LogWriteRestartAreaState.cs source code in C# .NET

Source code for the .NET framework in C#

                        

Code:

/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / WCF / Log / System / IO / Log / LogWriteRestartAreaState.cs / 1305376 / LogWriteRestartAreaState.cs

                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------
namespace System.IO.Log
{ 
    using System;
    using System.Collections.Generic; 
    using System.Diagnostics; 
    using System.Runtime.InteropServices;
    using System.Threading; 


    internal struct LogWriteRestartAreaState
    { 
        enum State
        { 
            Unprepared = 0, 
            Prepared,
            AwaitCompletion, 
            AwaitPolicyCompletion,
            AwaitSecondCompletion,
            Completed
        } 

        //=========================================================== 
        // Inputs 
        //===========================================================
        IList> data; 
        long totalRecordSize;
        ulong newBaseLsn;
        LogReservationCollection reservationCollection;
        LogRecordSequence recordSequence; 
        LogWriteRestartAreaAsyncResult asyncResult;
 
        //============================================================ 
        // Internal State
        //=========================================================== 
        State currentState;
        Exception exceptionResult;

        object boxedResultLsn; 
        byte[] restartArea;
        long reservationSize; 
        int flags; 

        //============================================================ 
        // Pinned State
        //============================================================
        GCHandle pinnedResultHandle;
 
        //===========================================================
        // Parameters 
        //============================================================ 
        public LogWriteRestartAreaAsyncResult AsyncResult
        { 
            /* get { return this.asyncResult; } */
            set { this.asyncResult = value; }
        }
 
        public IList> Data
        { 
            /* get { return this.data; } */ 
            set { this.data = value; }
        } 

        public ulong NewBaseLsn
        {
            /* get { return this.newBaseLsn; } */ 
            set { this.newBaseLsn = value; }
        } 
 
        public LogRecordSequence RecordSequence
        { 
            /* get { return this.recordSequence; } */
            set { this.recordSequence = value; }
        }
 
        public LogReservationCollection ReservationCollection
        { 
            /* get { return this.reservationCollection; } */ 
            set { this.reservationCollection = value; }
        } 

        public long TotalRecordSize
        {
            /* get { return this.totalRecordSize; } */ 
            set { this.totalRecordSize = value; }
        } 
 
        //===========================================================
        // Results 
        //===========================================================
        public ulong ResultLsn
        {
            get { return (ulong)(this.boxedResultLsn); } 
        }
 
        //=============================================================== 
        // Execution: State Machine
        //================================================================ 
        public void Start()
        {
            if (this.currentState != State.Unprepared)
            { 
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of 
                // log records, we failfast the process. 
                DiagnosticUtility.FailFast("Calling Start twice (write restart area)");
            } 
            Prepare();

            bool complete = false;
            try 
            {
                // We use our boxed LSN as a syncRoot, since nobody else 
                // is ever going to see it. We take the lock here to 
                // avoid ----s with IO completion.
                // 
                lock(this.boxedResultLsn)
                {
                    Pin();
 
                    this.currentState = State.AwaitCompletion;
                    uint errorCode = WriteLogRestartArea(); 
                    if (errorCode == Error.ERROR_IO_PENDING) 
                    {
                        return; 
                    }
                    else
                    {
                        AwaitCompletion_Complete(errorCode); 
                    }
 
                    // Make sure to check for completion BEFORE 
                    // leaving the lock, or there's a ---- with IO
                    // completion that may cause double-completes. 
                    //
                    complete = (this.currentState == State.Completed);
                }
            } 
#pragma warning suppress 56500 // We will be terminating the process with any exception in this call
            catch(Exception e) 
            { 
                // The code in the try block should not throw any exceptions.
                // If an exception is caught here, IO.Log may be in an unknown state. 
                // We prefer to failfast instead of risking the possibility of log corruption.
                // Any client code using IO.Log must have a recovery model that can deal
                // with appdomain and process failures.
                DiagnosticUtility.InvokeFinalHandler(e); 
            }
 
            if (complete) 
            {
                if (this.asyncResult != null) 
                {
                    this.asyncResult.Complete(true, this.exceptionResult);
                }
                else if (this.exceptionResult != null) 
                {
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(this.exceptionResult); 
                } 
            }
            else 
            {
                if (this.asyncResult == null)
                {
                    // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing 
                    // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                    // log records, we failfast the process. 
                    DiagnosticUtility.FailFast("What am I doing returning early without an AsyncResult?"); 
                }
            } 
        }

        public void IOComplete(uint errorCode)
        { 
            if (this.asyncResult == null)
            { 
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing 
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                // log records, we failfast the process. 
                DiagnosticUtility.FailFast("What am I doing in IO completion without an AsyncResult?");
            }

            try 
            {
                bool complete = false; 
 
