CrossContextChannel.cs source code in C# .NET

                        Code:
                         / FXUpdate3074 / FXUpdate3074 / 1.1 / untmp / whidbey / QFE / ndp / clr / src / BCL / System / Runtime / Remoting / CrossContextChannel.cs / 1 / CrossContextChannel.cs
                        
                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
//
// Remoting Infrastructure Sink for making calls across context 
// boundaries. 
//
namespace System.Runtime.Remoting.Channels { 

    using System;
    using System.Collections;
    using System.Threading; 
    using System.Runtime.Remoting;
    using System.Runtime.Remoting.Contexts; 
    using System.Runtime.Remoting.Messaging; 
    using System.Runtime.Serialization;
 
    /* package scope */
    // deliberately not [serializable]
    internal class CrossContextChannel : InternalSink, IMessageSink
    { 
        private const String _channelName = "XCTX";
        private const int _channelCapability = 0; 
        private const String _channelURI = "XCTX_URI"; 

        private static CrossContextChannel messageSink 
        {
            get { return Thread.GetDomain().RemotingData.ChannelServicesData.xctxmessageSink; }
            set { Thread.GetDomain().RemotingData.ChannelServicesData.xctxmessageSink = value; }
        } 

        private static Object staticSyncObject = new Object(); 
        private static InternalCrossContextDelegate s_xctxDel = new InternalCrossContextDelegate(SyncProcessMessageCallback); 

        internal static IMessageSink MessageSink 
        {
            get
            {
                if (messageSink == null) 
                {
                    CrossContextChannel tmpSink = new CrossContextChannel(); 
 
                    lock (staticSyncObject)
                    { 
                        if (messageSink == null)
                        {
                            messageSink = tmpSink;
                        } 
                    }
                    //Interlocked.CompareExchange(out messageSink, tmpSink, null); 
                } 
                return messageSink;
            } 
        }

        internal static Object SyncProcessMessageCallback(Object[] args)
        { 
            IMessage reqMsg = args[0] as IMessage;
            Context  srvCtx = args[1] as Context; 
            IMessage replyMsg = null; 

            // If profiling of remoting is active, must tell the profiler that we have received 
            // a message.
            if (RemotingServices.CORProfilerTrackRemoting())
            {
                Guid g = Guid.Empty; 

                if (RemotingServices.CORProfilerTrackRemotingCookie()) 
                { 
                    Object obj = reqMsg.Properties["CORProfilerCookie"];
 
                    if (obj != null)
                    {
                        g = (Guid) obj;
                    } 
                }
 
                RemotingServices.CORProfilerRemotingServerReceivingMessage(g, false); 
            }
 
            Message.DebugOut("::::::::::::::::::::::::: CrossContext Channel: passign to ServerContextChain");

            // Server side notifications for dynamic sinks are done
            // in the x-context channel ... this is to maintain 
            // symmetry of the point of notification between
            // the client and server context 
            srvCtx.NotifyDynamicSinks( 
                        reqMsg,
                        false,  // bCliSide 
                        true,   // bStart
                        false,  // bAsync
                        true);  // bNotifyGlobals
 
            replyMsg = srvCtx.GetServerContextChain().SyncProcessMessage(reqMsg);
            srvCtx.NotifyDynamicSinks( 
                        replyMsg, 
                        false,  // bCliSide
                        false,  // bStart 
                        false,  // bAsync
                        true);  // bNotifyGlobals

            Message.DebugOut("::::::::::::::::::::::::: CrossContext Channel: back from ServerContextChain"); 

            // If profiling of remoting is active, must tell the profiler that we are sending a 
            // reply message. 
            if (RemotingServices.CORProfilerTrackRemoting())
            { 
                Guid g;

                RemotingServices.CORProfilerRemotingServerSendingReply(out g, false);
 
                if (RemotingServices.CORProfilerTrackRemotingCookie())
                { 
                    replyMsg.Properties["CORProfilerCookie"] = g; 
                }
            } 
            return replyMsg;
        }

        public virtual IMessage     SyncProcessMessage(IMessage reqMsg) 
        {
            Object[] args = new Object[] { null, null }; 
            IMessage replyMsg = null; 

            try 
            {
                Message.DebugOut("\n::::::::::::::::::::::::: CrossContext Channel: Sync call starting");
                IMessage errMsg = ValidateMessage(reqMsg);
                if (errMsg != null) 
                {
                    return errMsg; 
                } 

