ExecutionContext.cs source code in C# .NET

                        
Code:
                         / Dotnetfx_Win7_3.5.1 / Dotnetfx_Win7_3.5.1 / 3.5.1 / DEVDIV / depot / DevDiv / releases / whidbey / NetFXspW7 / ndp / clr / src / BCL / System / Threading / ExecutionContext.cs / 1 / ExecutionContext.cs
                        

                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
/*============================================================ 
**
** Class:  ExecutionContext 
** 
**
** Purpose: Capture execution  context for a thread 
**
**
===========================================================*/
namespace System.Threading 
{
    using System; 
    using System.Security; 
    using System.Runtime.Remoting;
    using System.Security.Principal; 
    using System.Collections;
    using System.Reflection;
    using System.Runtime.Serialization;
    using System.Security.Permissions; 
    using System.Runtime.Remoting.Contexts;
    using System.Runtime.Remoting.Messaging; 
    using System.Runtime.InteropServices; 
    using System.Runtime.CompilerServices;
    using System.Runtime.ConstrainedExecution; 

    internal enum ExceptionType
    {
        InvalidOperation = 0, 
        Security = 1,
        EE = 2, 
        Generic = 3 
    }
    // helper delegate to statically bind to Wait method 
    internal delegate int WaitDelegate(IntPtr[] waitHandles, bool waitAll, int millisecondsTimeout);


    internal struct ExecutionContextSwitcher: IDisposable 
    {
        internal ExecutionContext prevEC; // previous EC we need to restore on Undo 
        internal ExecutionContext currEC; // current EC that we store for checking correctness 
        internal SecurityContextSwitcher scsw;
        internal SynchronizationContextSwitcher sysw; 
        internal Object hecsw;
        internal Thread thread;

        public override bool Equals(Object obj) 
        {
            if (obj == null || !(obj is ExecutionContextSwitcher)) 
                return false; 
            ExecutionContextSwitcher sw = (ExecutionContextSwitcher)obj;
            return (this.prevEC == sw.prevEC && this.currEC == sw.currEC && this.scsw == sw.scsw && 
                this.sysw == sw.sysw && this.hecsw == sw.hecsw && this.thread == sw.thread);
        }

        public override int GetHashCode() 
        {
            return ToString().GetHashCode(); 
        } 

        public static bool operator ==(ExecutionContextSwitcher c1, ExecutionContextSwitcher c2) 
        {
            return c1.Equals(c2);
        }
 
        public static bool operator !=(ExecutionContextSwitcher c1, ExecutionContextSwitcher c2)
        { 
            return !c1.Equals(c2); 
        }
 
        /// 
        void IDisposable.Dispose()
        {
            Undo(); 
        }
 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)] 
        internal bool UndoNoThrow()
        { 
            try
            {
                Undo();
            } 
            catch
            { 
                return false; 
            }
            return true; 
        }

        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        public void Undo() 
        {
            if (thread == null) 
            { 
                return; // Don't do anything
            } 
            if (thread != Thread.CurrentThread)
            {
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotUseSwitcherOtherThread"));
            } 
            if ( currEC != Thread.CurrentThread.GetExecutionContextNoCreate())
            { 
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_SwitcherCtxMismatch")); 
            }
            BCLDebug.Assert(currEC != null, " ExecutionContext can't be null"); 


            // Any critical failure inside scsw will cause FailFast
            scsw.Undo(); 

            try 
            { 
                HostExecutionContextSwitcher.Undo(hecsw);
            } 
            finally
            {
                // Even if HostExecutionContextSwitcher.Undo(hecsw) throws, we need to revert
                // synchronizationContext. If that throws, we'll be throwing an ex during an exception 
                // unwind. That's OK - we'll just have nested exceptions.
                sysw.Undo(); 
            } 

            // restore the saved Execution Context 
            Thread.CurrentThread.SetExecutionContext(prevEC);
            thread = null; // this will prevent the switcher object being used again

 
        }
    } 
 

    public struct AsyncFlowControl: IDisposable 
    {
        private bool useEC;
        private ExecutionContext _ec;
        private SecurityContext _sc; 
        private Thread _thread;
        internal void Setup(SecurityContextDisableFlow flags) 
        { 
            useEC = false;
            _sc = Thread.CurrentThread.ExecutionContext.SecurityContext; 
            _sc._disableFlow = flags;
            _thread = Thread.CurrentThread;
        }
        internal void Setup() 
        {
            useEC = true; 
            _ec = Thread.CurrentThread.ExecutionContext; 
            _ec.isFlowSuppressed = true;
            _thread = Thread.CurrentThread; 
        }

