VolatileEnlistmentMultiplexing.cs source code in C# .NET

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Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / tx / System / Transactions / VolatileEnlistmentMultiplexing.cs / 1305376 / VolatileEnlistmentMultiplexing.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Transactions 
{ 
    using System;
    using System.Diagnostics; 
    using System.Threading;
    using System.Transactions;
    using System.Transactions.Diagnostics;
 

    // The volatile Demultiplexer is a fanout point for promoted volatile enlistments. 
    // When a transaction is promoted a single volatile enlistment is created in the new 
    // transaction for all volitile enlistments on the transaction.  When the VolatileDemux
    // receives a preprepare it will fan that notification out to all of the enlistments 
    // on the transaction.  When it has gathered all of the responses it will send a
    // single vote back to the DistributedTransactionManager.
    internal abstract class VolatileDemultiplexer : IEnlistmentNotificationInternal
    { 
        // Reference the transactions so that we have access to it's enlistments
        protected InternalTransaction transaction; 
 
        // Store the IVolatileEnlistment interface to call back to the Distributed TM
        internal IPromotedEnlistment oletxEnlistment; 
        internal IPromotedEnlistment preparingEnlistment;

        public VolatileDemultiplexer( InternalTransaction transaction )
        { 
            this.transaction = transaction;
        } 
 

        internal void BroadcastCommitted( ref VolatileEnlistmentSet volatiles ) 
        {
            // Broadcast preprepare to the volatile subordinates
            for( int i = 0; i < volatiles.volatileEnlistmentCount; i++ )
            { 
                volatiles.volatileEnlistments [i].twoPhaseState.InternalCommitted(
                    volatiles.volatileEnlistments [i] ); 
            } 
        }
 

        // This broadcast is used by the state machines and therefore must be internal.
        internal void BroadcastRollback( ref VolatileEnlistmentSet volatiles )
        { 
            // Broadcast preprepare to the volatile subordinates
            for( int i = 0; i < volatiles.volatileEnlistmentCount; i++ ) 
            { 
                volatiles.volatileEnlistments [i].twoPhaseState.InternalAborted(
                    volatiles.volatileEnlistments [i] ); 
            }
        }

 
        internal void BroadcastInDoubt( ref VolatileEnlistmentSet volatiles )
        { 
            // Broadcast preprepare to the volatile subordinates 
            for( int i = 0; i < volatiles.volatileEnlistmentCount; i++ )
            { 
                volatiles.volatileEnlistments [i].twoPhaseState.InternalIndoubt(
                    volatiles.volatileEnlistments [i] );
            }
        } 

 
        // Object for synchronizing access to the entire class( avoiding lock( typeof( ... )) ) 
        private static object classSyncObject;
        internal static object ClassSyncObject 
        {
            get
            {
                if( classSyncObject == null ) 
                {
                    object o = new object(); 
                    Interlocked.CompareExchange( ref classSyncObject, o, null ); 
                }
                return classSyncObject; 
            }
        }

 
        private static WaitCallback prepareCallback;
        private static WaitCallback PrepareCallback 
        { 
            get
            { 
                if( prepareCallback == null )
                {
                    lock( ClassSyncObject )
                    { 
                        if( prepareCallback == null )
                        { 
                            WaitCallback temp = new WaitCallback( PoolablePrepare ); 
                            Thread.MemoryBarrier();
                            prepareCallback = temp; 
                        }
                    }
                }
 
                return prepareCallback;
            } 
        } 

        protected static void PoolablePrepare( object state ) 
        {
            VolatileDemultiplexer demux = (VolatileDemultiplexer) state;

            // Don't block an enlistment thread (or a thread pool thread).  So 
            // try to get the transaction lock but if unsuccessfull give up and
            // queue this operation to try again later. 
            bool tookLock = false; 
            try
            { 
                System.Threading.Monitor.TryEnter(demux.transaction, 250, ref tookLock);
                if (tookLock)
                {
                    demux.InternalPrepare(); 
                }
                else 
                { 
                    if (!ThreadPool.QueueUserWorkItem(PrepareCallback, demux))
                    { 
                        throw TransactionException.CreateInvalidOperationException(
                            SR.GetString(SR.TraceSourceLtm),
                            SR.GetString(SR.UnexpectedFailureOfThreadPool),
                            null 
                            );
                    } 
                } 
            }
            finally 
            {
                if (tookLock)
                {
                    System.Threading.Monitor.Exit(demux.transaction); 
                }
            } 
        } 

 
        private static WaitCallback commitCallback;
        private static WaitCallback CommitCallback
        {
            get 
            {
                if( commitCallback == null ) 
                { 
                    lock( ClassSyncObject )
                    { 
                        if( commitCallback == null )
                        {
                            WaitCallback temp = new WaitCallback( PoolableCommit );
                            Thread.MemoryBarrier(); 
                            commitCallback = temp;
                        } 
                    } 
                }
 
                return commitCallback;
            }
        }
 

        protected static void PoolableCommit( object state ) 
        { 
            VolatileDemultiplexer demux = (VolatileDemultiplexer) state;
 
