* This is Melanie's XEngine script engine. I've not tested this real well, however, it's confirmed to compile and OpenSimulator to run successfully without this script engine active.

ThirdParty/SmartThreadPool/AssemblyInfo.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Reflection;
+using System.Runtime.InteropServices;
+
+//
+// General Information about an assembly is controlled through the following 
+// set of attributes. Change these attribute values to modify the information
+// associated with an assembly.
+//
+[assembly: AssemblyTitle("")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("")]
+[assembly: AssemblyCopyright("")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]        
+[assembly: ComVisible(false)]
+[assembly: CLSCompliant(true)]
+
+//
+// Version information for an assembly consists of the following four values:
+//
+//      Major Version
+//      Minor Version 
+//      Build Number
+//      Revision
+//
+// You can specify all the values or you can default the Revision and Build Numbers 
+// by using the '*' as shown below:
+
+[assembly: AssemblyVersion("1.0.*")]
+
+//
+// In order to sign your assembly you must specify a key to use. Refer to the 
+// Microsoft .NET Framework documentation for more information on assembly signing.
+//
+// Use the attributes below to control which key is used for signing. 
+//
+// Notes: 
+//   (*) If no key is specified, the assembly is not signed.
+//   (*) KeyName refers to a key that has been installed in the Crypto Service
+//       Provider (CSP) on your machine. KeyFile refers to a file which contains
+//       a key.
+//   (*) If the KeyFile and the KeyName values are both specified, the 
+//       following processing occurs:
+//       (1) If the KeyName can be found in the CSP, that key is used.
+//       (2) If the KeyName does not exist and the KeyFile does exist, the key 
+//           in the KeyFile is installed into the CSP and used.
+//   (*) In order to create a KeyFile, you can use the sn.exe (Strong Name) utility.
+//       When specifying the KeyFile, the location of the KeyFile should be
+//       relative to the project output directory which is
+//       %Project Directory%\obj\<configuration>. For example, if your KeyFile is
+//       located in the project directory, you would specify the AssemblyKeyFile 
+//       attribute as [assembly: AssemblyKeyFile("..\\..\\mykey.snk")]
+//   (*) Delay Signing is an advanced option - see the Microsoft .NET Framework
+//       documentation for more information on this.
+//
+[assembly: AssemblyDelaySign(false)]
+[assembly: AssemblyKeyFile("")]
+[assembly: AssemblyKeyName("")]

ThirdParty/SmartThreadPool/CallerThreadContext.cs

@@ -0,0 +1,223 @@
+using System;
+using System.Diagnostics;
+using System.Threading;
+using System.Reflection;
+using System.Web;
+using System.Runtime.Remoting.Messaging;
+
+
+namespace Amib.Threading
+{
+    #region CallerThreadContext class
+
+    /// <summary>
+    /// This class stores the caller call context in order to restore
+    /// it when the work item is executed in the thread pool environment. 
+    /// </summary>
+    internal class CallerThreadContext 
+    {
+        #region Prepare reflection information
+
+        // Cached type information.
+        private static MethodInfo getLogicalCallContextMethodInfo =
+            typeof(Thread).GetMethod("GetLogicalCallContext", BindingFlags.Instance | BindingFlags.NonPublic);
+
+        private static MethodInfo setLogicalCallContextMethodInfo =
+            typeof(Thread).GetMethod("SetLogicalCallContext", BindingFlags.Instance | BindingFlags.NonPublic);
+
+        private static string HttpContextSlotName = GetHttpContextSlotName();
+
+        private static string GetHttpContextSlotName()
+        {
+            FieldInfo fi = typeof(HttpContext).GetField("CallContextSlotName", BindingFlags.Static | BindingFlags.NonPublic);
+
+            if( fi != null )
+                return (string)fi.GetValue(null);
+            else // Use the default "HttpContext" slot name
+                return "HttpContext";
+        }
+
+        #endregion
+
+        #region Private fields
+
+        private HttpContext _httpContext = null;
+        private LogicalCallContext _callContext = null;
+
+        #endregion
+
+        /// <summary>
+        /// Constructor
+        /// </summary>
+        private CallerThreadContext()
+        {
+        }
+
+        public bool CapturedCallContext
+        {
+            get
+            {
+                return (null != _callContext);
+            }
+        }
+
+        public bool CapturedHttpContext
+        {
+            get
+            {
+                return (null != _httpContext);
+            }
+        }
+
+        /// <summary>
+        /// Captures the current thread context
+        /// </summary>
+        /// <returns></returns>
+        public static CallerThreadContext Capture(
+            bool captureCallContext, 
+            bool captureHttpContext)
+        {
+            Debug.Assert(captureCallContext || captureHttpContext);
+
+            CallerThreadContext callerThreadContext = new CallerThreadContext();
+
+            // TODO: In NET 2.0, redo using the new feature of ExecutionContext class - Capture()
+            // Capture Call Context
+            if(captureCallContext && (getLogicalCallContextMethodInfo != null))
+            {
+                callerThreadContext._callContext = (LogicalCallContext)getLogicalCallContextMethodInfo.Invoke(Thread.CurrentThread, null);
+                if (callerThreadContext._callContext != null)
+                {
+                    callerThreadContext._callContext = (LogicalCallContext)callerThreadContext._callContext.Clone();
+                }
+            }
+
+            // Capture httpContext
+            if (captureHttpContext && (null != HttpContext.Current))
+            {
+                callerThreadContext._httpContext = HttpContext.Current;
+            }
+
+            return callerThreadContext;
+        }
+
+        /// <summary>
+        /// Applies the thread context stored earlier
+        /// </summary>
+        /// <param name="callerThreadContext"></param>
+        public static void Apply(CallerThreadContext callerThreadContext)
+        {
+            if (null == callerThreadContext) 
+            {
+                throw new ArgumentNullException("callerThreadContext");            
+            }
+
+            // Todo: In NET 2.0, redo using the new feature of ExecutionContext class - Run()
+            // Restore call context
+            if ((callerThreadContext._callContext != null) && (setLogicalCallContextMethodInfo != null))
+            {
+                setLogicalCallContextMethodInfo.Invoke(Thread.CurrentThread, new object[] { callerThreadContext._callContext });
+            }
+
+            // Restore HttpContext 
+            if (callerThreadContext._httpContext != null)
+            {
+                CallContext.SetData(HttpContextSlotName, callerThreadContext._httpContext);
+            }
+        }
+    }
+
+    #endregion
+
+}
+
+
+/*
+// Ami Bar
+// amibar@gmail.com
+
+using System;
+using System.Threading;
+using System.Globalization;
+using System.Security.Principal;
+using System.Reflection;
+using System.Runtime.Remoting.Contexts;
+
+namespace Amib.Threading.Internal
+{
+    #region CallerThreadContext class
+
+    /// <summary>
+    /// This class stores the caller thread context in order to restore
+    /// it when the work item is executed in the context of the thread 
+    /// from the pool.
+    /// Note that we can't store the thread's CompressedStack, because 
+    /// it throws a security exception
+    /// </summary>
+    public class CallerThreadContext
+    {
+        private CultureInfo _culture = null;
+        private CultureInfo _cultureUI = null;
+        private IPrincipal _principal;
+        private System.Runtime.Remoting.Contexts.Context _context;
+
+        private static FieldInfo _fieldInfo = GetFieldInfo();
+
+        private static FieldInfo GetFieldInfo()
+        {
+            Type threadType = typeof(Thread);
+            return threadType.GetField(
+                "m_Context",
+                BindingFlags.Instance | BindingFlags.NonPublic);
+        }
+
+        /// <summary>
+        /// Constructor
+        /// </summary>
+        private CallerThreadContext()
+        {
+        }
+
+        /// <summary>
+        /// Captures the current thread context
+        /// </summary>
+        /// <returns></returns>
+        public static CallerThreadContext Capture()
+        {
+            CallerThreadContext callerThreadContext = new CallerThreadContext();
+
+            Thread thread = Thread.CurrentThread;
+            callerThreadContext._culture = thread.CurrentCulture;
+            callerThreadContext._cultureUI = thread.CurrentUICulture;
+            callerThreadContext._principal = Thread.CurrentPrincipal;
+            callerThreadContext._context = Thread.CurrentContext;
+            return callerThreadContext;
+        }
+
+        /// <summary>
+        /// Applies the thread context stored earlier
+        /// </summary>
+        /// <param name="callerThreadContext"></param>
+        public static void Apply(CallerThreadContext callerThreadContext)
+        {
+            Thread thread = Thread.CurrentThread;
+            thread.CurrentCulture = callerThreadContext._culture;
+            thread.CurrentUICulture = callerThreadContext._cultureUI;
+            Thread.CurrentPrincipal = callerThreadContext._principal;
+
+            // Uncomment the following block to enable the Thread.CurrentThread
+/*
+            if (null != _fieldInfo)
+            {
+                _fieldInfo.SetValue(
+                    Thread.CurrentThread, 
+                    callerThreadContext._context);
+            }
+* /            
+        }
+    }
+
+    #endregion
+}
+*/
+

ThirdParty/SmartThreadPool/Exceptions.cs

@@ -0,0 +1,81 @@
+// Ami Bar
+// amibar@gmail.com
+
+using System;
+using System.Runtime.Serialization;
+
+namespace Amib.Threading
+{
+    #region Exceptions
+
+    /// <summary>
+    /// Represents an exception in case IWorkItemResult.GetResult has been canceled
+    /// </summary>
+    [Serializable]
+    public sealed class WorkItemCancelException : ApplicationException
+    {
+        public WorkItemCancelException() : base()
+        {
+        }
+
+        public WorkItemCancelException(string message) : base(message)
+        {
+        }
+
+        public WorkItemCancelException(string message, Exception e) : base(message, e)
+        {
+        }
+
+        public WorkItemCancelException(SerializationInfo si, StreamingContext sc) : base(si, sc)
+        {
+        }
+    }
+
+    /// <summary>
+    /// Represents an exception in case IWorkItemResult.GetResult has been timed out
+    /// </summary>
+    [Serializable]
+    public sealed class WorkItemTimeoutException : ApplicationException
+    {
+        public WorkItemTimeoutException() : base()
+        {
+        }
+
+        public WorkItemTimeoutException(string message) : base(message)
+        {
+        }
+
+        public WorkItemTimeoutException(string message, Exception e) : base(message, e)
+        {
+        }
+
+        public WorkItemTimeoutException(SerializationInfo si, StreamingContext sc) : base(si, sc)
+        {
+        }
+    }
+
+    /// <summary>
+    /// Represents an exception in case IWorkItemResult.GetResult has been timed out
+    /// </summary>
+    [Serializable]
+    public sealed class WorkItemResultException : ApplicationException
+    {
+        public WorkItemResultException() : base()
+        {
+        }
+
+        public WorkItemResultException(string message) : base(message)
+        {
+        }
+
+        public WorkItemResultException(string message, Exception e) : base(message, e)
+        {
+        }
+
+        public WorkItemResultException(SerializationInfo si, StreamingContext sc) : base(si, sc)
+        {
+        }
+    }
+
+    #endregion
+}