        /// 
        void IDisposable.Dispose() 
        {
            Undo(); 
        } 

        public void Undo() 
        {
            if (_thread == null)
            {
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotUseAFCMultiple")); 
            }
            if (_thread != Thread.CurrentThread) 
            { 
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotUseAFCOtherThread"));
            } 
            if (useEC)
            {
                if (Thread.CurrentThread.ExecutionContext != _ec)
                { 
                    throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_AsyncFlowCtrlCtxMismatch"));
                } 
                ExecutionContext.RestoreFlow(); 
            }
            else 
            {
                if (Thread.CurrentThread.ExecutionContext.SecurityContext != _sc)
                {
                    throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_AsyncFlowCtrlCtxMismatch")); 
                }
                SecurityContext.RestoreFlow(); 
            } 
            _thread = null;
        } 

        public override int GetHashCode()
        {
            // review - [....] 
            return _thread == null ? ToString().GetHashCode() : _thread.GetHashCode();
        } 
 
        public override bool Equals(Object obj)
        { 
            if (obj is AsyncFlowControl)
                return Equals((AsyncFlowControl)obj);
            else
                return false; 
        }
 
        public bool Equals(AsyncFlowControl obj) 
        {
            return obj.useEC == useEC && obj._ec == _ec && 
                obj._sc == _sc && obj._thread == _thread;
        }

        public static bool operator ==(AsyncFlowControl a, AsyncFlowControl b) 
        {
            return a.Equals(b); 
        } 

        public static bool operator !=(AsyncFlowControl a, AsyncFlowControl b) 
        {
            return !(a == b);
        }
    	 
    }
 
    [System.Runtime.InteropServices.ComVisible(true)] 
    public delegate void ContextCallback(Object state);
 

    [Serializable()]
    public sealed class ExecutionContext : ISerializable
    { 
        /*=========================================================================
        ** Data accessed from managed code that needs to be defined in 
        ** ExecutionContextObject  to maintain alignment between the two classes. 
        ** DON'T CHANGE THESE UNLESS YOU MODIFY ExecutionContextObject in vm\object.h
        =========================================================================*/ 
        private HostExecutionContext _hostExecutionContext;
        private SynchronizationContext _syncContext;
        private SecurityContext     _securityContext;
        private LogicalCallContext  _logicalCallContext; 
        private IllogicalCallContext _illogicalCallContext;  // this call context follows the physical thread
        private Thread          _thread; 
        internal bool isNewCapture = false; 
        internal bool isFlowSuppressed = false;
 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        internal ExecutionContext()
        {
        } 

        internal LogicalCallContext LogicalCallContext 
        { 
            get
            { 
                if (_logicalCallContext == null)
                {
                _logicalCallContext = new LogicalCallContext();
                } 
                return _logicalCallContext;
            } 
            set 
            {
                _logicalCallContext = value; 
            }
        }

        internal IllogicalCallContext IllogicalCallContext 
        {
            get 
            { 
                if (_illogicalCallContext == null)
                { 
                _illogicalCallContext = new IllogicalCallContext();
                }
                return _illogicalCallContext;
            } 
            set
            { 
                _illogicalCallContext = value; 
            }
        } 
        internal Thread Thread
        {
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
            set 
            {
                _thread = value; 
            } 
        }
 
        internal SynchronizationContext SynchronizationContext
        {
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
            get 
            {
                return _syncContext; 
            } 
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
            set 
            {
                _syncContext = value;
            }
        } 

    internal HostExecutionContext HostExecutionContext 
    { 
            get
            { 
                return _hostExecutionContext;
            }
            set
            { 
                _hostExecutionContext = value;
            } 
    } 

        internal  SecurityContext SecurityContext 
        {
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
            get
            { 
                return _securityContext;
            } 
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
            set
            { 
                        // store the new security context
                        _securityContext = value;
                        // perform the reverse link too
                        if (value != null) 
                            _securityContext.ExecutionContext = this;
            } 
        } 

 
        [SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.Infrastructure),
         DynamicSecurityMethodAttribute()]
        public static void Run(ExecutionContext executionContext, ContextCallback callback,  Object state)
        { 
            if (executionContext == null )
            { 
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_NullContext")); 
            }
 
            if (!executionContext.isNewCapture)
            {
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_NotNewCaptureContext"));
            } 

            executionContext.isNewCapture = false; 
 
            ExecutionContext ec = Thread.CurrentThread.GetExecutionContextNoCreate();
            if ( (ec == null || ec.IsDefaultFTContext()) && SecurityContext.CurrentlyInDefaultFTSecurityContext(ec) 
                && executionContext.IsDefaultFTContext())
            {
                callback(state);
            } 
            else
            { 
                RunInternal(executionContext, callback, state); 
            }
        } 

        internal static void RunInternal(ExecutionContext executionContext, ContextCallback callback,  Object state)
        {
            if (cleanupCode == null) 
            {
                tryCode = new RuntimeHelpers.TryCode(runTryCode); 
                cleanupCode = new RuntimeHelpers.CleanupCode(runFinallyCode); 
            }
 
