path: root/OpenSim/Region/ScriptEngine/XMREngine/XMREngine.cs

/*
 * 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 OpenSimulator 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.
 */

// based on XMREngine from Mike Rieker (Dreamnation) and Melanie Thielker
// but with several changes to be more cross platform.


using log4net;
using Mono.Addins;
using Nini.Config;
using OpenSim.Framework;
using OpenSim.Framework.Console;
using OpenSim.Framework.Monitoring;
using OpenSim.Region.ClientStack.Linden;
using OpenSim.Region.Framework.Interfaces;
using OpenSim.Region.Framework.Scenes;
using OpenSim.Region.ScriptEngine.Interfaces;
using OpenSim.Region.ScriptEngine.Shared;
using OpenSim.Region.ScriptEngine.Shared.Api;
using OpenMetaverse;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Reflection;
using System.Reflection.Emit;
using System.Text;
using System.Threading;
using System.Timers;
using System.Xml;

using LSL_Float = OpenSim.Region.ScriptEngine.Shared.LSL_Types.LSLFloat;
using LSL_Integer = OpenSim.Region.ScriptEngine.Shared.LSL_Types.LSLInteger;
using LSL_Key = OpenSim.Region.ScriptEngine.Shared.LSL_Types.LSLString;
using LSL_List = OpenSim.Region.ScriptEngine.Shared.LSL_Types.list;
using LSL_Rotation = OpenSim.Region.ScriptEngine.Shared.LSL_Types.Quaternion;
using LSL_String = OpenSim.Region.ScriptEngine.Shared.LSL_Types.LSLString;
using LSL_Vector = OpenSim.Region.ScriptEngine.Shared.LSL_Types.Vector3;

[assembly: Addin("XMREngine", OpenSim.VersionInfo.VersionNumber)]
[assembly: AddinDependency("OpenSim.Region.Framework", OpenSim.VersionInfo.VersionNumber)]

namespace OpenSim.Region.ScriptEngine.XMREngine
{
    [Extension(Path = "/OpenSim/RegionModules", NodeName = "RegionModule", Id = "XMREngine")]
    public partial class XMREngine : INonSharedRegionModule, IScriptEngine,
            IScriptModule
    {
        public  static readonly DetectParams[] zeroDetectParams = new DetectParams[0];
        private static ArrayList noScriptErrors = new ArrayList();
        public  static readonly ILog m_log =
            LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
        private static readonly string[] scriptReferencedAssemblies = new string[0];

        private bool m_LateInit;
        private bool m_TraceCalls;
        public  bool m_Verbose;
        public  bool m_ScriptDebug;
        public  Scene m_Scene;
        private IConfigSource m_ConfigSource;
        private IConfig m_Config;
        private string m_ScriptBasePath;
        private bool m_Enabled = false;
        public  bool m_StartProcessing = false;
        public  bool m_UseSourceHashCode = false;
        public  ConstructorInfo uThreadCtor;
        private Dictionary<UUID, ArrayList> m_ScriptErrors =
                new Dictionary<UUID, ArrayList>();
        private Dictionary<UUID, List<UUID>> m_ObjectItemList =
                new Dictionary<UUID, List<UUID>>();
        private Dictionary<UUID, XMRInstance[]> m_ObjectInstArray =
                new Dictionary<UUID, XMRInstance[]>();
        public  Dictionary<string,FieldInfo> m_XMRInstanceApiCtxFieldInfos =
                new Dictionary<string,FieldInfo> ();
        private int m_StackSize;
        private int m_HeapSize;

        private XMRScriptThread[] m_ScriptThreads;
        private int    m_WakeUpOne  = 0;
        public  object m_WakeUpLock = new object();
        private Dictionary<Thread,XMRScriptThread> m_AllThreads = new Dictionary<Thread,XMRScriptThread> ();

        private bool m_SuspendScriptThreadFlag = false;
        /**
         * @brief Something was just added to the Start or Yield queue so
         *        wake one of the XMRScriptThread instances to run it.
         */

        private Thread m_SleepThread = null;
        private bool m_Exiting = false;

        private int m_MaintenanceInterval = 10;
        private System.Timers.Timer m_MaintenanceTimer;
        public  int numThreadScriptWorkers;

        private object m_FrameUpdateLock = new object ();
        private event ThreadStart m_FrameUpdateList = null;

         // Various instance lists:
         //   m_InstancesDict = all known instances
         //                     find an instance given its itemID
         //   m_StartQueue = instances that have just had event queued to them
         //   m_YieldQueue = instances that are ready to run right now
         //   m_SleepQueue = instances that have m_SleepUntil valid
         //                  sorted by ascending m_SleepUntil

        private Dictionary<UUID, XMRInstance> m_InstancesDict =
                new Dictionary<UUID, XMRInstance>();
        public  Queue<ThreadStart> m_ThunkQueue = new Queue<ThreadStart> ();
        public  XMRInstQueue m_StartQueue = new XMRInstQueue();
        public  XMRInstQueue m_YieldQueue = new XMRInstQueue();
        public  XMRInstQueue m_SleepQueue = new XMRInstQueue();
        private string m_LockedDict = "nobody";

        public XMREngine()
        {
        }

        public string Name
        {
            get { return "XMREngine"; }
        }

        public Type ReplaceableInterface
        {
            get { return null; }
        }

        public string ScriptEnginePath
        {
            get { return m_ScriptBasePath; }
        }

        public string ScriptClassName
        {
            get { return "XMREngineScript"; }
        }

        public string ScriptBaseClassName
        {
            get { return typeof (XMRInstance).FullName; }
        }

        public ParameterInfo[] ScriptBaseClassParameters
        {
            get { return typeof(XMRInstance).GetConstructor (new Type[] { typeof (WaitHandle) }).GetParameters (); }
        }

        public string[] ScriptReferencedAssemblies
        {
            get { return scriptReferencedAssemblies; }
        }

        public void WakeUpOne()
        {
            lock (m_WakeUpLock)
            {
                m_WakeUpOne++;
                Monitor.Pulse(m_WakeUpLock);
            }
        }

        public void AddThread(Thread thd, XMRScriptThread xthd)
        {
            lock(m_AllThreads)
                m_AllThreads.Add(thd, xthd);
        }

        public void RemoveThread(Thread thd)
        {
            lock(m_AllThreads)
                m_AllThreads.Remove(thd);
        }

        public XMRScriptThread CurrentScriptThread ()
        {
            XMRScriptThread st;
            lock (m_AllThreads)
                m_AllThreads.TryGetValue (Thread.CurrentThread, out st);

            return st;
        }

        public void Initialise(IConfigSource config)
        {
            TraceCalls("[XMREngine]: Initialize entry");
            m_ConfigSource = config;

            ////foreach (IConfig icfg in config.Configs) {
            ////    m_log.Debug("[XMREngine]: Initialise: configs[" + icfg.Name + "]");
            ////    foreach (string key in icfg.GetKeys ()) {
            ////        m_log.Debug("[XMREngine]: Initialise:     " + key + "=" + icfg.GetExpanded (key));
            ////    }
            ////}

            m_Enabled = false;
            m_Config = config.Configs["XMREngine"];
            if (m_Config == null)
            {
                m_log.Info("[XMREngine]: no config, assuming disabled");
                return;
            }

            m_Enabled = m_Config.GetBoolean("Enabled", false);
            m_log.InfoFormat("[XMREngine]: config enabled={0}", m_Enabled);
            if (!m_Enabled)
                return;

            Type uThreadType = null;
            uThreadType = typeof (ScriptUThread_Nul);
            uThreadCtor = uThreadType.GetConstructor (new Type[] { typeof (XMRInstance) });

            m_UseSourceHashCode    = m_Config.GetBoolean("UseSourceHashCode", false);
            numThreadScriptWorkers = m_Config.GetInt("NumThreadScriptWorkers", 3);
            m_ScriptThreads        = new XMRScriptThread[numThreadScriptWorkers];

            m_TraceCalls           = m_Config.GetBoolean("TraceCalls", false);
            m_Verbose              =  m_Config.GetBoolean("Verbose", false);
            m_ScriptDebug          = m_Config.GetBoolean("ScriptDebug", false);