ThirdParty/SmartThreadPool/Interfaces.cs

@@ -0,0 +1,271 @@
+// Ami Bar
+// amibar@gmail.com
+
+using System;
+using System.Threading;
+
+namespace Amib.Threading
+{
+    #region Delegates
+
+    /// <summary>
+    /// A delegate that represents the method to run as the work item
+    /// </summary>
+    /// <param name="state">A state object for the method to run</param>
+    public delegate object WorkItemCallback(object state);
+
+    /// <summary>
+    /// A delegate to call after the WorkItemCallback completed
+    /// </summary>
+    /// <param name="wir">The work item result object</param>
+    public delegate void PostExecuteWorkItemCallback(IWorkItemResult wir);
+
+    /// <summary>
+    /// A delegate to call when a WorkItemsGroup becomes idle
+    /// </summary>
+    /// <param name="workItemsGroup">A reference to the WorkItemsGroup that became idle</param>
+    public delegate void WorkItemsGroupIdleHandler(IWorkItemsGroup workItemsGroup);
+
+    #endregion
+
+    #region WorkItem Priority
+
+    public enum WorkItemPriority
+    {
+        Lowest,
+        BelowNormal,
+        Normal,
+        AboveNormal,
+        Highest,
+    }
+
+    #endregion
+
+    #region IHasWorkItemPriority interface 
+
+    public interface IHasWorkItemPriority
+    {
+        WorkItemPriority WorkItemPriority { get; }
+    }
+
+    #endregion
+
+    #region IWorkItemsGroup interface 
+
+    /// <summary>
+    /// IWorkItemsGroup interface
+    /// </summary>
+    public interface IWorkItemsGroup
+    {
+        /// <summary>
+        /// Get/Set the name of the WorkItemsGroup
+        /// </summary>
+        string Name { get; set; }
+
+        IWorkItemResult QueueWorkItem(WorkItemCallback callback);
+        IWorkItemResult QueueWorkItem(WorkItemCallback callback, WorkItemPriority workItemPriority);
+        IWorkItemResult QueueWorkItem(WorkItemCallback callback, object state);
+        IWorkItemResult QueueWorkItem(WorkItemCallback callback, object state, WorkItemPriority workItemPriority);
+        IWorkItemResult QueueWorkItem(WorkItemCallback callback, object state, PostExecuteWorkItemCallback postExecuteWorkItemCallback);
+        IWorkItemResult QueueWorkItem(WorkItemCallback callback, object state, PostExecuteWorkItemCallback postExecuteWorkItemCallback, WorkItemPriority workItemPriority);
+        IWorkItemResult QueueWorkItem(WorkItemCallback callback, object state, PostExecuteWorkItemCallback postExecuteWorkItemCallback, CallToPostExecute callToPostExecute);
+        IWorkItemResult QueueWorkItem(WorkItemCallback callback, object state, PostExecuteWorkItemCallback postExecuteWorkItemCallback, CallToPostExecute callToPostExecute, WorkItemPriority workItemPriority);
+
+        IWorkItemResult QueueWorkItem(WorkItemInfo workItemInfo, WorkItemCallback callback);
+        IWorkItemResult QueueWorkItem(WorkItemInfo workItemInfo, WorkItemCallback callback, object state);
+
+        void WaitForIdle();
+        bool WaitForIdle(TimeSpan timeout);
+        bool WaitForIdle(int millisecondsTimeout);
+
+        int WaitingCallbacks { get; }
+        event WorkItemsGroupIdleHandler OnIdle;
+
+        void Cancel();
+        void Start();
+    }
+
+    #endregion
+
+    #region CallToPostExecute enumerator
+
+    [Flags]
+    public enum CallToPostExecute
+    {
+        Never                    = 0x00,
+        WhenWorkItemCanceled     = 0x01,
+        WhenWorkItemNotCanceled  = 0x02,
+        Always                   = WhenWorkItemCanceled | WhenWorkItemNotCanceled,
+    }
+
+    #endregion
+
+    #region IWorkItemResult interface
+
+    /// <summary>
+    /// IWorkItemResult interface
+    /// </summary>
+    public interface IWorkItemResult
+    {
+        /// <summary>
+        /// Get the result of the work item.
+        /// If the work item didn't run yet then the caller waits.
+        /// </summary>
+        /// <returns>The result of the work item</returns>
+        object GetResult();
+
+        /// <summary>
+        /// Get the result of the work item.
+        /// If the work item didn't run yet then the caller waits until timeout.
+        /// </summary>
+        /// <returns>The result of the work item</returns>
+        /// On timeout throws WorkItemTimeoutException
+        object GetResult(
+            int millisecondsTimeout,
+            bool exitContext);
+
+        /// <summary>
+        /// Get the result of the work item.
+        /// If the work item didn't run yet then the caller waits until timeout.
+        /// </summary>
+        /// <returns>The result of the work item</returns>
+        /// On timeout throws WorkItemTimeoutException
+        object GetResult(            
+            TimeSpan timeout,
+            bool exitContext);
+
+        void Abort();
+
+        /// <summary>
+        /// Get the result of the work item.
+        /// If the work item didn't run yet then the caller waits until timeout or until the cancelWaitHandle is signaled.
+        /// </summary>
+        /// <param name="millisecondsTimeout">Timeout in milliseconds, or -1 for infinite</param>
+        /// <param name="exitContext">
+        /// true to exit the synchronization domain for the context before the wait (if in a synchronized context), and reacquire it; otherwise, false. 
+        /// </param>
+        /// <param name="cancelWaitHandle">A cancel wait handle to interrupt the blocking if needed</param>
+        /// <returns>The result of the work item</returns>
+        /// On timeout throws WorkItemTimeoutException
+        /// On cancel throws WorkItemCancelException
+        object GetResult(            
+            int millisecondsTimeout,
+            bool exitContext,
+            WaitHandle cancelWaitHandle);
+
+        /// <summary>
+        /// Get the result of the work item.
+        /// If the work item didn't run yet then the caller waits until timeout or until the cancelWaitHandle is signaled.
+        /// </summary>
+        /// <returns>The result of the work item</returns>
+        /// On timeout throws WorkItemTimeoutException
+        /// On cancel throws WorkItemCancelException
+        object GetResult(            
+            TimeSpan timeout,
+            bool exitContext,
+            WaitHandle cancelWaitHandle);
+
+        /// <summary>
+        /// Get the result of the work item.
+        /// If the work item didn't run yet then the caller waits.
+        /// </summary>
+        /// <param name="e">Filled with the exception if one was thrown</param>
+        /// <returns>The result of the work item</returns>
+        object GetResult(out Exception e);
+
+        /// <summary>
+        /// Get the result of the work item.
+        /// If the work item didn't run yet then the caller waits until timeout.
+        /// </summary>
+        /// <param name="e">Filled with the exception if one was thrown</param>
+        /// <returns>The result of the work item</returns>
+        /// On timeout throws WorkItemTimeoutException
+        object GetResult(
+            int millisecondsTimeout,
+            bool exitContext,
+            out Exception e);
+
+        /// <summary>
+        /// Get the result of the work item.
+        /// If the work item didn't run yet then the caller waits until timeout.
+        /// </summary>
+        /// <param name="e">Filled with the exception if one was thrown</param>
+        /// <returns>The result of the work item</returns>
+        /// On timeout throws WorkItemTimeoutException
+        object GetResult(            
+            TimeSpan timeout,
+            bool exitContext,
+            out Exception e);
+
+        /// <summary>
+        /// Get the result of the work item.
+        /// If the work item didn't run yet then the caller waits until timeout or until the cancelWaitHandle is signaled.
+        /// </summary>
+        /// <param name="millisecondsTimeout">Timeout in milliseconds, or -1 for infinite</param>
+        /// <param name="exitContext">
+        /// true to exit the synchronization domain for the context before the wait (if in a synchronized context), and reacquire it; otherwise, false. 
+        /// </param>
+        /// <param name="cancelWaitHandle">A cancel wait handle to interrupt the blocking if needed</param>
+        /// <param name="e">Filled with the exception if one was thrown</param>
+        /// <returns>The result of the work item</returns>
+        /// On timeout throws WorkItemTimeoutException
+        /// On cancel throws WorkItemCancelException
+        object GetResult(            
+            int millisecondsTimeout,
+            bool exitContext,
+            WaitHandle cancelWaitHandle,
+            out Exception e);
+
+        /// <summary>
+        /// Get the result of the work item.
+        /// If the work item didn't run yet then the caller waits until timeout or until the cancelWaitHandle is signaled.
+        /// </summary>
+        /// <returns>The result of the work item</returns>
+        /// <param name="e">Filled with the exception if one was thrown</param>
+        /// On timeout throws WorkItemTimeoutException
+        /// On cancel throws WorkItemCancelException
+        object GetResult(            
+            TimeSpan timeout,
+            bool exitContext,
+            WaitHandle cancelWaitHandle,
+            out Exception e);
+
+        /// <summary>
+        /// Gets an indication whether the asynchronous operation has completed.
+        /// </summary>
+        bool IsCompleted { get; }
+
+        /// <summary>
+        /// Gets an indication whether the asynchronous operation has been canceled.
+        /// </summary>
+        bool IsCanceled { get; }
+
+        /// <summary>
+        /// Gets a user-defined object that qualifies or contains information about an asynchronous operation.
+        /// </summary>
+        object State { get; }
+
+        /// <summary>
+        /// Cancel the work item if it didn't start running yet.
+        /// </summary>
+        /// <returns>Returns true on success or false if the work item is in progress or already completed</returns>
+        bool Cancel();
+
+        /// <summary>
+        /// Get the work item's priority
+        /// </summary>
+        WorkItemPriority WorkItemPriority { get; }
+
+        /// <summary>
+        /// Return the result, same as GetResult()
+        /// </summary>
+        object Result { get; }
+
+        /// <summary>
+        /// Returns the exception if occured otherwise returns null.
+        /// </summary>
+        object Exception { get; }
+    }
+
+    #endregion
+}