            ExecutionContextRunData runData = new ExecutionContextRunData(executionContext, callback, state);
            RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(tryCode, cleanupCode, runData);
        }
 
        internal class ExecutionContextRunData
        { 
            internal ExecutionContext ec; 
            internal ContextCallback callBack;
            internal Object state; 
            internal ExecutionContextSwitcher ecsw;
            internal ExecutionContextRunData(ExecutionContext executionContext, ContextCallback cb, Object state)
            {
                this.ec = executionContext; 
                this.callBack = cb;
                this.state = state; 
                ecsw = new ExecutionContextSwitcher(); 
            }
        } 

        static internal void runTryCode(Object userData)
        {
            ExecutionContextRunData rData = (ExecutionContextRunData) userData; 
            rData.ecsw = SetExecutionContext(rData.ec);
            rData.callBack(rData.state); 
 
        }
 
        [PrePrepareMethod]
        static internal void runFinallyCode(Object userData, bool exceptionThrown)
        {
            ExecutionContextRunData rData = (ExecutionContextRunData) userData; 
            rData.ecsw.Undo();
        } 
 
        static internal RuntimeHelpers.TryCode tryCode;
        static internal RuntimeHelpers.CleanupCode cleanupCode; 


        // Sets the given execution context object on the thread.
        // Returns the previous one. 
        [DynamicSecurityMethodAttribute()]
        [MethodImplAttribute(MethodImplOptions.NoInlining)] // Methods containing StackCrawlMark local var has to be marked non-inlineable 
        internal  static ExecutionContextSwitcher SetExecutionContext(ExecutionContext executionContext) 
        {
            StackCrawlMark stackMark = StackCrawlMark.LookForMyCaller; 
            BCLDebug.Assert(executionContext != null, "ExecutionContext cannot be null here.");


            // Set up the switcher object to return; 
            ExecutionContextSwitcher ecsw = new ExecutionContextSwitcher();
 
            ecsw.thread = Thread.CurrentThread; 
            ecsw.prevEC = Thread.CurrentThread.GetExecutionContextNoCreate(); // prev
            ecsw.currEC = executionContext; //current 

            // Update the EC on thread
            Thread.CurrentThread.SetExecutionContext(executionContext);
 
            RuntimeHelpers.PrepareConstrainedRegions();
            try 
            { 
                if (executionContext != null)
                { 
                    //set the security context
                    SecurityContext sc = executionContext.SecurityContext;
                    if (sc != null)
                    { 
                        // non-null SC: needs to be set
                        SecurityContext prevSeC = (ecsw.prevEC != null) ? ecsw.prevEC.SecurityContext : null; 
                        ecsw.scsw = SecurityContext.SetSecurityContext(sc, prevSeC, ref stackMark); 
                    }
                    else if (!SecurityContext.CurrentlyInDefaultFTSecurityContext(ecsw.prevEC)) 
                    {
                        // null incoming SC, but we're currently not in FT: use static FTSC to set
                        SecurityContext prevSeC = (ecsw.prevEC != null) ? ecsw.prevEC.SecurityContext : null;
                        ecsw.scsw = SecurityContext.SetSecurityContext(SecurityContext.FullTrustSecurityContext, prevSeC, ref stackMark); 
                    }
 
                    // set the [....] context 
                    SynchronizationContext syncContext = executionContext.SynchronizationContext;
                    if (syncContext != null) 
                    {
                            SynchronizationContext prevSyC = (ecsw.prevEC != null) ? ecsw.prevEC.SynchronizationContext : null;
                            ecsw.sysw = SynchronizationContext.SetSynchronizationContext(syncContext, prevSyC);
                    } 

                    // set the Host Context 
                    HostExecutionContext hostContext = executionContext.HostExecutionContext; 
                    if (hostContext != null)
                    { 
                        ecsw.hecsw = HostExecutionContextManager.SetHostExecutionContextInternal(hostContext);
                    }

