
newInfo, validationErr := verifyIncompleteWitnesses(payload.MainTransaction, nKeys)
if validationErr != nil {
n.Config.Log.Info("verification of main notary transaction failed; fallback transaction will be completed",
zap.String("main hash", payload.MainTransaction.Hash().StringLE()),
zap.String("fallback hash", payload.FallbackTransaction.Hash().StringLE()),
zap.String("verification error", validationErr.Error()))
}
n.reqMtx.Lock()
defer n.reqMtx.Unlock()
r, exists := n.requests[payload.MainTransaction.Hash()]
if exists {
r.lock.Lock() // RLock doesn't fit here since we modify r.minNotValidBefore below.
defer r.lock.Unlock()
if slices.ContainsFunc(r.fallbacks, func(fb *transaction.Transaction) bool {
return fb.Hash().Equals(payload.FallbackTransaction.Hash())
}) {
n.reqMtx.Unlock()
return // then we already have processed this request
}
r.minNotValidBefore = min(r.minNotValidBefore, nvbFallback)
Expand All @@ -270,8 +275,11 @@ func (n *Notary) OnNewRequest(payload *payload.P2PNotaryRequest) {
main: payload.MainTransaction.Copy(),
minNotValidBefore: nvbFallback,
}
r.lock.Lock()
defer r.lock.Unlock()
n.requests[payload.MainTransaction.Hash()] = r
}
n.reqMtx.Unlock()
if r.witnessInfo == nil && validationErr == nil {
r.witnessInfo = newInfo
}
Expand Down Expand Up @@ -347,21 +355,21 @@ func (n *Notary) OnRequestRemoval(pld *payload.P2PNotaryRequest) {
return
}

n.reqMtx.Lock()
defer n.reqMtx.Unlock()
n.reqMtx.RLock()
r, ok := n.requests[pld.MainTransaction.Hash()]
n.reqMtx.RUnlock()
if !ok {
return
}

r.lock.Lock()
for i, fb := range r.fallbacks {
if fb.Hash().Equals(pld.FallbackTransaction.Hash()) {
r.fallbacks = append(r.fallbacks[:i], r.fallbacks[i+1:]...)
break
}
}
if len(r.fallbacks) == 0 {
delete(n.requests, r.main.Hash())
}
r.lock.Unlock()
}

// PostPersist is a callback which is called after a new block event is received.
Expand All @@ -379,12 +387,18 @@ func (n *Notary) PostPersist() {
defer n.reqMtx.Unlock()
currHeight := n.Config.Chain.BlockHeight()
for h, r := range n.requests {
r.lock.Lock()
if len(r.fallbacks) == 0 {
delete(n.requests, r.main.Hash())
continue
}
if !r.isSent && r.isMainCompleted() && r.minNotValidBefore > currHeight {
if err := n.finalize(acc, r.main, h); err != nil {
n.Config.Log.Error("failed to finalize main transaction after PostPersist, waiting for the next block to retry",
zap.String("hash", r.main.Hash().StringLE()),
zap.Error(err))
}
r.lock.Unlock()
continue
}
if r.minNotValidBefore <= currHeight { // then at least one of the fallbacks can already be sent.
Expand All @@ -400,6 +414,7 @@ func (n *Notary) PostPersist() {
}
}
}
r.lock.Unlock()
}
}

Expand Down Expand Up @@ -446,53 +461,56 @@ func (n *Notary) newTxCallbackLoop() {
for {
select {
case tx := <-n.newTxs:
isMain := tx.tx.Hash() == tx.mainHash

n.reqMtx.Lock()
n.reqMtx.RLock()
r, ok := n.requests[tx.mainHash]
if !ok || isMain && (r.isSent || r.minNotValidBefore <= n.Config.Chain.BlockHeight()) {
n.reqMtx.Unlock()
n.reqMtx.RUnlock()
if !ok {
continue
}
if !isMain {
// Ensure that fallback was not already completed.
var isPending = slices.ContainsFunc(r.fallbacks, func(fb *transaction.Transaction) bool {
return fb.Hash() == tx.tx.Hash()
})
if !isPending {
n.reqMtx.Unlock()
continue
}
}
n.handleNewTx(r, tx)
case <-n.stopCh:
return
}
}
}

