LogRecordSequence.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 / LogRecordSequence.cs / 1305376 / LogRecordSequence.cs

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

    public sealed class LogRecordSequence : IRecordSequence 
    { 
        const uint INFINITE = 0xFFFFFFFF;
 
        const int DefaultWriteBufferCount = 10;
        const int DefaultReadBufferCount = unchecked((int)INFINITE);
        const int DefaultBufferSize = 64 * 1024;
 
        // This is just a common-sense buffer size, to prevent
        // accidental integer overflow and such. 
        // 
        const int MaxBufferSize = 0x40000000;
 
        const int CLFS_SECTOR_SIZE = 0x00000200;
        const int CLFS_SECTOR_ALIGN = (CLFS_SECTOR_SIZE-1);

        LogStore store; 
        int bufferSize;
        int writeBufferCount; 
        bool ownStore; 
        bool retryAppend;
 
        SafeMarshalContext marshalContext;

        // The LogStore constructor will demand full trust, so we don't have to.
        public LogRecordSequence( 
            string path,
            FileMode mode) 
        { 
            this.store = new LogStore(path, mode);
            this.ownStore = true; 

            this.bufferSize = GetBufferSize(DefaultBufferSize);
            this.writeBufferCount = DefaultWriteBufferCount;
        } 

        // The LogStore constructor will demand full trust, so we don't have to. 
        public LogRecordSequence( 
            string path,
            FileMode mode, 
            FileAccess access)
        {
            this.store = new LogStore(path, mode, access);
            this.ownStore = true; 

            this.bufferSize = GetBufferSize(DefaultBufferSize); 
            this.writeBufferCount = DefaultWriteBufferCount; 
        }
 
        // The LogStore constructor will demand full trust, so we don't have to.
        public LogRecordSequence(
            string path,
            FileMode mode, 
            FileAccess access,
            FileShare share) 
        { 
            this.store = new LogStore(path, mode, access, share);
            this.ownStore = true; 

            this.bufferSize = GetBufferSize(DefaultBufferSize);
            this.writeBufferCount = DefaultWriteBufferCount;
        } 

        // The LogStore constructor will demand full trust, so we don't have to. 
        public LogRecordSequence( 
            string path,
            FileMode mode, 
            FileAccess access,
            FileShare share,
            int bufferSize,
            int bufferCount) 
        {
            if (bufferSize <= 0) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferSize")); 
            if (bufferCount <= 0)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferCount")); 

            this.store = new LogStore(path, mode, access, share);
            this.ownStore = true;
 
            this.bufferSize = GetBufferSize(bufferSize);
            this.writeBufferCount = bufferCount; 
        } 

        // The LogStore constructor will demand full trust, so we don't have to. 
        public LogRecordSequence(
            string path,
            FileMode mode,
            FileAccess access, 
            FileShare share,
            int bufferSize, 
            int bufferCount, 
            FileSecurity fileSecurity)
        { 
            if (bufferSize <= 0)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferSize"));
            if (bufferCount <= 0)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferCount")); 

            this.store = new LogStore(path, 
                                      mode, 
                                      access,
                                      share, 
                                      fileSecurity);
            this.ownStore = true;

            this.bufferSize = GetBufferSize(bufferSize); 
            this.writeBufferCount = bufferCount;
        } 
 
        [PermissionSetAttribute(SecurityAction.Demand, Name="FullTrust")]
        public LogRecordSequence(LogStore logStore) 
        {
            if (logStore == null)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("logStore"));
 
            this.store = logStore;
            this.ownStore = false; 
 
            this.bufferSize = GetBufferSize(DefaultBufferSize);
            this.writeBufferCount = DefaultWriteBufferCount; 
        }

        [PermissionSetAttribute(SecurityAction.Demand, Name="FullTrust")]
        public LogRecordSequence( 
            LogStore logStore,
            int bufferSize, 
            int bufferCount) 
        {
            if (logStore == null) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("logStore"));

            if (bufferSize <= 0)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferSize")); 
            if (bufferCount <= 0)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferCount")); 
 
            this.store = logStore;
            this.ownStore = false; 

            this.bufferSize = GetBufferSize(bufferSize);
            this.writeBufferCount = bufferCount;
        } 

        public SequenceNumber BaseSequenceNumber 
        { 
            get
            { 
                return this.store.BaseSequenceNumber;
            }
        }
 