             // Verify that our ScriptEventCode's match OpenSim's scriptEvent's.
            bool err = false;
            for (int i = 0; i < 32; i ++)
            {
                string mycode = "undefined";
                string oscode = "undefined";
                try
                {
                    mycode = ((ScriptEventCode)i).ToString();
                    Convert.ToInt32(mycode);
                    mycode = "undefined";
                }
                catch { }
                try
                {
                    oscode = ((OpenSim.Region.Framework.Scenes.scriptEvents)(1 << i)).ToString();
                    Convert.ToInt32(oscode);
                    oscode = "undefined";
                }
                catch { }
                if (mycode != oscode)
                {
                    m_log.ErrorFormat("[XMREngine]: {0} mycode={1}, oscode={2}", i, mycode, oscode);
                    err = true;
                }
            }
            if (err)
            {
                m_Enabled = false;
                return;
            }

            for (int i = 0; i < numThreadScriptWorkers; i ++)
            {
                m_ScriptThreads[i] = new XMRScriptThread(this, i);;
            }


            m_SleepThread = StartMyThread(RunSleepThread, "xmrengine sleep", ThreadPriority.Normal);

            m_StackSize = m_Config.GetInt("ScriptStackSize", 2048) << 10;
            m_HeapSize  = m_Config.GetInt("ScriptHeapSize",  1024) << 10;

            m_log.InfoFormat("[XMREngine]: Enabled, {0}.{1} Meg (0x{2}) stacks",
                    (m_StackSize >> 20).ToString (),
                    (((m_StackSize % 0x100000) * 1000) 
                            >> 20).ToString ("D3"),
                    m_StackSize.ToString ("X"));

            m_log.InfoFormat("[XMREngine]:  ... {0}.{1} Meg (0x{2}) heaps",
                    (m_HeapSize >> 20).ToString (),
                    (((m_HeapSize % 0x100000) * 1000) 
                            >> 20).ToString ("D3"),
                    m_HeapSize.ToString ("X"));

            m_MaintenanceInterval = m_Config.GetInt("MaintenanceInterval", 10);

            if (m_MaintenanceInterval > 0)
            {
                m_MaintenanceTimer = new System.Timers.Timer(m_MaintenanceInterval * 60000);
                m_MaintenanceTimer.Elapsed += DoMaintenance;
                m_MaintenanceTimer.Start();
            }

            MainConsole.Instance.Commands.AddCommand("xmr", false,
                    "xmr",
                    "xmr [...|help|...] ...",
                    "Run xmr script engine commands",
                    RunTest);

            TraceCalls("[XMREngine]: Initialize successful");
        }

        public void AddRegion(Scene scene)
        {
            if (!m_Enabled)
                return;

            TraceCalls("[XMREngine]: XMREngine.AddRegion({0})", scene.RegionInfo.RegionName);

            m_Scene = scene;

            m_Scene.RegisterModuleInterface<IScriptModule>(this);

            m_ScriptBasePath = m_Config.GetString ("ScriptBasePath", "ScriptData");
            m_ScriptBasePath = Path.Combine (m_ScriptBasePath, scene.RegionInfo.RegionID.ToString());

            Directory.CreateDirectory(m_ScriptBasePath);

            m_Scene.EventManager.OnRezScript += OnRezScript;

            m_Scene.StackModuleInterface<IScriptModule>(this);
        }

        private void OneTimeLateInitialization ()
        {
             // Build list of defined APIs and their 'this' types and define a field in XMRInstanceSuperType.
            ApiManager am = new ApiManager ();
            Dictionary<string,Type> apiCtxTypes = new Dictionary<string,Type> ();
            foreach (string api in am.GetApis ())
            {
                m_log.Debug ("[XMREngine]: adding api " + api);
                IScriptApi scriptApi = am.CreateApi (api);
                Type apiCtxType = scriptApi.GetType ();
                if (api == "LSL") apiCtxType = typeof (XMRLSL_Api);
                apiCtxTypes[api] = apiCtxType;
            }

            if (ScriptCodeGen.xmrInstSuperType == null) // Only create type once!
            {
                 // Start creating type XMRInstanceSuperType that contains a field
                 // m_ApiManager_<APINAME> that points to the per-instance context
                 // struct for that API, ie, the 'this' value passed to all methods
                 // in that API.  It is in essence:

                 //  public class XMRInstanceSuperType : XMRInstance {
                 //      public XMRLSL_Api m_ApiManager_LSL;   // 'this' value for all ll...() functions
                 //      public MOD_Api    m_ApiManager_MOD;   // 'this' value for all mod...() functions
                 //      public OSSL_Api   m_ApiManager_OSSL;  // 'this' value for all os...() functions
                 //              ....
                 //  }

                AssemblyName assemblyName = new AssemblyName ();
                assemblyName.Name = "XMRInstanceSuperAssembly";
                AssemblyBuilder assemblyBuilder = Thread.GetDomain().DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);
#if DEBUG
                Type daType = typeof(DebuggableAttribute);
                ConstructorInfo daCtor = daType.GetConstructor(new Type[] { typeof(DebuggableAttribute.DebuggingModes) });

                CustomAttributeBuilder daBuilder = new CustomAttributeBuilder(daCtor, new object[] {
                    DebuggableAttribute.DebuggingModes.DisableOptimizations |
                    DebuggableAttribute.DebuggingModes.EnableEditAndContinue |
                    DebuggableAttribute.DebuggingModes.IgnoreSymbolStoreSequencePoints |
                    DebuggableAttribute.DebuggingModes.Default });

                assemblyBuilder.SetCustomAttribute(daBuilder);
#endif
                ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule("XMRInstanceSuperModule");
                TypeBuilder typeBuilder = moduleBuilder.DefineType("XMRInstanceSuperType", TypeAttributes.Public | TypeAttributes.Class);
                typeBuilder.SetParent(typeof (XMRInstance));

                foreach (string apiname in apiCtxTypes.Keys)
                {
                    string fieldName = "m_ApiManager_" + apiname;
                    typeBuilder.DefineField (fieldName, apiCtxTypes[apiname], FieldAttributes.Public);
                }

                 // Finalize definition of XMRInstanceSuperType.
                 // Give the compiler a short name to reference it by,
                 // otherwise it will try to use the AssemblyQualifiedName
                 // and fail miserably.
                ScriptCodeGen.xmrInstSuperType = typeBuilder.CreateType ();
                ScriptObjWriter.DefineInternalType ("xmrsuper", ScriptCodeGen.xmrInstSuperType);
            }

             // Tell the compiler about all the constants and methods for each API.
             // We also tell the compiler how to get the per-instance context for each API
             // by reading the corresponding m_ApiManager_<APINAME> field of XMRInstanceSuperType.

            foreach (KeyValuePair<string,Type> kvp in apiCtxTypes)
            {
                // get API name and the corresponding per-instance context type
                string api = kvp.Key;
                Type apiCtxType = kvp.Value;

                // give script compiler an abbreviated name for the API context type
                ScriptObjWriter.DefineInternalType ("apimanager_" + api, apiCtxType);

                // this field tells the compiled code where the per-instance API context object is
                // eg, for the OSSL API, it is in ((XMRInstanceSuperType)inst).m_ApiManager_OSSL
                string fieldName = "m_ApiManager_" + api;
                FieldInfo fieldInfo = ScriptCodeGen.xmrInstSuperType.GetField (fieldName);
                m_XMRInstanceApiCtxFieldInfos[api] = fieldInfo;

                // now tell the compiler about the constants and methods for the API
                ScriptConst.AddInterfaceConstants   (null, apiCtxType.GetFields ());
                TokenDeclInline.AddInterfaceMethods (null, apiCtxType.GetMethods (), fieldInfo);
            }

             // Add sim-specific APIs to the compiler.

            IScriptModuleComms comms = m_Scene.RequestModuleInterface<IScriptModuleComms> ();
            if (comms != null)
            {
                 // Add methods to list of built-in functions.
                Delegate[] methods = comms.GetScriptInvocationList ();
                foreach (Delegate m in methods)
                {
                    MethodInfo mi = m.Method;
                    try
                    {
                        CommsCallCodeGen cccg = new CommsCallCodeGen (mi, comms, m_XMRInstanceApiCtxFieldInfos["MOD"]);
                        Verbose ("[XMREngine]: added comms function " + cccg.fullName);
                    }
                    catch (Exception e)
                    {
                        m_log.Error ("[XMREngine]: failed to add comms function " + mi.Name);
                        m_log.Error ("[XMREngine]: - " + e.ToString ());
                    }
                }

                 // Add constants to list of built-in constants.