                } 
            }
            catch 
            { 
                ecsw.UndoNoThrow();
                throw; 
            }
            return ecsw;
        }
 
        public ExecutionContext CreateCopy()
        { 
            if (!isNewCapture) 
            {
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotCopyUsedContext")); 
            }
            ExecutionContext ec = new ExecutionContext();
            ec.isNewCapture = true;
            ec._syncContext = _syncContext == null?null:_syncContext.CreateCopy(); 
            // capture the host execution context
            ec._hostExecutionContext = _hostExecutionContext == null ? null : _hostExecutionContext.CreateCopy(); 
            if (_securityContext != null) 
            {
                ec._securityContext = _securityContext.CreateCopy(); 
                ec._securityContext.ExecutionContext = ec;
            }
            if (this._logicalCallContext != null)
            { 
                LogicalCallContext lc = (LogicalCallContext)this.LogicalCallContext;
                ec.LogicalCallContext = (LogicalCallContext)lc.Clone(); 
            } 
            if (this._illogicalCallContext != null)
            { 
                IllogicalCallContext ilcc = (IllogicalCallContext)this.IllogicalCallContext;
                ec.IllogicalCallContext = (IllogicalCallContext)ilcc.Clone();
            }
 
            return ec;
        } 
 
        [SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.Infrastructure)]
        public static AsyncFlowControl SuppressFlow() 
        {
            if (IsFlowSuppressed())
            {
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotSupressFlowMultipleTimes")); 
            }
            AsyncFlowControl afc = new AsyncFlowControl(); 
            afc.Setup(); 
            return afc;
        } 

        public static void RestoreFlow()
        {
            ExecutionContext ec = Thread.CurrentThread.GetExecutionContextNoCreate(); 
            if (ec == null || !ec.isFlowSuppressed)
            { 
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotRestoreUnsupressedFlow")); 
            }
            ec.isFlowSuppressed = false; 
        }

        public static bool IsFlowSuppressed()
        { 
            ExecutionContext ec = Thread.CurrentThread.GetExecutionContextNoCreate();
            if (ec == null) 
                return false; 
            else
                return ec.isFlowSuppressed; 
        }

        [MethodImplAttribute(MethodImplOptions.NoInlining)] // Methods containing StackCrawlMark local var has to be marked non-inlineable
        public static ExecutionContext Capture() 
        {
            // set up a stack mark for finding the caller 
            StackCrawlMark stackMark = StackCrawlMark.LookForMyCaller; 
            return ExecutionContext.Capture(ref stackMark);
        } 

    // internal helper to capture the current execution context using a passed in stack mark
        static internal ExecutionContext Capture(ref StackCrawlMark stackMark)
        { 
            // check to see if Flow is suppressed
            if (IsFlowSuppressed()) 
                return null; 

            ExecutionContext ecCurrent = Thread.CurrentThread.GetExecutionContextNoCreate(); 
            ExecutionContext ecNew = new ExecutionContext();
            ecNew.isNewCapture = true;

            // capture the security context 
            ecNew.SecurityContext = SecurityContext.Capture(ecCurrent, ref stackMark);
            if (ecNew.SecurityContext != null) 
                ecNew.SecurityContext.ExecutionContext = ecNew; 

             // capture the host execution context 
            ecNew._hostExecutionContext = HostExecutionContextManager.CaptureHostExecutionContext();    		


            if (ecCurrent != null) 
            {
                // capture the [....] context 
                ecNew._syncContext = (ecCurrent._syncContext == null) ?null: ecCurrent._syncContext.CreateCopy(); 

                // copy over the Logical Call Context 
                if (ecCurrent._logicalCallContext != null)
                {
                    LogicalCallContext lc = (LogicalCallContext)ecCurrent.LogicalCallContext;
                    ecNew.LogicalCallContext = (LogicalCallContext)lc.Clone(); 
                }
 
            } 
            return ecNew;
        } 

        //
        // Implementation of ISerializable
        // 

        [SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.SerializationFormatter)] 		 
        public void GetObjectData(SerializationInfo info, StreamingContext context) 
        {
            if (info==null) 
                throw new ArgumentNullException("info");

            if (_logicalCallContext != null)
            { 
                info.AddValue("LogicalCallContext", _logicalCallContext, typeof(LogicalCallContext));
            } 
        } 

        private ExecutionContext(SerializationInfo info, StreamingContext context) 
        {
            SerializationInfoEnumerator e = info.GetEnumerator();
            while (e.MoveNext())
            { 
                if (e.Name.Equals("LogicalCallContext"))
                { 
                    _logicalCallContext = (LogicalCallContext) e.Value; 
                }
            } 
            this.Thread = Thread.CurrentThread;
        } // ObjRef .ctor
        static internal void ClearSyncContext(ExecutionContext ec)
        { 
            if (ec != null)
                ec.SynchronizationContext = null; 
        } 
        internal bool IsDefaultFTContext()
        { 
            if (_hostExecutionContext != null)
                return false;
            if (_syncContext != null)
                return false; 
            if (_securityContext != null && !_securityContext.IsDefaultFTSecurityContext())
                return false; 
            if (_logicalCallContext != null && _logicalCallContext.HasInfo) 
                return false;
            if (_illogicalCallContext != null && _illogicalCallContext.HasUserData) 
                return false;
            return true;
        }
    } // class ExecutionContext 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
/*============================================================ 
**
** Class:  ExecutionContext 
** 
**
** Purpose: Capture execution  context for a thread 
**
**
===========================================================*/
namespace System.Threading 
{
    using System; 
    using System.Security; 
    using System.Runtime.Remoting;
    using System.Security.Principal; 
    using System.Collections;
    using System.Reflection;
    using System.Runtime.Serialization;
    using System.Security.Permissions; 
    using System.Runtime.Remoting.Contexts;
    using System.Runtime.Remoting.Messaging; 
    using System.Runtime.InteropServices; 
    using System.Runtime.CompilerServices;
    using System.Runtime.ConstrainedExecution; 