        public SequenceNumber LastSequenceNumber
        { 
            get 
            {
                return this.store.LastSequenceNumber; 
            }
        }

        public LogStore LogStore 
        {
            get 
            { 
                return this.store;
            } 
        }

        internal SafeMarshalContext MarshalContext
        { 
            get
            { 
                EnsureMarshalContext(); 
                return this.marshalContext;
            } 
        }

        internal SafeMarshalContext InternalMarshalContext
        { 
            get
            { 
                return this.marshalContext; 
            }
        } 

        public long MaximumRecordLength
        {
            get 
            {
                return this.bufferSize - LogLogRecordHeader.Size; 
            } 
        }
 
        public long ReservedBytes
        {
            get
            { 
                CLFS_INFORMATION info;
                this.store.GetLogFileInformation(out info); 
 
                return checked((long)(info.TotalUndoCommitment));
            } 
        }

        public bool RetryAppend
        { 
            get
            { 
                return this.retryAppend; 
            }
 
            set
            {
                this.retryAppend = value;
            } 
        }
 
        public SequenceNumber RestartSequenceNumber 
        {
            get 
            {
                CLFS_INFORMATION info;
                this.store.GetLogFileInformation(out info);
 
                if(info.RestartLsn == Const.CLFS_LSN_INVALID)
                    return SequenceNumber.Invalid; 
 
                return new SequenceNumber(info.RestartLsn);
            } 
        }

        public event EventHandler TailPinned
        { 
            add
            { 
                this.store.LogManagement.TailPinned += value; 
            }
 
            remove
            {
                this.store.LogManagement.TailPinned -= value;
            } 
        }
 
        public void AdvanceBaseSequenceNumber( 
            SequenceNumber newBaseSequenceNumber)
        { 
            this.store.ValidateSequenceNumber(
                ref newBaseSequenceNumber,
                SequenceNumberConstraint.Arbitrary,
                "newBaseSequenceNumber"); 

            ulong newBaseLsn = newBaseSequenceNumber.High; 
 
            EnsureMarshalContext();
 
            UnsafeNativeMethods.AdvanceLogBaseSync(this.marshalContext,
                                                   ref newBaseLsn,
                                                   0);
        } 

        public SequenceNumber Append( 
            ArraySegment data, 
            SequenceNumber nextUndoRecord,
            SequenceNumber previousRecord, 
            RecordAppendOptions recordAppendOptions)
        {
            return Append(new ArraySegment[] { data },
                          nextUndoRecord, 
                          previousRecord,
                          recordAppendOptions); 
        } 

 
        public SequenceNumber Append(
            ArraySegment data,
            SequenceNumber nextUndoRecord,
            SequenceNumber previousRecord, 
            RecordAppendOptions recordAppendOptions,
            ReservationCollection reservations) 
        { 
            return Append(new ArraySegment[] { data },
                          nextUndoRecord, 
                          previousRecord,
                          recordAppendOptions,
                          reservations);
        } 

        public SequenceNumber Append( 
            IList> data, 
            SequenceNumber userRecord,
            SequenceNumber previousRecord, 
            RecordAppendOptions recordAppendOptions)
        {
            return Append(
                data, 
                userRecord,
                previousRecord, 
                recordAppendOptions, 
                null);
        } 

        public SequenceNumber Append(
            IList> data,
            SequenceNumber userRecord, 
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions, 
            ReservationCollection reservations) 
        {
            long totalRecordSize; 
            LogReservationCollection lrc;

            if ((this.store.Access & FileAccess.Write) == 0)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.NotSupported(SR.NotSupported_ReadOnly));
            } 
 
            if(recordAppendOptions > (RecordAppendOptions.ForceAppend | RecordAppendOptions.ForceFlush) ||
               recordAppendOptions < RecordAppendOptions.None) 
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("recordAppendOptions"));
            }
 
            this.store.ValidateSequenceNumber(
                ref userRecord, 
                SequenceNumberConstraint.Arbitrary, 
                "userRecord");
            this.store.ValidateSequenceNumber( 
                ref previousRecord,
                SequenceNumberConstraint.Arbitrary,
                "previousRecord");
 
            totalRecordSize = ValidateData(data);
            lrc = ValidateReservationCollection(reservations); 
 
            EnsureMarshalContext();
 