ThirdParty/SmartThreadPool/PriorityQueue.cs

@@ -0,0 +1,240 @@
+// Ami Bar
+// amibar@gmail.com
+
+using System;
+using System.Collections;
+using System.Diagnostics;
+
+namespace Amib.Threading.Internal
+{
+    #region PriorityQueue class
+
+    /// <summary>
+    /// PriorityQueue class
+    /// This class is not thread safe because we use external lock
+    /// </summary>
+    public sealed class PriorityQueue : IEnumerable
+    {
+        #region Private members
+
+        /// <summary>
+        /// The number of queues, there is one for each type of priority
+        /// </summary>
+        private const int _queuesCount = WorkItemPriority.Highest-WorkItemPriority.Lowest+1;
+
+        /// <summary>
+        /// Work items queues. There is one for each type of priority
+        /// </summary>
+        private Queue [] _queues = new Queue[_queuesCount];
+
+        /// <summary>
+        /// The total number of work items within the queues 
+        /// </summary>
+        private int _workItemsCount = 0;
+
+        /// <summary>
+        /// Use with IEnumerable interface
+        /// </summary>
+        private int _version = 0;
+
+        #endregion
+
+        #region Contructor
+
+        public PriorityQueue()
+        {
+            for(int i = 0; i < _queues.Length; ++i)
+            {
+                _queues[i] = new Queue();
+            }
+        }
+
+        #endregion
+
+        #region Methods
+
+        /// <summary>
+        /// Enqueue a work item.
+        /// </summary>
+        /// <param name="workItem">A work item</param>
+        public void Enqueue(IHasWorkItemPriority workItem)
+        {
+            Debug.Assert(null != workItem);
+
+            int queueIndex = _queuesCount-(int)workItem.WorkItemPriority-1;
+            Debug.Assert(queueIndex >= 0);
+            Debug.Assert(queueIndex < _queuesCount);
+
+            _queues[queueIndex].Enqueue(workItem);
+            ++_workItemsCount;
+            ++_version;
+        }
+
+        /// <summary>
+        /// Dequeque a work item.
+        /// </summary>
+        /// <returns>Returns the next work item</returns>
+        public IHasWorkItemPriority Dequeue()
+        {
+            IHasWorkItemPriority workItem = null;
+
+            if(_workItemsCount > 0)
+            {
+                int queueIndex = GetNextNonEmptyQueue(-1);
+                Debug.Assert(queueIndex >= 0);
+                workItem = _queues[queueIndex].Dequeue() as IHasWorkItemPriority;
+                Debug.Assert(null != workItem);
+                --_workItemsCount;
+                ++_version;
+            }
+
+            return workItem;
+        }
+
+        /// <summary>
+        /// Find the next non empty queue starting at queue queueIndex+1
+        /// </summary>
+        /// <param name="queueIndex">The index-1 to start from</param>
+        /// <returns>
+        /// The index of the next non empty queue or -1 if all the queues are empty
+        /// </returns>
+        private int GetNextNonEmptyQueue(int queueIndex)
+        {
+            for(int i = queueIndex+1; i < _queuesCount; ++i)
+            {
+                if(_queues[i].Count > 0)
+                {
+                    return i;
+                }
+            }
+            return -1;
+        }
+
+        /// <summary>
+        /// The number of work items 
+        /// </summary>
+        public int Count
+        {
+            get
+            {
+                return _workItemsCount;
+            }
+        }
+
+        /// <summary>
+        /// Clear all the work items 
+        /// </summary>
+        public void Clear()
+        {
+            if (_workItemsCount > 0)
+            {
+                foreach(Queue queue in _queues)
+                {
+                    queue.Clear();
+                }
+                _workItemsCount = 0;
+                ++_version;
+            }
+        }
+
+        #endregion
+
+        #region IEnumerable Members
+
+        /// <summary>
+        /// Returns an enumerator to iterate over the work items
+        /// </summary>
+        /// <returns>Returns an enumerator</returns>
+        public IEnumerator GetEnumerator()
+        {
+            return new PriorityQueueEnumerator(this);
+        }
+
+        #endregion
+
+        #region PriorityQueueEnumerator
+
+        /// <summary>
+        /// The class the implements the enumerator
+        /// </summary>
+        private class PriorityQueueEnumerator : IEnumerator
+        {
+            private PriorityQueue _priorityQueue;
+            private int _version;
+            private int _queueIndex;
+            private IEnumerator _enumerator;
+
+            public PriorityQueueEnumerator(PriorityQueue priorityQueue)
+            {
+                _priorityQueue = priorityQueue;
+                _version = _priorityQueue._version;
+                _queueIndex = _priorityQueue.GetNextNonEmptyQueue(-1);
+                if (_queueIndex >= 0)
+                {
+                    _enumerator = _priorityQueue._queues[_queueIndex].GetEnumerator();
+                }
+                else
+                {
+                    _enumerator = null;
+                }
+            }
+
+            #region IEnumerator Members
+
+            public void Reset()
+            {
+                _version = _priorityQueue._version;
+                _queueIndex = _priorityQueue.GetNextNonEmptyQueue(-1);
+                if (_queueIndex >= 0)
+                {
+                    _enumerator = _priorityQueue._queues[_queueIndex].GetEnumerator();
+                }
+                else
+                {
+                    _enumerator = null;
+                }
+            }
+
+            public object Current
+            {
+                get
+                {
+                    Debug.Assert(null != _enumerator);
+                    return _enumerator.Current;
+                }
+            }
+
+            public bool MoveNext()
+            {
+                if (null == _enumerator)
+                {
+                    return false;
+                }
+
+                if(_version != _priorityQueue._version)
+                {
+                    throw new InvalidOperationException("The collection has been modified");
+
+                }
+                if (!_enumerator.MoveNext())
+                {
+                    _queueIndex = _priorityQueue.GetNextNonEmptyQueue(_queueIndex);
+                    if(-1 == _queueIndex)
+                    {
+                        return false;
+                    }
+                    _enumerator = _priorityQueue._queues[_queueIndex].GetEnumerator();
+                    _enumerator.MoveNext();
+                    return true;
+                }
+                return true;
+            }
+
+            #endregion
+        }
+
+        #endregion
+    }
+
+    #endregion
+}

ThirdParty/SmartThreadPool/STPPerformanceCounter.cs

@@ -0,0 +1,352 @@
+using System;
+using System.Diagnostics;
+
+namespace Amib.Threading.Internal
+{
+    internal enum STPPerformanceCounterType
+    {
+        // Fields
+        ActiveThreads                = 0,
+        InUseThreads                = 1,
+        OverheadThreads                = 2,
+        OverheadThreadsPercent        = 3,
+        OverheadThreadsPercentBase    = 4,
+
+        WorkItems                    = 5,
+        WorkItemsInQueue            = 6,
+        WorkItemsProcessed            = 7,
+
+        WorkItemsQueuedPerSecond    = 8,
+        WorkItemsProcessedPerSecond    = 9,
+
+        AvgWorkItemWaitTime            = 10,
+        AvgWorkItemWaitTimeBase        = 11,
+
+        AvgWorkItemProcessTime        = 12,
+        AvgWorkItemProcessTimeBase    = 13,
+
+        WorkItemsGroups                = 14,
+
+        LastCounter                    = 14,
+    }
+ 
+
+    /// <summary>
+    /// Summary description for STPPerformanceCounter.
+    /// </summary>
+    internal class STPPerformanceCounter
+    {
+        // Fields
+        private PerformanceCounterType _pcType;
+        protected string _counterHelp;
+        protected string _counterName;
+
+        // Methods
+        public STPPerformanceCounter(
+            string counterName, 
+            string counterHelp, 
+            PerformanceCounterType pcType)
+        {
+            this._counterName = counterName;
+            this._counterHelp = counterHelp;
+            this._pcType = pcType;
+        }
+
+        public void AddCounterToCollection(CounterCreationDataCollection counterData)
+        {
+            CounterCreationData counterCreationData = new CounterCreationData(
+                _counterName, 
+                _counterHelp, 
+                _pcType);
+
+            counterData.Add(counterCreationData);
+        }
+ 
+        // Properties
+        public string Name
+        {
+            get
+            {
+                return _counterName;
+            }
+        }
+    }
+
+    internal class STPPerformanceCounters
+    {
+        // Fields
+        internal STPPerformanceCounter[] _stpPerformanceCounters;
+        private static STPPerformanceCounters _instance;
+        internal const string _stpCategoryHelp = "SmartThreadPool performance counters";
+        internal const string _stpCategoryName = "SmartThreadPool";
+
+        // Methods
+        static STPPerformanceCounters()
+        {
+            _instance = new STPPerformanceCounters();
+        }
+ 
+        private STPPerformanceCounters()
+        {
+            STPPerformanceCounter[] stpPerformanceCounters = new STPPerformanceCounter[] 
+                { 
+                    new STPPerformanceCounter("Active threads", "The current number of available in the thread pool.", PerformanceCounterType.NumberOfItems32), 
+                    new STPPerformanceCounter("In use threads", "The current number of threads that execute a work item.", PerformanceCounterType.NumberOfItems32), 
+                    new STPPerformanceCounter("Overhead threads", "The current number of threads that are active, but are not in use.", PerformanceCounterType.NumberOfItems32), 
+                    new STPPerformanceCounter("% overhead threads", "The current number of threads that are active, but are not in use in percents.", PerformanceCounterType.RawFraction), 
+                    new STPPerformanceCounter("% overhead threads base", "The current number of threads that are active, but are not in use in percents.", PerformanceCounterType.RawBase), 
+
+                    new STPPerformanceCounter("Work Items", "The number of work items in the Smart Thread Pool. Both queued and processed.", PerformanceCounterType.NumberOfItems32), 
+                    new STPPerformanceCounter("Work Items in queue", "The current number of work items in the queue", PerformanceCounterType.NumberOfItems32), 
+                    new STPPerformanceCounter("Work Items processed", "The number of work items already processed", PerformanceCounterType.NumberOfItems32), 
+
+                    new STPPerformanceCounter("Work Items queued/sec", "The number of work items queued per second", PerformanceCounterType.RateOfCountsPerSecond32), 
+                    new STPPerformanceCounter("Work Items processed/sec", "The number of work items processed per second", PerformanceCounterType.RateOfCountsPerSecond32), 
+
+                    new STPPerformanceCounter("Avg. Work Item wait time/sec", "The average time a work item supends in the queue waiting for its turn to execute.", PerformanceCounterType.AverageCount64), 
+                    new STPPerformanceCounter("Avg. Work Item wait time base", "The average time a work item supends in the queue waiting for its turn to execute.", PerformanceCounterType.AverageBase), 
+
+                    new STPPerformanceCounter("Avg. Work Item process time/sec", "The average time it takes to process a work item.", PerformanceCounterType.AverageCount64), 
+                    new STPPerformanceCounter("Avg. Work Item process time base", "The average time it takes to process a work item.", PerformanceCounterType.AverageBase), 
+
+                    new STPPerformanceCounter("Work Items Groups", "The current number of work item groups associated with the Smart Thread Pool.", PerformanceCounterType.NumberOfItems32), 
+                };
+
+            _stpPerformanceCounters = stpPerformanceCounters;
+            SetupCategory();
+        }
+ 
+        private void SetupCategory()
+        {
+            if (!PerformanceCounterCategory.Exists(_stpCategoryName))
+            {
+                CounterCreationDataCollection counters = new CounterCreationDataCollection();
+
+                for (int i = 0; i < _stpPerformanceCounters.Length; i++)
+                {
+                    _stpPerformanceCounters[i].AddCounterToCollection(counters);
+                }
+
+
+                // *********** Remark for .NET 2.0 ***********
+                // If you are here, it means you got the warning that this overload
+                // of the method is deprecated in .NET 2.0. To use the correct 
+                // method overload, uncomment the third argument of the method.
+                PerformanceCounterCategory.Create(
+                    _stpCategoryName, 
+                    _stpCategoryHelp, 
+                    //PerformanceCounterCategoryType.MultiInstance,
+                    counters);
+                    
+            }
+        }
+ 
+        // Properties
+        public static STPPerformanceCounters Instance
+        {
+            get
+            {
+                return _instance;
+            }
+        }
+     }
+
+    internal class STPInstancePerformanceCounter : IDisposable
+    {
+        // Fields
+        private PerformanceCounter _pcs;
+
+        // Methods
+        protected STPInstancePerformanceCounter()
+        {
+        }
+
+        public STPInstancePerformanceCounter(
+            string instance, 
+            STPPerformanceCounterType spcType)
+        {
+            STPPerformanceCounters counters = STPPerformanceCounters.Instance;
+            _pcs = new PerformanceCounter(
+                STPPerformanceCounters._stpCategoryName, 
+                counters._stpPerformanceCounters[(int) spcType].Name, 
+                instance, 
+                false);
+            _pcs.RawValue = _pcs.RawValue;
+        }
+
+        ~STPInstancePerformanceCounter()
+        {
+            Close();
+        }
+
+        public void Close()
+        {
+            if (_pcs != null)
+            {
+                _pcs.RemoveInstance();
+                _pcs.Close();
+                _pcs = null;
+            }
+        }
+ 
+        public void Dispose()
+        {
+            Close();
+            GC.SuppressFinalize(this);
+        }
+ 
+        public virtual void Increment()
+        {
+            _pcs.Increment();
+        }
+ 
+        public virtual void IncrementBy(long val)
+        {
+            _pcs.IncrementBy(val);
+        }
+
+        public virtual void Set(long val)
+        {
+            _pcs.RawValue = val;
+        }
+    }
+
+    internal class STPInstanceNullPerformanceCounter : STPInstancePerformanceCounter
+    {
+        // Methods
+        public STPInstanceNullPerformanceCounter() {}
+        public override void Increment() {}
+        public override void IncrementBy(long value) {}
+        public override void Set(long val) {}
+    }
+        
+    internal interface ISTPInstancePerformanceCounters : IDisposable
+    {
+        void Close();
+        void SampleThreads(long activeThreads, long inUseThreads);
+        void SampleWorkItems(long workItemsQueued, long workItemsProcessed);
+        void SampleWorkItemsWaitTime(TimeSpan workItemWaitTime);
+        void SampleWorkItemsProcessTime(TimeSpan workItemProcessTime);
+    }
+
+
+    internal class STPInstancePerformanceCounters : ISTPInstancePerformanceCounters, IDisposable
+    {
+        // Fields
+        private STPInstancePerformanceCounter[] _pcs;
+        private static STPInstancePerformanceCounter _stpInstanceNullPerformanceCounter;
+
+        // Methods
+        static STPInstancePerformanceCounters()
+        {
+            _stpInstanceNullPerformanceCounter = new STPInstanceNullPerformanceCounter();
+        }
+ 
+        public STPInstancePerformanceCounters(string instance)
+        {
+            _pcs = new STPInstancePerformanceCounter[(int)STPPerformanceCounterType.LastCounter];
+            STPPerformanceCounters counters = STPPerformanceCounters.Instance;
+            for (int i = 0; i < _pcs.Length; i++)
+            {
+                if (instance != null)
+                {
+                    _pcs[i] = new STPInstancePerformanceCounter(
+                        instance, 
+                        (STPPerformanceCounterType) i);
+                }
+                else
+                {
+                    _pcs[i] = _stpInstanceNullPerformanceCounter;
+                }
+            }
+        }
+ 
+
+        public void Close()
+        {
+            if (null != _pcs)
+            {
+                for (int i = 0; i < _pcs.Length; i++)
+                {
+                    if (null != _pcs[i])
+                    {
+                        _pcs[i].Close();
+                    }
+                }
+                _pcs = null;
+            }
+        }
+
+        ~STPInstancePerformanceCounters()
+        {
+            Close();
+        }
+
+        public void Dispose()
+        {
+            Close();
+            GC.SuppressFinalize(this);
+        }
+ 
+        private STPInstancePerformanceCounter GetCounter(STPPerformanceCounterType spcType)
+        {
+            return _pcs[(int) spcType];
+        }
+
+        public void SampleThreads(long activeThreads, long inUseThreads)
+        {
+            GetCounter(STPPerformanceCounterType.ActiveThreads).Set(activeThreads);
+            GetCounter(STPPerformanceCounterType.InUseThreads).Set(inUseThreads);
+            GetCounter(STPPerformanceCounterType.OverheadThreads).Set(activeThreads-inUseThreads);
+
+            GetCounter(STPPerformanceCounterType.OverheadThreadsPercentBase).Set(activeThreads-inUseThreads);
+            GetCounter(STPPerformanceCounterType.OverheadThreadsPercent).Set(inUseThreads);
+        }
+
+        public void SampleWorkItems(long workItemsQueued, long workItemsProcessed)
+        {
+            GetCounter(STPPerformanceCounterType.WorkItems).Set(workItemsQueued+workItemsProcessed);
+            GetCounter(STPPerformanceCounterType.WorkItemsInQueue).Set(workItemsQueued);
+            GetCounter(STPPerformanceCounterType.WorkItemsProcessed).Set(workItemsProcessed);
+
+            GetCounter(STPPerformanceCounterType.WorkItemsQueuedPerSecond).Set(workItemsQueued);
+            GetCounter(STPPerformanceCounterType.WorkItemsProcessedPerSecond).Set(workItemsProcessed);
+        }
+
+        public void SampleWorkItemsWaitTime(TimeSpan workItemWaitTime)
+        {
+            GetCounter(STPPerformanceCounterType.AvgWorkItemWaitTime).IncrementBy((long)workItemWaitTime.TotalMilliseconds);
+            GetCounter(STPPerformanceCounterType.AvgWorkItemWaitTimeBase).Increment();
+        }
+
+        public void SampleWorkItemsProcessTime(TimeSpan workItemProcessTime)
+        {
+            GetCounter(STPPerformanceCounterType.AvgWorkItemProcessTime).IncrementBy((long)workItemProcessTime.TotalMilliseconds);
+            GetCounter(STPPerformanceCounterType.AvgWorkItemProcessTimeBase).Increment();
+        }
+    }
+
+    internal class NullSTPInstancePerformanceCounters : ISTPInstancePerformanceCounters, IDisposable
+    {
+        static NullSTPInstancePerformanceCounters()
+        {
+        }
+
+        private static NullSTPInstancePerformanceCounters _instance = new NullSTPInstancePerformanceCounters(null);
+
+        public static NullSTPInstancePerformanceCounters Instance
+        {
+            get { return _instance; }
+        }
+
+        public NullSTPInstancePerformanceCounters(string instance) {}
+         public void Close() {}
+        public void Dispose() {}
+ 
+        public void SampleThreads(long activeThreads, long inUseThreads) {}
+        public void SampleWorkItems(long workItemsQueued, long workItemsProcessed) {}
+        public void SampleWorkItemsWaitTime(TimeSpan workItemWaitTime) {}
+        public void SampleWorkItemsProcessTime(TimeSpan workItemProcessTime) {}
+    }
+
+}