                // We use our boxed LSN as a syncRoot, since nobody
                // else is ever going to see it. 
                //
                lock(this.boxedResultLsn)
                {
                    switch(this.currentState) 
                    {
                    case State.AwaitCompletion: 
                        AwaitCompletion_Complete(errorCode); 
                        break;
 
                    case State.AwaitPolicyCompletion:
                        AwaitPolicyCompletion_Complete(errorCode);
                        break;
 
                    case State.AwaitSecondCompletion:
                        AwaitSecondCompletion_Complete(errorCode); 
                        break; 

                    default: 

                        // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                        // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                        // log records, we failfast the process. 
                        DiagnosticUtility.FailFast("Invalid state for IO completion");
                        break; 
                    } 

                    // Make sure to check for completion BEFORE 
                    // leaving the lock, or there's a ---- with IO
                    // completion that may cause double-completes.
                    //
                    complete = (this.currentState == State.Completed); 
                }
 
                if (complete) 
                {
                    this.asyncResult.Complete(false, this.exceptionResult); 
                }
            }
#pragma warning suppress 56500 // We will be terminating the process with any exception in this call
            catch(Exception e) 
            {
                // The code in the try block should not throw any exceptions. 
                // If an exception is caught here, IO.Log may be in an unknown state. 
                // We prefer to failfast instead of risking the possibility of log corruption.
                // Any client code using IO.Log must have a recovery model that can deal 
                // with appdomain and process failures.
                DiagnosticUtility.InvokeFinalHandler(e);
            }
        } 

        void AwaitCompletion_Complete(uint errorCode) 
        { 
            Unpin();
 
            if (errorCode == Error.ERROR_SUCCESS)
            {
                Complete(null);
            } 
            else if ((errorCode == Error.ERROR_NO_SYSTEM_RESOURCES) && (this.recordSequence.RetryAppend))
            { 
                this.currentState = State.AwaitPolicyCompletion; 
                errorCode = InvokePolicyEngine();
                if (errorCode == Error.ERROR_IO_PENDING) 
                {
                    return;
                }
 
                AwaitPolicyCompletion_Complete(errorCode);
            } 
            else 
            {
                Complete(UnsafeNativeMethods.WriteLogRestartAreaFilter(errorCode)); 
            }
        }

        void AwaitPolicyCompletion_Complete(uint errorCode) 
        {
            if (errorCode == Error.ERROR_SUCCESS) 
            { 
                Pin();
 
                this.currentState = State.AwaitSecondCompletion;
                errorCode = WriteLogRestartArea();
                if (errorCode == Error.ERROR_IO_PENDING)
                { 
                    return;
                } 
 
                AwaitSecondCompletion_Complete(errorCode);
            } 
            else
            {
                Complete(UnsafeNativeMethods.WriteLogRestartAreaFilter(errorCode));
            } 
        }
 
        void AwaitSecondCompletion_Complete(uint errorCode) 
        {
            Unpin(); 

            if (errorCode == Error.ERROR_SUCCESS)
            {
                Complete(null); 
            }
            else 
            { 
                Complete(UnsafeNativeMethods.WriteLogRestartAreaFilter(errorCode));
            } 
        }

        // Get everything ready to run. Only call this once, unlike Pin.
        // 
        void Prepare()
        { 
            if (this.currentState != State.Unprepared) 
            {
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing 
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                // log records, we failfast the process.
                DiagnosticUtility.FailFast("Calling Prepare Twice");
            } 

            // Box the result LSN. 
            // 
            ulong resultLsn = 0;
            this.boxedResultLsn = (object)(resultLsn); 

