Additional guard for reentrants

backend/src/Squidex.Infrastructure/EventSourcing/Grains/EventConsumerGrain.cs

@@ -22,6 +22,7 @@ namespace Squidex.Infrastructure.EventSourcing.Grains
         private readonly IEventDataFormatter eventDataFormatter;
         private readonly IEventStore eventStore;
         private readonly ISemanticLog log;
+        private readonly SemaphoreSlim semaphore = new SemaphoreSlim(1);
         private TaskScheduler? scheduler;
         private BatchSubscriber? currentSubscriber;
         private IEventConsumer? eventConsumer;
@@ -196,6 +197,9 @@ namespace Squidex.Infrastructure.EventSourcing.Grains
         }
 
         private async Task DoAndUpdateStateAsync(Func<Task> action, [CallerMemberName] string? caller = null)
+        {
+            await semaphore.WaitAsync();
+            try
             {
                 var previousState = State;
 
@@ -227,6 +231,11 @@ namespace Squidex.Infrastructure.EventSourcing.Grains
                     await state.WriteAsync();
                 }
             }
+            finally
+            {
+                semaphore.Release();
+            }
+        }
 
         private async Task ClearAsync()
         {

backend/tests/Squidex.Infrastructure.Tests/EventSourcing/Grains/EventConsumerManagerGrainTests.cs

@@ -166,12 +166,10 @@ namespace Squidex.Infrastructure.EventSourcing.Grains
         public async Task Should_fetch_infos_from_all_grains()
         {
             A.CallTo(() => grainA.GetStateAsync())
-                .Returns(new Immutable<EventConsumerInfo>(
+                .Returns(new EventConsumerInfo { Name = "A", Error = "A-Error", IsStopped = false, Position = "123" });
-                    new EventConsumerInfo { Name = "A", Error = "A-Error", IsStopped = false, Position = "123" }));
 
             A.CallTo(() => grainB.GetStateAsync())
-                .Returns(new Immutable<EventConsumerInfo>(
+                .Returns( new EventConsumerInfo { Name = "B", Error = "B-Error", IsStopped = false, Position = "456" });
-                    new EventConsumerInfo { Name = "B", Error = "B-Error", IsStopped = false, Position = "456" }));
 
             var infos = await sut.GetConsumersAsync();