            LogReserveAndAppendState state = new LogReserveAndAppendState();

            state.RecordSequence = this;
            state.Data = data; 
            state.TotalRecordSize = totalRecordSize;
            state.UserLsn = userRecord.High; 
            state.PreviousLsn = previousRecord.High; 
            state.RecordAppendOptions = recordAppendOptions;
            state.ReservationCollection = lrc; 

            state.Start();

            return new SequenceNumber(state.ResultLsn); 
        }
 
        public IAsyncResult BeginAppend( 
            ArraySegment data,
            SequenceNumber nextUndoRecord, 
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions,
            AsyncCallback callback,
            object state) 
        {
            return BeginAppend(new ArraySegment[] { data }, 
                               nextUndoRecord, 
                               previousRecord,
                               recordAppendOptions, 
                               callback,
                               state);
        }
 
        public IAsyncResult BeginAppend(
            ArraySegment data, 
            SequenceNumber nextUndoRecord, 
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions, 
            ReservationCollection reservations,
            AsyncCallback callback,
            object state)
        { 
            return BeginAppend(new ArraySegment[] { data },
                               nextUndoRecord, 
                               previousRecord, 
                               recordAppendOptions,
                               reservations, 
                               callback,
                               state);
        }
 
        public IAsyncResult BeginAppend(
            IList> data, 
            SequenceNumber userRecord, 
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions, 
            AsyncCallback callback,
            object state)
        {
            return BeginAppend( 
                data,
                userRecord, 
                previousRecord, 
                recordAppendOptions,
                null, 
                callback,
                state);
        }
 
        public IAsyncResult BeginAppend(
            IList> data, 
            SequenceNumber userRecord, 
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions, 
            ReservationCollection reservations,
            AsyncCallback callback,
            object state)
        { 
            long totalRecordSize;
            LogReservationCollection lrc; 
 
            if ((this.store.Access & FileAccess.Write) == 0)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.NotSupported(SR.NotSupported_ReadOnly));
            }

            if(recordAppendOptions > (RecordAppendOptions.ForceAppend | RecordAppendOptions.ForceFlush) || 
               recordAppendOptions < RecordAppendOptions.None)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("recordAppendOptions")); 
            }
 
            this.store.ValidateSequenceNumber(
                ref userRecord,
                SequenceNumberConstraint.Arbitrary,
                "userRecord"); 
            this.store.ValidateSequenceNumber(
                ref previousRecord, 
                SequenceNumberConstraint.Arbitrary, 
                "previousRecord");
 
            totalRecordSize = ValidateData(data);
            lrc = ValidateReservationCollection(reservations);

            EnsureMarshalContext(); 

            LogAppendAsyncResult result = new LogAppendAsyncResult(this, 
                                                                   callback, 
                                                                   state);
            result.Data = data; 
            result.TotalRecordSize = totalRecordSize;
            result.UserLsn = userRecord.High;
            result.PreviousLsn = previousRecord.High;
            result.RecordAppendOptions = recordAppendOptions; 
            result.ReservationCollection = lrc;
 
            result.Start(); 

            return result; 
        }

        public IAsyncResult BeginFlush(
            SequenceNumber sequenceNumber, 
            AsyncCallback callback,
            object state) 
        { 
            this.store.ValidateSequenceNumber(
                ref sequenceNumber, 
                SequenceNumberConstraint.Arbitrary,
                "sequenceNumber");

            EnsureMarshalContext(); 

            LogFlushAsyncResult flushResult = new LogFlushAsyncResult(this, 
                                                                      callback, 
                                                                      state);
            if (sequenceNumber == SequenceNumber.Invalid) 
            {
                flushResult.SequenceNumber = 0;
            }
            else 
            {
                flushResult.SequenceNumber = sequenceNumber.High; 
            } 

            flushResult.Start(); 
            return flushResult;
        }

        public IAsyncResult BeginReserveAndAppend( 
            ArraySegment data,
            SequenceNumber nextUndoRecord, 
            SequenceNumber previousRecord, 
            RecordAppendOptions recordAppendOptions,
            ReservationCollection reservationCollection, 
            long[] reservations,
            AsyncCallback callback,
            object state)
        { 
            return BeginReserveAndAppend(new ArraySegment[] { data },
                                         nextUndoRecord, 
                                         previousRecord, 
                                         recordAppendOptions,
                                         reservationCollection, 
                                         reservations,
                                         callback,
                                         state);
        } 