ThirdParty/SmartThreadPool/STPStartInfo.cs

@@ -0,0 +1,99 @@
+// Ami Bar
+// amibar@gmail.com
+
+using System.Threading;
+
+namespace Amib.Threading
+{
+    /// <summary>
+    /// Summary description for STPStartInfo.
+    /// </summary>
+    public class STPStartInfo : WIGStartInfo
+    {
+        /// <summary>
+        /// Idle timeout in milliseconds.
+        /// If a thread is idle for _idleTimeout milliseconds then 
+        /// it may quit.
+        /// </summary>
+        private int _idleTimeout;
+
+        /// <summary>
+        /// The lower limit of threads in the pool.
+        /// </summary>
+        private int _minWorkerThreads;
+
+        /// <summary>
+        /// The upper limit of threads in the pool.
+        /// </summary>
+        private int _maxWorkerThreads;
+
+        /// <summary>
+        /// The priority of the threads in the pool
+        /// </summary>
+        private ThreadPriority _threadPriority;
+
+        /// <summary>
+        /// If this field is not null then the performance counters are enabled
+        /// and use the string as the name of the instance.
+        /// </summary>
+        private string _pcInstanceName;
+
+        private int _stackSize;
+
+        public STPStartInfo() : base()
+        {
+            _idleTimeout = SmartThreadPool.DefaultIdleTimeout;
+            _minWorkerThreads = SmartThreadPool.DefaultMinWorkerThreads;
+            _maxWorkerThreads = SmartThreadPool.DefaultMaxWorkerThreads;
+            _threadPriority = SmartThreadPool.DefaultThreadPriority;
+            _pcInstanceName = SmartThreadPool.DefaultPerformanceCounterInstanceName;
+            _stackSize = SmartThreadPool.DefaultStackSize;
+        }
+
+        public STPStartInfo(STPStartInfo stpStartInfo) : base(stpStartInfo)
+        {
+            _idleTimeout = stpStartInfo._idleTimeout;
+            _minWorkerThreads = stpStartInfo._minWorkerThreads;
+            _maxWorkerThreads = stpStartInfo._maxWorkerThreads;
+            _threadPriority = stpStartInfo._threadPriority;
+            _pcInstanceName = stpStartInfo._pcInstanceName;
+            _stackSize = stpStartInfo._stackSize;
+        }
+
+        public int IdleTimeout
+        {
+            get { return _idleTimeout; }
+            set { _idleTimeout = value; }
+        }
+
+        public int MinWorkerThreads
+        {
+            get { return _minWorkerThreads; }
+            set { _minWorkerThreads = value; }
+        }
+
+        public int MaxWorkerThreads
+        {
+            get { return _maxWorkerThreads; }
+            set { _maxWorkerThreads = value; }
+        }
+
+        public ThreadPriority ThreadPriority
+        {
+            get { return _threadPriority; }
+            set { _threadPriority = value; }
+        }
+
+        public string PerformanceCounterInstanceName
+        {
+            get { return _pcInstanceName; }
+            set { _pcInstanceName = value; }
+        }
+
+        public int StackSize
+        {
+            get { return _stackSize; }
+            set { _stackSize = value; }
+        }
+    }
+}

ThirdParty/SmartThreadPool/WIGStartInfo.cs

@@ -0,0 +1,99 @@
+// Ami Bar
+// amibar@gmail.com
+
+namespace Amib.Threading
+{
+    /// <summary>
+    /// Summary description for WIGStartInfo.
+    /// </summary>
+    public class WIGStartInfo
+    {
+        /// <summary>
+        /// Use the caller's security context
+        /// </summary>
+        private bool _useCallerCallContext;
+
+        /// <summary>
+        /// Use the caller's HTTP context
+        /// </summary>
+        private bool _useCallerHttpContext;
+
+        /// <summary>
+        /// Dispose of the state object of a work item
+        /// </summary>
+        private bool _disposeOfStateObjects;
+
+        /// <summary>
+        /// The option to run the post execute
+        /// </summary>
+        private CallToPostExecute _callToPostExecute;
+
+        /// <summary>
+        /// A post execute callback to call when none is provided in 
+        /// the QueueWorkItem method.
+        /// </summary>
+        private PostExecuteWorkItemCallback _postExecuteWorkItemCallback;
+
+        /// <summary>
+        /// Indicate the WorkItemsGroup to suspend the handling of the work items
+        /// until the Start() method is called.
+        /// </summary>
+        private bool _startSuspended;
+
+        public WIGStartInfo()
+        {
+            _useCallerCallContext = SmartThreadPool.DefaultUseCallerCallContext;
+            _useCallerHttpContext = SmartThreadPool.DefaultUseCallerHttpContext;
+            _disposeOfStateObjects = SmartThreadPool.DefaultDisposeOfStateObjects;
+            _callToPostExecute = SmartThreadPool.DefaultCallToPostExecute;
+            _postExecuteWorkItemCallback = SmartThreadPool.DefaultPostExecuteWorkItemCallback;
+            _startSuspended = SmartThreadPool.DefaultStartSuspended;
+        }
+
+        public WIGStartInfo(WIGStartInfo wigStartInfo)
+        {
+            _useCallerCallContext = wigStartInfo._useCallerCallContext;
+            _useCallerHttpContext = wigStartInfo._useCallerHttpContext;
+            _disposeOfStateObjects = wigStartInfo._disposeOfStateObjects;
+            _callToPostExecute = wigStartInfo._callToPostExecute;
+            _postExecuteWorkItemCallback = wigStartInfo._postExecuteWorkItemCallback;
+            _startSuspended = wigStartInfo._startSuspended;
+        }
+
+        public bool UseCallerCallContext
+        {
+            get { return _useCallerCallContext; }
+            set { _useCallerCallContext = value; }
+        }
+
+        public bool UseCallerHttpContext
+        {
+            get { return _useCallerHttpContext; }
+            set { _useCallerHttpContext = value; }
+        }
+
+        public bool DisposeOfStateObjects
+        {
+            get { return _disposeOfStateObjects; }
+            set { _disposeOfStateObjects = value; }
+        }
+
+        public CallToPostExecute CallToPostExecute
+        {
+            get { return _callToPostExecute; }
+            set { _callToPostExecute = value; }
+        }
+
+        public PostExecuteWorkItemCallback PostExecuteWorkItemCallback
+        {
+            get { return _postExecuteWorkItemCallback; }
+            set { _postExecuteWorkItemCallback = value; }
+        }
+
+        public bool StartSuspended
+        {
+            get { return _startSuspended; }
+            set { _startSuspended = value; }
+        }
+    }
+}