    internal enum ExceptionType
    {
        InvalidOperation = 0, 
        Security = 1,
        EE = 2, 
        Generic = 3 
    }
    // helper delegate to statically bind to Wait method 
    internal delegate int WaitDelegate(IntPtr[] waitHandles, bool waitAll, int millisecondsTimeout);


    internal struct ExecutionContextSwitcher: IDisposable 
    {
        internal ExecutionContext prevEC; // previous EC we need to restore on Undo 
        internal ExecutionContext currEC; // current EC that we store for checking correctness 
        internal SecurityContextSwitcher scsw;
        internal SynchronizationContextSwitcher sysw; 
        internal Object hecsw;
        internal Thread thread;

        public override bool Equals(Object obj) 
        {
            if (obj == null || !(obj is ExecutionContextSwitcher)) 
                return false; 
            ExecutionContextSwitcher sw = (ExecutionContextSwitcher)obj;
            return (this.prevEC == sw.prevEC && this.currEC == sw.currEC && this.scsw == sw.scsw && 
                this.sysw == sw.sysw && this.hecsw == sw.hecsw && this.thread == sw.thread);
        }

        public override int GetHashCode() 
        {
            return ToString().GetHashCode(); 
        } 

        public static bool operator ==(ExecutionContextSwitcher c1, ExecutionContextSwitcher c2) 
        {
            return c1.Equals(c2);
        }
 
        public static bool operator !=(ExecutionContextSwitcher c1, ExecutionContextSwitcher c2)
        { 
            return !c1.Equals(c2); 
        }
 
        /// 
        void IDisposable.Dispose()
        {
            Undo(); 
        }
 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)] 
        internal bool UndoNoThrow()
        { 
            try
            {
                Undo();
            } 
            catch
            { 
                return false; 
            }
            return true; 
        }

        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        public void Undo() 
        {
            if (thread == null) 
            { 
                return; // Don't do anything
            } 
            if (thread != Thread.CurrentThread)
            {
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotUseSwitcherOtherThread"));
            } 
            if ( currEC != Thread.CurrentThread.GetExecutionContextNoCreate())
            { 
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_SwitcherCtxMismatch")); 
            }
            BCLDebug.Assert(currEC != null, " ExecutionContext can't be null"); 


            // Any critical failure inside scsw will cause FailFast
            scsw.Undo(); 

            try 
            { 
                HostExecutionContextSwitcher.Undo(hecsw);
            } 
            finally
            {
                // Even if HostExecutionContextSwitcher.Undo(hecsw) throws, we need to revert
                // synchronizationContext. If that throws, we'll be throwing an ex during an exception 
                // unwind. That's OK - we'll just have nested exceptions.
                sysw.Undo(); 
            } 

            // restore the saved Execution Context 
            Thread.CurrentThread.SetExecutionContext(prevEC);
            thread = null; // this will prevent the switcher object being used again

 
        }
    } 
 

    public struct AsyncFlowControl: IDisposable 
    {
        private bool useEC;
        private ExecutionContext _ec;
        private SecurityContext _sc; 
        private Thread _thread;
        internal void Setup(SecurityContextDisableFlow flags) 
        { 
            useEC = false;
            _sc = Thread.CurrentThread.ExecutionContext.SecurityContext; 
            _sc._disableFlow = flags;
            _thread = Thread.CurrentThread;
        }
        internal void Setup() 
        {
            useEC = true; 
            _ec = Thread.CurrentThread.ExecutionContext; 
            _ec.isFlowSuppressed = true;
            _thread = Thread.CurrentThread; 
        }