        public IAsyncResult BeginReserveAndAppend( 
            IList> data, 
            SequenceNumber userRecord,
            SequenceNumber previousRecord, 
            RecordAppendOptions recordAppendOptions,
            ReservationCollection reservationCollection,
            long[] reservations,
            AsyncCallback callback, 
            object state)
        { 
            long totalRecordSize; 
            LogReservationCollection lrc;
 
            this.store.ValidateSequenceNumber(
                ref userRecord,
                SequenceNumberConstraint.Arbitrary,
                "userRecord"); 
            this.store.ValidateSequenceNumber(
                ref previousRecord, 
                SequenceNumberConstraint.Arbitrary, 
                "previousRecord");
 
            if (reservationCollection == null)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("reservationCollection"));
            } 
            if (reservations == null)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("reservations")); 
            }
            ValidateReservations(reservations); 

            totalRecordSize = ValidateData(data);
            lrc = ValidateReservationCollection(reservationCollection);
 
            EnsureMarshalContext();
 
            LogAppendAsyncResult result = new LogAppendAsyncResult(this, 
                                                                   callback,
                                                                   state); 
            result.Data = data;
            result.TotalRecordSize = totalRecordSize;
            result.UserLsn = userRecord.High;
            result.PreviousLsn = previousRecord.High; 
            result.RecordAppendOptions = recordAppendOptions;
            result.ReservationCollection = lrc; 
            result.Reservations = reservations; 

            result.Start(); 

            return result;
        }
 
        public IAsyncResult BeginWriteRestartArea(
            ArraySegment data, 
            SequenceNumber newBaseSeqNum, 
            ReservationCollection reservation,
            AsyncCallback callback, 
            object state)
        {
            return BeginWriteRestartArea(new ArraySegment[] { data },
                                         newBaseSeqNum, 
                                         reservation,
                                         callback, 
                                         state); 
        }
 
        public IAsyncResult BeginWriteRestartArea(
            IList> data,
            SequenceNumber newBaseSeqNum,
            ReservationCollection reservationCollection, 
            AsyncCallback callback,
            object state) 
        { 
            long totalRecordSize;
            LogReservationCollection lrc; 

            this.store.ValidateSequenceNumber(
                ref newBaseSeqNum,
                SequenceNumberConstraint.Arbitrary, 
                "newBaseSeqNum");
 
            totalRecordSize = ValidateData(data); 
            lrc = ValidateReservationCollection(reservationCollection);
 
            EnsureMarshalContext();

            LogWriteRestartAreaAsyncResult result;
            result = new LogWriteRestartAreaAsyncResult(this, 
                                                        callback,
                                                        state); 
            result.Data = data; 
            result.TotalRecordSize = totalRecordSize;
            result.NewBaseLsn = newBaseSeqNum.High; 
            result.ReservationCollection = lrc;

            result.Start();
 
            return result;
        } 
 
        public ReservationCollection CreateReservationCollection()
        { 
            return new LogReservationCollection(this);
        }

        public void Dispose() 
        {
            if ((this.marshalContext != null) && 
                (!this.marshalContext.IsInvalid)) 
            {
                this.marshalContext.Close(); 
            }

            if (this.ownStore)
                this.store.Dispose(); 
        }
 
        public SequenceNumber EndAppend( 
            IAsyncResult result)
        { 
            LogAppendAsyncResult lar = result as LogAppendAsyncResult;
            if (lar == null)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.InvalidAsyncResult());
 
            // Having some reservations to make is a requirement of
            // calling BeginReserveAndAppend, so if we have some, we 
            // know this is not our AsyncResult. 
            //
            if (lar.Reservations != null) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.InvalidAsyncResult());

            lar.End();
 
            return new SequenceNumber(lar.ResultLsn);
        } 
 
        public SequenceNumber EndFlush(
            IAsyncResult result) 
        {
            LogFlushAsyncResult lar = result as LogFlushAsyncResult;
            if (lar == null)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.InvalidAsyncResult()); 

            lar.End(); 
 
            return new SequenceNumber(lar.ResultLsn);
        } 

        public SequenceNumber EndReserveAndAppend(
            IAsyncResult result)
        { 
            LogAppendAsyncResult lar = result as LogAppendAsyncResult;
            if (lar == null) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.InvalidAsyncResult()); 