ThirdParty/SmartThreadPool/WorkItemFactory.cs

@@ -0,0 +1,333 @@
+// Ami Bar
+// amibar@gmail.com
+
+using System;
+
+namespace Amib.Threading.Internal
+{
+    #region WorkItemFactory class 
+
+    public class WorkItemFactory
+    {
+        /// <summary>
+        /// Create a new work item
+        /// </summary>
+        /// <param name="wigStartInfo">Work item group start information</param>
+        /// <param name="callback">A callback to execute</param>
+        /// <returns>Returns a work item</returns>
+        public static WorkItem CreateWorkItem(
+            IWorkItemsGroup workItemsGroup,
+            WIGStartInfo wigStartInfo,
+            WorkItemCallback callback)
+        {
+            return CreateWorkItem(workItemsGroup, wigStartInfo, callback, null);
+        }
+
+        /// <summary>
+        /// Create a new work item
+        /// </summary>
+        /// <param name="wigStartInfo">Work item group start information</param>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="workItemPriority">The priority of the work item</param>
+        /// <returns>Returns a work item</returns>
+        public static WorkItem CreateWorkItem(
+            IWorkItemsGroup workItemsGroup,
+            WIGStartInfo wigStartInfo,
+            WorkItemCallback callback, 
+            WorkItemPriority workItemPriority)
+        {
+            return CreateWorkItem(workItemsGroup, wigStartInfo, callback, null, workItemPriority);
+        }
+
+        /// <summary>
+        /// Create a new work item
+        /// </summary>
+        /// <param name="wigStartInfo">Work item group start information</param>
+        /// <param name="workItemInfo">Work item info</param>
+        /// <param name="callback">A callback to execute</param>
+        /// <returns>Returns a work item</returns>
+        public static WorkItem CreateWorkItem(
+            IWorkItemsGroup workItemsGroup,
+            WIGStartInfo wigStartInfo,
+            WorkItemInfo workItemInfo, 
+            WorkItemCallback callback)
+        {
+            return CreateWorkItem(
+                workItemsGroup,
+                wigStartInfo,
+                workItemInfo, 
+                callback, 
+                null);
+        }
+
+        /// <summary>
+        /// Create a new work item
+        /// </summary>
+        /// <param name="wigStartInfo">Work item group start information</param>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <returns>Returns a work item</returns>
+        public static WorkItem CreateWorkItem(
+            IWorkItemsGroup workItemsGroup,
+            WIGStartInfo wigStartInfo,
+            WorkItemCallback callback, 
+            object state)
+        {
+            ValidateCallback(callback);
+
+            WorkItemInfo workItemInfo = new WorkItemInfo();
+            workItemInfo.UseCallerCallContext = wigStartInfo.UseCallerCallContext;
+            workItemInfo.UseCallerHttpContext = wigStartInfo.UseCallerHttpContext;
+            workItemInfo.PostExecuteWorkItemCallback = wigStartInfo.PostExecuteWorkItemCallback;
+            workItemInfo.CallToPostExecute = wigStartInfo.CallToPostExecute;
+            workItemInfo.DisposeOfStateObjects = wigStartInfo.DisposeOfStateObjects;
+
+            WorkItem workItem = new WorkItem(
+                workItemsGroup,
+                workItemInfo,
+                callback, 
+                state);
+            return workItem;
+        }
+
+        /// <summary>
+        /// Create a new work item
+        /// </summary>
+        /// <param name="wigStartInfo">Work item group start information</param>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <param name="workItemPriority">The work item priority</param>
+        /// <returns>Returns a work item</returns>
+        public static WorkItem CreateWorkItem(
+            IWorkItemsGroup workItemsGroup,
+            WIGStartInfo wigStartInfo,
+            WorkItemCallback callback, 
+            object state, 
+            WorkItemPriority workItemPriority)
+        {
+            ValidateCallback(callback);
+
+            WorkItemInfo workItemInfo = new WorkItemInfo();
+            workItemInfo.UseCallerCallContext = wigStartInfo.UseCallerCallContext;
+            workItemInfo.UseCallerHttpContext = wigStartInfo.UseCallerHttpContext;
+            workItemInfo.PostExecuteWorkItemCallback = wigStartInfo.PostExecuteWorkItemCallback;
+            workItemInfo.CallToPostExecute = wigStartInfo.CallToPostExecute;
+            workItemInfo.DisposeOfStateObjects = wigStartInfo.DisposeOfStateObjects;
+            workItemInfo.WorkItemPriority = workItemPriority;
+
+            WorkItem workItem = new WorkItem(
+                workItemsGroup,
+                workItemInfo,
+                callback, 
+                state);
+
+            return workItem;
+        }
+
+        /// <summary>
+        /// Create a new work item
+        /// </summary>
+        /// <param name="wigStartInfo">Work item group start information</param>
+        /// <param name="workItemInfo">Work item information</param>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <returns>Returns a work item</returns>
+        public static WorkItem CreateWorkItem(
+            IWorkItemsGroup workItemsGroup,
+            WIGStartInfo wigStartInfo,
+            WorkItemInfo workItemInfo, 
+            WorkItemCallback callback, 
+            object state)
+        {
+            ValidateCallback(callback);
+            ValidateCallback(workItemInfo.PostExecuteWorkItemCallback);
+
+            WorkItem workItem = new WorkItem(
+                workItemsGroup,
+                new WorkItemInfo(workItemInfo),
+                callback, 
+                state);
+
+            return workItem;
+        }
+
+        /// <summary>
+        /// Create a new work item
+        /// </summary>
+        /// <param name="wigStartInfo">Work item group start information</param>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <param name="postExecuteWorkItemCallback">
+        /// A delegate to call after the callback completion
+        /// </param>
+        /// <returns>Returns a work item</returns>
+        public static WorkItem CreateWorkItem(
+            IWorkItemsGroup workItemsGroup,
+            WIGStartInfo wigStartInfo,
+            WorkItemCallback callback, 
+            object state,
+            PostExecuteWorkItemCallback postExecuteWorkItemCallback)
+        {
+            ValidateCallback(callback);
+            ValidateCallback(postExecuteWorkItemCallback);
+
+            WorkItemInfo workItemInfo = new WorkItemInfo();
+            workItemInfo.UseCallerCallContext = wigStartInfo.UseCallerCallContext;
+            workItemInfo.UseCallerHttpContext = wigStartInfo.UseCallerHttpContext;
+            workItemInfo.PostExecuteWorkItemCallback = postExecuteWorkItemCallback;
+            workItemInfo.CallToPostExecute = wigStartInfo.CallToPostExecute;
+            workItemInfo.DisposeOfStateObjects = wigStartInfo.DisposeOfStateObjects;
+
+            WorkItem workItem = new WorkItem(
+                workItemsGroup,
+                workItemInfo,
+                callback, 
+                state);
+
+            return workItem;
+        }
+
+        /// <summary>
+        /// Create a new work item
+        /// </summary>
+        /// <param name="wigStartInfo">Work item group start information</param>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <param name="postExecuteWorkItemCallback">
+        /// A delegate to call after the callback completion
+        /// </param>
+        /// <param name="workItemPriority">The work item priority</param>
+        /// <returns>Returns a work item</returns>
+        public static WorkItem CreateWorkItem(
+            IWorkItemsGroup workItemsGroup,
+            WIGStartInfo wigStartInfo,
+            WorkItemCallback callback, 
+            object state,
+            PostExecuteWorkItemCallback postExecuteWorkItemCallback,
+            WorkItemPriority workItemPriority)
+        {
+            ValidateCallback(callback);
+            ValidateCallback(postExecuteWorkItemCallback);
+
+            WorkItemInfo workItemInfo = new WorkItemInfo();
+            workItemInfo.UseCallerCallContext = wigStartInfo.UseCallerCallContext;
+            workItemInfo.UseCallerHttpContext = wigStartInfo.UseCallerHttpContext;
+            workItemInfo.PostExecuteWorkItemCallback = postExecuteWorkItemCallback;
+            workItemInfo.CallToPostExecute = wigStartInfo.CallToPostExecute;
+            workItemInfo.DisposeOfStateObjects = wigStartInfo.DisposeOfStateObjects;
+            workItemInfo.WorkItemPriority = workItemPriority;
+
+            WorkItem workItem = new WorkItem(
+                workItemsGroup,
+                workItemInfo,
+                callback, 
+                state);
+
+            return workItem;
+        }
+
+        /// <summary>
+        /// Create a new work item
+        /// </summary>
+        /// <param name="wigStartInfo">Work item group start information</param>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <param name="postExecuteWorkItemCallback">
+        /// A delegate to call after the callback completion
+        /// </param>
+        /// <param name="callToPostExecute">Indicates on which cases to call to the post execute callback</param>
+        /// <returns>Returns a work item</returns>
+        public static WorkItem CreateWorkItem(
+            IWorkItemsGroup workItemsGroup,
+            WIGStartInfo wigStartInfo,
+            WorkItemCallback callback, 
+            object state,
+            PostExecuteWorkItemCallback postExecuteWorkItemCallback,
+            CallToPostExecute callToPostExecute)
+        {
+            ValidateCallback(callback);
+            ValidateCallback(postExecuteWorkItemCallback);
+
+            WorkItemInfo workItemInfo = new WorkItemInfo();
+            workItemInfo.UseCallerCallContext = wigStartInfo.UseCallerCallContext;
+            workItemInfo.UseCallerHttpContext = wigStartInfo.UseCallerHttpContext;
+            workItemInfo.PostExecuteWorkItemCallback = postExecuteWorkItemCallback;
+            workItemInfo.CallToPostExecute = callToPostExecute;
+            workItemInfo.DisposeOfStateObjects = wigStartInfo.DisposeOfStateObjects;
+
+            WorkItem workItem = new WorkItem(
+                workItemsGroup,
+                workItemInfo,
+                callback, 
+                state);
+
+            return workItem;
+        }
+
+        /// <summary>
+        /// Create a new work item
+        /// </summary>
+        /// <param name="wigStartInfo">Work item group start information</param>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <param name="postExecuteWorkItemCallback">
+        /// A delegate to call after the callback completion
+        /// </param>
+        /// <param name="callToPostExecute">Indicates on which cases to call to the post execute callback</param>
+        /// <param name="workItemPriority">The work item priority</param>
+        /// <returns>Returns a work item</returns>
+        public static WorkItem CreateWorkItem(
+            IWorkItemsGroup workItemsGroup,
+            WIGStartInfo wigStartInfo,
+            WorkItemCallback callback, 
+            object state,
+            PostExecuteWorkItemCallback postExecuteWorkItemCallback,
+            CallToPostExecute callToPostExecute,
+            WorkItemPriority workItemPriority)
+        {
+
+            ValidateCallback(callback);
+            ValidateCallback(postExecuteWorkItemCallback);
+
+            WorkItemInfo workItemInfo = new WorkItemInfo();
+            workItemInfo.UseCallerCallContext = wigStartInfo.UseCallerCallContext;
+            workItemInfo.UseCallerHttpContext = wigStartInfo.UseCallerHttpContext;
+            workItemInfo.PostExecuteWorkItemCallback = postExecuteWorkItemCallback;
+            workItemInfo.CallToPostExecute = callToPostExecute;
+            workItemInfo.WorkItemPriority = workItemPriority;
+            workItemInfo.DisposeOfStateObjects = wigStartInfo.DisposeOfStateObjects;
+
+            WorkItem workItem = new WorkItem(
+                workItemsGroup,
+                workItemInfo,
+                callback, 
+                state);
+            
+            return workItem;
+        }
+
+        private static void ValidateCallback(Delegate callback)
+        {
+            if(callback.GetInvocationList().Length > 1)
+            {
+                throw new NotSupportedException("SmartThreadPool doesn't support delegates chains");
+            }
+        }
+    }
+
+    #endregion
+}