                Dictionary<string,object> consts = comms.GetConstants ();
                foreach (KeyValuePair<string,object> kvp in consts)
                {
                    try
                    {
                        ScriptConst sc = ScriptConst.AddConstant (kvp.Key, kvp.Value);
                        Verbose ("[XMREngine]: added comms constant " + sc.name);
                    }
                    catch (Exception e)
                    {
                        m_log.Error ("[XMREngine]: failed to add comms constant " + kvp.Key);
                        m_log.Error ("[XMREngine]: - " + e.Message);
                    }
                }
            }
            else
            {
                Verbose ("[XMREngine]: comms not enabled");
            }
        }

        /**
         * @brief Generate code for the calls to the comms functions.
         *        It is a tRUlY EvIL interface.
         *        To call the function we must call an XMRInstanceSuperType.m_ApiManager_MOD.modInvoker?()
         *        method passing it the name of the function as a string and the script
         *        argument list wrapped up in an object[] array.  The modInvoker?() methods 
         *        do some sick type conversions (with corresponding mallocs) so we can't 
         *        call the methods directly.
         */
        private class CommsCallCodeGen : TokenDeclInline
        {
            private static Type[] modInvokerArgTypes = new Type[] { typeof (string), typeof (object[]) };
            public  static FieldInfo xmrInstModApiCtxField;

            private MethodInfo modInvokerMeth;
            private string methName;

            /**
             * @brief Constructor
             * @param mi = method to make available to scripts
             *        mi.Name = name that is used by scripts
             *        mi.GetParameters() = parameter list as defined by module
             *                             includes the 'UUID host','UUID script' parameters that script does not see
             *                             allowed types for script-visible parameters are as follows:
             *                                    Single -> float
             *                                     Int32 -> integer
             *                        OpenMetaverse.UUID -> key
             *                                  Object[] -> list
             *                  OpenMetaverse.Quaternion -> rotation
             *                                    String -> string
             *                     OpenMetaverse.Vector3 -> vector
             *        mi.ReturnType = return type as defined by module
             *                        types are same as allowed for parameters
             * @param comms = comms module the method came from
             * @param apictxfi = what field in XMRInstanceSuperType the 'this' value is for this method
             */
            public CommsCallCodeGen (MethodInfo mi, IScriptModuleComms comms, FieldInfo apictxfi)
                    : base (null, false, NameArgSig (mi), RetType (mi))
            {
                methName = mi.Name;
                string modInvokerName = comms.LookupModInvocation (methName);
                if (modInvokerName == null)
                    throw new Exception("cannot find comms method " + methName);
                modInvokerMeth = typeof(MOD_Api).GetMethod(modInvokerName, modInvokerArgTypes);
                xmrInstModApiCtxField = apictxfi;
            }

            // script-visible name(argtype,...) signature string
            private static string NameArgSig (MethodInfo mi)
            {
                StringBuilder sb = new StringBuilder ();
                sb.Append (mi.Name);
                sb.Append ('(');
                ParameterInfo[] mps = mi.GetParameters ();
                for (int i = 2; i < mps.Length; i ++)
                {
                    ParameterInfo pi = mps[i];
                    if (i > 2) sb.Append (',');
                    sb.Append (ParamType (pi.ParameterType));
                }
                sb.Append (')');
                return sb.ToString ();
            }

            // script-visible return type
            // note that although we support void, the comms stuff does not
            private static TokenType RetType (MethodInfo mi)
            {
                Type rt = mi.ReturnType;
                if (rt == typeof (float))                    return new TokenTypeFloat (null);
                if (rt == typeof (int))                      return new TokenTypeInt   (null);
                if (rt == typeof (object[]))                 return new TokenTypeList  (null);
                if (rt == typeof (OpenMetaverse.UUID))       return new TokenTypeKey   (null);
                if (rt == typeof (OpenMetaverse.Quaternion)) return new TokenTypeRot   (null);
                if (rt == typeof (string))                   return new TokenTypeStr   (null);
                if (rt == typeof (OpenMetaverse.Vector3))    return new TokenTypeVec   (null);
                if (rt == null || rt == typeof (void))       return new TokenTypeVoid  (null);
                throw new Exception ("unsupported return type " + rt.Name);
            }

            // script-visible parameter type
            private static string ParamType (Type t)
            {
                if (t == typeof (float))                    return "float";
                if (t == typeof (int))                      return "integer";
                if (t == typeof (OpenMetaverse.UUID))       return "key";
                if (t == typeof (object[]))                 return "list";
                if (t == typeof (OpenMetaverse.Quaternion)) return "rotation";
                if (t == typeof (string))                   return "string";
                if (t == typeof (OpenMetaverse.Vector3))    return "vector";
                throw new Exception ("unsupported parameter type " + t.Name);
            }

            /**
             * @brief Called by the compiler to generate a call to the comms function.
             * @param scg = which script is being compiled
             * @param errorAt = where in the source code the call is being made (for error messages)
             * @param result = a temp location to put the return value in if any
             * @param args = array of script-visible arguments being passed to the function
             */
            public override void CodeGen (ScriptCodeGen scg, Token errorAt, CompValuTemp result, CompValu[] args)
            {
                 // Set up 'this' pointer for modInvoker?() = value from ApiManager.CreateApi("MOD").
                scg.PushXMRInst ();
                scg.ilGen.Emit (errorAt, OpCodes.Castclass, xmrInstModApiCtxField.DeclaringType);
                scg.ilGen.Emit (errorAt, OpCodes.Ldfld, xmrInstModApiCtxField);

                 // Set up 'fname' argument to modInvoker?() = name of the function to be called.
                scg.ilGen.Emit (errorAt, OpCodes.Ldstr, methName);

                 // Set up 'parms' argument to modInvoker?() = object[] of the script-visible parameters,
                 // in their LSL-wrapped form.  Of course, the modInvoker?() method will malloc yet another 
                 // object[] and type-convert these parameters one-by-one with another round of unwrapping 
                 // and wrapping.
                 // Types allowed in this object[]:
                 //    LSL_Float, LSL_Integer, LSL_Key, LSL_List, LSL_Rotation, LSL_String, LSL_Vector

                int nargs = args.Length;
                scg.ilGen.Emit (errorAt, OpCodes.Ldc_I4, nargs);
                scg.ilGen.Emit (errorAt, OpCodes.Newarr, typeof (object));

                for (int i = 0; i < nargs; i ++)
                {
                    scg.ilGen.Emit (errorAt, OpCodes.Dup);
                    scg.ilGen.Emit (errorAt, OpCodes.Ldc_I4, i);

                    // get location and type of argument
                    CompValu arg = args[i];
                    TokenType argtype = arg.type;

                    // if already in a form acceptable to modInvoker?(),
                    // just push it to the stack and convert to object
                    // by boxing it if necessary

                    // but if something like a double, int, string, etc
                    // push to stack converting to the LSL-wrapped type
                    // then convert to object by boxing if necessary

                    Type boxit = null;
                    if (argtype is TokenTypeLSLFloat)
                    {
                        args[i].PushVal (scg, errorAt);
                        boxit = typeof (LSL_Float);
                    }
                    else if (argtype is TokenTypeLSLInt)
                    {
                        args[i].PushVal (scg, errorAt);
                        boxit = typeof (LSL_Integer);
                    }
                    else if (argtype is TokenTypeLSLKey)
                    {
                        args[i].PushVal (scg, errorAt);
                        boxit = typeof (LSL_Key);
                    }
                    else if (argtype is TokenTypeList)
                    {
                        args[i].PushVal (scg, errorAt);
                        boxit = typeof (LSL_List);
                    }
                    else if (argtype is TokenTypeRot)
                    {
                        args[i].PushVal (scg, errorAt);
                        boxit = typeof (LSL_Rotation);
                    }
                    else if (argtype is TokenTypeLSLString)
                    {
                        args[i].PushVal (scg, errorAt);
                        boxit = typeof (LSL_String);
                    }
                    else if (argtype is TokenTypeVec)
                    {
                        args[i].PushVal (scg, errorAt);
                        boxit = typeof (LSL_Vector);
                    }
                    else if (argtype is TokenTypeFloat)
                    {
                        args[i].PushVal (scg, errorAt, new TokenTypeLSLFloat (argtype));
                        boxit = typeof (LSL_Float);
                    }
                    else if (argtype is TokenTypeInt)
                    {
                        args[i].PushVal (scg, errorAt, new TokenTypeLSLInt (argtype));
                        boxit = typeof (LSL_Integer);
                    }
                    else if (argtype is TokenTypeKey)
                    {
                        args[i].PushVal (scg, errorAt, new TokenTypeLSLKey (argtype));
                        boxit = typeof (LSL_Key);
                    }
                    else if (argtype is TokenTypeStr)
                    {
                        args[i].PushVal (scg, errorAt, new TokenTypeLSLString (argtype));
                        boxit = typeof (LSL_String);
                    }
                    else
                        throw new Exception ("unsupported arg type " + argtype.GetType ().Name);

                    if (boxit.IsValueType)
                        scg.ilGen.Emit (errorAt, OpCodes.Box, boxit);

                    // pop the object into the object[]
                    scg.ilGen.Emit (errorAt, OpCodes.Stelem, typeof (object));
                }