            // Having some reservations to make is a requirement of 
            // calling BeginReserveAndAppend, so if we have none, we
            // know this is an AsyncResult for some OTHER method.
            //
            if (lar.Reservations == null) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.InvalidAsyncResult());
 
            lar.End(); 

            return new SequenceNumber(lar.ResultLsn); 
        }

        public SequenceNumber EndWriteRestartArea(
            IAsyncResult result) 
        {
            LogWriteRestartAreaAsyncResult lar = result as LogWriteRestartAreaAsyncResult; 
            if (lar == null) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.InvalidAsyncResult());
 
            lar.End();

            return new SequenceNumber(lar.ResultLsn);
        } 

        public SequenceNumber Flush() 
        { 
            return Flush(SequenceNumber.Invalid);
        } 

        public SequenceNumber Flush(SequenceNumber sequenceNumber)
        {
            this.store.ValidateSequenceNumber( 
                ref sequenceNumber,
                SequenceNumberConstraint.Arbitrary, 
                "sequenceNumber"); 

            ulong resultLsn; 
            ulong lsn;

             if (sequenceNumber == SequenceNumber.Invalid)
             { 
                 lsn = 0;
             } 
             else 
             {
                 lsn = sequenceNumber.High; 
             }

            EnsureMarshalContext();
            UnsafeNativeMethods.FlushLogToLsnSync(this.marshalContext, 
                                                  ref lsn,
                                                  out resultLsn); 
 
            return new SequenceNumber(resultLsn);
        } 

        public IEnumerable ReadLogRecords(
            SequenceNumber start,
            LogRecordEnumeratorType logRecordEnum) 
        {
            this.store.ValidateSequenceNumber( 
                ref start, 
                SequenceNumberConstraint.Arbitrary,
                "start"); 

            CLFS_CONTEXT_MODE mode;
            switch(logRecordEnum)
            { 
            case LogRecordEnumeratorType.User:
                mode = CLFS_CONTEXT_MODE.ClfsContextUndoNext; 
                break; 

            case LogRecordEnumeratorType.Previous: 
                mode = CLFS_CONTEXT_MODE.ClfsContextPrevious;
                break;

            case LogRecordEnumeratorType.Next: 
                mode = CLFS_CONTEXT_MODE.ClfsContextForward;
                break; 
 
            default:
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("logRecordEnum")); 
            }

            return new RecordEnumerable(this, mode, start.High);
        } 

        public IEnumerable ReadRestartAreas() 
        { 
            return new RestartAreaEnumerable(this);
        } 

        public SequenceNumber ReserveAndAppend(
            ArraySegment data,
            SequenceNumber nextUndoRecord, 
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions, 
            ReservationCollection reservationCollection, 
            params long[] reservations)
        { 
            return ReserveAndAppend(new ArraySegment[] { data },
                                    nextUndoRecord,
                                    previousRecord,
                                    recordAppendOptions, 
                                    reservationCollection,
                                    reservations); 
        } 

        public SequenceNumber ReserveAndAppend( 
            IList> data,
            SequenceNumber userRecord,
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions, 
            ReservationCollection reservationCollection,
            params long[] reservations) 
        { 
            long totalRecordSize;
            LogReservationCollection lrc; 

            this.store.ValidateSequenceNumber(
                ref userRecord,
                SequenceNumberConstraint.Arbitrary, 
                "userRecord");
            this.store.ValidateSequenceNumber( 
                ref previousRecord, 
                SequenceNumberConstraint.Arbitrary,
                "previousRecord"); 

            totalRecordSize = ValidateData(data);
            lrc = ValidateReservationCollection(reservationCollection);
            if (lrc == null) 
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("reservationCollection")); 
            } 
            if (reservations == null)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("reservations"));
            }
            ValidateReservations(reservations);
 
            EnsureMarshalContext();
 
