HostExecutionContextManager.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Threading / HostExecutionContextManager.cs / 1305376 / HostExecutionContextManager.cs
                        

                        
                            using System.Diagnostics.Contracts; 
// ==++==
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//
// [....] 
/*============================================================ 
**
** Class:  ExecutionContext 
**
**
** Purpose: Capture Host execution  context for a thread
** 
**
===========================================================*/ 
namespace System.Threading 
{
    using System.Security; 
    using System.Runtime.Remoting;
    using System.Runtime.CompilerServices;
    using System.Runtime.Serialization;
    using System.Security.Permissions; 
    using System.Runtime.Remoting.Messaging;
    using System.Runtime.ConstrainedExecution; 
    using System.Runtime.Versioning; 
    using System.Runtime.InteropServices;
 


    internal class HostExecutionContextSwitcher
    { 
        internal ExecutionContext            executionContext;
        internal HostExecutionContext        previousHostContext; 
        internal HostExecutionContext        currentHostContext; 

        [System.Security.SecurityCritical]  // auto-generated 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        static public void Undo(Object switcherObject)
        {
            if (switcherObject == null) 
               return;
            // otherwise call the host 
            HostExecutionContextManager hostMgr = HostExecutionContextManager.GetCurrentHostExecutionContextManager(); 
            if (hostMgr != null)
            { 
                hostMgr.Revert(switcherObject);
            }
        }
    } 

 
 
    public class HostExecutionContext : IDisposable
    { 
        private Object state;

        protected internal Object State {
            get { 
                return state;
            } 
            set { 
                state = value;
            } 
        }

        public HostExecutionContext()
        { 
        }
 
        public HostExecutionContext(Object state) 
        {
            this.state = state; 
        }

        [System.Security.SecuritySafeCritical]  // auto-generated
        public virtual HostExecutionContext CreateCopy() 
        {
                     Object newState = state; 
            if (state is IUnknownSafeHandle) 
            {
                            // Clone the IUnknown handle 
                            newState = ((IUnknownSafeHandle)state).Clone();
            }
            return new HostExecutionContext(state);
        } 

        public void Dispose() 
        { 
            Dispose(true);
            GC.SuppressFinalize(this); 
        }

        public virtual void Dispose(bool disposing)
        { 
            return;
        } 
    } 

    [System.Security.SecurityCritical]  // auto-generated 
    internal class IUnknownSafeHandle : SafeHandle
    {
        public IUnknownSafeHandle() : base(IntPtr.Zero, true)
        { 
        }
 
        public override bool IsInvalid { 
            [System.Security.SecurityCritical]
            get { return handle == IntPtr.Zero; } 
            }

        [System.Security.SecurityCritical]
        override protected bool ReleaseHandle() 
        {
            HostExecutionContextManager.ReleaseHostSecurityContext(this.handle); 
            return true; 
        }
 
             internal Object Clone()
             {
                IUnknownSafeHandle unkSafeHandleCloned = new IUnknownSafeHandle();
                // call into the Hosting API to CLONE the host context 
                // stores the output IUnknown in the safehandle,
                if (!IsInvalid) 
                { 
                    HostExecutionContextManager.CloneHostSecurityContext(this, unkSafeHandleCloned);
                } 
                return unkSafeHandleCloned;
             }
    }
 

 
    public class HostExecutionContextManager 
    {
        private static bool                _fIsHostedChecked; 
        private static bool                 _fIsHosted;
        private static HostExecutionContextManager _hostExecutionContextManager;

              [System.Security.SecurityCritical]  // auto-generated 
              [ResourceExposure(ResourceScope.None)]
              [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
              [MethodImplAttribute(MethodImplOptions.InternalCall)] 
            static private extern bool HostSecurityManagerPresent();
 
              [System.Security.SecurityCritical]  // auto-generated
              [ResourceExposure(ResourceScope.None)]
              [MethodImplAttribute(MethodImplOptions.InternalCall)]
        static internal extern int ReleaseHostSecurityContext(IntPtr context); 

              [System.Security.SecurityCritical]  // auto-generated 
              [ResourceExposure(ResourceScope.None)] 
              [MethodImplAttribute(MethodImplOptions.InternalCall)]
        static internal extern int CloneHostSecurityContext(SafeHandle context, SafeHandle clonedContext); 

               [System.Security.SecurityCritical]  // auto-generated
               [ResourceExposure(ResourceScope.None)]
              [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        static private extern int CaptureHostSecurityContext(SafeHandle capturedContext);
 
              [System.Security.SecurityCritical]  // auto-generated 
              [ResourceExposure(ResourceScope.None)]
              [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        static private extern int SetHostSecurityContext(SafeHandle context, bool fReturnPrevious, SafeHandle prevContext);

        [System.Security.SecurityCritical]  // auto-generated 
        internal static bool CheckIfHosted()
        { 
            if (!_fIsHostedChecked) 
            {
                _fIsHosted = HostSecurityManagerPresent(); 
                _fIsHostedChecked = true;
            }
            return _fIsHosted;
        } 

         // capture Host SecurityContext 
        [System.Security.SecuritySafeCritical]  // auto-generated 
        public virtual  HostExecutionContext Capture()
        { 
            HostExecutionContext context =  null;
            // check if we are hosted
            if (CheckIfHosted())
            { 
                IUnknownSafeHandle unkSafeHandle = new IUnknownSafeHandle();
                            context = new HostExecutionContext(unkSafeHandle); 
 