                 // Call the modInvoker?() method.
                 // It leaves an LSL-wrapped type on the stack.
                if (modInvokerMeth.IsVirtual)
                    scg.ilGen.Emit (errorAt, OpCodes.Callvirt, modInvokerMeth);
                else
                    scg.ilGen.Emit (errorAt, OpCodes.Call, modInvokerMeth);

                 // The 3rd arg to Pop() is the type on the stack, 
                 // ie, what modInvoker?() actually returns.
                 // The Pop() method will wrap/unwrap as needed.
                Type retSysType = modInvokerMeth.ReturnType;
                if (retSysType == null)
                    retSysType = typeof (void);
                TokenType retTokType = TokenType.FromSysType (errorAt, retSysType);
                result.Pop (scg, errorAt, retTokType);
            }
        }

        /**
         * @brief Called late in shutdown procedure,
         *        after the 'Shutting down..." message.
         */
        public void RemoveRegion(Scene scene)
        {
            if (!m_Enabled)
                return;

            TraceCalls("[XMREngine]: XMREngine.RemoveRegion({0})", scene.RegionInfo.RegionName);

             // Write script states out to .state files so it will be
             // available when the region is restarted.
            DoMaintenance(null, null);

             // Stop executing script threads and wait for final
             // one to finish (ie, script gets to CheckRun() call).
            m_Exiting = true;

            m_Scene.EventManager.OnFrame -= OnFrame;
            m_Scene.EventManager.OnRezScript -= OnRezScript;
            m_Scene.EventManager.OnRemoveScript -= OnRemoveScript;
            m_Scene.EventManager.OnScriptReset -= OnScriptReset;
            m_Scene.EventManager.OnStartScript -= OnStartScript;
            m_Scene.EventManager.OnStopScript -= OnStopScript;
            m_Scene.EventManager.OnGetScriptRunning -= OnGetScriptRunning;
            m_Scene.EventManager.OnShutdown -= OnShutdown;

            for (int i = 0; i < numThreadScriptWorkers; i ++)
            {
                XMRScriptThread scriptThread = m_ScriptThreads[i];
                if (scriptThread != null)
                {
                    scriptThread.WakeUpScriptThread();
                    Monitor.PulseAll (m_WakeUpLock);
                    scriptThread.Terminate();
                    m_ScriptThreads[i] = null;
                }
            }

            if (m_SleepThread != null)
            {
                lock (m_SleepQueue)
                {
                    Monitor.PulseAll (m_SleepQueue);
                }
                if(!m_SleepThread.Join(250))
                    m_SleepThread.Abort();
                m_SleepThread = null;
            }

            m_Enabled = false;
            m_Scene = null;
        }

        public void RegionLoaded(Scene scene)
        {
            if (!m_Enabled)
                return;

            TraceCalls("[XMREngine]: XMREngine.RegionLoaded({0})", scene.RegionInfo.RegionName);

            m_Scene.EventManager.OnFrame += OnFrame;
            m_Scene.EventManager.OnRemoveScript += OnRemoveScript;
            m_Scene.EventManager.OnScriptReset += OnScriptReset;
            m_Scene.EventManager.OnStartScript += OnStartScript;
            m_Scene.EventManager.OnStopScript += OnStopScript;
            m_Scene.EventManager.OnGetScriptRunning += OnGetScriptRunning;
            m_Scene.EventManager.OnShutdown += OnShutdown;

            InitEvents();
        }

        public void StartProcessing()
        {
            m_log.Debug ("[XMREngine]: StartProcessing entry");
            m_Scene.EventManager.TriggerEmptyScriptCompileQueue (0, "");
            m_StartProcessing = true;
            for (int i = 0; i < numThreadScriptWorkers; i ++) {
                WakeUpOne();
            }
            m_log.Debug ("[XMREngine]: StartProcessing return");
        }

        public void Close()
        {
            TraceCalls("[XMREngine]: XMREngine.Close()");
        }

        private void RunTest (string module, string[] args)
        {
            if (args.Length < 2)
            {
                m_log.Info ("[XMREngine]: missing command, try 'xmr help'");
                return;
            }

            switch (args[1])
            {
                case "cvv":
                    switch (args.Length)
                    {
                        case 2:
                            m_log.InfoFormat ("[XMREngine]: compiled version value = {0}", 
                                    ScriptCodeGen.COMPILED_VERSION_VALUE);
                            break;

                        case 3:
                            try
                            {
                                ScriptCodeGen.COMPILED_VERSION_VALUE = Convert.ToInt32 (args[2]);
                            }
                            catch
                            {
                                m_log.Error ("[XMREngine]: bad/missing version number");
                            }
                            break;

                        default:
                            m_log.Error ("[XMREngine]: xmr cvv [<new_compiled_version_value>]");
                            break;
                    }
                    break;

                case "echo":
                    for (int i = 0; i < args.Length; i ++)
                        m_log.Info ("[XMREngine]: echo[" + i + "]=<" + args[i] + ">");

                    break;

                case "gc":
                    GC.Collect();
                    break;

                case "help":
                case "?": 
                    m_log.Info ("[XMREngine]: xmr cvv [<newvalue>] - show/set compiled version value");
                    m_log.Info ("[XMREngine]: xmr gc");
                    m_log.Info ("[XMREngine]: xmr ls [-help ...]");
                    m_log.Info ("[XMREngine]: xmr mvv [<newvalue>] - show/set migration version value");
                    m_log.Info ("[XMREngine]: xmr pev [-help ...] - post event");
                    m_log.Info ("[XMREngine]: xmr reset [-help ...]");
                    m_log.Info ("[XMREngine]: xmr resume - resume script processing");
                    m_log.Info ("[XMREngine]: xmr suspend - suspend script processing");
                    m_log.Info ("[XMREngine]: xmr tracecalls [yes | no]");
                    m_log.Info ("[XMREngine]: xmr verbose [yes | no]");
                    break;

                case "ls":
                    XmrTestLs (args, 2);
                    break;

                case "mvv":
                    switch (args.Length)
                    {
                        case 2:
                            m_log.InfoFormat ("[XMREngine]: migration version value = {0}", 
                                    XMRInstance.migrationVersion);
                            break;

                        case 3:
                            try
                            {
                                int mvv = Convert.ToInt32 (args[2]);
                                if ((mvv < 0) || (mvv > 255)) throw new Exception ("out of range");
                                XMRInstance.migrationVersion = (byte) mvv;
                            }
                            catch (Exception e)
                            {
                                m_log.Error ("[XMREngine]: bad/missing version number (" + e.Message + ")");
                            }
                            break;

                        default:
                            m_log.Error ("[XMREngine]: xmr mvv [<new_migration_version_value>]");
                            break;
                    }
                    break;

                case "pev":
                    XmrTestPev (args, 2);
                    break;

                case "reset":
                    XmrTestReset (args, 2);
                    break;

                case "resume":
                    m_log.Info ("[XMREngine]: resuming scripts");
                    m_SuspendScriptThreadFlag = false;
                    for (int i = 0; i < numThreadScriptWorkers; i ++)
                         m_ScriptThreads[i].WakeUpScriptThread();
                    Monitor.PulseAll(m_WakeUpLock);
                    break;

                case "suspend":
                    m_log.Info ("[XMREngine]: suspending scripts");
                    m_SuspendScriptThreadFlag = true;
                    for (int i = 0; i < numThreadScriptWorkers; i ++)
                        m_ScriptThreads[i].WakeUpScriptThread();
                    Monitor.PulseAll(m_WakeUpLock);
                    break;

                case "tracecalls":
                    if (args.Length > 2)
                        m_TraceCalls = (args[2][0] & 1) != 0;
                    m_log.Info ("[XMREngine]: tracecalls " + (m_TraceCalls ? "yes" : "no"));
                    break;

                case "verbose":
                    if (args.Length > 2)
                        m_Verbose = (args[2][0] & 1) != 0;
                    m_log.Info ("[XMREngine]: verbose " + (m_Verbose ? "yes" : "no"));
                    break;

                default:
                    m_log.Error ("[XMREngine]: unknown command " + args[1] + ", try 'xmr help'");
                    break;
            }
        }

        // Not required when not using IScriptInstance
        //
        public IScriptWorkItem QueueEventHandler(object parms)
        {
            return null;
        }

        public Scene World
        {
            get { return m_Scene; }
        }

        public IScriptModule ScriptModule
        {
            get { return this; }
        }

        public void SaveAllState()
        {
            m_log.Error("[XMREngine]: XMREngine.SaveAllState() called!!");
        }

#pragma warning disable 0067
        public event ScriptRemoved OnScriptRemoved;
        public event ObjectRemoved OnObjectRemoved;
#pragma warning restore 0067

        // Events targeted at a specific script
        // ... like listen() for an llListen() call
        //
        public bool PostScriptEvent(UUID itemID, EventParams parms)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance == null) return false;