            // Don't block an enlistment thread (or a thread pool thread).  So
            // try to get the transaction lock but if unsuccessfull give up and
            // queue this operation to try again later.
            bool tookLock = false; 
            try
            { 
                System.Threading.Monitor.TryEnter(demux.transaction, 250, ref tookLock); 
                if (tookLock)
                { 
                    demux.InternalCommit();
                }
                else
                { 
                    if (!ThreadPool.QueueUserWorkItem(CommitCallback, demux))
                    { 
                        throw TransactionException.CreateInvalidOperationException( 
                            SR.GetString(SR.TraceSourceLtm),
                            SR.GetString(SR.UnexpectedFailureOfThreadPool), 
                            null
                            );
                    }
                } 
            }
            finally 
            { 
                if (tookLock)
                { 
                    System.Threading.Monitor.Exit(demux.transaction);
                }
            }
        } 

 
 
        private static WaitCallback rollbackCallback;
        private static WaitCallback RollbackCallback 
        {
            get
            {
                if( rollbackCallback  == null ) 
                {
                    lock( ClassSyncObject ) 
                    { 
                        if(rollbackCallback  == null )
                        { 
                            WaitCallback temp = new WaitCallback( PoolableRollback );
                            Thread.MemoryBarrier();
                            rollbackCallback = temp;
                        } 
                    }
                } 
 
                return rollbackCallback;
            } 
        }

        protected static void PoolableRollback( object state )
        { 
            VolatileDemultiplexer demux = (VolatileDemultiplexer) state;
 
            // Don't block an enlistment thread (or a thread pool thread).  So 
            // try to get the transaction lock but if unsuccessfull give up and
            // queue this operation to try again later. 
            bool tookLock = false;
            try
            {
                System.Threading.Monitor.TryEnter(demux.transaction, 250, ref tookLock); 
                if (tookLock)
                { 
                    demux.InternalRollback(); 
                }
                else 
                {
                    if (!ThreadPool.QueueUserWorkItem(RollbackCallback, demux))
                    {
                        throw TransactionException.CreateInvalidOperationException( 
                            SR.GetString(SR.TraceSourceLtm),
                            SR.GetString(SR.UnexpectedFailureOfThreadPool), 
                            null 
                            );
                    } 
                }
            }
            finally
            { 
                if (tookLock)
                { 
                    System.Threading.Monitor.Exit(demux.transaction); 
                }
            } 
        }


        private static WaitCallback inDoubtCallback; 
        private static WaitCallback InDoubtCallback
        { 
            get 
            {
                if(inDoubtCallback  == null ) 
                {
                    lock( ClassSyncObject )
                    {
                        if(inDoubtCallback  == null ) 
                        {
                            WaitCallback temp = new WaitCallback( PoolableInDoubt ); 
                            Thread.MemoryBarrier(); 
                            inDoubtCallback = temp;
                        } 
                    }
                }

                return inDoubtCallback; 
            }
        } 
 

        protected static void PoolableInDoubt( object state ) 
        {
            VolatileDemultiplexer demux = (VolatileDemultiplexer) state;

            // Don't block an enlistment thread (or a thread pool thread).  So 
            // try to get the transaction lock but if unsuccessfull give up and
            // queue this operation to try again later. 
            bool tookLock = false; 
            try
            { 
                System.Threading.Monitor.TryEnter(demux.transaction, 250, ref tookLock);
                if (tookLock)
                {
                    demux.InternalInDoubt(); 
                }
                else 
                { 
                    if (!ThreadPool.QueueUserWorkItem(InDoubtCallback, demux))
                    { 
                        throw TransactionException.CreateInvalidOperationException(
                            SR.GetString(SR.TraceSourceLtm),
                            SR.GetString(SR.UnexpectedFailureOfThreadPool),
                            null 
                            );
                    } 
                } 
            }
            finally 
            {
                if (tookLock)
                {
                    System.Threading.Monitor.Exit(demux.transaction); 
                }
            } 
        } 

 
        protected abstract void InternalPrepare();
        protected abstract void InternalCommit();
        protected abstract void InternalRollback();
        protected abstract void InternalInDoubt(); 

        #region IEnlistmentNotification Members 
 
        // Fanout Preprepare notifications
        public abstract void Prepare( IPromotedEnlistment en ); 

        public abstract void Commit( IPromotedEnlistment en );

        public abstract void Rollback( IPromotedEnlistment en ); 

        public abstract void InDoubt( IPromotedEnlistment en ); 
 