        /// 
        void IDisposable.Dispose() 
        {
            Undo(); 
        } 

        public void Undo() 
        {
            if (_thread == null)
            {
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotUseAFCMultiple")); 
            }
            if (_thread != Thread.CurrentThread) 
            { 
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotUseAFCOtherThread"));
            } 
            if (useEC)
            {
                if (Thread.CurrentThread.ExecutionContext != _ec)
                { 
                    throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_AsyncFlowCtrlCtxMismatch"));
                } 
                ExecutionContext.RestoreFlow(); 
            }
            else 
            {
                if (Thread.CurrentThread.ExecutionContext.SecurityContext != _sc)
                {
                    throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_AsyncFlowCtrlCtxMismatch")); 
                }
                SecurityContext.RestoreFlow(); 
            } 
            _thread = null;
        } 

        public override int GetHashCode()
        {
            // review - [....] 
            return _thread == null ? ToString().GetHashCode() : _thread.GetHashCode();
        } 
 
        public override bool Equals(Object obj)
        { 
            if (obj is AsyncFlowControl)
                return Equals((AsyncFlowControl)obj);
            else
                return false; 
        }
 
        public bool Equals(AsyncFlowControl obj) 
        {
            return obj.useEC == useEC && obj._ec == _ec && 
                obj._sc == _sc && obj._thread == _thread;
        }

        public static bool operator ==(AsyncFlowControl a, AsyncFlowControl b) 
        {
            return a.Equals(b); 
        } 

        public static bool operator !=(AsyncFlowControl a, AsyncFlowControl b) 
        {
            return !(a == b);
        }
    	 
    }
 
    [System.Runtime.InteropServices.ComVisible(true)] 
    public delegate void ContextCallback(Object state);
 

    [Serializable()]
    public sealed class ExecutionContext : ISerializable
    { 
        /*=========================================================================
        ** Data accessed from managed code that needs to be defined in 
        ** ExecutionContextObject  to maintain alignment between the two classes. 
        ** DON'T CHANGE THESE UNLESS YOU MODIFY ExecutionContextObject in vm\object.h
        =========================================================================*/ 
        private HostExecutionContext _hostExecutionContext;
        private SynchronizationContext _syncContext;
        private SecurityContext     _securityContext;
        private LogicalCallContext  _logicalCallContext; 
        private IllogicalCallContext _illogicalCallContext;  // this call context follows the physical thread
        private Thread          _thread; 
        internal bool isNewCapture = false; 
        internal bool isFlowSuppressed = false;
 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        internal ExecutionContext()
        {
        } 

        internal LogicalCallContext LogicalCallContext 
        { 
            get
            { 
                if (_logicalCallContext == null)
                {
                _logicalCallContext = new LogicalCallContext();
                } 
                return _logicalCallContext;
            } 
            set 
            {
                _logicalCallContext = value; 
            }
        }

        internal IllogicalCallContext IllogicalCallContext 
        {
            get 
            { 
                if (_illogicalCallContext == null)
                { 
                _illogicalCallContext = new IllogicalCallContext();
                }
                return _illogicalCallContext;
            } 
            set
            { 
                _illogicalCallContext = value; 
            }
        } 
        internal Thread Thread
        {
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
            set 
            {
                _thread = value; 
            } 
        }
 
        internal SynchronizationContext SynchronizationContext
        {
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
            get 
            {
                return _syncContext; 
            } 
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
            set 
            {
                _syncContext = value;
            }
        } 

    internal HostExecutionContext HostExecutionContext 
    { 
            get
            { 
                return _hostExecutionContext;
            }
            set
            { 
                _hostExecutionContext = value;
            } 
    } 

        internal  SecurityContext SecurityContext 
        {
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
            get
            { 
                return _securityContext;
            } 
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
            set
            { 
                        // store the new security context
                        _securityContext = value;
                        // perform the reverse link too
                        if (value != null) 
                            _securityContext.ExecutionContext = this;
            } 
        } 

 
        [SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.Infrastructure),
         DynamicSecurityMethodAttribute()]
        public static void Run(ExecutionContext executionContext, ContextCallback callback,  Object state)
        { 
            if (executionContext == null )
            { 
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_NullContext")); 
            }
 
            if (!executionContext.isNewCapture)
            {
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_NotNewCaptureContext"));
            } 

            executionContext.isNewCapture = false; 
 
            ExecutionContext ec = Thread.CurrentThread.GetExecutionContextNoCreate();
            if ( (ec == null || ec.IsDefaultFTContext()) && SecurityContext.CurrentlyInDefaultFTSecurityContext(ec) 
                && executionContext.IsDefaultFTContext())
            {
                callback(state);
            } 
            else
            { 
                RunInternal(executionContext, callback, state); 
            }
        } 

        internal static void RunInternal(ExecutionContext executionContext, ContextCallback callback,  Object state)
        {
            if (cleanupCode == null) 
            {
                tryCode = new RuntimeHelpers.TryCode(runTryCode); 
                cleanupCode = new RuntimeHelpers.CleanupCode(runFinallyCode); 
            }
 