            TraceCalls("[XMREngine]: XMREngine.PostScriptEvent({0},{1})", itemID.ToString(), parms.EventName);

            instance.PostEvent(parms);
            return true;
        }

        // Events targeted at all scripts in the given prim.
        //   localID = which prim
        //   parms   = event to post
        //
        public bool PostObjectEvent (uint localID, EventParams parms)
        {
            SceneObjectPart part = m_Scene.GetSceneObjectPart(localID);

            if (part == null)
                return false;

            TraceCalls("[XMREngine]: XMREngine.PostObjectEvent({0},{1})", localID.ToString(), parms.EventName);

             // In SecondLife, attach events go to all scripts of all prims
             // in a linked object.  So here we duplicate that functionality,
             // as all we ever get is a single attach event for the whole
             // object.
            if (parms.EventName == "attach")
            {
                bool posted = false;
                foreach (SceneObjectPart primpart in part.ParentGroup.Parts)
                {
                    posted |= PostPrimEvent (primpart, parms);
                }
                return posted;
            }

             // Other events go to just the scripts in that prim.
            return PostPrimEvent (part, parms);
        }

        private bool PostPrimEvent (SceneObjectPart part, EventParams parms)
        {
            UUID partUUID = part.UUID;

             // Get list of script instances running in the object.
            XMRInstance[] objInstArray;
            lock (m_InstancesDict)
            {
                if (!m_ObjectInstArray.TryGetValue (partUUID, out objInstArray))
                    return false;

                if (objInstArray == null)
                {
                    objInstArray = RebuildObjectInstArray (partUUID);
                    m_ObjectInstArray[partUUID] = objInstArray;
                }
            }

             // Post event to all script instances in the object.
            if (objInstArray.Length <= 0) return false;
            foreach (XMRInstance inst in objInstArray)
                inst.PostEvent (parms);

            return true;
        }

        public DetectParams GetDetectParams(UUID itemID, int number)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance == null)
                return null;
            return instance.GetDetectParams(number);
        }

        public void SetMinEventDelay(UUID itemID, double delay)
        {
        }

        public int GetStartParameter(UUID itemID)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance == null)
                return 0;
            return instance.StartParam;
        }

        // This is the "set running" method
        //
        public void SetScriptState(UUID itemID, bool state, bool self)
        {
            SetScriptState (itemID, state);
        }
        public void SetScriptState(UUID itemID, bool state)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance != null)
                instance.Running = state;
        }

        // Control display of the "running" checkbox
        //
        public bool GetScriptState(UUID itemID)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance == null)
                return false;
            return instance.Running;
        }

        public void SetState(UUID itemID, string newState)
        {
            TraceCalls("[XMREngine]: XMREngine.SetState({0},{1})", itemID.ToString(), newState);
        }

        public void ApiResetScript(UUID itemID)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance != null)
                instance.ApiReset();
        }

        public void ResetScript(UUID itemID)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance != null)
            {
                IUrlModule urlModule = m_Scene.RequestModuleInterface<IUrlModule>();
                if (urlModule != null)
                    urlModule.ScriptRemoved(itemID);

                instance.Reset();
            }
        }

        public IConfig Config
        {
            get { return m_Config; }
        }

        public IConfigSource ConfigSource
        {
            get { return m_ConfigSource; }
        }

        public string ScriptEngineName
        {
            get { return "XMREngine"; }
        }

        public IScriptApi GetApi(UUID itemID, string name)
        {
            FieldInfo fi;
            if (!m_XMRInstanceApiCtxFieldInfos.TryGetValue (name, out fi))
                return null;
            XMRInstance inst = GetInstance (itemID);
            if (inst == null) return null;
            return (IScriptApi)fi.GetValue (inst);
        }

        /**
         * @brief Get script's current state as an XML string
         *        - called by "Take", "Take Copy" and when object deleted (ie, moved to Trash)
         *        This includes the .state file
         */
        public string GetXMLState(UUID itemID)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance == null)
                return String.Empty;

            TraceCalls("[XMREngine]: XMREngine.GetXMLState({0})", itemID.ToString());

            if (!instance.m_HasRun)
                return String.Empty;

            XmlDocument doc = new XmlDocument();

            /*
             * Set up <State Engine="XMREngine" UUID="itemID" Asset="assetID"> tag.
             */
            XmlElement stateN = doc.CreateElement("", "State", "");
            doc.AppendChild(stateN);

            XmlAttribute engineA = doc.CreateAttribute("", "Engine", "");
            engineA.Value = ScriptEngineName;
            stateN.Attributes.Append(engineA);

            XmlAttribute uuidA = doc.CreateAttribute("", "UUID", "");
            uuidA.Value = itemID.ToString();
            stateN.Attributes.Append(uuidA);

            XmlAttribute assetA = doc.CreateAttribute("", "Asset", "");
            string assetID = instance.AssetID.ToString();
            assetA.Value = assetID;
            stateN.Attributes.Append(assetA);

             // Get <ScriptState>...</ScriptState> item that hold's script's state.
             // This suspends the script if necessary then takes a snapshot.
            XmlElement scriptStateN = instance.GetExecutionState(doc);
            stateN.AppendChild(scriptStateN);

            return doc.OuterXml;
        }

        // Set script's current state from an XML string
        // - called just before a script is instantiated
        // So we write the .state file so the .state file will be seen when 
        // the script is instantiated.
        public bool SetXMLState(UUID itemID, string xml)
        {
            XmlDocument doc = new XmlDocument();

            try
            {
                doc.LoadXml(xml);
            }
            catch
            {
                return false;
            }
            TraceCalls("[XMREngine]: XMREngine.SetXMLState({0})", itemID.ToString());

            // Make sure <State Engine="XMREngine"> so we know it is in our
            // format.
            XmlElement stateN = (XmlElement)doc.SelectSingleNode("State");
            if (stateN == null)
                return false;

            if (stateN.GetAttribute("Engine") != ScriptEngineName)
                return false;

            // <ScriptState>...</ScriptState> contains contents of .state file.
            XmlElement scriptStateN = (XmlElement)stateN.SelectSingleNode("ScriptState");
            if (scriptStateN == null)
                return false;

            string sen = stateN.GetAttribute("Engine");
            if ((sen == null) || (sen != ScriptEngineName))
                return false;

            XmlAttribute assetA = doc.CreateAttribute("", "Asset", "");
            assetA.Value = stateN.GetAttribute("Asset");
            scriptStateN.Attributes.Append(assetA);

            // Write out the .state file with the <ScriptState ...>...</ScriptState> XML text
            string statePath = XMRInstance.GetStateFileName(m_ScriptBasePath, itemID);
            FileStream ss = File.Create(statePath);
            StreamWriter sw = new StreamWriter(ss);
            sw.Write(scriptStateN.OuterXml);
            sw.Close();
            ss.Close();

            return true;
        }

        public bool PostScriptEvent(UUID itemID, string name, Object[] p)
        {
            if (!m_Enabled)
                return false;

            TraceCalls("[XMREngine]: XMREngine.PostScriptEvent({0},{1})", itemID.ToString(), name);

            return PostScriptEvent(itemID, new EventParams(name, p, zeroDetectParams));
        }

        public bool PostObjectEvent(UUID itemID, string name, Object[] p)
        {
            if (!m_Enabled)
                return false;

            TraceCalls("[XMREngine]: XMREngine.PostObjectEvent({0},{1})", itemID.ToString(), name);

            SceneObjectPart part = m_Scene.GetSceneObjectPart(itemID);
            if (part == null)
                return false;

            return PostObjectEvent(part.LocalId, new EventParams(name, p, zeroDetectParams));
        }

        // about the 3523rd entrypoint for a script to put itself to sleep
        public void SleepScript(UUID itemID, int delay)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance != null)
                instance.Sleep (delay);
        }

        // Get a script instance loaded, compiling it if necessary
        //
        //  localID     = the object as a whole, may contain many scripts
        //  itemID      = this instance of the script in this object
        //  script      = script source code
        //  startParam  = value passed to 'on_rez' event handler
        //  postOnRez   = true to post an 'on_rez' event to script on load
        //  defEngine   = default script engine
        //  stateSource = post this event to script on load

        public void OnRezScript(uint localID, UUID itemID, string script,
                int startParam, bool postOnRez, string defEngine, int stateSource)
        {
            SceneObjectPart part = m_Scene.GetSceneObjectPart(localID);
            TaskInventoryItem item = part.Inventory.GetInventoryItem(itemID);

            if (!m_LateInit)
            {
                m_LateInit = true;
                OneTimeLateInitialization ();
            }

            TraceCalls("[XMREngine]: OnRezScript(...,{0},...)", itemID.ToString());

