validate partition count for eventhubs

src/DurableTask.Netherite/TransportProviders/EventHubs/EventHubsTransport.cs

@@ -33,7 +33,6 @@ namespace DurableTask.Netherite.EventHubs
     {
         readonly TransportAbstraction.IHost host;
         readonly NetheriteOrchestrationServiceSettings settings;
-        readonly EventHubsConnections connections;
         readonly CloudStorageAccount cloudStorageAccount;
         readonly EventHubsTraceHelper traceHelper;
 
@@ -41,6 +40,8 @@ namespace DurableTask.Netherite.EventHubs
         TransportAbstraction.IClient client;
 
         TaskhubParameters parameters;
+        byte[] taskhubGuid;
+        EventHubsConnections connections;
 
         Task clientEventLoopTask = Task.CompletedTask;
         CancellationTokenSource shutdownSource;
@@ -59,12 +60,6 @@ namespace DurableTask.Netherite.EventHubs
             string namespaceName = TransportConnectionString.EventHubsNamespaceName(settings.EventHubsConnectionString);
             this.traceHelper = new EventHubsTraceHelper(loggerFactory, settings.TransportLogLevelLimit, this.cloudStorageAccount.Credentials.AccountName, settings.HubName, namespaceName);
             this.ClientId = Guid.NewGuid();
-            this.connections = new EventHubsConnections(settings.EventHubsConnectionString, EventHubsTransport.PartitionHubs, EventHubsTransport.ClientHubs)
-            {
-                Host = host,
-                TraceHelper = this.traceHelper,
-                UseJsonPackets = settings.UseJsonPackets,
-            };
             var blobContainerName = GetContainerName(settings.HubName);
             var cloudBlobClient = this.cloudStorageAccount.CreateCloudBlobClient();
             this.cloudBlobContainer = cloudBlobClient.GetContainerReference(blobContainerName);
@@ -149,6 +144,7 @@ namespace DurableTask.Netherite.EventHubs
             // load the taskhub parameters
             var jsonText = await this.taskhubParameters.DownloadTextAsync().ConfigureAwait(false);
             this.parameters = JsonConvert.DeserializeObject<TaskhubParameters>(jsonText);
+            this.taskhubGuid = this.parameters.TaskhubGuid.ToByteArray();
 
             // check that we are the correct taskhub!
             if (this.parameters.TaskhubName != this.settings.HubName)
@@ -158,7 +154,14 @@ namespace DurableTask.Netherite.EventHubs
           
             this.host.NumberPartitions = (uint) this.parameters.StartPositions.Length;
 
-            await this.connections.StartAsync();
+            this.connections = new EventHubsConnections(this.settings.EventHubsConnectionString, this.parameters.PartitionHubs, this.parameters.ClientHubs)
+            {
+                Host = host,
+                TraceHelper = this.traceHelper,
+                UseJsonPackets = this.settings.UseJsonPackets,
+            };
+
+            await this.connections.StartAsync(this.parameters.StartPositions.Length);
 
             this.client = this.host.AddClient(this.ClientId, this.parameters.TaskhubGuid, this);
 
@@ -220,7 +223,6 @@ namespace DurableTask.Netherite.EventHubs
 
         async Task ITaskHub.StopAsync(bool isForced)
         {
-            this.parameters = null;
             this.traceHelper.LogInformation("Shutting down EventHubsBackend");
             this.traceHelper.LogDebug("Stopping client event loop");
             this.shutdownSource.Cancel();
@@ -257,13 +259,13 @@ namespace DurableTask.Netherite.EventHubs
             {
                 case ClientEvent clientEvent:
                     var clientId = clientEvent.ClientId;
-                    var clientSender = this.connections.GetClientSender(clientEvent.ClientId, this.parameters.TaskhubGuid.ToByteArray());
+                    var clientSender = this.connections.GetClientSender(clientEvent.ClientId, this.taskhubGuid);
                     clientSender.Submit(clientEvent);
                     break;
 
                 case PartitionEvent partitionEvent:
                     var partitionId = partitionEvent.PartitionId;
-                    var partitionSender = this.connections.GetPartitionSender((int) partitionId, this.parameters.TaskhubGuid.ToByteArray());
+                    var partitionSender = this.connections.GetPartitionSender((int) partitionId, this.taskhubGuid);
                     partitionSender.Submit(partitionEvent);
                     break;