Mantis#1591. Thank you graciously, Sempuki for a patch that:

Currently module loading is done ad-hoc. I propose creating a simple 
loader class that leverages Mono.Addins (and perhaps the new .NET 
addins when they become available in mono). Attached is a basic 
patch for review that compiles into HEAD, but doesn't yet replace 
any existing ad-hoc loaders.

16 files changed, 217 insertions, 62 deletions

diff --git a/OpenSim/ApplicationPlugins/LoadRegions/LoadRegionsPlugin.cs b/OpenSim/ApplicationPlugins/LoadRegions/LoadRegionsPlugin.cs
index 4b11fd4..6743fb4 100644
--- a/OpenSim/ApplicationPlugins/LoadRegions/LoadRegionsPlugin.cs
+++ b/OpenSim/ApplicationPlugins/LoadRegions/LoadRegionsPlugin.cs
@@ -46,6 +46,19 @@ namespace OpenSim.ApplicationPlugins.LoadRegions
 
         #region IApplicationPlugin Members
 
+        // TODO: required by IPlugin, but likely not at all right
+        string m_name = "LoadRegionsPlugin";
+        string m_version = "0.0";
+
+        public string Version { get { return m_version; } }
+        public string Name { get { return m_name; } }
+
+        public void Initialise() 
+        { 
+            m_log.Info("[LOADREGIONS]: " + Name + " cannot be default-initialized!");
+            throw new PluginNotInitialisedException (Name);
+        }
+
         public void Initialise(OpenSimBase openSim)
         {
             m_log.Info("[LOADREGIONS]: Load Regions addin being initialised");
@@ -78,7 +91,7 @@ namespace OpenSim.ApplicationPlugins.LoadRegions
             openSim.ModuleLoader.ClearCache();
         }
 
-        public void Close()
+        public void Dispose()
         {
         }
 
@@ -113,4 +126,4 @@ namespace OpenSim.ApplicationPlugins.LoadRegions
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/OpenSim/ApplicationPlugins/RemoteController/RemoteAdminPlugin.cs b/OpenSim/ApplicationPlugins/RemoteController/RemoteAdminPlugin.cs
index 5063375..d3fe0e0 100644
--- a/OpenSim/ApplicationPlugins/RemoteController/RemoteAdminPlugin.cs
+++ b/OpenSim/ApplicationPlugins/RemoteController/RemoteAdminPlugin.cs
@@ -54,6 +54,19 @@ namespace OpenSim.ApplicationPlugins.RemoteController
         private BaseHttpServer m_httpd;
         private string requiredPassword = String.Empty;
 
+        // TODO: required by IPlugin, but likely not at all right
+        string m_name = "RemoteAdminPlugin";
+        string m_version = "0.0";
+
+        public string Version { get { return m_version; } }
+        public string Name { get { return m_name; } }
+
+        public void Initialise() 
+        { 
+            m_log.Info("[RADMIN]: " + Name + " cannot be default-initialized!");
+            throw new PluginNotInitialisedException (Name);
+        }
+
         public void Initialise(OpenSimBase openSim)
         {
             try
@@ -607,8 +620,8 @@ namespace OpenSim.ApplicationPlugins.RemoteController
             return response;
         }
 
-        public void Close()
+        public void Dispose()
         {
         }
     }
-}
\ No newline at end of file
+}
diff --git a/OpenSim/ApplicationPlugins/Rest/RestPlugin.cs b/OpenSim/ApplicationPlugins/Rest/RestPlugin.cs
index 4558d4d..78e0e66 100644
--- a/OpenSim/ApplicationPlugins/Rest/RestPlugin.cs
+++ b/OpenSim/ApplicationPlugins/Rest/RestPlugin.cs
@@ -188,6 +188,17 @@ namespace OpenSim.ApplicationPlugins.Rest
 