            // Determine if we are writing from reservation.
            // Get the best matching reservation if so. Allocate padding
            // if necessary. 
            //
            int paddingSize = 0; 
            if (this.reservationCollection != null) 
            {
                this.reservationSize = this.reservationCollection.GetMatchingReservation(this.totalRecordSize); 
                if (this.reservationSize < this.totalRecordSize)
                {
                    // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                    // Rather than proceeding with non-deterministic execution and risking the loss or corruption of 
                    // log records, we failfast the process.
                    DiagnosticUtility.FailFast("Somehow got a smaller reservation"); 
                } 
                if (this.reservationSize <= 0)
                { 
                    // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                    // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                    // log records, we failfast the process.
                    DiagnosticUtility.FailFast("Reservation size must be bigger than zero"); 
                }
 
                paddingSize = checked((int)(this.reservationSize - 
                                            this.totalRecordSize));
                this.flags = Const.CLFS_FLAG_USE_RESERVATION; 
            }

            // Allocate a new LogLogRecordHeader and set it up
            // correctly. 
            //
            byte[] headerBytes = new byte[LogLogRecordHeader.Size + paddingSize]; 
            LogLogRecordHeader header = new LogLogRecordHeader(headerBytes); 
            header.MajorVersion = LogLogRecordHeader.CurrentMajorVersion;
            header.MinorVersion = LogLogRecordHeader.CurrentMinorVersion; 
            header.Padding = (paddingSize != 0);
            if (paddingSize != 0)
            {
                LogLogRecordHeader.EncodePaddingSize(headerBytes, 
                                                     LogLogRecordHeader.Size,
                                                     paddingSize); 
            } 

            // Now we write-gather here, since WriteLogRestartArea does 
            // not support write-gather.
            //
            // (NOTE: totalRecordSize includes the size of the header,
            //        for consistency with reservations...) 
            //
            long restartAreaSize = this.totalRecordSize + paddingSize; 
            this.restartArea = new byte[restartAreaSize]; 
            restartAreaSize = 0;
 
            Array.Copy(header.Bits,
                       0,
                       this.restartArea,
                       restartAreaSize, 
                       header.Bits.Length);
            restartAreaSize += header.Bits.Length; 
 
            for (int i = 0; i < this.data.Count; i++)
            { 
                ArraySegment segment = this.data[i];

                Array.Copy(segment.Array,
                           segment.Offset, 
                           this.restartArea,
                           restartAreaSize, 
                           segment.Count); 
                restartAreaSize += segment.Count;
            } 

            if (restartAreaSize != this.restartArea.Length)
            {
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing 
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                // log records, we failfast the process. 
                DiagnosticUtility.FailFast("Did not do restartArea gather correctly"); 
            }
 
            this.currentState = State.Prepared;
        }

        void Pin() 
        {
            if (this.pinnedResultHandle.IsAllocated) 
            { 
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of 
                // log records, we failfast the process.
                DiagnosticUtility.FailFast("Already pinned");
            }
 
            this.pinnedResultHandle = GCHandle.Alloc(this.boxedResultLsn,
                                                     GCHandleType.Pinned); 
        } 

        void Unpin() 
        {
            if (!this.pinnedResultHandle.IsAllocated)
            {
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing 
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                // log records, we failfast the process. 
                DiagnosticUtility.FailFast("Already unpinned"); 
            }
 
            this.pinnedResultHandle.Free();
        }

        // Finish up. Synchronize the reservation collection, in the 
        // case of failure and success, capture the error (if any),
        // and change state to completed. 
        // 
        void Complete(Exception error)
        { 
            if (this.pinnedResultHandle.IsAllocated)
            {
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of 
                // log records, we failfast the process.
                DiagnosticUtility.FailFast("Must unpin before completing"); 
            } 

            if (error != null) 
            {
                // If we were writing from reservation, then we need
                // to put the reservation back...
                // 
                if (this.reservationCollection != null)
                { 
                    this.reservationCollection.InternalAddReservation(this.reservationSize); 
                    this.reservationSize = 0;
                } 
            }

            this.exceptionResult = error;
            this.currentState = State.Completed; 
        }
 
        uint WriteLogRestartArea() 
        {
            uint errorCode = Error.ERROR_SUCCESS; 

