From e8ca90e799fc6f76a7ac8d6af45310c26f1a016b Mon Sep 17 00:00:00 2001
From: Chris Gillum <cgillum@microsoft.com>
Date: Mon, 2 Dec 2024 18:19:21 -0800
Subject: [PATCH] Use consistent scaler IDs for target-based and scale monitor
 implementations

---
 .../AzureStorageDurabilityProvider.cs         | 27 ++++++++++++++-----
 .../Listener/DurableTaskScaleMonitor.cs       | 13 ++-------
 2 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/src/WebJobs.Extensions.DurableTask/AzureStorageDurabilityProvider.cs b/src/WebJobs.Extensions.DurableTask/AzureStorageDurabilityProvider.cs
index ea5350463..1640dbd63 100644
--- a/src/WebJobs.Extensions.DurableTask/AzureStorageDurabilityProvider.cs
+++ b/src/WebJobs.Extensions.DurableTask/AzureStorageDurabilityProvider.cs
@@ -243,6 +243,13 @@ internal DurableTaskMetricsProvider GetMetricsProvider(
             return new DurableTaskMetricsProvider(hubName, logger, performanceMonitor: null, storageAccount);
         }
 
+        // Common routine for getting the scaler ID. Note that we MUST use the same ID for both the
+        // scale monitor and the target scaler.
+        private static string GetScalerUniqueId(string hubName)
+        {
+            return $"DurableTask-AzureStorage:{hubName ?? "default"}";
+        }
+
         /// <inheritdoc/>
         public override bool TryGetScaleMonitor(
             string functionId,
@@ -255,11 +262,17 @@ public override bool TryGetScaleMonitor(
             {
                 if (this.singletonScaleMonitor == null)
                 {
-                    CloudStorageAccount storageAccount = this.storageAccountProvider.GetStorageAccountDetails(connectionName).ToCloudStorageAccount();
-                    DurableTaskMetricsProvider metricsProvider = this.GetMetricsProvider(hubName, storageAccount, this.logger);
+                    DurableTaskMetricsProvider metricsProvider = this.GetMetricsProvider(
+                        hubName,
+                        this.storageAccountProvider.GetStorageAccountDetails(connectionName).ToCloudStorageAccount(),
+                        this.logger);
+
+                    // Scalers in Durable Functions are shared for all functions in the same task hub.
+                    // So instead of using a function ID, we use the task hub name as the basis for the descriptor ID.
+                    string id = GetScalerUniqueId(hubName);
                     this.singletonScaleMonitor = new DurableTaskScaleMonitor(
+                        id,
                         hubName,
-                        storageAccount,
                         this.logger,
                         metricsProvider);
                 }
@@ -283,12 +296,14 @@ public override bool TryGetTargetScaler(
                 if (this.singletonTargetScaler == null)
                 {
                     // This is only called by the ScaleController, it doesn't run in the Functions Host process.
-                    CloudStorageAccount storageAccount = this.storageAccountProvider.GetStorageAccountDetails(connectionName).ToCloudStorageAccount();
-                    DurableTaskMetricsProvider metricsProvider = this.GetMetricsProvider(hubName, storageAccount, this.logger);
+                    DurableTaskMetricsProvider metricsProvider = this.GetMetricsProvider(
+                        hubName,
+                        this.storageAccountProvider.GetStorageAccountDetails(connectionName).ToCloudStorageAccount(),
+                        this.logger);
 
                     // Scalers in Durable Functions are shared for all functions in the same task hub.
                     // So instead of using a function ID, we use the task hub name as the basis for the descriptor ID.
-                    string id = $"DurableTask-AzureStorage:{hubName ?? "default"}";
+                    string id = GetScalerUniqueId(hubName);
                     this.singletonTargetScaler = new DurableTaskTargetScaler(id, metricsProvider, this, this.logger);
                 }
 
diff --git a/src/WebJobs.Extensions.DurableTask/Listener/DurableTaskScaleMonitor.cs b/src/WebJobs.Extensions.DurableTask/Listener/DurableTaskScaleMonitor.cs
index c24762e06..fc9225b72 100644
--- a/src/WebJobs.Extensions.DurableTask/Listener/DurableTaskScaleMonitor.cs
+++ b/src/WebJobs.Extensions.DurableTask/Listener/DurableTaskScaleMonitor.cs
@@ -9,7 +9,6 @@
 using DurableTask.AzureStorage.Monitoring;
 using Microsoft.Azure.WebJobs.Host.Scale;
 using Microsoft.Extensions.Logging;
-using Microsoft.WindowsAzure.Storage;
 using Newtonsoft.Json;
 
 namespace Microsoft.Azure.WebJobs.Extensions.DurableTask
@@ -17,27 +16,19 @@ namespace Microsoft.Azure.WebJobs.Extensions.DurableTask
     internal sealed class DurableTaskScaleMonitor : IScaleMonitor<DurableTaskTriggerMetrics>
     {
         private readonly string hubName;
-        private readonly CloudStorageAccount storageAccount;
         private readonly ScaleMonitorDescriptor scaleMonitorDescriptor;
         private readonly ILogger logger;
         private readonly DurableTaskMetricsProvider durableTaskMetricsProvider;
 
-        private DisconnectedPerformanceMonitor performanceMonitor;
-
         public DurableTaskScaleMonitor(
+            string id,
             string hubName,
-            CloudStorageAccount storageAccount,
             ILogger logger,
-            DurableTaskMetricsProvider durableTaskMetricsProvider,
-            DisconnectedPerformanceMonitor performanceMonitor = null)
+            DurableTaskMetricsProvider durableTaskMetricsProvider)
         {
             this.hubName = hubName;
-            this.storageAccount = storageAccount;
             this.logger = logger;
-            this.performanceMonitor = performanceMonitor;
             this.durableTaskMetricsProvider = durableTaskMetricsProvider;
-
-            string id = $"DurableTaskTrigger-{this.hubName}".ToLower();
 #if FUNCTIONS_V3_OR_GREATER
             // Scalers in Durable Functions are shared for all functions in the same task hub.
             // So instead of using a function ID, we use the task hub name as the basis for the descriptor ID.