             // Assume script uses the default engine, whatever that is.
            string engineName = defEngine;

             // Very first line might contain "//" scriptengine ":".
            string firstline = "";
            if (script.StartsWith("//")) {
                int lineEnd = script.IndexOf('\n');
                if (lineEnd > 1) firstline = script.Substring(0, lineEnd).Trim();
                int colon = firstline.IndexOf(':');
                if (colon >= 2) {
                    engineName = firstline.Substring(2, colon - 2).Trim();
                    if (engineName == "") engineName = defEngine;
                }
            }

             // Make sure the default or requested engine is us.
            if (engineName != ScriptEngineName) {

                 // Not us, if requested engine exists, silently ignore script and let
                 // requested engine handle it.
                IScriptModule[] engines = m_Scene.RequestModuleInterfaces<IScriptModule> ();
                foreach (IScriptModule eng in engines)
                {
                    if (eng.ScriptEngineName == engineName)
                        return;
                }

                 // Requested engine not defined, warn on console.
                 // Then we try to handle it if we're the default engine, else we ignore it.
                m_log.Warn ("[XMREngine]: " + itemID.ToString() + " requests undefined/disabled engine " + engineName);
                m_log.Info ("[XMREngine]: - " + part.GetWorldPosition ());
                m_log.Info ("[XMREngine]: first line: " + firstline);
                if (defEngine != ScriptEngineName)
                {
                    m_log.Info ("[XMREngine]: leaving it to the default script engine (" + defEngine + ") to process it");
                    return;
                }
                m_log.Info ("[XMREngine]: will attempt to processing it anyway as default script engine");
            }

             // Put on object/instance lists.
            XMRInstance instance   = (XMRInstance)Activator.CreateInstance (ScriptCodeGen.xmrInstSuperType);
            instance.m_LocalID     = localID;
            instance.m_ItemID      = itemID;
            instance.m_SourceCode  = script;
            instance.m_StartParam  = startParam;
            instance.m_PostOnRez   = postOnRez;
            instance.m_StateSource = (StateSource)stateSource;
            instance.m_Part        = part;
            instance.m_PartUUID    = part.UUID;
            instance.m_Item        = item;
            instance.m_DescName    = part.Name + ":" + item.Name;
            instance.m_IState      = XMRInstState.CONSTRUCT;

            lock (m_InstancesDict)
            {
                m_LockedDict = "RegisterInstance";

                // Insert on internal list of all scripts being handled by this engine instance.
                m_InstancesDict[instance.m_ItemID] = instance;

                // Insert on internal list of all scripts being handled by this engine instance
                // that are part of the object.
                List<UUID> itemIDList;
                if (!m_ObjectItemList.TryGetValue(instance.m_PartUUID, out itemIDList))
                {
                    itemIDList = new List<UUID>();
                    m_ObjectItemList[instance.m_PartUUID] = itemIDList;
                }
                if (!itemIDList.Contains(instance.m_ItemID))
                {
                    itemIDList.Add(instance.m_ItemID);
                    m_ObjectInstArray[instance.m_PartUUID] = null;
                }

                m_LockedDict = "~RegisterInstance";
            }

             // Compile and load it.
            lock (m_ScriptErrors)
                m_ScriptErrors.Remove (instance.m_ItemID);

            LoadThreadWork (instance);
        }

        /**
         * @brief This routine instantiates one script.
         */
        private void LoadThreadWork (XMRInstance instance)
        {
             // Compile and load the script in memory.

            ArrayList errors = new ArrayList();
            Exception initerr = null;
            try
            {
                instance.Initialize(this, m_ScriptBasePath, m_StackSize, m_HeapSize, errors);
            }
            catch (Exception e1)
            {
                initerr = e1;
            }
            if ((initerr != null) && !instance.m_ForceRecomp)
            {
                UUID itemID = instance.m_ItemID;
                Verbose ("[XMREngine]: {0}/{2} first load failed ({1}), retrying after recompile", 
                        itemID.ToString(), initerr.Message, instance.m_Item.AssetID.ToString());
                Verbose ("[XMREngine]:\n{0}", initerr.ToString ());
                initerr = null;
                errors = new ArrayList();
                instance.m_ForceRecomp = true;
                try
                {
                    instance.Initialize(this, m_ScriptBasePath, m_StackSize, m_HeapSize, errors);
                }
                catch (Exception e2)
                {
                    initerr = e2;
                }
            }
            if (initerr != null)
            {
                UUID itemID = instance.m_ItemID;
                Verbose ("[XMREngine]: Error starting script {0}/{2}: {1}",
                                  itemID.ToString(), initerr.Message, instance.m_Item.AssetID.ToString());
                if (initerr.Message != "compilation errors")
                {
                    Verbose ("[XMREngine]: - " + instance.m_Part.GetWorldPosition () + " " + instance.m_DescName);
                    Verbose ("[XMREngine]:   exception:\n{0}", initerr.ToString());
                }

                OnRemoveScript (0, itemID);

                 // Post errors where GetScriptErrors() can see them.

                if (errors.Count == 0)
                    errors.Add(initerr.Message);
                else
                {
                    foreach (Object err in errors)
                    {
                        if (m_ScriptDebug)
                            m_log.DebugFormat ("[XMREngine]:   {0}", err.ToString());
                    }
                }

                lock (m_ScriptErrors)
                    m_ScriptErrors[instance.m_ItemID] = errors;

                return;
            }

             // Tell GetScriptErrors() that we have finished compiling/loading
             // successfully (by posting a 0 element array).
            lock (m_ScriptErrors)
            {
                if (instance.m_IState != XMRInstState.CONSTRUCT) throw new Exception("bad state");
                m_ScriptErrors[instance.m_ItemID] = noScriptErrors;
            }

             // Transition from CONSTRUCT->ONSTARTQ and give to RunScriptThread().
             // Put it on the start queue so it will run any queued event handlers,
             // such as state_entry() or on_rez().  If there aren't any queued, it
             // will just go to idle state when RunOne() tries to dequeue an event.
            lock (instance.m_QueueLock)
            {
                if (instance.m_IState != XMRInstState.CONSTRUCT)
                    throw new Exception("bad state");
                instance.m_IState = XMRInstState.ONSTARTQ;
                if (!instance.m_Running)
                    instance.EmptyEventQueues ();
            }
            QueueToStart(instance);
        }

        public void OnRemoveScript(uint localID, UUID itemID)
        {
            TraceCalls("[XMREngine]: OnRemoveScript(...,{0})", itemID.ToString());

             // Remove from our list of known scripts.
             // After this, no more events can queue because we won't be
             // able to translate the itemID to an XMRInstance pointer.

            XMRInstance instance = null;
            lock (m_InstancesDict)
            {
                m_LockedDict = "OnRemoveScript:" + itemID.ToString();

                 // Tell the instance to free off everything it can.

                if (!m_InstancesDict.TryGetValue(itemID, out instance))
                {
                    m_LockedDict = "~OnRemoveScript";
                    return;
                }

                 // Tell it to stop executing anything.
                instance.suspendOnCheckRunHold = true;

                 // Remove it from our list of known script instances
                 // mostly so no more events can queue to it.
                m_InstancesDict.Remove(itemID);

                List<UUID> itemIDList;
                if (m_ObjectItemList.TryGetValue (instance.m_PartUUID, out itemIDList))
                {
                    itemIDList.Remove(itemID);
                    if (itemIDList.Count == 0)
                    {
                        m_ObjectItemList.Remove(instance.m_PartUUID);
                        m_ObjectInstArray.Remove(instance.m_PartUUID);
                    }
                    else
                        m_ObjectInstArray[instance.m_PartUUID] = null;
                }

                 // Delete the .state file as any needed contents were fetched with GetXMLState()
                 // and stored on the database server.
                string stateFileName = XMRInstance.GetStateFileName(m_ScriptBasePath, itemID);
                File.Delete(stateFileName);

                ScriptRemoved handlerScriptRemoved = OnScriptRemoved;
                if (handlerScriptRemoved != null)
                    handlerScriptRemoved(itemID);

                m_LockedDict = "~~OnRemoveScript";
            }

             // Free off its stack and fun things like that.
             // If it is running, abort it.
            instance.Dispose ();
        }

        public void OnScriptReset(uint localID, UUID itemID)
        {
            TraceCalls("[XMREngine]: XMREngine.OnScriptReset({0},{1})", localID.ToString(), itemID.ToString());
            ResetScript(itemID);
        }

        public void OnStartScript(uint localID, UUID itemID)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance != null)
                instance.Running = true;
        }

        public void OnStopScript(uint localID, UUID itemID)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance != null)
                instance.Running = false;
        }

        public void OnGetScriptRunning(IClientAPI controllingClient,
                UUID objectID, UUID itemID)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance != null)
            {
                TraceCalls("[XMREngine]: XMREngine.OnGetScriptRunning({0},{1})", objectID.ToString(), itemID.ToString());

