A lot of fixes for ugly race conditions.

src/Squidex.Infrastructure.GetEventStore/GetEventStoreSubscription.cs

@@ -19,7 +19,7 @@ using Squidex.Infrastructure.CQRS.Events;
 
 namespace Squidex.Infrastructure.GetEventStore
 {
-    internal sealed class EventStoreSubscription : IEventSubscription
+    internal sealed class EventStoreSubscription : DisposableObjectBase, IEventSubscription
     {
         private static readonly ConcurrentDictionary<string, bool> subscriptionsCreated = new ConcurrentDictionary<string, bool>();
         private readonly IEventStoreConnection connection;
@@ -40,10 +40,13 @@ namespace Squidex.Infrastructure.GetEventStore
 
             streamName = $"by-{prefix.Simplify()}-{streamFilter.Simplify()}";
         }
-       
-        public void Dispose()
+
+        protected override void DisposeObject(bool disposing)
         {
-            internalSubscription?.Stop();
+            if (disposing)
+            {
+                internalSubscription?.Stop();
+            }
         }
 
         public async Task SubscribeAsync(Func<StoredEvent, Task> onNext, Func<Exception, Task> onError = null)

src/Squidex.Infrastructure.MongoDb/EventStore/MongoEventStore.cs

@@ -26,6 +26,7 @@ namespace Squidex.Infrastructure.MongoDb.EventStore
 {
     public class MongoEventStore : MongoRepositoryBase<MongoEventCommit>, IEventStore, IDisposable
     {
+        private static readonly BsonTimestamp EmptyTimestamp = new BsonTimestamp(0);
         private static readonly FieldDefinition<MongoEventCommit, BsonTimestamp> TimestampField = Fields.Build(x => x.Timestamp);
         private static readonly FieldDefinition<MongoEventCommit, long> EventsCountField = Fields.Build(x => x.EventsCount);
         private static readonly FieldDefinition<MongoEventCommit, long> EventStreamOffsetField = Fields.Build(x => x.EventStreamOffset);
@@ -209,7 +210,8 @@ namespace Squidex.Infrastructure.MongoDb.EventStore
                     Events = commitEvents,
                     EventsCount = eventsCount,
                     EventStream = streamName,
-                    EventStreamOffset = expectedVersion
+                    EventStreamOffset = expectedVersion,
+                    Timestamp = EmptyTimestamp
                 }.ToBsonDocument();
 
                 pendingCommits.Enqueue((document, cts));

src/Squidex.Infrastructure.MongoDb/EventStore/PollingSubscription.cs

@@ -12,6 +12,8 @@ using Squidex.Infrastructure.CQRS.Events;
 using Squidex.Infrastructure.Tasks;
 using Squidex.Infrastructure.Timers;
 
+// ReSharper disable InvertIf
+
 namespace Squidex.Infrastructure.MongoDb.EventStore
 {
     public sealed class PollingSubscription : DisposableObjectBase, IEventSubscription
@@ -19,7 +21,8 @@ namespace Squidex.Infrastructure.MongoDb.EventStore
         private readonly IEventNotifier eventNotifier;
         private readonly MongoEventStore eventStore;
         private readonly string streamFilter;
-        private readonly string position;
+        private string position;
+        private IDisposable subscription;
         private CompletionTimer timer;
 
         public PollingSubscription(MongoEventStore eventStore, IEventNotifier eventNotifier, string streamFilter, string position)
@@ -34,7 +37,9 @@ namespace Squidex.Infrastructure.MongoDb.EventStore
         {
             if (disposing)
             {
-                timer.Dispose();
+                subscription?.Dispose();
+
+                timer?.Dispose();
             }
         }
 
@@ -42,7 +47,7 @@ namespace Squidex.Infrastructure.MongoDb.EventStore
         {
             Guard.NotNull(onNext, nameof(onNext));
 
-            if (timer == null)
+            if (timer != null)
             {
                 throw new InvalidOperationException("An handler has already been registered.");
             }
@@ -51,15 +56,26 @@ namespace Squidex.Infrastructure.MongoDb.EventStore
             {
                 try
                 {
-                    await eventStore.GetEventsAsync(onNext, ct, streamFilter, position);
+                    await eventStore.GetEventsAsync(async storedEvent =>
+                    {
+                        await onNext(storedEvent);
+
+                        position = storedEvent.EventPosition;
+                    }, ct, streamFilter, position);
                 }
-                catch (Exception ex)
+                catch (Exception ex) when (!(ex is OperationCanceledException))
                 {
                     onError?.Invoke(ex);
                 }
             });
 
-            eventNotifier.Subscribe(timer.Wakeup);
+            subscription = eventNotifier.Subscribe(() =>
+            {
+                if (!timer.IsDisposed)
+                {
+                    timer.Wakeup();
+                }
+            });
 
             return TaskHelper.Done;
         }

src/Squidex.Infrastructure/CQRS/Events/DefaultEventNotifier.cs

@@ -28,9 +28,9 @@ namespace Squidex.Infrastructure.CQRS.Events
             invalidator.Publish(ChannelName, string.Empty, true);
         }
 
-        public void Subscribe(Action handler)
+        public IDisposable Subscribe(Action handler)
         {
-            invalidator.Subscribe(ChannelName, x => handler());
+            return invalidator.Subscribe(ChannelName, x => handler());
         }
     }
 }

src/Squidex.Infrastructure/CQRS/Events/EventReceiver.cs

@@ -105,7 +105,7 @@ namespace Squidex.Infrastructure.CQRS.Events
 
                     var position = status.Position;
 
