Fixing scaler provider initialization pattern (Azure#38673)

Author: alrod

sdk/eventhub/Microsoft.Azure.WebJobs.Extensions.EventHubs/src/Config/EventHubWebJobsBuilderExtensions.cs

@@ -94,20 +94,9 @@ public static IWebJobsBuilder AddEventHubs(this IWebJobsBuilder builder, Action<
 
         internal static IWebJobsBuilder AddEventHubsScaleForTrigger(this IWebJobsBuilder builder, TriggerMetadata triggerMetadata)
         {
-            IServiceProvider serviceProvider = null;
-            Lazy<EventHubsScalerProvider> scalerProvider = new Lazy<EventHubsScalerProvider>(() => new EventHubsScalerProvider(serviceProvider, triggerMetadata));
-
-            builder.Services.AddSingleton<IScaleMonitorProvider>(resolvedServiceProvider =>
-            {
-                serviceProvider = serviceProvider ?? resolvedServiceProvider;
-                return scalerProvider.Value;
-            });
-
-            builder.Services.AddSingleton<ITargetScalerProvider>(resolvedServiceProvider =>
-            {
-                serviceProvider = serviceProvider ?? resolvedServiceProvider;
-                return scalerProvider.Value;
-            });
+            builder.Services.AddSingleton(serviceProvider => new EventHubsScalerProvider(serviceProvider, triggerMetadata));
+            builder.Services.AddSingleton<IScaleMonitorProvider>(serviceProvider => serviceProvider.GetRequiredService<EventHubsScalerProvider>());
+            builder.Services.AddSingleton<ITargetScalerProvider>(serviceProvider => serviceProvider.GetRequiredService<EventHubsScalerProvider>());
 
             return builder;
         }

sdk/servicebus/Microsoft.Azure.WebJobs.Extensions.ServiceBus/src/Config/ServiceBusHostBuilderExtensions.cs

@@ -108,20 +108,9 @@ public static IWebJobsBuilder AddServiceBus(this IWebJobsBuilder builder, Action
 
         internal static IWebJobsBuilder AddServiceBusScaleForTrigger(this IWebJobsBuilder builder, TriggerMetadata triggerMetadata)
         {
-            IServiceProvider serviceProvider = null;
-            Lazy<ServiceBusScalerProvider> scalerProvider = new Lazy<ServiceBusScalerProvider>(() => new ServiceBusScalerProvider(serviceProvider, triggerMetadata));
-
-            builder.Services.AddSingleton<IScaleMonitorProvider>(resolvedServiceProvider =>
-            {
-                serviceProvider = serviceProvider ?? resolvedServiceProvider;
-                return scalerProvider.Value;
-            });
-
-            builder.Services.AddSingleton<ITargetScalerProvider>(resolvedServiceProvider =>
-            {
-                serviceProvider = serviceProvider ?? resolvedServiceProvider;
-                return scalerProvider.Value;
-            });
+            builder.Services.AddSingleton(serviceProvider => new ServiceBusScalerProvider(serviceProvider, triggerMetadata));
+            builder.Services.AddSingleton<IScaleMonitorProvider>(serviceProvider => serviceProvider.GetRequiredService<ServiceBusScalerProvider>());
+            builder.Services.AddSingleton<ITargetScalerProvider>(serviceProvider => serviceProvider.GetRequiredService<ServiceBusScalerProvider>());
 
             return builder;
         }

sdk/storage/Microsoft.Azure.WebJobs.Extensions.Storage.Queues/src/StorageQueuesWebJobsBuilderExtensions.cs

@@ -74,20 +74,9 @@ public static IWebJobsBuilder AddAzureStorageQueues(this IWebJobsBuilder builder
         /// <returns></returns>
         public static IWebJobsBuilder AddAzureStorageQueuesScaleForTrigger(this IWebJobsBuilder builder, TriggerMetadata triggerMetadata)
         {
-            IServiceProvider serviceProvider = null;
-            Lazy<QueueScalerProvider> scalerProvider = new Lazy<QueueScalerProvider>(() => new QueueScalerProvider(serviceProvider, triggerMetadata));
-
-            builder.Services.AddSingleton<IScaleMonitorProvider>(resolvedServiceProvider =>
-            {
-                serviceProvider = serviceProvider ?? resolvedServiceProvider;
-                return scalerProvider.Value;
-            });
-
-            builder.Services.AddSingleton<ITargetScalerProvider>(resolvedServiceProvider =>
-            {
-                serviceProvider = serviceProvider ?? resolvedServiceProvider;
-                return scalerProvider.Value;
-            });
+            builder.Services.AddSingleton(serviceProvider => new QueueScalerProvider(serviceProvider, triggerMetadata));
+            builder.Services.AddSingleton<IScaleMonitorProvider>(serviceProvider => serviceProvider.GetRequiredService<QueueScalerProvider>());
+            builder.Services.AddSingleton<ITargetScalerProvider>(serviceProvider => serviceProvider.GetRequiredService<QueueScalerProvider>());
 
             return builder;
         }