                IEventQueue eq = World.RequestModuleInterface<IEventQueue>();
                if (eq == null)
                {
                    controllingClient.SendScriptRunningReply(objectID, itemID,
                            instance.Running);
                }
                else
                {
                    eq.Enqueue(EventQueueHelper.ScriptRunningReplyEvent(objectID,
                            itemID, instance.Running, true),
                            controllingClient.AgentId);
                }
            }
        }

        public bool HasScript(UUID itemID, out bool running)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance == null)
            {
                running = true;
                return false;
            }
            running = instance.Running;
            return true;
        }

        /**
         * @brief Called once per frame update to see if scripts have
         *        any such work to do.
         */
        private void OnFrame ()
        {
            if (m_FrameUpdateList != null)
            {
                ThreadStart frameupdates;
                lock (m_FrameUpdateLock)
                {
                    frameupdates = m_FrameUpdateList;
                    m_FrameUpdateList = null;
                }
                frameupdates ();
            }
        }

        /**
         * @brief Add a one-shot delegate to list of things to do
         *        synchronized with frame updates.
         */
        public void AddOnFrameUpdate (ThreadStart thunk)
        {
            lock (m_FrameUpdateLock)
                m_FrameUpdateList += thunk;
        }

        /**
         * @brief Gets called early as part of shutdown,
         *        right after "Persisting changed objects" message.
         */
        public void OnShutdown()
        {
            TraceCalls("[XMREngine]: XMREngine.OnShutdown()");
        }

        /**
         * @brief Queue an instance to the StartQueue so it will run.
         *        This queue is used for instances that have just had
         *        an event queued to them when they were previously
         *        idle.  It must only be called by the thread that
         *        transitioned the thread to XMRInstState.ONSTARTQ so
         *        we don't get two threads trying to queue the same
         *        instance to the m_StartQueue at the same time.
         */
        public void QueueToStart(XMRInstance inst)
        {
            lock (m_StartQueue)
            {
                if (inst.m_IState != XMRInstState.ONSTARTQ) throw new Exception("bad state");
                m_StartQueue.InsertTail(inst);
            }
            WakeUpOne();
        }

        public void QueueToTrunk(ThreadStart thds)
        {
            lock (m_WakeUpLock)
                    m_ThunkQueue.Enqueue (thds);
            WakeUpOne();
        }

        /**
         * @brief A script may be sleeping, in which case we wake it.
         */
        public void WakeFromSleep(XMRInstance inst)
        {
             // Remove from sleep queue unless someone else already woke it.
            lock (m_SleepQueue)
            {
                if (inst.m_IState != XMRInstState.ONSLEEPQ)
                    return;

                m_SleepQueue.Remove(inst);
                inst.m_IState = XMRInstState.REMDFROMSLPQ;
            }

             // Put on end of list of scripts that are ready to run.
            lock (m_YieldQueue)
            {
                inst.m_IState = XMRInstState.ONYIELDQ;
                m_YieldQueue.InsertTail(inst);
            }


             // Make sure the OS thread is running so it will see the script.
            WakeUpOne();
        }

        /**
         * @brief An instance has just finished running for now,
         *        figure out what to do with it next.
         * @param inst = instance in question, not on any queue at the moment
         * @param newIState = its new state
         * @returns with instance inserted onto proper queue (if any)
         */
        public void HandleNewIState(XMRInstance inst, XMRInstState newIState)
        {

             // RunOne() should have left the instance in RUNNING state.
            if (inst.m_IState != XMRInstState.RUNNING)
                throw new Exception("bad state");


             // Now see what RunOne() wants us to do with the instance next.
            switch (newIState)
            {

                 // Instance has set m_SleepUntil to when it wants to sleep until.
                 // So insert instance in sleep queue by ascending wake time.
                 // Then wake the timer thread if this is the new first entry
                 // so it will reset its timer.
                case XMRInstState.ONSLEEPQ:
                    lock (m_SleepQueue)
                     {
                        XMRInstance after;

                        inst.m_IState = XMRInstState.ONSLEEPQ;
                        for (after = m_SleepQueue.PeekHead(); after != null; after = after.m_NextInst)
                        {
                            if (after.m_SleepUntil > inst.m_SleepUntil)
                                break;
                        }
                        m_SleepQueue.InsertBefore(inst, after);
                        if (m_SleepQueue.PeekHead() == inst)
                        {
                            Monitor.Pulse (m_SleepQueue);
                        }
                    }
                    break;

                 // Instance just took a long time to run and got wacked by the
                 // slicer.  So put on end of yield queue to let someone else
                 // run.  If there is no one else, it will run again right away.
                case XMRInstState.ONYIELDQ:
                    lock (m_YieldQueue)
                    {
                        inst.m_IState = XMRInstState.ONYIELDQ;
                        m_YieldQueue.InsertTail(inst);
                    }
                    break;

                 // Instance finished executing an event handler.  So if there is
                 // another event queued for it, put it on the start queue so it
                 // will process the new event.  Otherwise, mark it idle and the
                 // next event to queue to it will start it up.
                case XMRInstState.FINISHED:
                    Monitor.Enter(inst.m_QueueLock);
                    if (!inst.m_Suspended && (inst.m_EventQueue.Count > 0))
                    {
                        Monitor.Exit(inst.m_QueueLock);
                        lock (m_StartQueue)
                        {
                            inst.m_IState = XMRInstState.ONSTARTQ;
                            m_StartQueue.InsertTail (inst);
                        }
                    }
                    else
                    {
                        inst.m_IState = XMRInstState.IDLE;
                        Monitor.Exit(inst.m_QueueLock);
                    }
                    break;

                 // Its m_SuspendCount > 0.
                 // Don't put it on any queue and it won't run.
                 // Since it's not IDLE, even queuing an event won't start it.
                case XMRInstState.SUSPENDED:
                    inst.m_IState = XMRInstState.SUSPENDED;
                    break;

                 // It has been disposed of.
                 // Just set the new state and all refs should theoretically drop off
                 // as the instance is no longer in any list.
                case XMRInstState.DISPOSED:
                    inst.m_IState = XMRInstState.DISPOSED;
                    break;

                 // RunOne returned something bad.
                default:
                     throw new Exception("bad new state");
            }
        }

        /**
         * @brief Thread that moves instances from the Sleep queue to the Yield queue.
         */
        private void RunSleepThread()
        {
            double deltaTS;
            int deltaMS;
            XMRInstance inst;

            while (true)
            {
                lock (m_SleepQueue)
                {

                     // Wait here until there is a script on the timer queue that has expired.
                    while (true)
                    {
                        UpdateMyThread ();
                        if (m_Exiting)
                        {
                            MyThreadExiting ();
                            return;
                        }
                        inst = m_SleepQueue.PeekHead();
                        if (inst == null)
                        {
                            Monitor.Wait (m_SleepQueue, Watchdog.DEFAULT_WATCHDOG_TIMEOUT_MS / 2);
                            continue;
                        }
                        if (inst.m_IState != XMRInstState.ONSLEEPQ) throw new Exception("bad state");
                        deltaTS = (inst.m_SleepUntil - DateTime.UtcNow).TotalMilliseconds;
                        if (deltaTS <= 0.0)
                            break;
                        deltaMS = Int32.MaxValue;
                        if (deltaTS < Int32.MaxValue)
                            deltaMS = (int)deltaTS;
                        if (deltaMS > Watchdog.DEFAULT_WATCHDOG_TIMEOUT_MS / 2)
                        {
                            deltaMS = Watchdog.DEFAULT_WATCHDOG_TIMEOUT_MS / 2;
                        }
                        Monitor.Wait (m_SleepQueue, deltaMS);
                    }

                     // Remove the expired entry from the timer queue.
                    m_SleepQueue.RemoveHead();
                    inst.m_IState = XMRInstState.REMDFROMSLPQ;
                }

                 // Post the script to the yield queue so it will run and wake a script thread to run it.
                lock (m_YieldQueue)
                {
                    inst.m_IState = XMRInstState.ONYIELDQ;
                    m_YieldQueue.InsertTail(inst);
                }
                WakeUpOne ();
            }
        }

        /**
         * @brief Thread that runs a time slicer.
         */
        public void Suspend(UUID itemID, int ms)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance != null)
                instance.Sleep(ms);
        }

        public void Die(UUID itemID)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance != null)
            {
                TraceCalls("[XMREngine]: XMREngine.Die({0})", itemID.ToString());
                instance.Die();
            }
        }

