Exposing common scaling code to consume by SC v3

build/common.props

@@ -1,7 +1,7 @@
 <Project>
   <PropertyGroup>
     <!-- Packages can have independent versions and only increment when released -->
-    <Version>3.0.36$(VersionSuffix)</Version>
+    <Version>3.0.36-11991</Version>
     <HostStorageVersion>5.0.0-beta.2$(VersionSuffix)</HostStorageVersion>
     <LoggingVersion>4.0.3$(VersionSuffix)</LoggingVersion>
 

src/Microsoft.Azure.WebJobs.Host.Storage/BlobStorageConcurrencyStatusRepository.cs

@@ -17,7 +17,7 @@
 
 namespace Microsoft.Azure.WebJobs.Host
 {
-    internal class BlobStorageConcurrencyStatusRepository : IConcurrencyStatusRepository
+    public class BlobStorageConcurrencyStatusRepository : IConcurrencyStatusRepository
     {
         private readonly IHostIdProvider _hostIdProvider;
         private readonly ILogger _logger;

src/Microsoft.Azure.WebJobs.Host/Hosting/ITriggerScaleConfigure.cs

@@ -0,0 +1,24 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using Microsoft.Extensions.Hosting;
+
+namespace Microsoft.Azure.WebJobs.Hosting
+{
+    /// <summary>
+    /// Interface defining a trigger scale configuration action.
+    /// as part of host startup.
+    /// </summary>
+    public interface IConfigureTriggerScale
+    {
+        /// <summary>
+        /// Performs the scale configuration action for a trigger. The host will call this
+        /// method at the right time during scale host initialization for each trigger.
+        /// </summary>
+        /// <param name="builder">The <see cref="IHostBuilder"/> that can be used to
+        /// configure the trigger scale.</param>
+        /// <param name="triggerScaleContext">he <see cref="HostBuilderContext"/> hat can be used to
+        /// configure the trigger scale.</param>
+        void ConfigureTriggerScale(IHostBuilder builder, HostBuilderContext triggerScaleContext);
+    }
+}

src/Microsoft.Azure.WebJobs.Host/Hosting/WebJobsHostBuilderExtensions.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Linq;
 using Microsoft.Azure.WebJobs;
+using Microsoft.Azure.WebJobs.Host.Scale;
 using Microsoft.Azure.WebJobs.Hosting;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Configuration.EnvironmentVariables;
@@ -135,6 +136,22 @@ public static IHostBuilder ConfigureWebJobs(this IHostBuilder builder, Action<Ho
             return builder;
         }
 
+        /// <summary>
+        /// Applies scale configuration to the specified <see cref="IHostBuilder"/>.
+        /// </summary>
+        /// <param name="builder">The <see cref="IHostBuilder"/> to configure.</param>
+        /// <returns>The <see cref="IHostBuilder"/>.</returns>
+        public static IHostBuilder AddScale(this IHostBuilder builder)
+        {
+            builder.ConfigureServices((services) =>
+            {
+                services.TryAddSingleton<IScaleManager, ScaleManager>();
+                services.TryAddSingleton<IHostedService, ScaleMonitorService>();
+            });
+
+            return builder;
+        }
+
         private static IConfigurationBuilder TryAddDefaultConfigurationSources(this IConfigurationBuilder config)
         {
             if (!config.Sources.OfType<JsonConfigurationSource>().Any(p => string.Equals(p.Path, "appsettings.json", StringComparison.OrdinalIgnoreCase)))

src/Microsoft.Azure.WebJobs.Host/Scale/IScaleManager.cs

@@ -0,0 +1,27 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Microsoft.Azure.WebJobs.Host.Scale
+{
+    public interface IScaleManager
+    {
+        /// <summary>
+        /// Gets aggrigated <see cref="ScaleStatus"> for all the trigger.
+        /// </summary>
+        /// <param name="context">The scale status context.</param>
+        /// <returns></returns>
+        Task<ScaleStatus> GetScaleStatusAsync(ScaleStatusContext context);
+
+        /// <summary>
+        /// Gets <see cref="ScaleStatus"> for each trigger.
+        /// </summary>
+        /// <param name="context"></param>
+        /// <returns></returns>
+        Task<IDictionary<string, ScaleStatus>> GetScaleStatusesAsync(ScaleStatusContext context);
+    }
+}

src/Microsoft.Azure.WebJobs.Host/Scale/IScaleMetricsRepository.cs

@@ -0,0 +1,28 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace Microsoft.Azure.WebJobs.Host.Scale
+{
+    /// <summary>
+    /// Interface defining methods for reading/writing scale metrics to a persistent store.
+    /// </summary>
+    public interface IScaleMetricsRepository
+    {
+        /// <summary>
+        /// Persist the metrics for each monitor.
+        /// </summary>
+        /// <param name="monitorMetrics">The collection of metrics for each monitor.</param>
+        /// <returns>A task.</returns>
+        Task WriteMetricsAsync(IDictionary<IScaleMonitor, ScaleMetrics> monitorMetrics);
+
+        /// <summary>
+        /// Read the metrics.
+        /// </summary>
+        /// <param name="monitors">The current collection of monitors.</param>
+        /// <returns>Map of metrics per monitor.</returns>
+        Task<IDictionary<IScaleMonitor, IList<ScaleMetrics>>> ReadMetricsAsync(IEnumerable<IScaleMonitor> monitors);
+    }
+}