Exposed the ability to attach a custom exception handler

This provides a way for clients using Topshelf to act upon any exceptions that are thrown within the service (including unhandled exceptions).

src/SampleTopshelfService/Program.cs

@@ -51,6 +51,11 @@ static int Main()
                     x.AddCommandLineSwitch("throwonstart", v => throwOnStart = v);
                     x.AddCommandLineSwitch("throwonstop", v => throwOnStop = v);
                     x.AddCommandLineSwitch("throwunhandled", v => throwUnhandled = v);
+
+                    x.AddExceptionHandler(ex =>
+                    {
+                        Console.WriteLine("Exception thrown - " + ex.Message);
+                    });
                 });
         }
 

src/Topshelf/Configuration/HostConfigurators/HostConfigurator.cs

@@ -116,5 +116,12 @@ public interface HostConfigurator
         /// <param name="name"></param>
         /// <param name="callback"></param>
         void AddCommandLineDefinition(string name, Action<string> callback);
+
+        /// <summary>
+        /// Adds custom exception handler that will be called for any exception caught
+        /// by Topshelf while a service is starting, running or stopping.
+        /// </summary>
+        /// <param name="callback"></param>
+        void AddExceptionHandler(Action<Exception> callback);
     }
 }

src/Topshelf/Configuration/HostConfigurators/HostConfiguratorImpl.cs

@@ -182,6 +182,11 @@ public void AddCommandLineDefinition(string name, Action<string> callback)
             _commandLineOptionConfigurators.Add(configurator);
         }
 
+        public void AddExceptionHandler(Action<Exception> callback)
+        {
+            _settings.ExceptionHandler = callback;
+        }
+
         public Host CreateHost()
         {
             Type type = typeof(HostFactory);

src/Topshelf/Hosts/ConsoleRunHost.cs

@@ -102,6 +102,10 @@ public TopshelfExitCode Run()
             }
             catch (Exception ex)
             {
+                // Call the custom exception handler if it is not null
+                //
+                _settings.ExceptionHandler?.Invoke(ex);
+
                 _log.Error("An exception occurred", ex);
 
                 return TopshelfExitCode.AbnormalExit;
@@ -144,6 +148,10 @@ void HostControl.Restart()
 
         void CatchUnhandledException(object sender, UnhandledExceptionEventArgs e)
         {
+            // Call the custom exception handler if it is not null
+            //
+            _settings.ExceptionHandler?.Invoke((Exception)e.ExceptionObject);
+
             _log.Fatal("The service threw an unhandled exception", (Exception)e.ExceptionObject);
 
             HostLogger.Shutdown();
@@ -185,6 +193,10 @@ void StopService()
             }
             catch (Exception ex)
             {
+                // Call the custom exception handler if it is not null
+                //
+                _settings.ExceptionHandler?.Invoke(ex);
+
                 _log.Error("The service did not shut down gracefully", ex);
             }
             finally

src/Topshelf/Hosts/InstallHost.cs

@@ -204,6 +204,11 @@ public TimeSpan StopTimeOut
             {
               get { return _settings.StopTimeOut; }
             }
+
+            public Action<Exception> ExceptionHandler
+            {
+                get { return _settings.ExceptionHandler; }
+            }
         }
     }
 }

src/Topshelf/Runtime/HostSettings.cs

@@ -69,5 +69,10 @@ public interface HostSettings
         /// The amount of time to wait for the service to stop before timing out. Default is 10 seconds.
         /// </summary>
         TimeSpan StopTimeOut { get; }
+
+        /// <summary>
+        /// A callback to provide additional exception handling beyond what is already provided
+        /// </summary>
+        Action<Exception> ExceptionHandler { get; }
     }
 }

src/Topshelf/Runtime/Windows/WindowsHostSettings.cs

@@ -105,5 +105,7 @@ public string ServiceName
         public TimeSpan StartTimeOut { get; set; }
 
         public TimeSpan StopTimeOut { get; set; }
+
+        public Action<Exception> ExceptionHandler { get; set; }
     }
 }

src/Topshelf/Runtime/Windows/WindowsServiceHost.cs

@@ -130,6 +130,10 @@ protected override void OnStart(string[] args)
             }
             catch (Exception ex)
             {
+                // Call the custom exception handler if it is not null
+                //
+                _settings.ExceptionHandler?.Invoke(ex);
+
                 _log.Fatal("The service did not start successfully", ex);
 
                 ExitCode = (int)TopshelfExitCode.StartServiceFailed;
@@ -150,6 +154,10 @@ protected override void OnStop()
             }
             catch (Exception ex)
             {
+                // Call the custom exception handler if it is not null
+                //
+                _settings.ExceptionHandler?.Invoke(ex);
+
                 _log.Fatal("The service did not shut down gracefully", ex);
                 ExitCode = (int)TopshelfExitCode.StopServiceFailed;
                 throw;
@@ -176,6 +184,10 @@ protected override void OnPause()
             }
             catch (Exception ex)
             {
+                // Call the custom exception handler if it is not null
+                //
+                _settings.ExceptionHandler?.Invoke(ex);
+
                 _log.Fatal("The service did not pause gracefully", ex);
                 throw;
             }
@@ -194,6 +206,10 @@ protected override void OnContinue()
             }
             catch (Exception ex)
             {
+                // Call the custom exception handler if it is not null
+                //
+                _settings.ExceptionHandler?.Invoke(ex);
+
                 _log.Fatal("The service did not resume successfully", ex);
                 throw;
             }
@@ -211,6 +227,10 @@ protected override void OnShutdown()
             }
             catch (Exception ex)
             {
+                // Call the custom exception handler if it is not null
+                //
+                _settings.ExceptionHandler?.Invoke(ex);
+
                 _log.Fatal("The service did not shut down gracefully", ex);
                 ExitCode = (int)TopshelfExitCode.StopServiceFailed;
                 throw;
@@ -231,6 +251,10 @@ protected override void OnSessionChange(SessionChangeDescription changeDescripti
             }
             catch (Exception ex)
             {
+                // Call the custom exception handler if it is not null
+                //
+                _settings.ExceptionHandler?.Invoke(ex);
+
                 _log.Fatal("The service did not shut down gracefully", ex);
                 ExitCode = (int)TopshelfExitCode.StopServiceFailed;
                 throw;
@@ -249,6 +273,10 @@ protected override void OnCustomCommand(int command)
             }
             catch (Exception ex)
             {
+                // Call the custom exception handler if it is not null
+                //
+                _settings.ExceptionHandler?.Invoke(ex);
+
                 _log.Error("Unhandled exception during custom command processing detected", ex);
             }
         }
@@ -268,6 +296,10 @@ protected override void Dispose(bool disposing)
 
         void CatchUnhandledException(object sender, UnhandledExceptionEventArgs e)
         {
+            // Call the custom exception handler if it is not null
+            //
+            _settings.ExceptionHandler?.Invoke((Exception)e.ExceptionObject);
+
             _log.Fatal("The service threw an unhandled exception", (Exception)e.ExceptionObject);
 
             HostLogger.Shutdown();