use atomic for lock-free

client/internal/engine.go

@@ -14,6 +14,7 @@ import (
 	"sort"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/hashicorp/go-multierror"
@@ -199,8 +200,8 @@ type Engine struct {
 	srWatcher    *guard.SRWatcher
 
 	// Sync response persistence
-	persistSyncResponse bool
+	persistSyncResponse atomic.Bool
-	latestSyncResponse  *mgmProto.SyncResponse
+	latestSyncResponse  atomic.Pointer[mgmProto.SyncResponse]
 	connSemaphore       *semaphoregroup.SemaphoreGroup
 	flowManager         nftypes.FlowManager
 
@@ -661,10 +662,8 @@ func (e *Engine) removePeer(peerKey string) error {
 	return nil
 }
 
+// 1. xyzzz
 func (e *Engine) handleSync(update *mgmProto.SyncResponse) error {
-	e.syncMsgMux.Lock()
-	defer e.syncMsgMux.Unlock()
-
 	if update.GetNetbirdConfig() != nil {
 		wCfg := update.GetNetbirdConfig()
 		err := e.updateTURNs(wCfg.GetTurns())
@@ -703,10 +702,11 @@ func (e *Engine) handleSync(update *mgmProto.SyncResponse) error {
 	if nm == nil {
 		return nil
 	}
+	persistSyncResponse := e.persistSyncResponse.Load()
 
 	// Store sync response if persistence is enabled
-	if e.persistSyncResponse {
+	if persistSyncResponse {
-		e.latestSyncResponse = update
+		e.latestSyncResponse.Store(update)
 		log.Debugf("sync response persisted with serial %d", nm.GetSerial())
 	}
 
@@ -927,16 +927,9 @@ func (e *Engine) receiveJobEvents() {
 }
 
 func (e *Engine) handleBundle(params *mgmProto.BundleParameters) (*mgmProto.JobResponse_Bundle, error) {
-	// Access sync response directly without calling exported method to avoid deadlock
+	syncResponse, err := e.GetLatestSyncResponse()
-	// This is safe because we're in a goroutine that doesn't hold the syncMsgMux
+	if err != nil {
-	var syncResponse *mgmProto.SyncResponse
+		return nil, fmt.Errorf("get latest sync response: %w", err)
-	if e.persistSyncResponse && e.latestSyncResponse != nil {
-		log.Debugf("Retrieving latest sync response with size %d bytes", proto.Size(e.latestSyncResponse))
-		if sr, ok := proto.Clone(e.latestSyncResponse).(*mgmProto.SyncResponse); ok {
-			syncResponse = sr
-		} else {
-			return nil, fmt.Errorf("failed to clone sync response")
-		}
 	}
 
 	if syncResponse == nil {
@@ -1823,36 +1816,34 @@ func (e *Engine) stopDNSServer() {
 
 // SetSyncResponsePersistence enables or disables sync response persistence
 func (e *Engine) SetSyncResponsePersistence(enabled bool) {
-	e.syncMsgMux.Lock()
+	persistSyncResponse := e.persistSyncResponse.Load()
-	defer e.syncMsgMux.Unlock()
+	if enabled == persistSyncResponse {
-
-	if enabled == e.persistSyncResponse {
 		return
 	}
-	e.persistSyncResponse = enabled
+	e.persistSyncResponse.Store(enabled)
 	log.Debugf("Sync response persistence is set to %t", enabled)
 
 	if !enabled {
-		e.latestSyncResponse = nil
+		e.latestSyncResponse.Store(nil)
 	}
 }
 
 // GetLatestSyncResponse returns the stored sync response if persistence is enabled
 func (e *Engine) GetLatestSyncResponse() (*mgmProto.SyncResponse, error) {
-	e.syncMsgMux.Lock()
+	persistSyncResponse := e.persistSyncResponse.Load()
-	defer e.syncMsgMux.Unlock()
 
-	if !e.persistSyncResponse {
+	if !persistSyncResponse {
 		return nil, errors.New("sync response persistence is disabled")
 	}
 
-	if e.latestSyncResponse == nil {
+	latestSyncResponse := e.latestSyncResponse.Load()
+	if latestSyncResponse == nil {
 		//nolint:nilnil
 		return nil, nil
 	}
 
-	log.Debugf("Retrieving latest sync response with size %d bytes", proto.Size(e.latestSyncResponse))
+	log.Debugf("Retrieving latest sync response with size %d bytes", proto.Size(latestSyncResponse))
-	sr, ok := proto.Clone(e.latestSyncResponse).(*mgmProto.SyncResponse)
+	sr, ok := proto.Clone(latestSyncResponse).(*mgmProto.SyncResponse)
 	if !ok {
 		return nil, fmt.Errorf("failed to clone sync response")
 	}