                ServerIdentity srvID = GetServerIdentity(reqMsg); 
                Message.DebugOut("Got Server identity \n");
                BCLDebug.Assert(null != srvID,"null != srvID");

 
                BCLDebug.Assert(null != srvID.ServerContext, "null != srvID.ServerContext");
 
                args[0] = reqMsg; 
                args[1] = srvID.ServerContext;
                replyMsg = (IMessage) Thread.CurrentThread.InternalCrossContextCallback(srvID.ServerContext, s_xctxDel, args); 
            }
            catch(Exception e)
            {
                Message.DebugOut("Arrgh.. XCTXSink::throwing exception " + e + "\n"); 
                replyMsg = new ReturnMessage(e, (IMethodCallMessage)reqMsg);
                if (reqMsg!=null) 
                { 
                    ((ReturnMessage)replyMsg).SetLogicalCallContext(
                            (LogicalCallContext) 
                            reqMsg.Properties[Message.CallContextKey]);
                }
            }
 
            Message.DebugOut("::::::::::::::::::::::::::: CrossContext Channel: Sync call returning!!\n");
            return replyMsg; 
        } 

        internal static Object AsyncProcessMessageCallback(Object[] args) 
        {
            AsyncWorkItem   workItem = null;

            IMessage        reqMsg      = (IMessage) args[0]; 
            IMessageSink    replySink   = (IMessageSink) args[1];
            Context         oldCtx      = (Context) args[2]; 
            Context         srvCtx      = (Context) args[3]; 
            IMessageCtrl    msgCtrl     = null;
 
            // we use the work item just as our replySink in this case
            if (replySink != null)
            {
                workItem = new AsyncWorkItem(replySink, oldCtx); 
            }
 
            Message.DebugOut("::::::::::::::::::::::::: CrossContext Channel: passign to ServerContextChain"); 

            srvCtx.NotifyDynamicSinks( 
                     reqMsg,
                     false,  // bCliSide
                     true,   // bStart
                     true,   // bAsync 
                     true);  // bNotifyGlobals
 
            // call the server context chain 
            msgCtrl =
                srvCtx.GetServerContextChain().AsyncProcessMessage( 
                    reqMsg,
                    (IMessageSink)workItem);

            // Note: for async calls, we will do the return notification 
            // for dynamic properties only when the async call
            // completes (i.e. when the replySink gets called) 
 
            Message.DebugOut("::::::::::::::::::::::::: CrossContext Channel: back from ServerContextChain");
 
            return msgCtrl;
        }

        public virtual IMessageCtrl AsyncProcessMessage(IMessage reqMsg, IMessageSink replySink) 
        {
            Message.DebugOut("::::::::::::::::::::::::::: CrossContext Channel: Async call starting!!\n"); 
            // One way Async notifications may potentially pass a null reply sink. 
            IMessage errMsg = ValidateMessage(reqMsg);
 
            Object[] args = new Object[] { null, null, null, null };

            IMessageCtrl    msgCtrl  = null;
            if (errMsg != null) 
            {
                if (replySink!=null) 
                { 
                    replySink.SyncProcessMessage(errMsg);
                } 
            }
            else
            {
                ServerIdentity srvID = GetServerIdentity(reqMsg); 

                // If active, notify the profiler that an asynchronous remoting message was received. 
                if (RemotingServices.CORProfilerTrackRemotingAsync()) 
                {
                    Guid g = Guid.Empty; 

                    if (RemotingServices.CORProfilerTrackRemotingCookie())
                    {
                        Object obj = reqMsg.Properties["CORProfilerCookie"]; 

                        if (obj != null) 
                        { 
                            g = (Guid) obj;
                        } 
                    }

                    RemotingServices.CORProfilerRemotingServerReceivingMessage(g, true);
 
                    // Only wrap the replySink if the call wants a reply
                    if (replySink != null) 
                    { 
                        // Now wrap the reply sink in our own so that we can notify the profiler of
                        // when the reply is sent.  Upon invocation, it will notify the profiler 
                        // then pass control on to the replySink passed in above.
                        IMessageSink profSink = new ServerAsyncReplyTerminatorSink(replySink);

                        // Replace the reply sink with our own 
                        replySink = profSink;
                    } 
                } 

                Context         srvCtx   = srvID.ServerContext; 
                if (srvCtx.IsThreadPoolAware)
                {
                    // this is the case when we do not queue the work item since the
                    // server context claims to be doing its own threading. 

                    args[0] = reqMsg; 
                    args[1] = replySink; 
                    args[2] = Thread.CurrentContext;
                    args[3] = srvCtx; 

                    InternalCrossContextDelegate xctxDel = new InternalCrossContextDelegate(AsyncProcessMessageCallback);

                    msgCtrl = (IMessageCtrl) Thread.CurrentThread.InternalCrossContextCallback(srvCtx, xctxDel, args); 
                }
                else 
                { 
                    AsyncWorkItem   workItem = null;
 
                    // This is the case where we take care of returning the calling
                    // thread asap by using the ThreadPool for completing the call.

