From feddd422bcbb33e54fe865ac4251c549c9d41e60 Mon Sep 17 00:00:00 2001
From: Halil ibrahim Kalkan <hi_kalkan@yahoo.com>
Date: Tue, 23 Oct 2018 09:23:01 +0300
Subject: [PATCH] Resolved #557: Implement NullBackgroundJobManager.

---
 .../BackgroundJobManagerExtensions.cs         | 12 +++++++++
 .../NullBackgroundJobManager.cs               | 25 +++++++++++++++++++
 .../RabbitMQ/RabbitMqBackgroundJobManager.cs  |  1 +
 .../Abp/BackgroundJobs/BackgroundJobWorker.cs |  3 ---
 .../DefaultBackgroundJobManager.cs            |  5 +---
 .../Volo/Abp/Emailing/EmailSenderBase.cs      |  6 +++++
 6 files changed, 45 insertions(+), 7 deletions(-)
 create mode 100644 framework/src/Volo.Abp.BackgroundJobs.Abstractions/Volo/Abp/BackgroundJobs/NullBackgroundJobManager.cs

diff --git a/framework/src/Volo.Abp.BackgroundJobs.Abstractions/Volo/Abp/BackgroundJobs/BackgroundJobManagerExtensions.cs b/framework/src/Volo.Abp.BackgroundJobs.Abstractions/Volo/Abp/BackgroundJobs/BackgroundJobManagerExtensions.cs
index 18a772f01f..4cc93fa533 100644
--- a/framework/src/Volo.Abp.BackgroundJobs.Abstractions/Volo/Abp/BackgroundJobs/BackgroundJobManagerExtensions.cs
+++ b/framework/src/Volo.Abp.BackgroundJobs.Abstractions/Volo/Abp/BackgroundJobs/BackgroundJobManagerExtensions.cs
@@ -1,4 +1,5 @@
 using System;
+using Volo.Abp.DynamicProxy;
 using Volo.Abp.Threading;
 
 namespace Volo.Abp.BackgroundJobs
@@ -20,5 +21,16 @@ namespace Volo.Abp.BackgroundJobs
         {
             return AsyncHelper.RunSync(() => backgroundJobManager.EnqueueAsync<TArgs>(args, priority, delay));
         }
+
+        /// <summary>
+        /// Checks if background job system has a real implementation.
+        /// It returns false if the current implementation is <see cref="NullBackgroundJobManager"/>.
+        /// </summary>
+        /// <param name="backgroundJobManager"></param>
+        /// <returns></returns>
+        public static bool IsAvailable(this IBackgroundJobManager backgroundJobManager)
+        {
+            return !(ProxyHelper.UnProxy(backgroundJobManager) is NullBackgroundJobManager);
+        }
     }
 }
diff --git a/framework/src/Volo.Abp.BackgroundJobs.Abstractions/Volo/Abp/BackgroundJobs/NullBackgroundJobManager.cs b/framework/src/Volo.Abp.BackgroundJobs.Abstractions/Volo/Abp/BackgroundJobs/NullBackgroundJobManager.cs
new file mode 100644
index 0000000000..f7d9fdd88a
--- /dev/null
+++ b/framework/src/Volo.Abp.BackgroundJobs.Abstractions/Volo/Abp/BackgroundJobs/NullBackgroundJobManager.cs
@@ -0,0 +1,25 @@
+using System;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+using Volo.Abp.DependencyInjection;
+
+namespace Volo.Abp.BackgroundJobs
+{
+    [Dependency(TryRegister = true)]
+    public class NullBackgroundJobManager : IBackgroundJobManager, ISingletonDependency
+    {
+        public ILogger<NullBackgroundJobManager> Logger { get; set; }
+
+        public NullBackgroundJobManager()
+        {
+            Logger = NullLogger<NullBackgroundJobManager>.Instance;
+        }
+
+        public virtual Task<string> EnqueueAsync<TArgs>(TArgs args, BackgroundJobPriority priority = BackgroundJobPriority.Normal,
+            TimeSpan? delay = null)
+        {
+            throw new AbpException("Background job system has not a real implementation. If it's mandatory, use an implementation (either the default provider or a 3rd party implementation). If it's optional, check IBackgroundJobManager.IsAvailable() extension method and act based on it.");
+        }
+    }
+}
\ No newline at end of file
diff --git a/framework/src/Volo.Abp.BackgroundJobs.RabbitMQ/Volo/Abp/BackgroundJobs/RabbitMQ/RabbitMqBackgroundJobManager.cs b/framework/src/Volo.Abp.BackgroundJobs.RabbitMQ/Volo/Abp/BackgroundJobs/RabbitMQ/RabbitMqBackgroundJobManager.cs
index 75b7dd801a..c2976e43fb 100644
--- a/framework/src/Volo.Abp.BackgroundJobs.RabbitMQ/Volo/Abp/BackgroundJobs/RabbitMQ/RabbitMqBackgroundJobManager.cs
+++ b/framework/src/Volo.Abp.BackgroundJobs.RabbitMQ/Volo/Abp/BackgroundJobs/RabbitMQ/RabbitMqBackgroundJobManager.cs
@@ -4,6 +4,7 @@ using Volo.Abp.DependencyInjection;
 