 
         #region methods
+        // TODO: required by IPlugin, but likely not at all right
+        string m_version = "0.0";
+
+        public string Version { get { return m_version; } }
+
+        public void Initialise() 
+        { 
+            m_log.Info("[RESTPLUGIN]: " + Name + " cannot be default-initialized!");
+            throw new PluginNotInitialisedException (Name);
+        }
+
         /// <summary>
         /// This method is called by OpenSimMain immediately after loading the
         /// plugin and after basic server setup,  but before running any server commands.
@@ -357,6 +368,11 @@ namespace OpenSim.ApplicationPlugins.Rest
             _agents   = null;
         }
 
+        public virtual void Dispose()
+        {
+            Close();
+        }
+
         /// <summary>
         /// Return a failure message.
         /// </summary>
diff --git a/OpenSim/Data/AssetDataBase.cs b/OpenSim/Data/AssetDataBase.cs
index e3b5c25..ca1de5a 100644
--- a/OpenSim/Data/AssetDataBase.cs
+++ b/OpenSim/Data/AssetDataBase.cs
@@ -42,5 +42,6 @@ namespace OpenSim.Data
         public abstract string Name { get; }
         public abstract void Initialise(string connect);
         public abstract void Initialise();
+        public abstract void Dispose();
     }
 }
diff --git a/OpenSim/Data/MSSQL/MSSQLAssetData.cs b/OpenSim/Data/MSSQL/MSSQLAssetData.cs
index 50e2e3a..44d78ed 100644
--- a/OpenSim/Data/MSSQL/MSSQLAssetData.cs
+++ b/OpenSim/Data/MSSQL/MSSQLAssetData.cs
@@ -218,6 +218,8 @@ namespace OpenSim.Data.MSSQL
 
         #region IPlugin Members
 
+        override public void Dispose() { }
+
         /// <summary>
         /// <para>Initialises asset interface</para>
         /// <para>
diff --git a/OpenSim/Data/MySQL/MySQLAssetData.cs b/OpenSim/Data/MySQL/MySQLAssetData.cs
index a64a256..ac7fa1d 100644
--- a/OpenSim/Data/MySQL/MySQLAssetData.cs
+++ b/OpenSim/Data/MySQL/MySQLAssetData.cs
@@ -39,7 +39,7 @@ namespace OpenSim.Data.MySQL
     /// <summary>
     /// A MySQL Interface for the Asset Server
     /// </summary>
-    internal class MySQLAssetData : AssetDataBase, IPlugin
+    internal class MySQLAssetData : AssetDataBase
     {
         private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
 
@@ -109,6 +109,8 @@ namespace OpenSim.Data.MySQL
 
         }
 
+        override public void Dispose() { }
+
         #region IAssetProvider Members
 
         /// <summary>
diff --git a/OpenSim/Data/NHibernate/NHibernateAssetData.cs b/OpenSim/Data/NHibernate/NHibernateAssetData.cs
index 89f907f..a339ee3 100644
--- a/OpenSim/Data/NHibernate/NHibernateAssetData.cs
+++ b/OpenSim/Data/NHibernate/NHibernateAssetData.cs
@@ -43,7 +43,7 @@ namespace OpenSim.Data.NHibernate
     /// <summary>
     /// A User storage interface for the DB4o database system
     /// </summary>
-    public class NHibernateAssetData : AssetDataBase, IDisposable
+    public class NHibernateAssetData : AssetDataBase
     {
         private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
 
@@ -51,6 +51,8 @@ namespace OpenSim.Data.NHibernate
         private ISessionFactory factory;
         private ISession session;
 
+        override public void Dispose() { }
+
         public override void Initialise()
         {
             Initialise("SQLiteDialect;SqliteClientDriver;URI=file:Asset.db,version=3");
@@ -173,9 +175,5 @@ namespace OpenSim.Data.NHibernate
             get { return "0.1"; }
         }
 
-        public void Dispose()
-        {
-
-        }
     }
 }
diff --git a/OpenSim/Data/SQLite/SQLiteAssetData.cs b/OpenSim/Data/SQLite/SQLiteAssetData.cs
index f560b9e..018501f 100644
--- a/OpenSim/Data/SQLite/SQLiteAssetData.cs
+++ b/OpenSim/Data/SQLite/SQLiteAssetData.cs
@@ -56,6 +56,8 @@ namespace OpenSim.Data.SQLite
 
         private SqliteConnection m_conn;
 