            // Ensure we are packed now
            //
            if (this.asyncResult != null) 
            {
                this.asyncResult.Pack(this.boxedResultLsn); 
            } 

            try 
            {
                unsafe
                {
                    NativeOverlapped* overlapped; 
                    if (this.asyncResult != null)
                    { 
                        overlapped = this.asyncResult.NativeOverlapped; 
                        if (overlapped == null)
                        { 
                            // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                            // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                            // log records, we failfast the process.
                            DiagnosticUtility.FailFast("Should have packed the async result already"); 
                        }
                    } 
                    else 
                    {
                        overlapped = null; 
                    }

                    fixed (byte* pRestartArea = this.restartArea)
                    { 
                        if (this.newBaseLsn != UInt64.MaxValue)
                        { 
                            errorCode = UnsafeNativeMethods.WriteLogRestartArea( 
                                this.recordSequence.MarshalContext,
                                pRestartArea, 
                                this.restartArea.Length,
                                ref this.newBaseLsn,
                                this.flags,
                                IntPtr.Zero, 
                                this.pinnedResultHandle.AddrOfPinnedObject(),
                                overlapped); 
                        } 
                        else
                        { 
                            errorCode = UnsafeNativeMethods.WriteLogRestartAreaNoBase(
                                this.recordSequence.MarshalContext,
                                pRestartArea,
                                this.restartArea.Length, 
                                this.flags,
                                IntPtr.Zero, 
                                this.pinnedResultHandle.AddrOfPinnedObject(), 
                                overlapped);
                        } 
                    }
                }
            }
            finally 
            {
                if (this.asyncResult != null && 
                    errorCode != Error.ERROR_IO_PENDING) 
                {
                    this.asyncResult.Free(); 
                }
            }

            return errorCode; 
        }
 
        uint InvokePolicyEngine() 
        {
            HandleLogFullCallback callback = null; 
            if (this.asyncResult != null)
            {
                callback = new HandleLogFullCallback(this.asyncResult.IOCompleted);
            } 

            LogManagementAsyncResult logManagement; 
            logManagement = this.recordSequence.LogStore.LogManagement; 

            return logManagement.HandleLogFull(callback); 
        }
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------
namespace System.IO.Log
{ 
    using System;
    using System.Collections.Generic; 
    using System.Diagnostics; 
    using System.Runtime.InteropServices;
    using System.Threading; 


    internal struct LogWriteRestartAreaState
    { 
        enum State
        { 
            Unprepared = 0, 
            Prepared,
            AwaitCompletion, 
            AwaitPolicyCompletion,
            AwaitSecondCompletion,
            Completed
        } 

        //=========================================================== 
        // Inputs 
        //===========================================================
        IList> data; 
        long totalRecordSize;
        ulong newBaseLsn;
        LogReservationCollection reservationCollection;
        LogRecordSequence recordSequence; 
        LogWriteRestartAreaAsyncResult asyncResult;
 
        //============================================================ 
        // Internal State
        //=========================================================== 
        State currentState;
        Exception exceptionResult;

        object boxedResultLsn; 
        byte[] restartArea;
        long reservationSize; 
        int flags; 

        //============================================================ 
        // Pinned State
        //============================================================
        GCHandle pinnedResultHandle;
 
        //===========================================================
        // Parameters 
        //============================================================ 
        public LogWriteRestartAreaAsyncResult AsyncResult
        { 
            /* get { return this.asyncResult; } */
            set { this.asyncResult = value; }
        }
 
        public IList> Data
        { 
            /* get { return this.data; } */ 
            set { this.data = value; }
        } 

        public ulong NewBaseLsn
        {
            /* get { return this.newBaseLsn; } */ 
            set { this.newBaseLsn = value; }
        } 
 
        public LogRecordSequence RecordSequence
        { 
            /* get { return this.recordSequence; } */
            set { this.recordSequence = value; }
        }
 
        public LogReservationCollection ReservationCollection
        { 
            /* get { return this.reservationCollection; } */ 
            set { this.reservationCollection = value; }
        } 

        public long TotalRecordSize
        {
            /* get { return this.totalRecordSize; } */ 
            set { this.totalRecordSize = value; }
        } 
 
        //===========================================================
        // Results 
        //===========================================================
        public ulong ResultLsn
        {
            get { return (ulong)(this.boxedResultLsn); } 
        }
 
