Ensure the DI scope flows through async calls

Author: fabiocav

src/WebJobs.Script.WebHost/DependencyInjection/DryIoc/AsyncScopeContext.cs

@@ -0,0 +1,39 @@
+// 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.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using DryIoc;
+
+namespace Microsoft.Azure.WebJobs.Script.WebHost.DependencyInjection.DryIoc
+{
+    public class AsyncScopeContext : IScopeContext
+    {
+        private static AsyncLocal<IScope> _asyncLocalScope = new AsyncLocal<IScope>();
+
+        public IScope GetCurrentOrDefault()
+        {
+            return _asyncLocalScope.Value;
+        }
+
+        public IScope SetCurrent(SetCurrentScopeHandler setCurrentScope)
+        {
+            if (setCurrentScope == null)
+            {
+                throw new ArgumentNullException(nameof(setCurrentScope));
+            }
+
+            var oldScope = GetCurrentOrDefault();
+            var newScope = setCurrentScope(oldScope);
+            _asyncLocalScope.Value = newScope;
+            return newScope;
+        }
+
+        public void Dispose()
+        {
+        }
+    }
+}

src/WebJobs.Script.WebHost/DependencyInjection/DryIoc/Container.cs

@@ -34,7 +34,6 @@ namespace DryIoc
     using System.Text;
     using System.Threading;
     using System.Diagnostics.CodeAnalysis;  // for SuppressMessage
-    using System.Diagnostics;               // for StackTrace
 
     using ImTools;
     using static ImTools.ArrayTools;
@@ -64,6 +63,7 @@ namespace DryIoc
     using NewArrayExpr = System.Linq.Expressions.NewArrayExpression;
     using MemberAssignmentExpr = System.Linq.Expressions.MemberAssignment;
     using FactoryDelegateExpr = System.Linq.Expressions.Expression<FactoryDelegate>;
+    using global::Microsoft.Azure.WebJobs.Script.WebHost.DependencyInjection.DryIoc;
 
 #endif
 
@@ -1942,7 +1942,7 @@ private Container(Rules rules, Ref<Registry> registry, IScope singletonScope,
             _registry = registry;
 
             _singletonScope = singletonScope;
-            _scopeContext = scopeContext;
+            _scopeContext = scopeContext ?? new AsyncScopeContext();
             _ownCurrentScope = ownCurrentScope;
 
             _disposed = disposed;