refactored defaultServiceLoop into its own method

pkg/backend/snapshot.go

@@ -639,6 +639,38 @@ func (sm *SnapshotManager) saveSnapshot() error {
 	return nil
 }
 
+// defaultServiceLoop saves a Snapshot whenever a mutation occurs
+func (sm *SnapshotManager) defaultServiceLoop(mutationRequests chan mutationRequest, done chan error) {
+	// True if we have elided writes since the last actual write.
+	hasElidedWrites := false
+
+	// Service each mutation request in turn.
+serviceLoop:
+	for {
+		select {
+		case request := <-mutationRequests:
+			var err error
+			if request.mutator() {
+				err = sm.saveSnapshot()
+				hasElidedWrites = false
+			} else {
+				hasElidedWrites = true
+			}
+			request.result <- err
+		case <-sm.cancel:
+			break serviceLoop
+		}
+	}
+
+	// If we still have elided writes once the channel has closed, flush the snapshot.
+	var err error
+	if hasElidedWrites {
+		logging.V(9).Infof("SnapshotManager: flushing elided writes...")
+		err = sm.saveSnapshot()
+	}
+	done <- err
+}
+
 // unsafeServiceLoop doesn't save Snapshots when mutations occur and instead saves Snapshots when
 // SnapshotManager.Close() is invoked. It trades reliability for speed as every mutation does not
 // cause a Snapshot to be serialized to the user's state backend.
@@ -677,46 +709,12 @@ func NewSnapshotManager(persister SnapshotPersister, baseSnap *deploy.Snapshot)
 		done:             done,
 	}
 
-	go func() {
-		unsafeEnabled := os.Getenv(experimentalSnapshotManagerFlag) != ""
-		if unsafeEnabled {
-			// This codepath skips writing back snapshots on all mutations.
-			// The final snapshot is written back when `SnapshotManager.Close()` is called.
-			// This trades reliability for speed and can cause state to be lost if Close()
-			// is not called or successful.
-			manager.unsafeServiceLoop(mutationRequests, done)
-			return
-		}
-
-		// True if we have elided writes since the last actual write.
-		hasElidedWrites := false
-
-		// Service each mutation request in turn.
-	serviceLoop:
-		for {
-			select {
-			case request := <-mutationRequests:
-				var err error
-				if request.mutator() {
-					err = manager.saveSnapshot()
-					hasElidedWrites = false
-				} else {
-					hasElidedWrites = true
-				}
-				request.result <- err
-			case <-cancel:
-				break serviceLoop
-			}
-		}
-
-		// If we still have elided writes once the channel has closed, flush the snapshot.
-		var err error
-		if hasElidedWrites {
-			logging.V(9).Infof("SnapshotManager: flushing elided writes...")
-			err = manager.saveSnapshot()
-		}
-		done <- err
-	}()
+	serviceLoop := manager.defaultServiceLoop
+	unsafeEnabled := os.Getenv(experimentalSnapshotManagerFlag) != ""
+	if unsafeEnabled {
+		serviceLoop = manager.unsafeServiceLoop
+	}
+	go serviceLoop(mutationRequests, done)
 
 	return manager
 }