        /**
         * @brief Get specific script instance for which OnRezScript()
         *        has been called for an XMREngine script, and that
         *        OnRemoveScript() has not been called since.
         * @param itemID = as passed to OnRezScript() identifying a specific script instance
         * @returns null: not one of our scripts (maybe XEngine etc)
         *          else: points to the script instance
         */
        public XMRInstance GetInstance(UUID itemID)
        {
            XMRInstance instance;
            lock (m_InstancesDict)
            {
                if (!m_InstancesDict.TryGetValue(itemID, out instance))
                    instance = null;
            }
            return instance;
        }

        // Called occasionally to write script state to .state file so the
        // script will restart from its last known state if the region crashes
        // and gets restarted.
        private void DoMaintenance(object source, ElapsedEventArgs e)
        {
            XMRInstance[] instanceArray;

            lock (m_InstancesDict)
                instanceArray = System.Linq.Enumerable.ToArray(m_InstancesDict.Values);

            foreach (XMRInstance ins in instanceArray)
            {
                // Don't save attachments
                if (ins.m_Part.ParentGroup.IsAttachment)
                    continue;
                ins.GetExecutionState(new XmlDocument());
            }
        }

        /**
         * @brief Retrieve errors generated by a previous call to OnRezScript().
         *        We are guaranteed this routine will not be called before the
         *        corresponding OnRezScript() has returned.  It blocks until the
         *        compile has completed.
         */
        public ArrayList GetScriptErrors(UUID itemID)
        {
            ArrayList errors;

            lock (m_ScriptErrors)
            {
                while (!m_ScriptErrors.TryGetValue (itemID, out errors))
                {
                    Monitor.Wait (m_ScriptErrors);
                }
                m_ScriptErrors.Remove (itemID);
            }
            return errors;
        }

        /**
         * @brief Return a list of all script execution times.
         */
        public Dictionary<uint, float> GetObjectScriptsExecutionTimes ()
        {
            Dictionary<uint, float> topScripts = new Dictionary<uint, float> ();
            lock (m_InstancesDict)
            {
                foreach (XMRInstance instance in m_InstancesDict.Values)
                {
                    uint rootLocalID = instance.m_Part.ParentGroup.LocalId;
                    float oldTotal;
                    if (!topScripts.TryGetValue (rootLocalID, out oldTotal))
                        oldTotal = 0;

                    topScripts[rootLocalID] = (float)instance.m_CPUTime + oldTotal;
                }
            }
            return topScripts;
        }

        /**
         * @brief A float the value is a representative execution time in
         *        milliseconds of all scripts in the link set.
         * @param itemIDs = list of scripts in the link set
         * @returns milliseconds for all those scripts
         */
        public float GetScriptExecutionTime (List<UUID> itemIDs)
        {
            if ((itemIDs == null) || (itemIDs.Count == 0))
                return 0;

            float time = 0;
            foreach (UUID itemID in itemIDs)
            {
                XMRInstance instance = GetInstance (itemID);
                if ((instance != null) && instance.Running)
                    time += (float) instance.m_CPUTime;
            }
            return time;
        }

        /**
         * @brief Block script from dequeuing events.
         */
        public void SuspendScript(UUID itemID)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance != null)
            {
                TraceCalls("[XMREngine]: XMREngine.SuspendScript({0})", itemID.ToString());
                instance.SuspendIt();
            }
        }

        /**
         * @brief Allow script to dequeue events.
         */
        public void ResumeScript(UUID itemID)
        {
            XMRInstance instance = GetInstance (itemID);
            if (instance != null)
            {
                TraceCalls("[XMREngine]: XMREngine.ResumeScript({0})", itemID.ToString());
                instance.ResumeIt();
            }
            else
            {
                // probably an XEngine script
            }
        }

        /**
         * @brief Rebuild m_ObjectInstArray[partUUID] from m_ObjectItemList[partUUID]
         * @param partUUID = which object in scene to rebuild for
         */
        private XMRInstance[] RebuildObjectInstArray (UUID partUUID)
        {
            List<UUID> itemIDList = m_ObjectItemList[partUUID];
            int n = 0;
            foreach (UUID itemID in itemIDList)
            {
                if (m_InstancesDict.ContainsKey(itemID))
                    n ++;
            }
            XMRInstance[] a = new XMRInstance[n];
            n = 0;
            foreach (UUID itemID in itemIDList)
            {
                if (m_InstancesDict.TryGetValue (itemID, out a[n]))
                    n ++;
            }
            m_ObjectInstArray[partUUID] = a;
            return a;
        }

        public void TraceCalls (string format, params object[] args)
        {
            if (m_TraceCalls)
                m_log.DebugFormat (format, args);
        }
        public void Verbose (string format, params object[] args)
        {
            if (m_Verbose)
                m_log.DebugFormat (format, args);
        }

        /**
         * @brief Manage our threads.
         */
        public static Thread StartMyThread (ThreadStart start, string name, ThreadPriority priority)
        {
            m_log.Debug ("[XMREngine]: starting thread " + name);
            Thread thread   = new Thread (start);
            thread.Name     = name;
            thread.Priority = priority;
            thread.IsBackground = true;
            thread.Start ();

            Watchdog.ThreadWatchdogInfo info = new Watchdog.ThreadWatchdogInfo (thread, Watchdog.DEFAULT_WATCHDOG_TIMEOUT_MS, name);
            Watchdog.AddThread (info, name, true);

            return thread;
        }

        public static void UpdateMyThread ()
        {
            Watchdog.UpdateThread();
        }

        public static void MyThreadExiting ()
        {
            Watchdog.RemoveThread(true);
        }

        public void RunScriptThread(XMRScriptThread xthd)
        {
            XMRInstance inst;
            while (!m_Exiting)
            {
                Watchdog.UpdateThread();

                /*
                 * Handle 'xmr resume/suspend' commands.
                 */
                if (m_SuspendScriptThreadFlag)
                {
                    lock (m_WakeUpLock)
                    {
                        while (m_SuspendScriptThreadFlag &&
                               !m_Exiting &&
                               (m_ThunkQueue.Count == 0))
                        {
                            Monitor.Wait (m_WakeUpLock, Watchdog.DEFAULT_WATCHDOG_TIMEOUT_MS / 2);
                            XMREngine.UpdateMyThread ();
                        }
                    }
                }

                /*
                 * Maybe there are some scripts waiting to be migrated in or out.
                 */
                ThreadStart thunk = null;
                lock (m_WakeUpLock)
                {
                    if (m_ThunkQueue.Count > 0)
                        thunk = m_ThunkQueue.Dequeue ();
                }
                if (thunk != null)
                {
                    inst = (XMRInstance)thunk.Target;
                    thunk ();
                    if (m_Exiting || m_SuspendScriptThreadFlag)
                        continue;
                }

                if (m_StartProcessing)
                {
                     // If event just queued to any idle scripts
                     // start them right away.  But only start so
                     // many so we can make some progress on yield
                     // queue.

                    int numStarts;
                    for (numStarts = 5; -- numStarts >= 0;)
                    {
                        lock (m_StartQueue)
                        {
                            inst = m_StartQueue.RemoveHead();
                        }
                        if (inst == null) break;
                        if (inst.m_IState != XMRInstState.ONSTARTQ) throw new Exception("bad state");
                        xthd.RunInstance (inst);
                        if (m_Exiting || m_SuspendScriptThreadFlag)
                            continue;
                    }

                     // If there is something to run, run it
                     // then rescan from the beginning in case
                     // a lot of things have changed meanwhile.
                     //
                     // These are considered lower priority than
                     // m_StartQueue as they have been taking at
                     // least one quantum of CPU time and event
                     // handlers are supposed to be quick.

                    lock (m_YieldQueue)
                    {
                        inst = m_YieldQueue.RemoveHead();
                    }
                    if (inst != null)
                    {
                        if (inst.m_IState != XMRInstState.ONYIELDQ) throw new Exception("bad state");
                        xthd.RunInstance(inst);
                        numStarts = -1;
                    }

                     // If we left something dangling in the m_StartQueue or m_YieldQueue, go back to check it.
                    if (m_Exiting || numStarts < 0)
                        continue;
                }

                 // Nothing to do, sleep.
                lock (m_WakeUpLock)
                {
                    if (!xthd.m_WakeUpThis && (m_WakeUpOne <= 0) && !m_Exiting)
                        Monitor.Wait(m_WakeUpLock, Watchdog.DEFAULT_WATCHDOG_TIMEOUT_MS / 2);

                    xthd.m_WakeUpThis = false;
                    if ((m_WakeUpOne > 0) && (--m_WakeUpOne > 0))
                        Monitor.Pulse (m_WakeUpLock);
                }
            }
            Watchdog.RemoveThread(true);
        }
    }
}