app/vminsert/netstorage: refactor snb rebuild

Signed-off-by: Zakhar Bessarab <z.bessarab@victoriametrics.com>

app/vminsert/netstorage/netstorage.go

@@ -648,41 +648,23 @@ func initStorageNodes(addrs []string, hashSeed uint64) *storageNodesBucket {
 	// Watch for node become healthy and rebuild snb.
 	for _, sn := range brokenNodes {
 		wg.Add(1)
-		go func(sn *storageNode) {
+		sn := sn
+		go watchStorageNodeHealthy(sn, func() {
 			defer wg.Done()
+			// rebuild snb in order to update consistent hash with an ID of the healthy storage node
 			for {
-				sn.brLock.Lock()
-				for !sn.isReady() {
-					select {
-					case <-sn.stopCh:
-						sn.brLock.Unlock()
-						return
-					default:
-						sn.brCond.Wait()
-					}
-				}
-				sn.brLock.Unlock()
-
-				select {
-				case <-sn.stopCh:
-					return
-				default:
-				}
-
-				if sn.isReady() {
-				again:
-					currentSnb := getStorageNodesBucket()
-					newSnb := initStorageNodes(addrs, hashSeed)
-					if !storageNodes.CompareAndSwap(currentSnb, newSnb) {
-						mustStopStorageNodes(newSnb)
-						goto again
-					}
-
-					mustStopStorageNodes(currentSnb)
-					break
+				currentSnb := getStorageNodesBucket()
+				newSnb := initStorageNodes(addrs, hashSeed)
+				if !storageNodes.CompareAndSwap(currentSnb, newSnb) {
+					// snb has been changed, so we need to stop the newSnb and try again
+					mustStopStorageNodes(newSnb)
+					continue
 				}
+				// stop previous snb and exit
+				mustStopStorageNodes(currentSnb)
+				break
 			}
-		}(sn)
+		})
 	}
 
 	return snb
@@ -697,6 +679,34 @@ func mustStopStorageNodes(snb *storageNodesBucket) {
 	metrics.UnregisterSet(snb.ms, true)
 }
 
+// watchStorageNodeHealthy watches for sn become healthy and calls cb once it is ready.
+func watchStorageNodeHealthy(sn *storageNode, cb func()) {
+	for {
+		sn.brLock.Lock()
+		for !sn.isReady() {
+			select {
+			case <-sn.stopCh:
+				sn.brLock.Unlock()
+				return
+			default:
+				sn.brCond.Wait()
+			}
+		}
+		sn.brLock.Unlock()
+
+		select {
+		case <-sn.stopCh:
+			return
+		default:
+		}
+
+		if sn.isReady() {
+			cb()
+			return
+		}
+	}
+}
+
 // rerouteRowsToReadyStorageNodes reroutes src from not ready snSource to ready storage nodes.
 //
 // The function blocks until src is fully re-routed.