            LogReserveAndAppendState state = new LogReserveAndAppendState(); 

            state.RecordSequence = this; 
            state.Data = data;
            state.TotalRecordSize = totalRecordSize;
            state.UserLsn = userRecord.High;
            state.PreviousLsn = previousRecord.High; 
            state.RecordAppendOptions = recordAppendOptions;
            state.ReservationCollection = lrc; 
            state.Reservations = reservations; 

            state.Start(); 

            return new SequenceNumber(state.ResultLsn);
        }
 
        public void SetLastRecord(
            SequenceNumber sequenceNumber) 
        { 
            this.store.ValidateSequenceNumber(
                ref sequenceNumber, 
                SequenceNumberConstraint.Arbitrary,
                "sequenceNumber");

            ulong lsn = sequenceNumber.High; 

            try 
            { 
                EnsureMarshalContext();
                UnsafeNativeMethods.TruncateLogSync(this.marshalContext, 
                                                                        ref lsn);
            }
            catch(EntryPointNotFoundException)
            { 
                // CLFS API for SetEndOfLog doesn;t update the client marshaling area and directly
                // uses the log handle. The client marshalling and kernal stats becomes out of [....] 
                // and will cause subsequent appends to fail. 
                // Work around - Invalidate the client marshall area. Call SetEndOfLog.
                // Subsequent Append calls will create a new marshalling context. 

                InvalidateMarshalContext();
                UnsafeNativeMethods.SetEndOfLogSync(this.store.Handle,
                                                    ref lsn); 
            }
        } 
 
        public SequenceNumber WriteRestartArea(
            ArraySegment data) 
        {
            return WriteRestartArea(new ArraySegment[] { data });
        }
 
        public SequenceNumber WriteRestartArea(
            IList> data) 
        { 
            return WriteRestartArea(data, SequenceNumber.Invalid);
        } 

        public SequenceNumber WriteRestartArea(
            ArraySegment data,
            SequenceNumber newBaseSeqNum) 
        {
            return WriteRestartArea(new ArraySegment[] { data }, 
                                    newBaseSeqNum); 
        }
 
        public SequenceNumber WriteRestartArea(
            IList> data,
            SequenceNumber newBaseSeqNum)
        { 
            return WriteRestartArea(data, newBaseSeqNum, null);
        } 
 
        public SequenceNumber WriteRestartArea(
            ArraySegment data, 
            SequenceNumber newBaseSeqNum,
            ReservationCollection reservations)
        {
            return WriteRestartArea(new ArraySegment[] { data }, 
                                    newBaseSeqNum,
                                    reservations); 
        } 

        public SequenceNumber WriteRestartArea( 
            IList> data,
            SequenceNumber newBaseSeqNum,
            ReservationCollection reservationCollection)
        { 
            long totalRecordSize;
            LogReservationCollection lrc; 
 
            this.store.ValidateSequenceNumber(
                ref newBaseSeqNum, 
                SequenceNumberConstraint.Arbitrary,
                "newBaseSeqNum");

            totalRecordSize = ValidateData(data); 
            lrc = ValidateReservationCollection(reservationCollection);
 
            EnsureMarshalContext(); 

            LogWriteRestartAreaState state = new LogWriteRestartAreaState(); 

            state.RecordSequence = this;
            state.Data = data;
            state.TotalRecordSize = totalRecordSize; 
            state.ReservationCollection = lrc;
            state.NewBaseLsn = newBaseSeqNum.High; 
 
            state.Start();
 
            return new SequenceNumber(state.ResultLsn);
        }

        void EnsureMarshalContext() 
        {
            // NOTE: Simple synchronization here may cause problems. I 
            //       am counting on the unfairness of the lock object to 
            //       make this fast enough.
            // 
            lock(this.store.SyncRoot)
            {
                if ((this.marshalContext != null) &&
                    (!this.marshalContext.IsInvalid)) 
                {
                    return; 
                } 

                try 
                {
                    this.marshalContext =
                        UnsafeNativeMethods.CreateLogMarshallingArea(
                            this.store.Handle, 
                            IntPtr.Zero,
                            IntPtr.Zero, 
                            IntPtr.Zero, 
                            this.bufferSize,
                            this.writeBufferCount, 
                            DefaultReadBufferCount);
                }
                catch(InvalidOperationException )
                { 
                    if (this.store.Extents.Count == 0)
                    { 
                        throw DiagnosticUtility.ExceptionUtility.ThrowHelperError( 
                                        Error.InvalidOperation(SR.InvalidOperation_MustHaveExtents));
                    } 
                    else
                    {
                        throw;
                    } 
                }
            } 
        } 

        void InvalidateMarshalContext() 
        {
            lock(this.store.SyncRoot)
            {
                if(this.marshalContext != null) 
                {
                    this.marshalContext.Close(); 
                    this.marshalContext = null; 
                }
            } 
        }