ThirdParty/SmartThreadPool/WorkItemInfo.cs

@@ -0,0 +1,102 @@
+// Ami Bar
+// amibar@gmail.com
+
+namespace Amib.Threading
+{
+    #region WorkItemInfo class
+
+    /// <summary>
+    /// Summary description for WorkItemInfo.
+    /// </summary>
+    public class WorkItemInfo
+    {
+        /// <summary>
+        /// Use the caller's security context
+        /// </summary>
+        private bool _useCallerCallContext;
+
+        /// <summary>
+        /// Use the caller's security context
+        /// </summary>
+        private bool _useCallerHttpContext;
+
+        /// <summary>
+        /// Dispose of the state object of a work item
+        /// </summary>
+        private bool _disposeOfStateObjects;
+
+        /// <summary>
+        /// The option to run the post execute
+        /// </summary>
+        private CallToPostExecute _callToPostExecute;
+
+        /// <summary>
+        /// A post execute callback to call when none is provided in 
+        /// the QueueWorkItem method.
+        /// </summary>
+        private PostExecuteWorkItemCallback _postExecuteWorkItemCallback;
+        
+        /// <summary>
+        /// The priority of the work item
+        /// </summary>
+        private WorkItemPriority _workItemPriority;
+
+        public WorkItemInfo()
+        {
+            _useCallerCallContext = SmartThreadPool.DefaultUseCallerCallContext;
+            _useCallerHttpContext = SmartThreadPool.DefaultUseCallerHttpContext;
+            _disposeOfStateObjects = SmartThreadPool.DefaultDisposeOfStateObjects;
+            _callToPostExecute = SmartThreadPool.DefaultCallToPostExecute;
+            _postExecuteWorkItemCallback = SmartThreadPool.DefaultPostExecuteWorkItemCallback;
+            _workItemPriority = SmartThreadPool.DefaultWorkItemPriority;
+        }
+
+        public WorkItemInfo(WorkItemInfo workItemInfo)
+        {
+            _useCallerCallContext = workItemInfo._useCallerCallContext;
+            _useCallerHttpContext = workItemInfo._useCallerHttpContext;
+            _disposeOfStateObjects = workItemInfo._disposeOfStateObjects;
+            _callToPostExecute = workItemInfo._callToPostExecute;
+            _postExecuteWorkItemCallback = workItemInfo._postExecuteWorkItemCallback;
+            _workItemPriority = workItemInfo._workItemPriority;
+        }
+
+        public bool UseCallerCallContext
+        {
+            get { return _useCallerCallContext; }
+            set { _useCallerCallContext = value; }
+        }
+
+        public bool UseCallerHttpContext
+        {
+            get { return _useCallerHttpContext; }
+            set { _useCallerHttpContext = value; }
+        }
+
+        public bool DisposeOfStateObjects
+        {
+            get { return _disposeOfStateObjects; }
+            set { _disposeOfStateObjects = value; }
+        }
+
+        public CallToPostExecute CallToPostExecute
+        {
+            get { return _callToPostExecute; }
+            set { _callToPostExecute = value; }
+        }
+
+        public PostExecuteWorkItemCallback PostExecuteWorkItemCallback
+        {
+            get { return _postExecuteWorkItemCallback; }
+            set { _postExecuteWorkItemCallback = value; }
+        }
+
+        public WorkItemPriority WorkItemPriority
+        {
+            get { return _workItemPriority; }
+            set { _workItemPriority = value; }
+        }
+    }
+
+    #endregion
+}

ThirdParty/SmartThreadPool/WorkItemsGroup.cs

@@ -0,0 +1,512 @@
+// Ami Bar
+// amibar@gmail.com
+
+using System;
+using System.Threading;
+using System.Runtime.CompilerServices;
+using System.Diagnostics;
+
+namespace Amib.Threading.Internal
+{
+    #region WorkItemsGroup class 
+
+    /// <summary>
+    /// Summary description for WorkItemsGroup.
+    /// </summary>
+    public class WorkItemsGroup : IWorkItemsGroup
+    {
+        #region Private members
+
+        private object _lock = new object();
+        /// <summary>
+        /// Contains the name of this instance of SmartThreadPool.
+        /// Can be changed by the user.
+        /// </summary>
+        private string _name = "WorkItemsGroup";
+
+        /// <summary>
+        /// A reference to the SmartThreadPool instance that created this 
+        /// WorkItemsGroup.
+        /// </summary>
+        private SmartThreadPool _stp;
+
+        /// <summary>
+        /// The OnIdle event
+        /// </summary>
+        private event WorkItemsGroupIdleHandler _onIdle;
+
+        /// <summary>
+        /// Defines how many work items of this WorkItemsGroup can run at once.
+        /// </summary>
+        private int _concurrency;
+
+        /// <summary>
+        /// Priority queue to hold work items before they are passed 
+        /// to the SmartThreadPool.
+        /// </summary>
+        private PriorityQueue _workItemsQueue;
+
+        /// <summary>
+        /// Indicate how many work items are waiting in the SmartThreadPool
+        /// queue.
+        /// This value is used to apply the concurrency.
+        /// </summary>
+        private int _workItemsInStpQueue;
+
+        /// <summary>
+        /// Indicate how many work items are currently running in the SmartThreadPool.
+        /// This value is used with the Cancel, to calculate if we can send new 
+        /// work items to the STP.
+        /// </summary>
+        private int _workItemsExecutingInStp = 0;
+
+        /// <summary>
+        /// WorkItemsGroup start information
+        /// </summary>
+        private WIGStartInfo _workItemsGroupStartInfo;
+
+        /// <summary>
+        /// Signaled when all of the WorkItemsGroup's work item completed.
+        /// </summary>
+        private ManualResetEvent _isIdleWaitHandle = new ManualResetEvent(true);
+
+        /// <summary>
+        /// A common object for all the work items that this work items group
+        /// generate so we can mark them to cancel in O(1)
+        /// </summary>
+        private CanceledWorkItemsGroup _canceledWorkItemsGroup = new CanceledWorkItemsGroup();
+
+        #endregion 
+
+        #region Construction
+
+        public WorkItemsGroup(
+            SmartThreadPool stp, 
+            int concurrency, 
+            WIGStartInfo wigStartInfo)
+        {
+            if (concurrency <= 0)
+            {
+                throw new ArgumentOutOfRangeException("concurrency", concurrency, "concurrency must be greater than zero");
+            }
+            _stp = stp;
+            _concurrency = concurrency;
+            _workItemsGroupStartInfo = new WIGStartInfo(wigStartInfo);
+            _workItemsQueue = new PriorityQueue();
+
+            // The _workItemsInStpQueue gets the number of currently executing work items,
+            // because once a work item is executing, it cannot be cancelled.
+            _workItemsInStpQueue = _workItemsExecutingInStp;
+        }
+
+        #endregion 
+
+        #region IWorkItemsGroup implementation
+
+        /// <summary>
+        /// Get/Set the name of the SmartThreadPool instance
+        /// </summary>
+        public string Name 
+        { 
+            get
+            {
+                return _name;
+            }
+
+            set
+            {
+                _name = value;
+            }
+        }
+
+        /// <summary>
+        /// Queue a work item
+        /// </summary>
+        /// <param name="callback">A callback to execute</param>
+        /// <returns>Returns a work item result</returns>
+        public IWorkItemResult QueueWorkItem(WorkItemCallback callback)
+        {
+            WorkItem workItem = WorkItemFactory.CreateWorkItem(this, _workItemsGroupStartInfo, callback);
+            EnqueueToSTPNextWorkItem(workItem);
+            return workItem.GetWorkItemResult();
+        }
+
+        /// <summary>
+        /// Queue a work item
+        /// </summary>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="workItemPriority">The priority of the work item</param>
+        /// <returns>Returns a work item result</returns>
+        public IWorkItemResult QueueWorkItem(WorkItemCallback callback, WorkItemPriority workItemPriority)
+        {
+            WorkItem workItem = WorkItemFactory.CreateWorkItem(this, _workItemsGroupStartInfo, callback, workItemPriority);
+            EnqueueToSTPNextWorkItem(workItem);
+            return workItem.GetWorkItemResult();
+        }
+
+        /// <summary>
+        /// Queue a work item
+        /// </summary>
+        /// <param name="workItemInfo">Work item info</param>
+        /// <param name="callback">A callback to execute</param>
+        /// <returns>Returns a work item result</returns>
+        public IWorkItemResult QueueWorkItem(WorkItemInfo workItemInfo, WorkItemCallback callback)
+        {
+            WorkItem workItem = WorkItemFactory.CreateWorkItem(this, _workItemsGroupStartInfo, workItemInfo, callback);
+            EnqueueToSTPNextWorkItem(workItem);
+            return workItem.GetWorkItemResult();
+        }
+
+        /// <summary>
+        /// Queue a work item
+        /// </summary>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <returns>Returns a work item result</returns>
+        public IWorkItemResult QueueWorkItem(WorkItemCallback callback, object state)
+        {
+            WorkItem workItem = WorkItemFactory.CreateWorkItem(this, _workItemsGroupStartInfo, callback, state);
+            EnqueueToSTPNextWorkItem(workItem);
+            return workItem.GetWorkItemResult();
+        }
+
+        /// <summary>
+        /// Queue a work item
+        /// </summary>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <param name="workItemPriority">The work item priority</param>
+        /// <returns>Returns a work item result</returns>
+        public IWorkItemResult QueueWorkItem(WorkItemCallback callback, object state, WorkItemPriority workItemPriority)
+        {
+            WorkItem workItem = WorkItemFactory.CreateWorkItem(this, _workItemsGroupStartInfo, callback, state, workItemPriority);
+            EnqueueToSTPNextWorkItem(workItem);
+            return workItem.GetWorkItemResult();
+        }
+
+        /// <summary>
+        /// Queue a work item
+        /// </summary>
+        /// <param name="workItemInfo">Work item information</param>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <returns>Returns a work item result</returns>
+        public IWorkItemResult QueueWorkItem(WorkItemInfo workItemInfo, WorkItemCallback callback, object state)
+        {