        //=============================================================== 
        // Execution: State Machine
        //================================================================ 
        public void Start()
        {
            if (this.currentState != State.Unprepared)
            { 
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of 
                // log records, we failfast the process. 
                DiagnosticUtility.FailFast("Calling Start twice (write restart area)");
            } 
            Prepare();

            bool complete = false;
            try 
            {
                // We use our boxed LSN as a syncRoot, since nobody else 
                // is ever going to see it. We take the lock here to 
                // avoid ----s with IO completion.
                // 
                lock(this.boxedResultLsn)
                {
                    Pin();
 
                    this.currentState = State.AwaitCompletion;
                    uint errorCode = WriteLogRestartArea(); 
                    if (errorCode == Error.ERROR_IO_PENDING) 
                    {
                        return; 
                    }
                    else
                    {
                        AwaitCompletion_Complete(errorCode); 
                    }
 
                    // Make sure to check for completion BEFORE 
                    // leaving the lock, or there's a ---- with IO
                    // completion that may cause double-completes. 
                    //
                    complete = (this.currentState == State.Completed);
                }
            } 
#pragma warning suppress 56500 // We will be terminating the process with any exception in this call
            catch(Exception e) 
            { 
                // The code in the try block should not throw any exceptions.
                // If an exception is caught here, IO.Log may be in an unknown state. 
                // We prefer to failfast instead of risking the possibility of log corruption.
                // Any client code using IO.Log must have a recovery model that can deal
                // with appdomain and process failures.
                DiagnosticUtility.InvokeFinalHandler(e); 
            }
 
            if (complete) 
            {
                if (this.asyncResult != null) 
                {
                    this.asyncResult.Complete(true, this.exceptionResult);
                }
                else if (this.exceptionResult != null) 
                {
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(this.exceptionResult); 
                } 
            }
            else 
            {
                if (this.asyncResult == null)
                {
                    // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing 
                    // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                    // log records, we failfast the process. 
                    DiagnosticUtility.FailFast("What am I doing returning early without an AsyncResult?"); 
                }
            } 
        }

        public void IOComplete(uint errorCode)
        { 
            if (this.asyncResult == null)
            { 
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing 
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                // log records, we failfast the process. 
                DiagnosticUtility.FailFast("What am I doing in IO completion without an AsyncResult?");
            }

            try 
            {
                bool complete = false; 
 
                // We use our boxed LSN as a syncRoot, since nobody
                // else is ever going to see it. 
                //
                lock(this.boxedResultLsn)
                {
                    switch(this.currentState) 
                    {
                    case State.AwaitCompletion: 
                        AwaitCompletion_Complete(errorCode); 
                        break;
 
                    case State.AwaitPolicyCompletion:
                        AwaitPolicyCompletion_Complete(errorCode);
                        break;
 
                    case State.AwaitSecondCompletion:
                        AwaitSecondCompletion_Complete(errorCode); 
                        break; 

                    default: 

                        // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                        // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                        // log records, we failfast the process. 
                        DiagnosticUtility.FailFast("Invalid state for IO completion");
                        break; 
                    } 

                    // Make sure to check for completion BEFORE 
                    // leaving the lock, or there's a ---- with IO
                    // completion that may cause double-completes.
                    //
                    complete = (this.currentState == State.Completed); 
                }
 
                if (complete) 
                {
                    this.asyncResult.Complete(false, this.exceptionResult); 
                }
            }
#pragma warning suppress 56500 // We will be terminating the process with any exception in this call
            catch(Exception e) 
            {
                // The code in the try block should not throw any exceptions. 
                // If an exception is caught here, IO.Log may be in an unknown state. 
                // We prefer to failfast instead of risking the possibility of log corruption.
                // Any client code using IO.Log must have a recovery model that can deal 
                // with appdomain and process failures.
                DiagnosticUtility.InvokeFinalHandler(e);
            }
        } 

        void AwaitCompletion_Complete(uint errorCode) 
        { 
            Unpin();
 
            if (errorCode == Error.ERROR_SUCCESS)
            {
                Complete(null);
            } 
            else if ((errorCode == Error.ERROR_NO_SYSTEM_RESOURCES) && (this.recordSequence.RetryAppend))
            { 
                this.currentState = State.AwaitPolicyCompletion; 
                errorCode = InvokePolicyEngine();
                if (errorCode == Error.ERROR_IO_PENDING) 
                {
                    return;
                }
 