-                    if (status.IsResetting || status.IsStopped)
+                    if (status.IsResetting)
                     {
                         currentSubscription?.Dispose();
                         currentSubscription = null;

src/Squidex.Infrastructure/CQRS/Events/IEventNotifier.cs

@@ -14,6 +14,6 @@ namespace Squidex.Infrastructure.CQRS.Events
     {
         void NotifyEventsStored();
 
-        void Subscribe(Action handler);
+        IDisposable Subscribe(Action handler);
     }
 }

src/Squidex/appsettings.json

@@ -1,70 +1,187 @@
 {
   "urls": {
+    /*
+     * Set the base url of your application, to generate correct urls in background process.
+     */
     "baseUrl": "http://localhost:5000"
   },
+
   "logging": {
-    "human": false 
+    /*
+     * Setting the flag to true, enables well formatteds json logs.
+     */
+    "human": false
   },
+
+  /*
+   * The pub sub mechanmism distributes messages between the nodes.
+   */
   "pubSub": {
+    /*
+     * Define the type of the read store. 
+     * 
+     * Supported: InMemory (for single node only), Redis (for cluster)
+     */
     "type": "InMemory",
     "redis": {
+      /*
+       * Connection string to your redis server.
+       *
+       * Read More: https://github.com/ServiceStack/ServiceStack.Redis#redis-connection-strings
+       */
       "configuration": "localhost:6379,resolveDns=1"
     }
   },
+
   "assetStore": {
+    /*
+     * Define the type of the read store. 
+     * 
+     * Supported: Folder (local folder), GoogleCloud (hosted in Google Cloud only)
+     */
     "type": "Folder",
     "folder": {
+      /*
+       * The relative or absolute path to the folder to store the assets.
+       */
       "path": "Assets"
     },
     "googleCloud": {
+      /*
+       * The name of the bucket in google cloud store.
+       */
       "bucket": "squidex-assets"
     }
   },
+
   "eventStore": {
+    /*
+     * Define the type of the event store. 
+     * 
+     * Supported: MongoDb, GetEventStore
+     */
     "type": "MongoDb",
     "mongoDb": {
+      /*
+       * The connection string to your Mongo Server.
+       * 
+       * Read More: https://docs.mongodb.com/manual/reference/connection-string/
+       */
       "configuration": "mongodb://localhost",
+      /*
+       * The name of the event store database.
+       */
       "database": "Squidex"
     },
     "getEventStore": {
+      /*
+       * The connection string to your EventStore.
+       * 
+       * Read Mode: http://docs.geteventstore.com/dotnet-api/4.0.0/connecting-to-a-server/
+       */
       "configuration": "ConnectTo=tcp://admin:changeit@localhost:1113; HeartBeatTimeout=500",
+      /*
+       * The host name of your EventStore where projection requests will be sent to.
+       */
       "projectionHost": "localhost",
+      /*
+       * Prefix for all streams and projections (for multiple installations).
+       */
       "prefix": "squidex"
     },
+    /*
+     * Consume the events on this server (Ensure that it is only enabled on a single node).
+     */
     "consume": true
   },
+
   "eventPublishers": {
+    /*
+     * Additional event publishers (advanced usage only): (Name => Config)
+     */
     "allToRabbitMq": {
+      /*
+       * Example:: Push all events to RabbitMq.
+       */
       "type": "RabbitMq",
       "configuration": "amqp://guest:guest@localhost/",
       "exchange": "squidex",
       "enabled": false,
-      "eventsFilter": "*"
-    } 
-  }, 
+      "eventsFilter": ".*"
+    }
+  },
+
   "store": {
+    /*
+     * Define the type of the read store. 
+     * 
+     * Supported: MongoDb
+     */
     "type": "MongoDb",
     "mongoDb": {
+      /*
+       * The connection string to your Mongo Server.
+       * 
+       * Read More: https://docs.mongodb.com/manual/reference/connection-string/
+       */
       "configuration": "mongodb://localhost",
+      /*
+       * The database for all your content collections (one collection per app).
+       */
       "contentDatabase": "SquidexContent",
+      /*
+       * The database for all your other read collections.
+       */
       "database": "Squidex"
     }
   },
+
   "identity": {
+    /*
+     * Enable password auth.
+     */
     "allowPasswordAuth": true,
+    /*
+     * Settings for Google auth (keep empty to disable).
+     */
     "googleClient": "1006817248705-t3lb3ge808m9am4t7upqth79hulk456l.apps.googleusercontent.com",
     "googleSecret": "QsEi-fHqkGw2_PjJmtNHf2wg",
+    /*
+     * Settings for Github auth (keep empty to disable).
+     */
     "githubClient": "211ea00e726baf754c78",
     "githubSecret": "d0a0d0fe2c26469ae20987ac265b3a339fd73132",
+    /*
+     * Settings for Microsoft auth (keep empty to disable).
+     */
     "microsoftClient": "b55da740-6648-4502-8746-b9003f29d5f1",
     "microsoftSecret": "idWbANxNYEF4cB368WXJhjN",
+    /*
+     * Lock new users automatically, the administrator must unlock them.
+     */
     "lockAutomatically": true,
+
     "keysStore": {
+      /*
+       * Define the type of the key store. 
+       * 
+       * Supported: InMemory (development only), Folder (shared or local), Redis
+       * 
+       * Read More: https://docs.microsoft.com/en-us/aspnet/core/security/data-protection/implementation/key-storage-providers
+       */
       "type": "InMemory",
       "redis": {
+        /*
+         * Connection string to your redis server.
+         *
+         * Read More: https://github.com/ServiceStack/ServiceStack.Redis#redis-connection-strings
+         */
         "configuration": "localhost:6379,resolveDns=1"
       },
       "folder": {
+        /*
+         * Relative or absolute path to your encryption keys folder.
+         */
         "path": "keys"
       }
     }