+        override public void Dispose() { }
+
         /// <summary>
         /// <list type="bullet">
         /// <item>Initialises AssetData interface</item>
diff --git a/OpenSim/Framework/IAssetProvider.cs b/OpenSim/Framework/IAssetProvider.cs
index 5c02ff1..dcb79ea 100644
--- a/OpenSim/Framework/IAssetProvider.cs
+++ b/OpenSim/Framework/IAssetProvider.cs
@@ -38,4 +38,4 @@ namespace OpenSim.Framework
         void CommitAssets(); // force a sync to the database
         void Initialise(string connect);
     }
-}
\ No newline at end of file
+}
diff --git a/OpenSim/Framework/IPlugin.cs b/OpenSim/Framework/IPlugin.cs
index 8a0b2b1..342918c 100644
--- a/OpenSim/Framework/IPlugin.cs
+++ b/OpenSim/Framework/IPlugin.cs
@@ -25,12 +25,24 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+using System;
+
 namespace OpenSim.Framework
 {
     /// <summary>
+    /// Exception thrown if Initialise has been called, but failed.
+    /// </summary>
+    public class PluginNotInitialisedException : Exception
+    {
+        public PluginNotInitialisedException () : base() {}
+        public PluginNotInitialisedException (string msg) : base(msg) {}
+        public PluginNotInitialisedException (string msg, Exception e) : base(msg, e) {}
+    }
+
+    /// <summary>
     /// This interface, describes a generic plugin
     /// </summary>
-    public interface IPlugin
+    public interface IPlugin : System.IDisposable
     {
         /// <summary>
         /// Returns the plugin version
@@ -45,8 +57,8 @@ namespace OpenSim.Framework
         string Name { get; }
 
         /// <summary>
-        /// Initialises the plugin (artificial constructor)
+        /// Default-initialises the plugin
         /// </summary>
         void Initialise();
     }
-}
\ No newline at end of file
+}
diff --git a/OpenSim/Framework/PluginLoader.cs b/OpenSim/Framework/PluginLoader.cs
new file mode 100644
index 0000000..26df3d1
--- /dev/null
+++ b/OpenSim/Framework/PluginLoader.cs
@@ -0,0 +1,115 @@
+/*

+ * Copyright (c) Contributors, http://opensimulator.org/

+ * See CONTRIBUTORS.TXT for a full list of copyright holders.

+ *

+ * Redistribution and use in source and binary forms, with or without

+ * modification, are permitted provided that the following conditions are met:

+ *     * Redistributions of source code must retain the above copyright

+ *       notice, this list of conditions and the following disclaimer.

+ *     * Redistributions in binary form must reproduce the above copyright

+ *       notice, this list of conditions and the following disclaimer in the

+ *       documentation and/or other materials provided with the distribution.

+ *     * Neither the name of the OpenSim Project nor the

+ *       names of its contributors may be used to endorse or promote products

+ *       derived from this software without specific prior written permission.

+ *

+ * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY

+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

+ * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY

+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

+ */

+

+using System;

+using System.IO;

+using System.Collections.Generic;

+using System.Reflection;

+using log4net;

+using Mono.Addins;

+

+namespace OpenSim.Framework

+{

+    public class PluginLoader <T> : IDisposable where T : IPlugin

+    {

+        private static readonly ILog log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

+        private List<T> loaded = new List<T>();

+

+        public PluginLoader (string dir)

+        {            

+            AddPluginDir (dir);

+        }

+

+        public void AddPluginDir (string dir)

+        {

+            suppress_console_output_ (true);

+            AddinManager.Initialize (dir);

+            suppress_console_output_ (false);

+        }

+

+        public delegate void Initialiser (IPlugin p);

+        private void default_initialiser_ (IPlugin p) { p.Initialise(); }

+

+        public void Load (string extpoint)

+        {

+            Load (extpoint, default_initialiser_);

+        }

+

+        public void Load (string extpoint, Initialiser initialize)

+        {

+            AddinManager.Registry.Update (null);

+

+            ExtensionNodeList ns = AddinManager.GetExtensionNodes(extpoint);

