[xsp] Improved single app mode shutdown sequence.

When XSP/mod-mono-server are operating in the single app mode, the application runs in the same AppDomain what the Server instance. This requires special attention to handling of the AppDomain's unload. This commit adds code which waits for the AppDomain unload process to complete before recreating the domain. Without this code it may happen that the main listening socket will not be destroyed in the "old" domain before the "new" domain attempts to bind its own listening socket to the same port (which leads to bind failure and exit from the process). The code is not very elegant but it is portable.
mono · Oct 25, 2010 · 9455071 · 9455071
1 parent fcf139c
commit 9455071
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Showing 2 changed files with 63 additions and 5 deletions.
diff --git a/src/Mono.WebServer.Apache/main.cs b/src/Mono.WebServer.Apache/main.cs
@@ -80,6 +80,9 @@ public ApplicationSettings ()
 			}
 		}
 
+		static bool singleAppUnloading;
+		static AppDomain singleAppDomain;
+
 		static void ShowVersion ()
 		{
 			Assembly assembly = Assembly.GetExecutingAssembly ();
@@ -219,6 +222,10 @@ public static void CurrentDomain_UnhandledException (object sender, UnhandledExc
 				Console.Error.WriteLine (ex);
 		}
 
+		void ApplicationDomainUnloading (object sender, EventArgs args)
+		{
+			singleAppUnloading = true;
+		}
 
 		public static int Main (string [] args)
 		{
@@ -228,10 +235,31 @@ public static int Main (string [] args)
 				try {
 					return new Server ().RealMain (args, true, null, quiet);
 				} catch (ThreadAbortException) {
+					Console.WriteLine ("Single application mode and ASP.NET AppDomain has unloaded.");
 					// Single-app mode and ASP.NET appdomain unloaded
 					Thread.ResetAbort ();
 					quiet = true; // hush 'RealMain'
 				}
+				if (singleAppUnloading && singleAppDomain != null) {
+					Console.WriteLine ("Waiting for the AppDomain unload to finish.");
+					while (true) {
+						try {
+							if (!singleAppDomain.IsFinalizingForUnload ())
+								break;
+							Thread.Sleep (500);
+						} catch (AppDomainUnloadedException) {
+							Console.WriteLine ("AppDomain unloaded.");
+							break;
+						} catch (ThreadAbortException) {
+							Thread.ResetAbort ();
+						} catch (Exception ex) {
+							Console.WriteLine ("Unload exception: {0}", ex);
+							break;
+						}
+					}
+					singleAppDomain = null;
+					singleAppUnloading = false;
+				}
 			}
 		}
 
@@ -414,7 +442,9 @@ public int RealMain (string [] args, bool root, IApplicationHost ext_apphost, bo
 			if (root && vh != null) {
 				// Redo in new domain
 				vh.CreateHost (server, webSource);
-				Server svr = (Server) vh.AppHost.Domain.CreateInstanceAndUnwrap (GetType ().Assembly.GetName ().ToString (), GetType ().FullName);
+				singleAppDomain = vh.AppHost.Domain;
+				singleAppDomain.DomainUnload += ApplicationDomainUnloading;
+				Server svr = (Server) singleAppDomain.CreateInstanceAndUnwrap (GetType ().Assembly.GetName ().ToString (), GetType ().FullName);
 				webSource.Dispose ();
 				return svr.RealMain (args, false, vh.AppHost, quiet);
 			}

diff --git a/src/Mono.WebServer.XSP/main.cs b/src/Mono.WebServer.XSP/main.cs
@@ -77,6 +77,8 @@ public ApplicationSettings ()
 		}
 
 		static RSA key;
+		static bool singleAppUnloading;
+		static AppDomain singleAppDomain;
 
 		static void ShowVersion ()
 		{
@@ -249,19 +251,44 @@ public static void CurrentDomain_UnhandledException (object sender, UnhandledExc
 				Console.WriteLine (ex);
 		}
 
+		void ApplicationDomainUnloading (object sender, EventArgs args)
+		{
+			singleAppUnloading = true;
+		}
+
 		public static int Main (string [] args)
 		{
 			AppDomain.CurrentDomain.UnhandledException += new UnhandledExceptionEventHandler (CurrentDomain_UnhandledException);
 			bool quiet = false;
 			while (true) {
 				try {
 					return new Server ().RealMain (args, true, null, quiet);
-				} catch (ThreadAbortException ex) {
-					Console.WriteLine (ex);
+				} catch (ThreadAbortException) {
+					Console.WriteLine ("Single application mode and ASP.NET AppDomain is unloading.");
 					// Single-app mode and ASP.NET appdomain unloaded
 					Thread.ResetAbort ();
 					quiet = true; // hush 'RealMain'
 				}
+				if (singleAppUnloading && singleAppDomain != null) {
+					Console.WriteLine ("\twaiting for the unload to finish...");
+					while (true) {
+						try {
+							if (!singleAppDomain.IsFinalizingForUnload ())
+								break;
+							Thread.Sleep (500);
+						} catch (AppDomainUnloadedException) {
+							Console.WriteLine ("\tdone...");
+							break;
+						} catch (ThreadAbortException) {
+							Thread.ResetAbort ();
+						} catch (Exception ex) {
+							Console.WriteLine ("\tunload exception: {0} ({1})", ex.GetType (), ex.Message);
+							break;
+						}
+					}
+					singleAppDomain = null;
+					singleAppUnloading = false;
+				}
 			}
 		}
 
@@ -446,12 +473,13 @@ public int RealMain (string [] args, bool root, IApplicationHost ext_apphost, bo
 			if (settings.Apps == null && settings.AppConfigDir == null && settings.AppConfigFile == null)
 				server.AddApplicationsFromCommandLine ("/:.");
 
-
 			VPathToHost vh = server.GetSingleApp ();
 			if (root && vh != null) {
 				// Redo in new domain
 				vh.CreateHost (server, webSource);
-				Server svr = (Server) vh.AppHost.Domain.CreateInstanceAndUnwrap (GetType ().Assembly.GetName ().ToString (), GetType ().FullName);
+				singleAppDomain = vh.AppHost.Domain;
+				singleAppDomain.DomainUnload += ApplicationDomainUnloading;
+				Server svr = (Server) singleAppDomain.CreateInstanceAndUnwrap (GetType ().Assembly.GetName ().ToString (), GetType ().FullName);
 				webSource.Dispose ();
 				return svr.RealMain (args, false, vh.AppHost, quiet);
 			}