        #endregion
 
    }


    // This class implements the phase 0 version of a volatile demux. 
    internal class Phase0VolatileDemultiplexer : VolatileDemultiplexer
    { 
        public Phase0VolatileDemultiplexer( InternalTransaction transaction ) : base( transaction ) {} 

        protected override void InternalPrepare() 
        {
            try
            {
                this.transaction.State.ChangeStatePromotedPhase0( this.transaction ); 
            }
            catch( TransactionAbortedException e ) 
            { 
                this.oletxEnlistment.ForceRollback(e);
                if ( DiagnosticTrace.Verbose ) 
                {
                    ExceptionConsumedTraceRecord.Trace( SR.GetString( SR.TraceSourceLtm ),
                        e );
                } 
            }
            catch( TransactionInDoubtException e ) 
            { 
                this.oletxEnlistment.EnlistmentDone();
                if ( DiagnosticTrace.Verbose ) 
                {
                    ExceptionConsumedTraceRecord.Trace( SR.GetString( SR.TraceSourceLtm ),
                        e );
                } 
            }
        } 
 
        protected override void InternalCommit()
        { 
            // Respond immediately to the TM
            this.oletxEnlistment.EnlistmentDone();

            this.transaction.State.ChangeStatePromotedCommitted( this.transaction ); 
        }
 
        protected override void InternalRollback() 
        {
            // Respond immediately to the TM 
            this.oletxEnlistment.EnlistmentDone();

            this.transaction.State.ChangeStatePromotedAborted( this.transaction );
        } 

        protected override void InternalInDoubt() 
        { 
            this.transaction.State.InDoubtFromDtc( this.transaction );
        } 

        #region IEnlistmentNotification Members

        // Fanout Preprepare notifications 
        public override void Prepare( IPromotedEnlistment en )
        { 
            this.preparingEnlistment = en; 
            PoolablePrepare( this );
        } 


        public override void Commit( IPromotedEnlistment en )
        { 
            this.oletxEnlistment = en;
            PoolableCommit( this ); 
        } 

 
        public override void Rollback( IPromotedEnlistment en )
        {
            this.oletxEnlistment = en;
            PoolableRollback( this ); 
        }
 
 
        public override void InDoubt( IPromotedEnlistment en )
        { 
            this.oletxEnlistment = en;
            PoolableInDoubt( this );
        }
 
        #endregion
    } 
 
    // This class implements the phase 1 version of a volatile demux.
    internal class Phase1VolatileDemultiplexer : VolatileDemultiplexer 
    {
        public Phase1VolatileDemultiplexer( InternalTransaction transaction ) : base( transaction ) {}

        protected override void InternalPrepare() 
        {
            try 
            { 
                this.transaction.State.ChangeStatePromotedPhase1( this.transaction );
            } 
            catch( TransactionAbortedException e )
            {
                this.oletxEnlistment.ForceRollback(e);
                if ( DiagnosticTrace.Verbose ) 
                {
                    ExceptionConsumedTraceRecord.Trace( SR.GetString( SR.TraceSourceLtm ), 
                        e ); 
                }
            } 
            catch( TransactionInDoubtException e )
            {
                this.oletxEnlistment.EnlistmentDone();
                if ( DiagnosticTrace.Verbose ) 
                {
                    ExceptionConsumedTraceRecord.Trace( SR.GetString( SR.TraceSourceLtm ), 
                        e ); 
                }
            } 
        }


        protected override void InternalCommit() 
        {
            // Respond immediately to the TM 
            this.oletxEnlistment.EnlistmentDone(); 

            this.transaction.State.ChangeStatePromotedCommitted( this.transaction ); 
        }


        protected override void InternalRollback() 
        {
            // Respond immediately to the TM 
            this.oletxEnlistment.EnlistmentDone(); 

            this.transaction.State.ChangeStatePromotedAborted( this.transaction ); 
        }


        protected override void InternalInDoubt() 
        {
            this.transaction.State.InDoubtFromDtc( this.transaction ); 
        } 

 
        // Fanout Preprepare notifications
        public override void Prepare( IPromotedEnlistment en )
        {
            this.preparingEnlistment = en; 
            PoolablePrepare( this );
        } 
 

        public override void Commit( IPromotedEnlistment en ) 
        {
            this.oletxEnlistment = en;
            PoolableCommit( this );
        } 

 
        public override void Rollback( IPromotedEnlistment en ) 
        {
            this.oletxEnlistment = en; 
            PoolableRollback( this );
        }

 
        public override void InDoubt( IPromotedEnlistment en )
        { 
            this.oletxEnlistment = en; 
            PoolableInDoubt( this );
        } 
    }


 
    internal struct VolatileEnlistmentSet
    { 
        internal InternalEnlistment[] volatileEnlistments; 
        internal int volatileEnlistmentCount;
        internal int volatileEnlistmentSize; 
        internal int dependentClones;

        // Track the number of volatile enlistments that have prepared.
        internal int preparedVolatileEnlistments; 

        // This is a single pinpoint enlistment to represent all volatile enlistments that 
        // may exist on a promoted transaction.  This member should only be initialized if 
        // a transaction is promoted.
        private VolatileDemultiplexer volatileDemux; 
        internal VolatileDemultiplexer VolatileDemux
        {
            get
            { 
                return this.volatileDemux;
            } 
            set 
            {
                Debug.Assert( this.volatileDemux == null, "volatileDemux can only be set once." ); 
                this.volatileDemux = value;
            }
        }
    } 
}

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

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