+            WorkItem workItem = WorkItemFactory.CreateWorkItem(this, _workItemsGroupStartInfo, workItemInfo, callback, state);
+            EnqueueToSTPNextWorkItem(workItem);
+            return workItem.GetWorkItemResult();
+        }
+
+        /// <summary>
+        /// Queue a work item
+        /// </summary>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <param name="postExecuteWorkItemCallback">
+        /// A delegate to call after the callback completion
+        /// </param>
+        /// <returns>Returns a work item result</returns>
+        public IWorkItemResult QueueWorkItem(
+            WorkItemCallback callback, 
+            object state,
+            PostExecuteWorkItemCallback postExecuteWorkItemCallback)
+        {
+            WorkItem workItem = WorkItemFactory.CreateWorkItem(this, _workItemsGroupStartInfo, callback, state, postExecuteWorkItemCallback);
+            EnqueueToSTPNextWorkItem(workItem);
+            return workItem.GetWorkItemResult();
+        }
+
+        /// <summary>
+        /// Queue a work item
+        /// </summary>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <param name="postExecuteWorkItemCallback">
+        /// A delegate to call after the callback completion
+        /// </param>
+        /// <param name="workItemPriority">The work item priority</param>
+        /// <returns>Returns a work item result</returns>
+        public IWorkItemResult QueueWorkItem(
+            WorkItemCallback callback, 
+            object state,
+            PostExecuteWorkItemCallback postExecuteWorkItemCallback,
+            WorkItemPriority workItemPriority)
+        {
+            WorkItem workItem = WorkItemFactory.CreateWorkItem(this, _workItemsGroupStartInfo, callback, state, postExecuteWorkItemCallback, workItemPriority);
+            EnqueueToSTPNextWorkItem(workItem);
+            return workItem.GetWorkItemResult();
+        }
+
+        /// <summary>
+        /// Queue a work item
+        /// </summary>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <param name="postExecuteWorkItemCallback">
+        /// A delegate to call after the callback completion
+        /// </param>
+        /// <param name="callToPostExecute">Indicates on which cases to call to the post execute callback</param>
+        /// <returns>Returns a work item result</returns>
+        public IWorkItemResult QueueWorkItem(
+            WorkItemCallback callback, 
+            object state,
+            PostExecuteWorkItemCallback postExecuteWorkItemCallback,
+            CallToPostExecute callToPostExecute)
+        {
+            WorkItem workItem = WorkItemFactory.CreateWorkItem(this, _workItemsGroupStartInfo, callback, state, postExecuteWorkItemCallback, callToPostExecute);
+            EnqueueToSTPNextWorkItem(workItem);
+            return workItem.GetWorkItemResult();
+        }
+
+        /// <summary>
+        /// Queue a work item
+        /// </summary>
+        /// <param name="callback">A callback to execute</param>
+        /// <param name="state">
+        /// The context object of the work item. Used for passing arguments to the work item. 
+        /// </param>
+        /// <param name="postExecuteWorkItemCallback">
+        /// A delegate to call after the callback completion
+        /// </param>
+        /// <param name="callToPostExecute">Indicates on which cases to call to the post execute callback</param>
+        /// <param name="workItemPriority">The work item priority</param>
+        /// <returns>Returns a work item result</returns>
+        public IWorkItemResult QueueWorkItem(
+            WorkItemCallback callback, 
+            object state,
+            PostExecuteWorkItemCallback postExecuteWorkItemCallback,
+            CallToPostExecute callToPostExecute,
+            WorkItemPriority workItemPriority)
+        {
+            WorkItem workItem = WorkItemFactory.CreateWorkItem(this, _workItemsGroupStartInfo, callback, state, postExecuteWorkItemCallback, callToPostExecute, workItemPriority);
+            EnqueueToSTPNextWorkItem(workItem);
+            return workItem.GetWorkItemResult();
+        }
+
+        /// <summary>
+        /// Wait for the thread pool to be idle
+        /// </summary>
+        public void WaitForIdle()
+        {
+            WaitForIdle(Timeout.Infinite);
+        }
+
+        /// <summary>
+        /// Wait for the thread pool to be idle
+        /// </summary>
+        public bool WaitForIdle(TimeSpan timeout)
+        {
+            return WaitForIdle((int)timeout.TotalMilliseconds);
+        }
+
+        /// <summary>
+        /// Wait for the thread pool to be idle
+        /// </summary>
+        public bool WaitForIdle(int millisecondsTimeout)
+        {
+            _stp.ValidateWorkItemsGroupWaitForIdle(this);
+            return _isIdleWaitHandle.WaitOne(millisecondsTimeout, false);
+        }
+
+        public int WaitingCallbacks
+        {
+            get
+            {
+                return _workItemsQueue.Count;
+            }
+        }
+
+        public event WorkItemsGroupIdleHandler OnIdle
+        {
+            add
+            {
+                _onIdle += value;
+            }
+            remove
+            {
+                _onIdle -= value;
+            }
+        }
+
+        public void Cancel()
+        {
+            lock(_lock)
+            {
+                _canceledWorkItemsGroup.IsCanceled = true;
+                _workItemsQueue.Clear();
+                _workItemsInStpQueue = 0;
+                _canceledWorkItemsGroup = new CanceledWorkItemsGroup();
+            }
+        }
+
+        public void Start()
+        {
+            lock (this)
+            {
+                if (!_workItemsGroupStartInfo.StartSuspended)
+                {
+                    return;
+                }
+                _workItemsGroupStartInfo.StartSuspended = false;
+            }
+            
+            for(int i = 0; i < _concurrency; ++i)
+            {
+                EnqueueToSTPNextWorkItem(null, false);
+            }
+        }
+
+        #endregion 
+
+        #region Private methods
+
+        private void RegisterToWorkItemCompletion(IWorkItemResult wir)
+        {
+            IInternalWorkItemResult iwir = wir as IInternalWorkItemResult;
+            iwir.OnWorkItemStarted += new WorkItemStateCallback(OnWorkItemStartedCallback);
+            iwir.OnWorkItemCompleted += new WorkItemStateCallback(OnWorkItemCompletedCallback);
+        }
+
+        public void OnSTPIsStarting()
+        {
+            lock (this)
+            {
+                if (_workItemsGroupStartInfo.StartSuspended)
+                {
+                    return;
+                }
+            }
+            
+            for(int i = 0; i < _concurrency; ++i)
+            {
+                EnqueueToSTPNextWorkItem(null, false);
+            }
+        }
+
+        private object FireOnIdle(object state)
+        {
+            FireOnIdleImpl(_onIdle);
+            return null;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private void FireOnIdleImpl(WorkItemsGroupIdleHandler onIdle)
+        {
+            if(null == onIdle)
+            {
+                return;
+            }
+
+            Delegate[] delegates = onIdle.GetInvocationList();
+            foreach(WorkItemsGroupIdleHandler eh in delegates)
+            {
+                try
+                {
+                    eh(this);
+                }
+                    // Ignore exceptions
+                catch{} 
+            }
+        }
+
+        private void OnWorkItemStartedCallback(WorkItem workItem)
+        {
+            lock(_lock)
+            {
+                ++_workItemsExecutingInStp;
+            }
+        }
+
+        private void OnWorkItemCompletedCallback(WorkItem workItem)
+        {
+            EnqueueToSTPNextWorkItem(null, true);
+        }
+
+        private void EnqueueToSTPNextWorkItem(WorkItem workItem)
+        {
+            EnqueueToSTPNextWorkItem(workItem, false);
+        }
+
+        private void EnqueueToSTPNextWorkItem(WorkItem workItem, bool decrementWorkItemsInStpQueue)
+        {
+            lock(_lock)
+            {
+                // Got here from OnWorkItemCompletedCallback()
+                if (decrementWorkItemsInStpQueue)
+                {
+                    --_workItemsInStpQueue;
+
+                    if(_workItemsInStpQueue < 0)
+                    {
+                        _workItemsInStpQueue = 0;
+                    }
+
+                    --_workItemsExecutingInStp;
+
+                    if(_workItemsExecutingInStp < 0)
+                    {
+                        _workItemsExecutingInStp = 0;
+                    }
+                }
+
+                // If the work item is not null then enqueue it
+                if (null != workItem)
+                {
+                    workItem.CanceledWorkItemsGroup = _canceledWorkItemsGroup;
+
+                    RegisterToWorkItemCompletion(workItem.GetWorkItemResult());
+                    _workItemsQueue.Enqueue(workItem);
+                    //_stp.IncrementWorkItemsCount();
+
+                    if ((1 == _workItemsQueue.Count) && 
+                        (0 == _workItemsInStpQueue))
+                    {
+                        _stp.RegisterWorkItemsGroup(this);
+                        Trace.WriteLine("WorkItemsGroup " + Name + " is NOT idle");
+                        _isIdleWaitHandle.Reset();
+                    }
+                }
+
+                // If the work items queue of the group is empty than quit
+                if (0 == _workItemsQueue.Count)
+                {
+                    if (0 == _workItemsInStpQueue)
+                    {
+                        _stp.UnregisterWorkItemsGroup(this);
+                        Trace.WriteLine("WorkItemsGroup " + Name + " is idle");
+                        _isIdleWaitHandle.Set();
+                        _stp.QueueWorkItem(new WorkItemCallback(this.FireOnIdle));
+                    }
+                    return;
+                }
+
+                if (!_workItemsGroupStartInfo.StartSuspended)
+                {
+                    if (_workItemsInStpQueue < _concurrency)
+                    {
+                        WorkItem nextWorkItem = _workItemsQueue.Dequeue() as WorkItem;
+                        _stp.Enqueue(nextWorkItem, true);
+                        ++_workItemsInStpQueue;
+                    }
+                }
+            }
+        }
+
+        #endregion
+    }
+
+    #endregion
+}