        int GetBufferSize(int bufferSize)
        { 
            if (bufferSize > MaxBufferSize)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferSize")); 
            }
 
            bufferSize += LogLogRecordHeader.Size;
            bufferSize = (bufferSize + CLFS_SECTOR_ALIGN) & ~CLFS_SECTOR_ALIGN;

            return bufferSize; 
        }
 
        long ValidateData(IList> data) 
        {
            if (data == null) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("data"));

            long dataLength = 0;
            for (int i = 0; i < data.Count; i++) 
            {
                ArraySegment segment = data[i]; 
 
                dataLength = checked(dataLength + segment.Count);
                if (dataLength > MaximumRecordLength) 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentInvalid(SR.LogRecSeq_Append_TooBig));
            }

            return dataLength + LogLogRecordHeader.Size; 
        }
 
        LogReservationCollection ValidateReservationCollection( 
            ReservationCollection reservations)
        { 
            LogReservationCollection lrc = null;
            if (reservations != null)
            {
                lrc = reservations as LogReservationCollection; 
                if (lrc == null)
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError( 
                                        Error.ArgumentInvalid(SR.LogRecSeq_InvalidReservationCollection)); 

                if (lrc.RecordSequence != this) 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(
                                        Error.ArgumentInvalid(SR.LogRecSeq_InvalidReservationCollection));
            }
 
            return lrc;
        } 
 
        void ValidateReservations(long[] reservations)
        { 
            foreach(long reservation in reservations)
            {
                if ((reservation < 0) || (reservation > MaximumRecordLength))
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("reservations")); 
            }
        } 
 
        class RecordEnumerable : IEnumerable
        { 
            LogRecordSequence recordSequence;
            CLFS_CONTEXT_MODE mode;
            ulong             startLsn;
 
            internal RecordEnumerable(LogRecordSequence recordSequence,
                                      CLFS_CONTEXT_MODE mode, 
                                      ulong startLsn) 
            {
                this.recordSequence = recordSequence; 
                this.mode = mode;
                this.startLsn = startLsn;
            }
 
            IEnumerator IEnumerable.GetEnumerator()
            { 
                return this.GetEnumerator(); 
            }
 
            public IEnumerator GetEnumerator()
            {
                return new LogLogRecordEnumerator(this.recordSequence,
                                                  this.mode, 
                                                  this.startLsn);
            } 
        } 

        class RestartAreaEnumerable : IEnumerable 
        {
            LogRecordSequence recordSequence;

            internal RestartAreaEnumerable(LogRecordSequence recordSequence) 
            {
                this.recordSequence = recordSequence; 
            } 

            IEnumerator IEnumerable.GetEnumerator() 
            {
                return this.GetEnumerator();
            }
 
            public IEnumerator GetEnumerator()
            { 
                return new LogRestartAreaEnumerator(this.recordSequence); 
            }
        } 
    }
}

// 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; 
    using System.Collections.Generic; 
    using System.IO;
    using System.Runtime.InteropServices; 
    using System.Security.AccessControl;
    using System.Security.Permissions;
    using System.Threading;
 

    public sealed class LogRecordSequence : IRecordSequence 
    { 
        const uint INFINITE = 0xFFFFFFFF;
 
        const int DefaultWriteBufferCount = 10;
        const int DefaultReadBufferCount = unchecked((int)INFINITE);
        const int DefaultBufferSize = 64 * 1024;
 
        // This is just a common-sense buffer size, to prevent
        // accidental integer overflow and such. 
        // 
        const int MaxBufferSize = 0x40000000;
 
        const int CLFS_SECTOR_SIZE = 0x00000200;
        const int CLFS_SECTOR_ALIGN = (CLFS_SECTOR_SIZE-1);

        LogStore store; 
        int bufferSize;
        int writeBufferCount; 
        bool ownStore; 
        bool retryAppend;
 
        SafeMarshalContext marshalContext;

        // The LogStore constructor will demand full trust, so we don't have to.
        public LogRecordSequence( 
            string path,
            FileMode mode) 
        { 
            this.store = new LogStore(path, mode);
            this.ownStore = true; 

            this.bufferSize = GetBufferSize(DefaultBufferSize);
            this.writeBufferCount = DefaultWriteBufferCount;
        } 