                // call into the Hosting API to capture the host context
                // stores the output IUnknown in the safehandle, 
                CaptureHostSecurityContext(unkSafeHandle);
            }

            // otherwise 
            return context;
 
        } 
        // Set Host SecurityContext
        [System.Security.SecurityCritical]  // auto-generated_required 
        public virtual Object SetHostExecutionContext(HostExecutionContext hostExecutionContext)
        {
            if (hostExecutionContext == null)
            { 
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_NotNewCaptureContext"));
            } 
            Contract.EndContractBlock(); 

            HostExecutionContextSwitcher switcher = new HostExecutionContextSwitcher(); 
                     ExecutionContext currentExecutionContext = Thread.CurrentThread.ExecutionContext;

            switcher.executionContext = currentExecutionContext;
            switcher.currentHostContext = hostExecutionContext; 
                     switcher.previousHostContext = null;
 
            if (CheckIfHosted()) 
            {
                if (hostExecutionContext.State is IUnknownSafeHandle) 
                {
                                    // setup the previous unknown handle
                                   IUnknownSafeHandle unkPrevSafeHandle = new IUnknownSafeHandle();
                            switcher.previousHostContext = new HostExecutionContext(unkPrevSafeHandle); 

                                    // get the current handle 
                    IUnknownSafeHandle unkSafeHandle  = (IUnknownSafeHandle)hostExecutionContext.State; 

                                   // call into the Hosting API to set the host context 
                                   // second arg indicates whether we want to retrieve the previous context
                      SetHostSecurityContext(unkSafeHandle,true,unkPrevSafeHandle);
                }
            } 

                    // store the current HostExecutionContext in the ExecutionContext. 
            currentExecutionContext.HostExecutionContext = hostExecutionContext; 

            return switcher; 
        }

        // this method needs to be reliable
        [System.Security.SecurityCritical]  // auto-generated_required 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        public virtual void Revert(Object previousState) 
        { 
            HostExecutionContextSwitcher hostContextSwitcher = previousState as HostExecutionContextSwitcher;
            if (hostContextSwitcher == null) 
            {
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotOverrideSetWithoutRevert"));
            }
 
            // check Undo is happening on the correct thread
            ExecutionContext executionContext = Thread.CurrentThread.ExecutionContext; 
 
            if (executionContext != hostContextSwitcher.executionContext)
            { 
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotUseSwitcherOtherThread"));
            }
            hostContextSwitcher.executionContext = null; // Make sure switcher cannot be re-used.
 
            HostExecutionContext revertFromHostContext = executionContext.HostExecutionContext;
            // if the current host context is not the same as the one in the switcher, then revert is being called out of order 
            if (revertFromHostContext != hostContextSwitcher.currentHostContext) 
            {
                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_CannotUseSwitcherOtherThread")); 
            }

            // get the previous host context
            HostExecutionContext revertToHostContext = hostContextSwitcher.previousHostContext; 

            // now check if we are hosted and revert the context in the host 
            if (CheckIfHosted()) 
            {
                // try restore the previous context as the current context 
                if (revertToHostContext != null && revertToHostContext.State is IUnknownSafeHandle)
                {
                    IUnknownSafeHandle unkprevSafeHandle = (IUnknownSafeHandle)revertToHostContext.State;
                    // call into the Hosting API to set the host context 
                    SetHostSecurityContext(unkprevSafeHandle, false, null);
                } 
            } 

            //restore the previous host context in the executioncontext 
            executionContext.HostExecutionContext = revertToHostContext;

        }
 
        [System.Security.SecurityCritical]  // auto-generated
        internal static HostExecutionContext CaptureHostExecutionContext() 
        { 
            HostExecutionContext hostContext = null;
            // capture the host execution context 
            HostExecutionContextManager hostMgr = HostExecutionContextManager.GetCurrentHostExecutionContextManager();
            if (hostMgr != null)
            {
                hostContext = hostMgr.Capture(); 
            }
            return hostContext; 
        } 

        [System.Security.SecurityCritical]  // auto-generated 
        internal static Object SetHostExecutionContextInternal(HostExecutionContext hostContext)
        {
            HostExecutionContextManager hostMgr = HostExecutionContextManager.GetCurrentHostExecutionContextManager();
            Object switcher = null; 
            if (hostMgr != null)
            { 
                switcher = hostMgr.SetHostExecutionContext(hostContext); 
                //
            } 
            return switcher;
        }

              // retun the HostExecutionContextManager for the current AppDomain 
        [System.Security.SecurityCritical]  // auto-generated
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
        internal static HostExecutionContextManager GetCurrentHostExecutionContextManager() 
        {
            // this is called during AppDomainManager initialization, this is a thread safe place 
            // to setup the HostExecutionContextManager for the current AppDomain
            if (AppDomainManager.CurrentAppDomainManager != null) {

                return AppDomainManager.CurrentAppDomainManager.HostExecutionContextManager; 
            }
            return null; 
        } 

              // retun the HostExecutionContextManager for the current AppDomain 
        internal static HostExecutionContextManager GetInternalHostExecutionContextManager()
        {
            if (_hostExecutionContextManager == null) {
                // setup the HostExecutionContextManager for the current AppDomain 
                Contract.Assert(_hostExecutionContextManager == null, "HostExecutionContextManager should be null");
                _hostExecutionContextManager = new HostExecutionContextManager(); 
            } 
            return _hostExecutionContextManager;
        } 
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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