            ExecutionContextRunData runData = new ExecutionContextRunData(executionContext, callback, state);
            RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(tryCode, cleanupCode, runData);
        }
 
        internal class ExecutionContextRunData
        { 
            internal ExecutionContext ec; 
            internal ContextCallback callBack;
            internal Object state; 
            internal ExecutionContextSwitcher ecsw;
            internal ExecutionContextRunData(ExecutionContext executionContext, ContextCallback cb, Object state)
            {
                this.ec = executionContext; 
                this.callBack = cb;
                this.state = state; 
                ecsw = new ExecutionContextSwitcher(); 
            }
        } 

        static internal void runTryCode(Object userData)
        {
            ExecutionContextRunData rData = (ExecutionContextRunData) userData; 
            rData.ecsw = SetExecutionContext(rData.ec);
            rData.callBack(rData.state); 
 
        }
 
        [PrePrepareMethod]
        static internal void runFinallyCode(Object userData, bool exceptionThrown)
        {
            ExecutionContextRunData rData = (ExecutionContextRunData) userData; 
            rData.ecsw.Undo();
        } 
 
        static internal RuntimeHelpers.TryCode tryCode;
        static internal RuntimeHelpers.CleanupCode cleanupCode; 


        // Sets the given execution context object on the thread.
        // Returns the previous one. 
        [DynamicSecurityMethodAttribute()]
        [MethodImplAttribute(MethodImplOptions.NoInlining)] // Methods containing StackCrawlMark local var has to be marked non-inlineable 
        internal  static ExecutionContextSwitcher SetExecutionContext(ExecutionContext executionContext) 
        {
            StackCrawlMark stackMark = StackCrawlMark.LookForMyCaller; 
            BCLDebug.Assert(executionContext != null, "ExecutionContext cannot be null here.");


            // Set up the switcher object to return; 
            ExecutionContextSwitcher ecsw = new ExecutionContextSwitcher();
 
            ecsw.thread = Thread.CurrentThread; 
            ecsw.prevEC = Thread.CurrentThread.GetExecutionContextNoCreate(); // prev
            ecsw.currEC = executionContext; //current 

            // Update the EC on thread
            Thread.CurrentThread.SetExecutionContext(executionContext);
 
            RuntimeHelpers.PrepareConstrainedRegions();
            try 
            { 
                if (executionContext != null)
                { 
                    //set the security context
                    SecurityContext sc = executionContext.SecurityContext;
                    if (sc != null)
                    { 
                        // non-null SC: needs to be set
                        SecurityContext prevSeC = (ecsw.prevEC != null) ? ecsw.prevEC.SecurityContext : null; 
                        ecsw.scsw = SecurityContext.SetSecurityContext(sc, prevSeC, ref stackMark); 
                    }
                    else if (!SecurityContext.CurrentlyInDefaultFTSecurityContext(ecsw.prevEC)) 
                    {
                        // null incoming SC, but we're currently not in FT: use static FTSC to set
                        SecurityContext prevSeC = (ecsw.prevEC != null) ? ecsw.prevEC.SecurityContext : null;
                        ecsw.scsw = SecurityContext.SetSecurityContext(SecurityContext.FullTrustSecurityContext, prevSeC, ref stackMark); 
                    }
 
                    // set the [....] context 
                    SynchronizationContext syncContext = executionContext.SynchronizationContext;
                    if (syncContext != null) 
                    {
                            SynchronizationContext prevSyC = (ecsw.prevEC != null) ? ecsw.prevEC.SynchronizationContext : null;
                            ecsw.sysw = SynchronizationContext.SetSynchronizationContext(syncContext, prevSyC);
                    } 

                    // set the Host Context 
                    HostExecutionContext hostContext = executionContext.HostExecutionContext; 
                    if (hostContext != null)
                    { 
                        ecsw.hecsw = HostExecutionContextManager.SetHostExecutionContextInternal(hostContext);
                    }