ThirdParty/SmartThreadPool/WorkItemsQueue.cs

@@ -0,0 +1,600 @@
+// Ami Bar
+// amibar@gmail.com
+
+using System;
+using System.Threading;
+
+namespace Amib.Threading.Internal
+{
+    #region WorkItemsQueue class
+
+    /// <summary>
+    /// WorkItemsQueue class.
+    /// </summary>
+    public class WorkItemsQueue : IDisposable
+    {
+        #region Member variables
+
+        /// <summary>
+        /// Waiters queue (implemented as stack).
+        /// </summary>
+        private WaiterEntry _headWaiterEntry = new WaiterEntry();
+
+        /// <summary>
+        /// Waiters count
+        /// </summary>
+        private int _waitersCount = 0;
+
+        /// <summary>
+        /// Work items queue
+        /// </summary>
+        private PriorityQueue _workItems = new PriorityQueue();
+
+        /// <summary>
+        /// Indicate that work items are allowed to be queued
+        /// </summary>
+        private bool _isWorkItemsQueueActive = true;
+
+        /// <summary>
+        /// Each thread in the thread pool keeps its own waiter entry.
+        /// </summary>
+        [ThreadStatic]
+        private static WaiterEntry _waiterEntry;
+
+        /// <summary>
+        /// A flag that indicates if the WorkItemsQueue has been disposed.
+        /// </summary>
+        private bool _isDisposed = false;
+
+        #endregion
+
+        #region Public properties
+
+        /// <summary>
+        /// Returns the current number of work items in the queue
+        /// </summary>
+        public int Count
+        {
+            get
+            {
+                lock(this)
+                {
+                    ValidateNotDisposed();
+                    return _workItems.Count;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Returns the current number of waiters
+        /// </summary>
+        public int WaitersCount
+        {
+            get
+            {
+                lock(this)
+                {
+                    ValidateNotDisposed();
+                    return _waitersCount;
+                }
+            }
+        }
+
+
+        #endregion
+
+        #region Public methods
+
+        /// <summary>
+        /// Enqueue a work item to the queue.
+        /// </summary>
+        public bool EnqueueWorkItem(WorkItem workItem)
+        {
+            // A work item cannot be null, since null is used in the
+            // WaitForWorkItem() method to indicate timeout or cancel
+            if (null == workItem)
+            {
+                throw new ArgumentNullException("workItem" , "workItem cannot be null");
+            }
+
+            bool enqueue = true;
+
+            // First check if there is a waiter waiting for work item. During 
+            // the check, timed out waiters are ignored. If there is no 
+            // waiter then the work item is queued.
+            lock(this)
+            {
+                ValidateNotDisposed();
+
+                if (!_isWorkItemsQueueActive)
+                {
+                    return false;
+                }
+
+                while(_waitersCount > 0)
+                {
+                    // Dequeue a waiter.
+                    WaiterEntry waiterEntry = PopWaiter();
+
+                    // Signal the waiter. On success break the loop
+                    if (waiterEntry.Signal(workItem))
+                    {
+                        enqueue = false;
+                        break;
+                    }
+                }
+
+                if (enqueue)
+                {
+                    // Enqueue the work item
+                    _workItems.Enqueue(workItem);
+                }
+            }
+            return true;
+        }
+
+
+        /// <summary>
+        /// Waits for a work item or exits on timeout or cancel
+        /// </summary>
+        /// <param name="millisecondsTimeout">Timeout in milliseconds</param>
+        /// <param name="cancelEvent">Cancel wait handle</param>
+        /// <returns>Returns true if the resource was granted</returns>
+        public WorkItem DequeueWorkItem(
+            int millisecondsTimeout, 
+            WaitHandle cancelEvent)
+        {
+            /// This method cause the caller to wait for a work item.
+            /// If there is at least one waiting work item then the 
+            /// method returns immidiately with true.
+            /// 
+            /// If there are no waiting work items then the caller 
+            /// is queued between other waiters for a work item to arrive.
+            /// 
+            /// If a work item didn't come within millisecondsTimeout or 
+            /// the user canceled the wait by signaling the cancelEvent 
+            /// then the method returns false to indicate that the caller 
+            /// didn't get a work item.
+
+            WaiterEntry waiterEntry = null;
+            WorkItem workItem = null;
+
+            lock(this)
+            {
+                ValidateNotDisposed();
+
+                // If there are waiting work items then take one and return.
+                if (_workItems.Count > 0)
+                {
+                    workItem = _workItems.Dequeue() as WorkItem;
+                    return workItem;
+                }
+                    // No waiting work items ...
+                else
+                {
+                    // Get the wait entry for the waiters queue
+                    waiterEntry = GetThreadWaiterEntry();
+
+                    // Put the waiter with the other waiters
+                    PushWaiter(waiterEntry);
+                }
+            }
+
+            // Prepare array of wait handle for the WaitHandle.WaitAny()
+            WaitHandle [] waitHandles = new WaitHandle [] { 
+                                                                waiterEntry.WaitHandle, 
+                                                                cancelEvent };
+
+            // Wait for an available resource, cancel event, or timeout.
+
+            // During the wait we are supposes to exit the synchronization 
+            // domain. (Placing true as the third argument of the WaitAny())
+            // It just doesn't work, I don't know why, so I have lock(this) 
+            // statments insted of one.
+
+            int index = WaitHandle.WaitAny(
+                waitHandles,
+                millisecondsTimeout, 
+                true);
+
+            lock(this)
+            {
+                // success is true if it got a work item.
+                bool success = (0 == index);
+
+                // The timeout variable is used only for readability.
+                // (We treat cancel as timeout)
+                bool timeout = !success;
+
+                // On timeout update the waiterEntry that it is timed out
+                if (timeout)
+                {
+                    // The Timeout() fails if the waiter has already been signaled
+                    timeout = waiterEntry.Timeout();
+
+                    // On timeout remove the waiter from the queue.
+                    // Note that the complexity is O(1).
+                    if(timeout)
+                    {
+                        RemoveWaiter(waiterEntry, false);
+                    }
+
+                    // Again readability
+                    success = !timeout;
+                }
+
+                // On success return the work item
+                if (success)
+                {
+                    workItem = waiterEntry.WorkItem;
+
+                    if (null == workItem)
+                    {
+                        workItem = _workItems.Dequeue() as WorkItem;
+                    }
+                }
+            }
+            // On failure return null.
+            return workItem;
+        }
+
+        /// <summary>
+        /// Cleanup the work items queue, hence no more work 
+        /// items are allowed to be queue
+        /// </summary>
+        protected virtual void Cleanup()
+        {
+            lock(this)
+            {
+                // Deactivate only once
+                if (!_isWorkItemsQueueActive)
+                {
+                    return;
+                }
+
+                // Don't queue more work items
+                _isWorkItemsQueueActive = false;
+
+                foreach(WorkItem workItem in _workItems)
+                {
+                    workItem.DisposeOfState();
+                }
+
+                // Clear the work items that are already queued
+                _workItems.Clear();
+
+                // Note: 
+                // I don't iterate over the queue and dispose of work items's states, 
+                // since if a work item has a state object that is still in use in the 
+                // application then I must not dispose it.
+
+                // Tell the waiters that they were timed out.
+                // It won't signal them to exit, but to ignore their
+                // next work item.
+                while(_waitersCount > 0)
+                {
+                    WaiterEntry waiterEntry = PopWaiter();
+                    waiterEntry.Timeout();
+                }
+            }
+        }
+
+        #endregion
+
+        #region Private methods
+
+        /// <summary>
+        /// Returns the WaiterEntry of the current thread
+        /// </summary>
+        /// <returns></returns>
+        /// In order to avoid creation and destuction of WaiterEntry
+        /// objects each thread has its own WaiterEntry object.
+        private WaiterEntry GetThreadWaiterEntry()
+        {
+            if (null == _waiterEntry)
+            {
+                _waiterEntry = new WaiterEntry();
+            }
+            _waiterEntry.Reset();
+            return _waiterEntry;
+        }
+
+        #region Waiters stack methods
+
+        /// <summary>
+        /// Push a new waiter into the waiter's stack
+        /// </summary>
+        /// <param name="newWaiterEntry">A waiter to put in the stack</param>
+        public void PushWaiter(WaiterEntry newWaiterEntry)
+        {
+            // Remove the waiter if it is already in the stack and 
+            // update waiter's count as needed
+            RemoveWaiter(newWaiterEntry, false);
+
+            // If the stack is empty then newWaiterEntry is the new head of the stack 
+            if (null == _headWaiterEntry._nextWaiterEntry)
+            {
+                _headWaiterEntry._nextWaiterEntry = newWaiterEntry;
+                newWaiterEntry._prevWaiterEntry = _headWaiterEntry;
+
+            }
+            // If the stack is not empty then put newWaiterEntry as the new head 
+            // of the stack.
+            else
+            {
+                // Save the old first waiter entry
+                WaiterEntry oldFirstWaiterEntry = _headWaiterEntry._nextWaiterEntry;
+
+                // Update the links
+                _headWaiterEntry._nextWaiterEntry = newWaiterEntry;
+                newWaiterEntry._nextWaiterEntry = oldFirstWaiterEntry;
+                newWaiterEntry._prevWaiterEntry = _headWaiterEntry;
+                oldFirstWaiterEntry._prevWaiterEntry = newWaiterEntry;
+            }
+
+            // Increment the number of waiters
+            ++_waitersCount;
+        }
+
+        /// <summary>
+        /// Pop a waiter from the waiter's stack
+        /// </summary>
+        /// <returns>Returns the first waiter in the stack</returns>
+        private WaiterEntry PopWaiter()
+        {
+            // Store the current stack head
+            WaiterEntry oldFirstWaiterEntry = _headWaiterEntry._nextWaiterEntry;
+
+            // Store the new stack head
+            WaiterEntry newHeadWaiterEntry = oldFirstWaiterEntry._nextWaiterEntry;
+
+            // Update the old stack head list links and decrement the number
+            // waiters.
+            RemoveWaiter(oldFirstWaiterEntry, true);
+
+            // Update the new stack head
+            _headWaiterEntry._nextWaiterEntry = newHeadWaiterEntry;
+            if (null != newHeadWaiterEntry)
+            {
+                newHeadWaiterEntry._prevWaiterEntry = _headWaiterEntry;
+            }
+
+            // Return the old stack head
+            return oldFirstWaiterEntry;
+        }
+
+        /// <summary>
+        /// Remove a waiter from the stack
+        /// </summary>
+        /// <param name="waiterEntry">A waiter entry to remove</param>
+        /// <param name="popDecrement">If true the waiter count is always decremented</param>
+        private void RemoveWaiter(WaiterEntry waiterEntry, bool popDecrement)
+        {
+            // Store the prev entry in the list
+            WaiterEntry prevWaiterEntry = waiterEntry._prevWaiterEntry;
+
+            // Store the next entry in the list
+            WaiterEntry nextWaiterEntry = waiterEntry._nextWaiterEntry;
+
+            // A flag to indicate if we need to decrement the waiters count.
+            // If we got here from PopWaiter then we must decrement.
+            // If we got here from PushWaiter then we decrement only if
+            // the waiter was already in the stack.
+            bool decrementCounter = popDecrement;
+
+            // Null the waiter's entry links
+            waiterEntry._prevWaiterEntry = null;
+            waiterEntry._nextWaiterEntry = null;
+
+            // If the waiter entry had a prev link then update it.
+            // It also means that the waiter is already in the list and we
+            // need to decrement the waiters count.
+            if (null != prevWaiterEntry)
+            {
+                prevWaiterEntry._nextWaiterEntry = nextWaiterEntry;
+                decrementCounter = true;
+            }
+
+            // If the waiter entry had a next link then update it.
+            // It also means that the waiter is already in the list and we
+            // need to decrement the waiters count.
+            if (null != nextWaiterEntry)
+            {
+                nextWaiterEntry._prevWaiterEntry = prevWaiterEntry;
+                decrementCounter = true;
+            }
+
+            // Decrement the waiters count if needed
+            if (decrementCounter)
+            {
+                --_waitersCount;
+            }
+        }
+
+        #endregion
+
+        #endregion
+
+        #region WaiterEntry class 
+
+        // A waiter entry in the _waiters queue.
+        public class WaiterEntry : IDisposable
+        {
+            #region Member variables
+
+            /// <summary>
+            /// Event to signal the waiter that it got the work item.
+            /// </summary>
+            private AutoResetEvent _waitHandle = new AutoResetEvent(false);
+
+            /// <summary>
+            /// Flag to know if this waiter already quited from the queue 
+            /// because of a timeout.
+            /// </summary>
+            private bool _isTimedout = false;
+
+            /// <summary>
+            /// Flag to know if the waiter was signaled and got a work item. 
+            /// </summary>
+            private bool _isSignaled = false;
+
+            /// <summary>
+            /// A work item that passed directly to the waiter withou going 
+            /// through the queue
+            /// </summary>
+            private WorkItem _workItem = null;
+
+            private bool _isDisposed = false;
+
+            // Linked list members
+            internal WaiterEntry _nextWaiterEntry = null;
+            internal WaiterEntry _prevWaiterEntry = null;
+
+            #endregion
+
+            #region Construction
+
+            public WaiterEntry()
+            {
+                Reset();
+            }
+                        
+            #endregion
+
+            #region Public methods
+
+            public WaitHandle WaitHandle
+            {
+                get { return _waitHandle; }
+            }
+
+            public WorkItem WorkItem
+            {
+                get
+                {
+                    lock(this)
+                    {
+                        return _workItem;
+                    }
+                }
+            }
+
+            /// <summary>
+            /// Signal the waiter that it got a work item.
+            /// </summary>
+            /// <returns>Return true on success</returns>
+            /// The method fails if Timeout() preceded its call
+            public bool Signal(WorkItem workItem)
+            {
+                lock(this)
+                {
+                    if (!_isTimedout)
+                    {
+                        _workItem = workItem;
+                        _isSignaled = true;
+                        _waitHandle.Set();
+                        return true;
+                    }
+                }
+                return false;
+            }
+
+            /// <summary>
+            /// Mark the wait entry that it has been timed out
+            /// </summary>
+            /// <returns>Return true on success</returns>
+            /// The method fails if Signal() preceded its call
+            public bool Timeout()
+            {
+                lock(this)
+                {
+                    // Time out can happen only if the waiter wasn't marked as
+                    // signaled
+                    if (!_isSignaled)
+                    {
+                        // We don't remove the waiter from the queue, the DequeueWorkItem 
+                        // method skips _waiters that were timed out.
+                        _isTimedout = true;
+                        return true;
+                    }
+                }
+                return false;
+            }
+
+            /// <summary>
+            /// Reset the wait entry so it can be used again
+            /// </summary>
+            public void Reset()
+            {
+                _workItem = null;
+                _isTimedout = false;
+                _isSignaled = false;
+                _waitHandle.Reset();
+            }
+
+            /// <summary>
+            /// Free resources
+            /// </summary>
+            public void Close()
+            {
+                if (null != _waitHandle)
+                {
+                    _waitHandle.Close();
+                    _waitHandle = null;
+                }
+            }
+
+            #endregion
+
+            #region IDisposable Members
+
+            public void Dispose()
+            {
+                if (!_isDisposed)
+                {
+                    Close();
+                    _isDisposed = true;
+                }
+            }
+
+            ~WaiterEntry()
+            {
+                Dispose();
+            }
+
+            #endregion
+        }
+
+        #endregion
+
+        #region IDisposable Members
+
+        public void Dispose()
+        {
+            if (!_isDisposed)
+            {
+                Cleanup();
+                _isDisposed = true;
+                GC.SuppressFinalize(this);
+            }
+        }
+
+        ~WorkItemsQueue()
+        {
+            Cleanup();
+        }
+
+        private void ValidateNotDisposed()
+        {
+            if(_isDisposed)
+            {
+                throw new ObjectDisposedException(GetType().ToString(), "The SmartThreadPool has been shutdown");
+            }
+        }
+
+        #endregion
+    }
+
+    #endregion
+}
+