                    // we use a more elaborate WorkItem and delegate the work to the thread pool 
                    workItem = new AsyncWorkItem(reqMsg,
                                                 replySink, 
                                                 Thread.CurrentContext, 
                                                 srvID);
 
                    WaitCallback threadFunc = new WaitCallback(workItem.FinishAsyncWork);
                    // Note: Dynamic sinks are notified in the threadFunc
                    ThreadPool.QueueUserWorkItem(threadFunc);
                } 
            }
 
            Message.DebugOut("::::::::::::::::::::::::::: CrossContext Channel: Async call returning!!\n"); 
            return msgCtrl;
        } // AsyncProcessMessage 

        internal static Object DoAsyncDispatchCallback(Object[] args)
        {
            AsyncWorkItem   workItem = null; 

            IMessage        reqMsg      = (IMessage) args[0]; 
            IMessageSink    replySink   = (IMessageSink) args[1]; 
            Context         oldCtx      = (Context) args[2];
            Context         srvCtx      = (Context) args[3]; 
            IMessageCtrl    msgCtrl     = null;


            // we use the work item just as our replySink in this case 
            if (replySink != null)
            { 
                 workItem = new AsyncWorkItem(replySink, oldCtx); 
            }
            Message.DebugOut("::::::::::::::::::::::::: CrossContext Channel: passign to ServerContextChain"); 
            // call the server context chain
            msgCtrl =
                srvCtx.GetServerContextChain().AsyncProcessMessage(reqMsg, (IMessageSink)workItem);
            Message.DebugOut("::::::::::::::::::::::::: CrossContext Channel: back from ServerContextChain"); 

            return msgCtrl; 
        } 

 
        internal static IMessageCtrl DoAsyncDispatch(IMessage reqMsg, IMessageSink replySink)
        {
            Object[] args = new Object[] { null, null, null, null };
 
            ServerIdentity srvID = GetServerIdentity(reqMsg);
 
            // If active, notify the profiler that an asynchronous remoting message was received. 
            if (RemotingServices.CORProfilerTrackRemotingAsync())
            { 
                Guid g = Guid.Empty;

                if (RemotingServices.CORProfilerTrackRemotingCookie())
                { 
                    Object obj = reqMsg.Properties["CORProfilerCookie"];
                    if (obj != null) 
                        g = (Guid) obj; 
                }
 
                RemotingServices.CORProfilerRemotingServerReceivingMessage(g, true);

                // Only wrap the replySink if the call wants a reply
                if (replySink != null) 
                {
                    // Now wrap the reply sink in our own so that we can notify the profiler of 
                    // when the reply is sent.  Upon invocation, it will notify the profiler 
                    // then pass control on to the replySink passed in above.
                    IMessageSink profSink = 
                        new ServerAsyncReplyTerminatorSink(replySink);

                    // Replace the reply sink with our own
                    replySink = profSink; 
                }
            } 
 
            IMessageCtrl msgCtrl = null;
            Context srvCtx = srvID.ServerContext; 

            //if (srvCtx.IsThreadPoolAware)
            //{
                // this is the case when we do not queue the work item since the 
                // server context claims to be doing its own threading.
 
                args[0] = reqMsg; 
                args[1] = replySink;
                args[2] = Thread.CurrentContext; 
                args[3] = srvCtx;

                InternalCrossContextDelegate xctxDel = new InternalCrossContextDelegate(DoAsyncDispatchCallback);
 
                msgCtrl = (IMessageCtrl) Thread.CurrentThread.InternalCrossContextCallback(srvCtx, xctxDel, args);
 
            //} 

            return msgCtrl; 
        } // DoDispatch

        public IMessageSink NextSink
        { 
            get
            { 
                // We are a terminating sink for this chain. 
                return null;
            } 
        }
  }