                AwaitPolicyCompletion_Complete(errorCode);
            } 
            else 
            {
                Complete(UnsafeNativeMethods.WriteLogRestartAreaFilter(errorCode)); 
            }
        }

        void AwaitPolicyCompletion_Complete(uint errorCode) 
        {
            if (errorCode == Error.ERROR_SUCCESS) 
            { 
                Pin();
 
                this.currentState = State.AwaitSecondCompletion;
                errorCode = WriteLogRestartArea();
                if (errorCode == Error.ERROR_IO_PENDING)
                { 
                    return;
                } 
 
                AwaitSecondCompletion_Complete(errorCode);
            } 
            else
            {
                Complete(UnsafeNativeMethods.WriteLogRestartAreaFilter(errorCode));
            } 
        }
 
        void AwaitSecondCompletion_Complete(uint errorCode) 
        {
            Unpin(); 

            if (errorCode == Error.ERROR_SUCCESS)
            {
                Complete(null); 
            }
            else 
            { 
                Complete(UnsafeNativeMethods.WriteLogRestartAreaFilter(errorCode));
            } 
        }

        // Get everything ready to run. Only call this once, unlike Pin.
        // 
        void Prepare()
        { 
            if (this.currentState != State.Unprepared) 
            {
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing 
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                // log records, we failfast the process.
                DiagnosticUtility.FailFast("Calling Prepare Twice");
            } 

            // Box the result LSN. 
            // 
            ulong resultLsn = 0;
            this.boxedResultLsn = (object)(resultLsn); 

            // Determine if we are writing from reservation.
            // Get the best matching reservation if so. Allocate padding
            // if necessary. 
            //
            int paddingSize = 0; 
            if (this.reservationCollection != null) 
            {
                this.reservationSize = this.reservationCollection.GetMatchingReservation(this.totalRecordSize); 
                if (this.reservationSize < this.totalRecordSize)
                {
                    // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                    // Rather than proceeding with non-deterministic execution and risking the loss or corruption of 
                    // log records, we failfast the process.
                    DiagnosticUtility.FailFast("Somehow got a smaller reservation"); 
                } 
                if (this.reservationSize <= 0)
                { 
                    // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                    // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                    // log records, we failfast the process.
                    DiagnosticUtility.FailFast("Reservation size must be bigger than zero"); 
                }
 
                paddingSize = checked((int)(this.reservationSize - 
                                            this.totalRecordSize));
                this.flags = Const.CLFS_FLAG_USE_RESERVATION; 
            }

            // Allocate a new LogLogRecordHeader and set it up
            // correctly. 
            //
            byte[] headerBytes = new byte[LogLogRecordHeader.Size + paddingSize]; 
            LogLogRecordHeader header = new LogLogRecordHeader(headerBytes); 
            header.MajorVersion = LogLogRecordHeader.CurrentMajorVersion;
            header.MinorVersion = LogLogRecordHeader.CurrentMinorVersion; 
            header.Padding = (paddingSize != 0);
            if (paddingSize != 0)
            {
                LogLogRecordHeader.EncodePaddingSize(headerBytes, 
                                                     LogLogRecordHeader.Size,
                                                     paddingSize); 
            } 

            // Now we write-gather here, since WriteLogRestartArea does 
            // not support write-gather.
            //
            // (NOTE: totalRecordSize includes the size of the header,
            //        for consistency with reservations...) 
            //
            long restartAreaSize = this.totalRecordSize + paddingSize; 
            this.restartArea = new byte[restartAreaSize]; 
            restartAreaSize = 0;
 
            Array.Copy(header.Bits,
                       0,
                       this.restartArea,
                       restartAreaSize, 
                       header.Bits.Length);
            restartAreaSize += header.Bits.Length; 
 
            for (int i = 0; i < this.data.Count; i++)
            { 
                ArraySegment segment = this.data[i];