 namespace Volo.Abp.BackgroundJobs.RabbitMQ
 {
+    [Dependency(ReplaceServices = true)]
     public class RabbitMqBackgroundJobManager : IBackgroundJobManager, ITransientDependency
     {
         private readonly IJobQueueManager _jobQueueManager;
diff --git a/framework/src/Volo.Abp.BackgroundJobs/Volo/Abp/BackgroundJobs/BackgroundJobWorker.cs b/framework/src/Volo.Abp.BackgroundJobs/Volo/Abp/BackgroundJobs/BackgroundJobWorker.cs
index 018a426940..964f076714 100644
--- a/framework/src/Volo.Abp.BackgroundJobs/Volo/Abp/BackgroundJobs/BackgroundJobWorker.cs
+++ b/framework/src/Volo.Abp.BackgroundJobs/Volo/Abp/BackgroundJobs/BackgroundJobWorker.cs
@@ -17,9 +17,6 @@ namespace Volo.Abp.BackgroundJobs
         protected IClock Clock { get; }
         protected IBackgroundJobSerializer Serializer { get; }
 
-        /// <summary>
-        /// Initializes a new instance of the <see cref="DefaultBackgroundJobManager"/> class.
-        /// </summary>
         public BackgroundJobWorker(
             IBackgroundJobStore store,
             AbpTimer timer,
diff --git a/framework/src/Volo.Abp.BackgroundJobs/Volo/Abp/BackgroundJobs/DefaultBackgroundJobManager.cs b/framework/src/Volo.Abp.BackgroundJobs/Volo/Abp/BackgroundJobs/DefaultBackgroundJobManager.cs
index 7f5723456b..0c8aff450c 100644
--- a/framework/src/Volo.Abp.BackgroundJobs/Volo/Abp/BackgroundJobs/DefaultBackgroundJobManager.cs
+++ b/framework/src/Volo.Abp.BackgroundJobs/Volo/Abp/BackgroundJobs/DefaultBackgroundJobManager.cs
@@ -9,7 +9,7 @@ namespace Volo.Abp.BackgroundJobs
     /// <summary>
     /// Default implementation of <see cref="IBackgroundJobManager"/>.
     /// </summary>
-    [Dependency(TryRegister = true)]
+    [Dependency(ReplaceServices = true)]
     public class DefaultBackgroundJobManager : IBackgroundJobManager, ISingletonDependency
     {
         protected IClock Clock { get; }
@@ -17,9 +17,6 @@ namespace Volo.Abp.BackgroundJobs
         protected IGuidGenerator GuidGenerator { get; }
         protected IBackgroundJobStore Store { get; }
         
-        /// <summary>
-        /// Initializes a new instance of the <see cref="DefaultBackgroundJobManager"/> class.
-        /// </summary>
         public DefaultBackgroundJobManager(
             IClock clock,
             IBackgroundJobSerializer serializer,
diff --git a/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/EmailSenderBase.cs b/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/EmailSenderBase.cs
index 4a2d7c16ef..14db8c10c2 100644
--- a/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/EmailSenderBase.cs
+++ b/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/EmailSenderBase.cs
@@ -68,6 +68,12 @@ namespace Volo.Abp.Emailing
 
         public virtual async Task QueueAsync(string to, string subject, string body, bool isBodyHtml = true)
         {
+            if (!BackgroundJobManager.IsAvailable())
+            {
+                await SendAsync(to, subject, body, isBodyHtml);
+                return;
+            }
+
             await BackgroundJobManager.EnqueueAsync(
                 new BackgroundEmailSendingJobArgs
                 {