do not send update if count was not changed

application/src/main/java/org/thingsboard/server/service/subscription/DefaultTbEntityDataSubscriptionService.java

@@ -33,6 +33,7 @@ import org.springframework.stereotype.Service;
 import org.springframework.web.socket.CloseStatus;
 import org.thingsboard.common.util.ThingsBoardExecutors;
 import org.thingsboard.common.util.ThingsBoardThreadFactory;
+import org.thingsboard.server.common.data.id.EntityId;
 import org.thingsboard.server.common.data.kv.BaseReadTsKvQuery;
 import org.thingsboard.server.common.data.kv.ReadTsKvQuery;
 import org.thingsboard.server.common.data.kv.ReadTsKvQueryResult;
@@ -59,6 +60,7 @@ import org.thingsboard.server.service.ws.telemetry.cmd.v2.AggHistoryCmd;
 import org.thingsboard.server.service.ws.telemetry.cmd.v2.AggKey;
 import org.thingsboard.server.service.ws.telemetry.cmd.v2.AggTimeSeriesCmd;
 import org.thingsboard.server.service.ws.telemetry.cmd.v2.AlarmCountCmd;
+import org.thingsboard.server.service.ws.telemetry.cmd.v2.AlarmCountUpdate;
 import org.thingsboard.server.service.ws.telemetry.cmd.v2.AlarmDataCmd;
 import org.thingsboard.server.service.ws.telemetry.cmd.v2.AlarmDataUpdate;
 import org.thingsboard.server.service.ws.telemetry.cmd.v2.AlarmStatusCmd;
@@ -426,15 +428,21 @@ public class DefaultTbEntityDataSubscriptionService implements TbEntityDataSubsc
             long end = System.currentTimeMillis();
             stats.getRegularQueryInvocationCnt().incrementAndGet();
             stats.getRegularQueryTimeSpent().addAndGet(end - start);
+            Set<EntityId> entitiesIds = ctx.getEntitiesIds();
             ctx.cancelTasks();
             ctx.clearAlarmSubscriptions();
-            ctx.fetchAlarmCount();
-            ctx.createAlarmSubscriptions();
-            TbAlarmCountSubCtx finalCtx = ctx;
-            ScheduledFuture<?> task = scheduler.scheduleWithFixedDelay(
-                    () -> refreshDynamicQuery(finalCtx),
-                    dynamicPageLinkRefreshInterval, dynamicPageLinkRefreshInterval, TimeUnit.SECONDS);
-            finalCtx.setRefreshTask(task);
+            if (entitiesIds != null && entitiesIds.isEmpty()) {
+                AlarmCountUpdate update = new AlarmCountUpdate(cmd.getCmdId(), 0);
+                ctx.sendWsMsg(update);
+            } else {
+                ctx.doFetchAlarmCount();
+                ctx.createAlarmSubscriptions();
+                TbAlarmCountSubCtx finalCtx = ctx;
+                ScheduledFuture<?> task = scheduler.scheduleWithFixedDelay(
+                        () -> refreshDynamicQuery(finalCtx),
+                        dynamicPageLinkRefreshInterval, dynamicPageLinkRefreshInterval, TimeUnit.SECONDS);
+                finalCtx.setRefreshTask(task);
+            }
         } else {
             log.debug("[{}][{}] Received duplicate command: {}", session.getSessionId(), cmd.getCmdId(), cmd);
         }

application/src/main/java/org/thingsboard/server/service/subscription/TbAlarmCountSubCtx.java

@@ -48,6 +48,7 @@ public class TbAlarmCountSubCtx extends TbAbstractEntityQuerySubCtx<AlarmCountQu
 
     protected final Map<Integer, EntityId> subToEntityIdMap;
 
+    @Getter
     private LinkedHashSet<EntityId> entitiesIds;
 
     private final int maxEntitiesPerAlarmSubscription;
@@ -102,26 +103,30 @@ public class TbAlarmCountSubCtx extends TbAbstractEntityQuerySubCtx<AlarmCountQu
         fetchAlarmCount();
     }
 
+    @Override
+    public boolean isDynamic() {
+        return true;
+    }
+
     public void fetchAlarmCount() {
         alarmCountInvocationAttempts++;
         log.trace("[{}] Fetching alarms: {}", cmdId, alarmCountInvocationAttempts);
         if (alarmCountInvocationAttempts <= maxAlarmQueriesPerRefreshInterval) {
-            doFetchAlarmCount();
+            int newCount = (int) alarmService.countAlarmsByQuery(getTenantId(), getCustomerId(), query, entitiesIds);
+            if (newCount != result) {
+                result = newCount;
+                sendWsMsg(new AlarmCountUpdate(cmdId, result));
+            }
         } else {
             log.trace("[{}] Ignore alarm count fetch due to rate limit: [{}] of maximum [{}]", cmdId, alarmCountInvocationAttempts, maxAlarmQueriesPerRefreshInterval);
         }
     }
 
-    private void doFetchAlarmCount() {
+    public void doFetchAlarmCount() {
         result = (int) alarmService.countAlarmsByQuery(getTenantId(), getCustomerId(), query, entitiesIds);
         sendWsMsg(new AlarmCountUpdate(cmdId, result));
     }
 
-    @Override
-    public boolean isDynamic() {
-        return true;
-    }
-
     private EntityDataQuery buildEntityDataQuery() {
         EntityDataPageLink edpl = new EntityDataPageLink(maxEntitiesPerAlarmSubscription, 0, null,
                 new EntityDataSortOrder(new EntityKey(EntityKeyType.ENTITY_FIELD, ModelConstants.CREATED_TIME_PROPERTY)));