                } 
            }
            catch 
            { 
                ecsw.UndoNoThrow();
                throw; 
            }
            return ecsw;
        }
 
        public ExecutionContext CreateCopy()
        { 
            if (!isNewCapture) 
            {
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotCopyUsedContext")); 
            }
            ExecutionContext ec = new ExecutionContext();
            ec.isNewCapture = true;
            ec._syncContext = _syncContext == null?null:_syncContext.CreateCopy(); 
            // capture the host execution context
            ec._hostExecutionContext = _hostExecutionContext == null ? null : _hostExecutionContext.CreateCopy(); 
            if (_securityContext != null) 
            {
                ec._securityContext = _securityContext.CreateCopy(); 
                ec._securityContext.ExecutionContext = ec;
            }
            if (this._logicalCallContext != null)
            { 
                LogicalCallContext lc = (LogicalCallContext)this.LogicalCallContext;
                ec.LogicalCallContext = (LogicalCallContext)lc.Clone(); 
            } 
            if (this._illogicalCallContext != null)
            { 
                IllogicalCallContext ilcc = (IllogicalCallContext)this.IllogicalCallContext;
                ec.IllogicalCallContext = (IllogicalCallContext)ilcc.Clone();
            }
 
            return ec;
        } 
 
        [SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.Infrastructure)]
        public static AsyncFlowControl SuppressFlow() 
        {
            if (IsFlowSuppressed())
            {
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotSupressFlowMultipleTimes")); 
            }
            AsyncFlowControl afc = new AsyncFlowControl(); 
            afc.Setup(); 
            return afc;
        } 

        public static void RestoreFlow()
        {
            ExecutionContext ec = Thread.CurrentThread.GetExecutionContextNoCreate(); 
            if (ec == null || !ec.isFlowSuppressed)
            { 
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotRestoreUnsupressedFlow")); 
            }
            ec.isFlowSuppressed = false; 
        }

        public static bool IsFlowSuppressed()
        { 
            ExecutionContext ec = Thread.CurrentThread.GetExecutionContextNoCreate();
            if (ec == null) 
                return false; 
            else
                return ec.isFlowSuppressed; 
        }

        [MethodImplAttribute(MethodImplOptions.NoInlining)] // Methods containing StackCrawlMark local var has to be marked non-inlineable
        public static ExecutionContext Capture() 
        {
            // set up a stack mark for finding the caller 
            StackCrawlMark stackMark = StackCrawlMark.LookForMyCaller; 
            return ExecutionContext.Capture(ref stackMark);
        } 

    // internal helper to capture the current execution context using a passed in stack mark
        static internal ExecutionContext Capture(ref StackCrawlMark stackMark)
        { 
            // check to see if Flow is suppressed
            if (IsFlowSuppressed()) 
                return null; 

            ExecutionContext ecCurrent = Thread.CurrentThread.GetExecutionContextNoCreate(); 
            ExecutionContext ecNew = new ExecutionContext();
            ecNew.isNewCapture = true;

            // capture the security context 
            ecNew.SecurityContext = SecurityContext.Capture(ecCurrent, ref stackMark);
            if (ecNew.SecurityContext != null) 
                ecNew.SecurityContext.ExecutionContext = ecNew; 

             // capture the host execution context 
            ecNew._hostExecutionContext = HostExecutionContextManager.CaptureHostExecutionContext();    		


            if (ecCurrent != null) 
            {
                // capture the [....] context 
                ecNew._syncContext = (ecCurrent._syncContext == null) ?null: ecCurrent._syncContext.CreateCopy(); 

                // copy over the Logical Call Context 
                if (ecCurrent._logicalCallContext != null)
                {
                    LogicalCallContext lc = (LogicalCallContext)ecCurrent.LogicalCallContext;
                    ecNew.LogicalCallContext = (LogicalCallContext)lc.Clone(); 
                }
 
            } 
            return ecNew;
        } 

        //
        // Implementation of ISerializable
        // 

        [SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.SerializationFormatter)] 		 
        public void GetObjectData(SerializationInfo info, StreamingContext context) 
        {
            if (info==null) 
                throw new ArgumentNullException("info");

            if (_logicalCallContext != null)
            { 
                info.AddValue("LogicalCallContext", _logicalCallContext, typeof(LogicalCallContext));
            } 
        } 

        private ExecutionContext(SerializationInfo info, StreamingContext context) 
        {
            SerializationInfoEnumerator e = info.GetEnumerator();
            while (e.MoveNext())
            { 
                if (e.Name.Equals("LogicalCallContext"))
                { 
                    _logicalCallContext = (LogicalCallContext) e.Value; 
                }
            } 
            this.Thread = Thread.CurrentThread;
        } // ObjRef .ctor
        static internal void ClearSyncContext(ExecutionContext ec)
        { 
            if (ec != null)
                ec.SynchronizationContext = null; 
        } 
        internal bool IsDefaultFTContext()
        { 
            if (_hostExecutionContext != null)
                return false;
            if (_syncContext != null)
                return false; 
            if (_securityContext != null && !_securityContext.IsDefaultFTSecurityContext())
                return false; 
            if (_logicalCallContext != null && _logicalCallContext.HasInfo) 
                return false;
            if (_illogicalCallContext != null && _illogicalCallContext.HasUserData) 
                return false;
            return true;
        }
    } // class ExecutionContext 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

                        

                        

                        
                        

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