Fix gRPC alarm cannot update settings from dynamic configuration source.(#10274) (#10275)

docs/en/changes/changes.md

@@ -77,6 +77,7 @@
 * Add the eBPF network profiling E2E Test in the per storage.
 * Fix TCP service instances are lack of instance properties like `pod` and `namespace`, which causes Pod log not to work for TCP workloads.
 * Add Python HBase happybase module component ID(94).
+* Fix gRPC alarm cannot update settings from dynamic configuration source.
 
 #### UI
 

oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/grpc/GRPCCallback.java

@@ -60,19 +60,15 @@ public class GRPCCallback implements AlarmCallback {
     @Override
     public void doAlarm(List<AlarmMessage> alarmMessage) {
 
-        if (alarmSetting == null || alarmSetting.isEmptySetting()) {
-            return;
-        }
-
         // recreate gRPC client and stub if host and port configuration changed.
         onGRPCAlarmSettingUpdated(alarmRulesWatcher.getGrpchookSetting());
 
-        GRPCStreamStatus status = new GRPCStreamStatus();
-
-        if (alarmServiceStub == null) {
+        if (alarmSetting == null || alarmSetting.isEmptySetting() || alarmServiceStub == null) {
             return;
         }
 
+        GRPCStreamStatus status = new GRPCStreamStatus();
+
         StreamObserver<org.apache.skywalking.oap.server.core.alarm.grpc.AlarmMessage> streamObserver =
             alarmServiceStub.withDeadlineAfter(10, TimeUnit.SECONDS).doAlarm(new StreamObserver<Response>() {
                 @Override
@@ -156,6 +152,7 @@ public class GRPCCallback implements AlarmCallback {
         }
 
         if (!grpcAlarmSetting.equals(alarmSetting)) {
+            alarmSetting = grpcAlarmSetting;
             if (grpcClient != null) {
                 grpcClient.shutdown();
             }