                Array.Copy(segment.Array,
                           segment.Offset, 
                           this.restartArea,
                           restartAreaSize, 
                           segment.Count); 
                restartAreaSize += segment.Count;
            } 

            if (restartAreaSize != this.restartArea.Length)
            {
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing 
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                // log records, we failfast the process. 
                DiagnosticUtility.FailFast("Did not do restartArea gather correctly"); 
            }
 
            this.currentState = State.Prepared;
        }

        void Pin() 
        {
            if (this.pinnedResultHandle.IsAllocated) 
            { 
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of 
                // log records, we failfast the process.
                DiagnosticUtility.FailFast("Already pinned");
            }
 
            this.pinnedResultHandle = GCHandle.Alloc(this.boxedResultLsn,
                                                     GCHandleType.Pinned); 
        } 

        void Unpin() 
        {
            if (!this.pinnedResultHandle.IsAllocated)
            {
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing 
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                // log records, we failfast the process. 
                DiagnosticUtility.FailFast("Already unpinned"); 
            }
 
            this.pinnedResultHandle.Free();
        }

        // Finish up. Synchronize the reservation collection, in the 
        // case of failure and success, capture the error (if any),
        // and change state to completed. 
        // 
        void Complete(Exception error)
        { 
            if (this.pinnedResultHandle.IsAllocated)
            {
                // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                // Rather than proceeding with non-deterministic execution and risking the loss or corruption of 
                // log records, we failfast the process.
                DiagnosticUtility.FailFast("Must unpin before completing"); 
            } 

            if (error != null) 
            {
                // If we were writing from reservation, then we need
                // to put the reservation back...
                // 
                if (this.reservationCollection != null)
                { 
                    this.reservationCollection.InternalAddReservation(this.reservationSize); 
                    this.reservationSize = 0;
                } 
            }

            this.exceptionResult = error;
            this.currentState = State.Completed; 
        }
 
        uint WriteLogRestartArea() 
        {
            uint errorCode = Error.ERROR_SUCCESS; 

            // Ensure we are packed now
            //
            if (this.asyncResult != null) 
            {
                this.asyncResult.Pack(this.boxedResultLsn); 
            } 

            try 
            {
                unsafe
                {
                    NativeOverlapped* overlapped; 
                    if (this.asyncResult != null)
                    { 
                        overlapped = this.asyncResult.NativeOverlapped; 
                        if (overlapped == null)
                        { 
                            // An internal consistency check has failed. The indicates a bug in IO.Log's internal processing
                            // Rather than proceeding with non-deterministic execution and risking the loss or corruption of
                            // log records, we failfast the process.
                            DiagnosticUtility.FailFast("Should have packed the async result already"); 
                        }
                    } 
                    else 
                    {
                        overlapped = null; 
                    }

                    fixed (byte* pRestartArea = this.restartArea)
                    { 
                        if (this.newBaseLsn != UInt64.MaxValue)
                        { 
                            errorCode = UnsafeNativeMethods.WriteLogRestartArea( 
                                this.recordSequence.MarshalContext,
                                pRestartArea, 
                                this.restartArea.Length,
                                ref this.newBaseLsn,
                                this.flags,
                                IntPtr.Zero, 
                                this.pinnedResultHandle.AddrOfPinnedObject(),
                                overlapped); 
                        } 
                        else
                        { 
                            errorCode = UnsafeNativeMethods.WriteLogRestartAreaNoBase(
                                this.recordSequence.MarshalContext,
                                pRestartArea,
                                this.restartArea.Length, 
                                this.flags,
                                IntPtr.Zero, 
                                this.pinnedResultHandle.AddrOfPinnedObject(), 
                                overlapped);
                        } 
                    }
                }
            }
            finally 
            {
                if (this.asyncResult != null && 
                    errorCode != Error.ERROR_IO_PENDING) 
                {
                    this.asyncResult.Free(); 
                }
            }

            return errorCode; 
        }
 
        uint InvokePolicyEngine() 
        {
            HandleLogFullCallback callback = null; 
            if (this.asyncResult != null)
            {
                callback = new HandleLogFullCallback(this.asyncResult.IOCompleted);
            } 

            LogManagementAsyncResult logManagement; 
            logManagement = this.recordSequence.LogStore.LogManagement; 

            return logManagement.HandleLogFull(callback); 
        }
    }
}

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

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