+            foreach (TypeExtensionNode n in ns)

+            {

+                T p = (T) n.CreateInstance();

+                initialize (p);

+                Plugins.Add (p);

+

+                log.Info("[PLUGINS]: Loading plugin " + n.Path + "/" + p.Name);

+            }

+        }

+

+        public List<T> Plugins

+        {

+            get { return loaded; } 

+        }

+

+        public void Dispose ()

+        {

+            foreach (T p in Plugins)

+                p.Dispose ();

+        }

+

+        public void ClearCache()

+        {

+            // The Mono addin manager (in Mono.Addins.dll version 0.2.0.0) occasionally seems to corrupt its addin cache

+            // Hence, as a temporary solution we'll remove it before each startup

+            if (Directory.Exists("addin-db-000"))

+                Directory.Delete("addin-db-000", true);

+

+            if (Directory.Exists("addin-db-001"))

+                Directory.Delete("addin-db-001", true);

+        }

+

+        private static TextWriter prev_console_;

+        public void suppress_console_output_ (bool save)

+        {

+            if (save)

+            {

+                prev_console_ = System.Console.Out;

+                System.Console.SetOut(new StreamWriter(Stream.Null));

+            }

+            else

+            {

+                if (prev_console_ != null) 

+                    System.Console.SetOut(prev_console_);

+            }

+        }

+

+    }

+}

diff --git a/OpenSim/Framework/Servers/OSHttpRequestPump.cs b/OpenSim/Framework/Servers/OSHttpRequestPump.cs
index 06e41e4..6214ab0 100644
--- a/OpenSim/Framework/Servers/OSHttpRequestPump.cs
+++ b/OpenSim/Framework/Servers/OSHttpRequestPump.cs
@@ -58,4 +58,4 @@ namespace OpenSim.Framework.Servers
             return pumps;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/OpenSim/Grid/GridServer/GridServerBase.cs b/OpenSim/Grid/GridServer/GridServerBase.cs
index 7891c29..010c250 100644
--- a/OpenSim/Grid/GridServer/GridServerBase.cs
+++ b/OpenSim/Grid/GridServer/GridServerBase.cs
@@ -116,26 +116,17 @@ namespace OpenSim.Grid.GridServer
             m_httpServer.AddStreamHandler(new RestStreamHandler("POST", "/regions/", m_gridManager.RestSetRegionMethod));
         }
 
-        protected void LoadGridPlugins()
+        protected void grid_plugin_initialiser_ (IPlugin plugin)
         {
-            // Temporary hack to stop mono-addins scanning warnings from coming out on the console
-            TextWriter oldOutput = Console.Out;
-            Console.SetOut(new StreamWriter(Stream.Null));
-
-            AddinManager.Initialize(".");
-            AddinManager.Registry.Update(null);
-
-            // Returns the console.writelines back to the console's stream
-            Console.SetOut(oldOutput);
+            IGridPlugin p = plugin as IGridPlugin;
+            p.Initialise (this);
+        }
 
-            ExtensionNodeList nodes = AddinManager.GetExtensionNodes("/OpenSim/GridServer");
-            foreach (TypeExtensionNode node in nodes)
-            {
-                m_log.Info("[GRID PLUGINS]: Loading OpenSim plugin " + node.Path);
-                IGridPlugin plugin = (IGridPlugin)node.CreateInstance();
-                plugin.Initialise(this);
-                m_plugins.Add(plugin);
-            }
+        protected void LoadGridPlugins()
+        {
+            PluginLoader<IGridPlugin> loader = new PluginLoader<IGridPlugin> (".");
+            loader.Load ("/OpenSim/GridServer", grid_plugin_initialiser_);
+            m_plugins = loader.Plugins;
         }
 
         protected virtual void SetupGridManager()
diff --git a/OpenSim/Grid/GridServer/IGridPlugin.cs b/OpenSim/Grid/GridServer/IGridPlugin.cs
index 47273a2..d51deb3 100644
--- a/OpenSim/Grid/GridServer/IGridPlugin.cs
+++ b/OpenSim/Grid/GridServer/IGridPlugin.cs
@@ -27,13 +27,14 @@
 */
 
 using Mono.Addins;
+using OpenSim.Framework;
 