n.reqMtx.Unlock()
err := n.onTransaction(tx.tx)
if err != nil {
n.Config.Log.Error("new transaction callback finished with error",
zap.Error(err),
zap.Bool("is main", isMain))
continue
}
// handleNewTx tries to send a finalized transaction (either main or fallback) to the network.
func (n *Notary) handleNewTx(r *request, tx txHashPair) {
isMain := tx.tx.Hash() == tx.mainHash

n.reqMtx.Lock()
if isMain {
r.isSent = true
} else {
for i := range r.fallbacks {
if r.fallbacks[i].Hash() == tx.tx.Hash() {
r.fallbacks = append(r.fallbacks[:i], r.fallbacks[i+1:]...)
break
}
}
if len(r.fallbacks) == 0 {
delete(n.requests, tx.mainHash)
}
}
n.reqMtx.Unlock()
case <-n.stopCh:
r.lock.Lock()
defer r.lock.Unlock()
if isMain && (r.isSent || r.minNotValidBefore <= n.Config.Chain.BlockHeight()) {
return
}

if !isMain {
// Ensure that fallback was not already completed.
var isPending = slices.ContainsFunc(r.fallbacks, func(fb *transaction.Transaction) bool {
return fb.Hash() == tx.tx.Hash()
})
if !isPending {
return
}
}

err := n.onTransaction(tx.tx)
if err != nil {
n.Config.Log.Error("new transaction callback finished with error",
zap.Error(err),
zap.Bool("is main", isMain))
return
}
if isMain {
r.isSent = true
} else {
for i := range r.fallbacks {
if r.fallbacks[i].Hash() == tx.tx.Hash() {
r.fallbacks = append(r.fallbacks[:i], r.fallbacks[i+1:]...)
break
}
}
}
}

// updateTxSize returns a transaction with re-calculated size and an error.
Expand All @@ -508,7 +526,7 @@ func updateTxSize(tx *transaction.Transaction) (*transaction.Transaction, error)
// verifyIncompleteWitnesses checks that the tx either doesn't have all witnesses attached (in this case none of them
// can be multisignature) or it only has a partial multisignature. It returns the request type (sig/multisig), the
// number of signatures to be collected, sorted public keys (for multisig request only) and an error.
func (n *Notary) verifyIncompleteWitnesses(tx *transaction.Transaction, nKeysExpected uint8) ([]witnessInfo, error) {
func verifyIncompleteWitnesses(tx *transaction.Transaction, nKeysExpected uint8) ([]witnessInfo, error) {
var nKeysActual uint8
if len(tx.Signers) < 2 {
return nil, errors.New("transaction should have at least 2 signers")
Expand Down
6 changes: 2 additions & 4 deletions pkg/services/notary/notary_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -47,9 +47,7 @@ func TestWallet(t *testing.T) {
}

func TestVerifyIncompleteRequest(t *testing.T) {
bc := fakechain.NewFakeChain()
notaryContractHash := nativehashes.Notary
_, ntr, _ := getTestNotary(t, bc, "./testdata/notary1.json", "one")
sig := append([]byte{byte(opcode.PUSHDATA1), keys.SignatureLen}, make([]byte, keys.SignatureLen)...) // we're not interested in signature correctness
acc1, _ := keys.NewPrivateKey()
acc2, _ := keys.NewPrivateKey()
Expand All @@ -65,7 +63,7 @@ func TestVerifyIncompleteRequest(t *testing.T) {
multisigScriptHash2 := hash.Hash160(multisigScript2)

checkErr := func(t *testing.T, tx *transaction.Transaction, nKeys uint8) {
witnessInfo, err := ntr.verifyIncompleteWitnesses(tx, nKeys)
witnessInfo, err := verifyIncompleteWitnesses(tx, nKeys)
require.Error(t, err)
require.Nil(t, witnessInfo)
}
Expand Down Expand Up @@ -475,7 +473,7 @@ func TestVerifyIncompleteRequest(t *testing.T) {

for name, testCase := range testCases {
t.Run(name, func(t *testing.T) {
actualInfo, err := ntr.verifyIncompleteWitnesses(testCase.tx, testCase.nKeys)
actualInfo, err := verifyIncompleteWitnesses(testCase.tx, testCase.nKeys)
require.NoError(t, err)
require.Equal(t, len(testCase.expectedInfo), len(actualInfo))
for i, expected := range testCase.expectedInfo {
Expand Down
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