    /* package */ 
    internal class AsyncWorkItem : IMessageSink
    { 
        // the replySink passed in to us in AsyncProcessMsg 
        private IMessageSink _replySink;
 
        // the server identity we are calling
        private ServerIdentity _srvID;

        // the original context of the thread calling AsyncProcessMsg 
        private Context _oldCtx;
 
        private LogicalCallContext _callCtx; 

        // the request msg passed in 
        private IMessage _reqMsg;

        internal AsyncWorkItem(IMessageSink replySink, Context oldCtx)
 
            : this(null, replySink, oldCtx, null) {
        } 
 
        internal AsyncWorkItem(IMessage reqMsg, IMessageSink replySink, Context oldCtx, ServerIdentity srvID)
        { 
            _reqMsg = reqMsg;
            _replySink = replySink;
            _oldCtx = oldCtx;
            _callCtx = CallContext.GetLogicalCallContext(); 
            _srvID = srvID;
        } 
 
        internal static Object SyncProcessMessageCallback(Object[] args)
        { 
            IMessageSink    replySink   = (IMessageSink) args[0];
            IMessage        msg         = (IMessage) args[1];

            return replySink.SyncProcessMessage(msg); 
        }
 
        public virtual IMessage     SyncProcessMessage(IMessage msg) 
        {
            // This gets called when the called object finishes the AsyncWork... 

            // This is called irrespective of whether we delegated the initial
            // work to a thread pool thread or not. Quite likely it will be
            // called on a user thread (i.e. a thread different from the 
            // forward call thread)
 
            // we just switch back to the old context before calling 
            // the next replySink
 
            IMessage retMsg = null;

            if (_replySink != null)
            { 
                // This assertt covers the common case (ThreadPool)
                // and checks that the reply thread for the async call 
                // indeed emerges from the server context. 
                BCLDebug.Assert(
                    (_srvID == null) 
                    || (_srvID.ServerContext == Thread.CurrentContext),
                    "Thread expected to be in the server context!");

                // Call the dynamic sinks to notify that the async call 
                // has completed
                Thread.CurrentContext.NotifyDynamicSinks( 
                    msg,    // this is the async reply 
                    false,  // bCliSide
                    false,  // bStart 
                    true,   // bAsync
                    true);  // bNotifyGlobals

                Object[] args = new Object[] { _replySink, msg }; 

                InternalCrossContextDelegate xctxDel = new InternalCrossContextDelegate(SyncProcessMessageCallback); 
 
                retMsg = (IMessage) Thread.CurrentThread.InternalCrossContextCallback(_oldCtx, xctxDel, args);
            } 
            return retMsg;
        }

        public virtual IMessageCtrl AsyncProcessMessage(IMessage msg, IMessageSink replySink) 
        {
            // Can't call the reply sink asynchronously! 
            throw new NotSupportedException( 
                Environment.GetResourceString("NotSupported_Method"));
        } 

        public IMessageSink NextSink
        {
            get 
            {
                return _replySink; 
            } 
        }
 
        internal static Object FinishAsyncWorkCallback(Object[] args)
        {
            AsyncWorkItem This = (AsyncWorkItem) args[0];
            Context srvCtx = This._srvID.ServerContext; 

            LogicalCallContext threadPoolCallCtx = 
                CallContext.SetLogicalCallContext(This._callCtx); 

            // Call the server context chain Async. We provide workItem as our 
            // replySink ... this will cause the replySink.ProcessMessage
            // to switch back to the context of the original caller thread.

            // Call the dynamic sinks to notify that the async call 
            // is starting
            srvCtx.NotifyDynamicSinks( 
                This._reqMsg, 
                false,  // bCliSide
                true,   // bStart 
                true,   // bAsync
                true);  // bNotifyGlobals

            // < 

            IMessageCtrl ctrl = 
               srvCtx.GetServerContextChain().AsyncProcessMessage( 
                    This._reqMsg,
                    (IMessageSink)This); 

            // change back to the old context
            CallContext.SetLogicalCallContext(threadPoolCallCtx);
 
            return null;
        } 
 
        /* package */
        internal virtual void FinishAsyncWork(Object stateIgnored) 
        {
            InternalCrossContextDelegate xctxDel = new InternalCrossContextDelegate(FinishAsyncWorkCallback);

            Object[] args = new Object[] { this }; 

            Thread.CurrentThread.InternalCrossContextCallback(_srvID.ServerContext, xctxDel, args); 
        } 
    }
} 

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