Merge pull request #48 from lucaslorentz/improve-await-untyped-task

Improve await of awaitable return types

Author: lucaslorentz

src/LLL.DurableTask.Worker/Activities/MethodTaskActivity.cs

@@ -6,6 +6,7 @@
 using DurableTask.Core;
 using DurableTask.Core.Serializing;
 using LLL.DurableTask.Core.Serializing;
+using LLL.DurableTask.Worker.Utils;
 using Newtonsoft.Json.Linq;
 
 namespace LLL.DurableTask.Worker.Orchestrations;
@@ -87,21 +88,7 @@ private object[] PrepareParameters(
 
     private async Task<string> SerializeResult(object result)
     {
-        if (result is Task task)
-        {
-            if (_methodInfo.ReturnType.IsGenericType)
-            {
-                result = await (dynamic)task;
-            }
-            else
-            {
-                await task;
-                result = null;
-            }
-        }
-
-        var serializedResult = _dataConverter.Serialize(result);
-
-        return serializedResult;
+        var awaitedResult = await TaskUtils.MaybeAwait(result, _methodInfo.ReturnType);
+        return _dataConverter.Serialize(awaitedResult);
     }
 }

src/LLL.DurableTask.Worker/Orchestrations/MethodTaskOrchestration.cs

@@ -6,6 +6,7 @@
 using DurableTask.Core;
 using DurableTask.Core.Serializing;
 using LLL.DurableTask.Core.Serializing;
+using LLL.DurableTask.Worker.Utils;
 
 namespace LLL.DurableTask.Worker.Orchestrations;
 
@@ -92,20 +93,9 @@ private object[] PrepareParameters(
 
     private async Task<string> SerializeResult(object result)
     {
-        if (result is Task task)
-        {
-            if (_methodInfo.ReturnType.IsGenericType)
-            {
-                result = await (dynamic)task;
-            }
-            else
-            {
-                await task;
-                result = null;
-            }
-        }
+        var awaitedResult = await TaskUtils.MaybeAwait(result, _methodInfo.ReturnType);
 
-        var serializedResult = _dataConverter.Serialize(result);
+        var serializedResult = _dataConverter.Serialize(awaitedResult);
 
         return serializedResult;
     }

src/LLL.DurableTask.Worker/Utils/TaskUtils.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Runtime.CompilerServices;
+using System.Threading.Tasks;
+
+namespace LLL.DurableTask.Worker.Utils;
+
+internal static class TaskUtils
+{
+    public static async Task<object> MaybeAwait(dynamic result, Type returnType)
+    {
+        var getAwaiterMethod = returnType.GetMethod(nameof(Task.GetAwaiter));
+        if (getAwaiterMethod is null)
+            return result;
+
+        var getResultMethod = getAwaiterMethod.ReturnType.GetMethod(nameof(TaskAwaiter<object>.GetResult));
+        if (getResultMethod is not null && getResultMethod.ReturnType != typeof(void))
+        {
+            return await result;
+        }
+        else
+        {
+            await result;
+            return null;
+        }
+    }
+}