 [assembly : AddinRoot("OpenSim", "0.5")]
 
 namespace OpenSim.Grid.GridServer
 {
     [TypeExtensionPoint("/OpenSim/GridServer")]
-    public interface IGridPlugin
+    public interface IGridPlugin : IPlugin
     {
         void Initialise(GridServerBase gridServer);
         void Close();
diff --git a/OpenSim/Region/Application/IApplicationPlugin.cs b/OpenSim/Region/Application/IApplicationPlugin.cs
index 7ca4383..e1187ae 100644
--- a/OpenSim/Region/Application/IApplicationPlugin.cs
+++ b/OpenSim/Region/Application/IApplicationPlugin.cs
@@ -26,15 +26,15 @@
  */
 
 using Mono.Addins;
+using OpenSim.Framework;
 
 [assembly : AddinRoot("OpenSim", "0.5")]
 
 namespace OpenSim
 {
     [TypeExtensionPoint("/OpenSim/Startup")]
-    public interface IApplicationPlugin
+    public interface IApplicationPlugin : IPlugin
     {
         void Initialise(OpenSimBase openSim);
-        void Close();
     }
 }
diff --git a/OpenSim/Region/Application/OpenSimBase.cs b/OpenSim/Region/Application/OpenSimBase.cs
index 49e1da3..d0d5378 100644
--- a/OpenSim/Region/Application/OpenSimBase.cs
+++ b/OpenSim/Region/Application/OpenSimBase.cs
@@ -149,24 +149,6 @@ namespace OpenSim
         {
             IConfig startupConfig = configSource.Configs["Startup"];
 
-            // The Mono addin manager (in Mono.Addins.dll version 0.2.0.0) occasionally seems to corrupt its addin cache
-            // Hence, as a temporary solution we'll remove it before each startup
-            if (Directory.Exists("addin-db-000"))
-                Directory.Delete("addin-db-000", true);
-
-            if (Directory.Exists("addin-db-001"))
-                Directory.Delete("addin-db-001", true);
-
-            // This blocks the scanning warnings from outputing to the console.
-            TextWriter oldOutput = Console.Out;
-            Console.SetOut(new StreamWriter(Stream.Null));
-
-            AddinManager.Initialize(".");
-            AddinManager.Registry.Update(null);
-
-            // Returns the console.writelines back to the console's stream
-            Console.SetOut(oldOutput);
-
             Application.iniFilePath = startupConfig.GetString("inifile", "OpenSim.ini");
 
             m_config = new OpenSimConfigSource();
@@ -347,6 +329,19 @@ namespace OpenSim
             m_networkServersInfo.loadFromConfiguration(m_config.Source);
         }
 
+        protected void plugin_initialiser_ (IPlugin plugin)
+        {
+            IApplicationPlugin p = plugin as IApplicationPlugin;
+            p.Initialise (this);
+        }
+
+        protected void LoadPlugins()
+        {
+            PluginLoader<IApplicationPlugin> loader = new PluginLoader<IApplicationPlugin> (".");
+            loader.Load ("/OpenSim/Startup", plugin_initialiser_);
+            m_plugins = loader.Plugins;
+        }
+
         /// <summary>
         /// Performs initialisation of the scene, such as loading configuration from disk.
         /// </summary>
@@ -403,14 +398,7 @@ namespace OpenSim
             // Create a ModuleLoader instance
             m_moduleLoader = new ModuleLoader(m_config.Source);
 
-            ExtensionNodeList nodes = AddinManager.GetExtensionNodes("/OpenSim/Startup");
-            foreach (TypeExtensionNode node in nodes)
-            {
-                m_log.InfoFormat("[PLUGINS]: Loading OpenSim application plugin {0}", node.Path);
-                IApplicationPlugin plugin = (IApplicationPlugin)node.CreateInstance();
-                plugin.Initialise(this);
-                m_plugins.Add(plugin);
-            }
+            LoadPlugins();
         }
 
         protected override void Initialize()
@@ -740,3 +728,4 @@ namespace OpenSim
     }
 }
 
+