From 0cb497371c2a5123285425b5709ce51eef2ef48c Mon Sep 17 00:00:00 2001
From: maliming <malimings@gmail.com>
Date: Thu, 11 May 2023 22:09:52 +0800
Subject: [PATCH] Add `LocalEventHandlerOrderAttribute`.

Resolve #16361
---
 .../Local/LocalEventHandlerOrderAttribute.cs  | 17 ++++++
 .../Volo/Abp/EventBus/Local/LocalEventBus.cs  | 15 ++++-
 .../Abp/EventBus/Local/EventBus_Order_Test.cs | 56 +++++++++++++++++++
 3 files changed, 87 insertions(+), 1 deletion(-)
 create mode 100644 framework/src/Volo.Abp.EventBus.Abstractions/Volo/Abp/EventBus/Local/LocalEventHandlerOrderAttribute.cs
 create mode 100644 framework/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/Local/EventBus_Order_Test.cs

diff --git a/framework/src/Volo.Abp.EventBus.Abstractions/Volo/Abp/EventBus/Local/LocalEventHandlerOrderAttribute.cs b/framework/src/Volo.Abp.EventBus.Abstractions/Volo/Abp/EventBus/Local/LocalEventHandlerOrderAttribute.cs
new file mode 100644
index 0000000000..7900885e3e
--- /dev/null
+++ b/framework/src/Volo.Abp.EventBus.Abstractions/Volo/Abp/EventBus/Local/LocalEventHandlerOrderAttribute.cs
@@ -0,0 +1,17 @@
+using System;
+
+namespace Volo.Abp.EventBus.Local;
+
+[AttributeUsage(AttributeTargets.Class, AllowMultiple = false, Inherited = true)]
+public class LocalEventHandlerOrderAttribute : Attribute
+{
+    /// <summary>
+    /// Handlers execute in ascending numeric value of the Order property.
+    /// </summary>
+    public int Order { get; set; }
+
+    public LocalEventHandlerOrderAttribute(int order)
+    {
+        Order = order;
+    }
+}
diff --git a/framework/src/Volo.Abp.EventBus/Volo/Abp/EventBus/Local/LocalEventBus.cs b/framework/src/Volo.Abp.EventBus/Volo/Abp/EventBus/Local/LocalEventBus.cs
index 9570bf80e1..e1edf3b12f 100644
--- a/framework/src/Volo.Abp.EventBus/Volo/Abp/EventBus/Local/LocalEventBus.cs
+++ b/framework/src/Volo.Abp.EventBus/Volo/Abp/EventBus/Local/LocalEventBus.cs
@@ -10,6 +10,7 @@ using Microsoft.Extensions.DependencyInjection;
 using Volo.Abp.DependencyInjection;
 using Volo.Abp.EventBus.Distributed;
 using Volo.Abp.MultiTenancy;
+using Volo.Abp.Reflection;
 using Volo.Abp.Threading;
 using Volo.Abp.Uow;
 
@@ -140,9 +141,21 @@ public class LocalEventBus : EventBusBase, ILocalEventBus, ISingletonDependency
     {
         var handlerFactoryList = new List<EventTypeWithEventHandlerFactories>();
 
+        var handlerWithTypes = new List<Tuple<IEventHandlerFactory, Type, int>>();
         foreach (var handlerFactory in HandlerFactories.Where(hf => ShouldTriggerEventForHandler(eventType, hf.Key)))
         {
-            handlerFactoryList.Add(new EventTypeWithEventHandlerFactories(handlerFactory.Key, handlerFactory.Value));
+            foreach (var factory in handlerFactory.Value)
+            {
+                handlerWithTypes.Add(new Tuple<IEventHandlerFactory, Type, int>(
+                    factory,
+                    handlerFactory.Key,
+                    ReflectionHelper.GetAttributesOfMemberOrDeclaringType<LocalEventHandlerOrderAttribute>(factory.GetHandler().EventHandler.GetType()).FirstOrDefault()?.Order ?? 0));
+            }
+        }
+
+        foreach (var handlerWithType in handlerWithTypes.OrderBy(x => x.Item3))
+        {
+            handlerFactoryList.Add(new EventTypeWithEventHandlerFactories(handlerWithType.Item2, new List<IEventHandlerFactory>{ handlerWithType.Item1 }));
         }
 
         return handlerFactoryList.ToArray();
diff --git a/framework/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/Local/EventBus_Order_Test.cs b/framework/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/Local/EventBus_Order_Test.cs
new file mode 100644
index 0000000000..3bf8c3a7b6
--- /dev/null
+++ b/framework/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/Local/EventBus_Order_Test.cs
@@ -0,0 +1,56 @@
+using System.Threading.Tasks;
+using Shouldly;
+using Volo.Abp.DependencyInjection;
+using Volo.Abp.Domain.Entities;
+using Volo.Abp.Domain.Entities.Events;
+using Xunit;
+
+namespace Volo.Abp.EventBus.Local;
+
+public class EventBus_Order_Test : EventBusTestBase
+{
+    public static string HandlerExecuteOrder { get; set; }
+
+    [Fact]
+    public async Task Handler_Should_Execute_By_Order()
+    {
+        HandlerExecuteOrder = "";
+        await LocalEventBus.PublishAsync(new MyOrderEventHandlerEventData());
+        HandlerExecuteOrder.ShouldBe("321");
+    }
+
+    public class MyOrderEventHandlerEventData
+    {
+
+    }
+
+    public class MyOrderEventHandler : ILocalEventHandler<MyOrderEventHandlerEventData>, ITransientDependency
+    {
+        public Task HandleEventAsync(MyOrderEventHandlerEventData eventData)
+        {
+            HandlerExecuteOrder += "1";
+            return Task.CompletedTask;
+        }
+    }
+
+    [LocalEventHandlerOrder(-2)]
+    public class MyOrderEventHandler2 : ILocalEventHandler<MyOrderEventHandlerEventData>, ITransientDependency
+    {
+        public Task HandleEventAsync(MyOrderEventHandlerEventData eventData)
+        {
+            HandlerExecuteOrder += "2";
+            return Task.CompletedTask;
+        }
+    }
+
+    [LocalEventHandlerOrder(-3)]
+    public class MyOrderEventHandler3 : ILocalEventHandler<MyOrderEventHandlerEventData>, ITransientDependency
+    {
+        public Task HandleEventAsync(MyOrderEventHandlerEventData eventData)
+        {
+            HandlerExecuteOrder += "3";
+            return Task.CompletedTask;
+        }
+    }
+
+}