        // The LogStore constructor will demand full trust, so we don't have to. 
        public LogRecordSequence( 
            string path,
            FileMode mode, 
            FileAccess access)
        {
            this.store = new LogStore(path, mode, access);
            this.ownStore = true; 

            this.bufferSize = GetBufferSize(DefaultBufferSize); 
            this.writeBufferCount = DefaultWriteBufferCount; 
        }
 
        // The LogStore constructor will demand full trust, so we don't have to.
        public LogRecordSequence(
            string path,
            FileMode mode, 
            FileAccess access,
            FileShare share) 
        { 
            this.store = new LogStore(path, mode, access, share);
            this.ownStore = true; 

            this.bufferSize = GetBufferSize(DefaultBufferSize);
            this.writeBufferCount = DefaultWriteBufferCount;
        } 

        // The LogStore constructor will demand full trust, so we don't have to. 
        public LogRecordSequence( 
            string path,
            FileMode mode, 
            FileAccess access,
            FileShare share,
            int bufferSize,
            int bufferCount) 
        {
            if (bufferSize <= 0) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferSize")); 
            if (bufferCount <= 0)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferCount")); 

            this.store = new LogStore(path, mode, access, share);
            this.ownStore = true;
 
            this.bufferSize = GetBufferSize(bufferSize);
            this.writeBufferCount = bufferCount; 
        } 

        // The LogStore constructor will demand full trust, so we don't have to. 
        public LogRecordSequence(
            string path,
            FileMode mode,
            FileAccess access, 
            FileShare share,
            int bufferSize, 
            int bufferCount, 
            FileSecurity fileSecurity)
        { 
            if (bufferSize <= 0)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferSize"));
            if (bufferCount <= 0)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferCount")); 

            this.store = new LogStore(path, 
                                      mode, 
                                      access,
                                      share, 
                                      fileSecurity);
            this.ownStore = true;

            this.bufferSize = GetBufferSize(bufferSize); 
            this.writeBufferCount = bufferCount;
        } 
 
        [PermissionSetAttribute(SecurityAction.Demand, Name="FullTrust")]
        public LogRecordSequence(LogStore logStore) 
        {
            if (logStore == null)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("logStore"));
 
            this.store = logStore;
            this.ownStore = false; 
 
            this.bufferSize = GetBufferSize(DefaultBufferSize);
            this.writeBufferCount = DefaultWriteBufferCount; 
        }

        [PermissionSetAttribute(SecurityAction.Demand, Name="FullTrust")]
        public LogRecordSequence( 
            LogStore logStore,
            int bufferSize, 
            int bufferCount) 
        {
            if (logStore == null) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("logStore"));

            if (bufferSize <= 0)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferSize")); 
            if (bufferCount <= 0)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferCount")); 
 
            this.store = logStore;
            this.ownStore = false; 

            this.bufferSize = GetBufferSize(bufferSize);
            this.writeBufferCount = bufferCount;
        } 

        public SequenceNumber BaseSequenceNumber 
        { 
            get
            { 
                return this.store.BaseSequenceNumber;
            }
        }
 
        public SequenceNumber LastSequenceNumber
        { 
            get 
            {
                return this.store.LastSequenceNumber; 
            }
        }

        public LogStore LogStore 
        {
            get 
            { 
                return this.store;
            } 
        }

        internal SafeMarshalContext MarshalContext
        { 
            get
            { 
                EnsureMarshalContext(); 
                return this.marshalContext;
            } 
        }

        internal SafeMarshalContext InternalMarshalContext
        { 
            get
            { 
                return this.marshalContext; 
            }
        } 

        public long MaximumRecordLength
        {
            get 
            {
                return this.bufferSize - LogLogRecordHeader.Size; 
            } 
        }
 
        public long ReservedBytes
        {
            get
            { 
                CLFS_INFORMATION info;
                this.store.GetLogFileInformation(out info); 
 
                return checked((long)(info.TotalUndoCommitment));
            } 
        }

        public bool RetryAppend
        { 
            get
            { 
                return this.retryAppend; 
            }
 
            set
            {
                this.retryAppend = value;
            } 
        }
 
        public SequenceNumber RestartSequenceNumber 
        {
            get 
            {
                CLFS_INFORMATION info;
                this.store.GetLogFileInformation(out info);
 
                if(info.RestartLsn == Const.CLFS_LSN_INVALID)
                    return SequenceNumber.Invalid; 
 
                return new SequenceNumber(info.RestartLsn);
            } 
        }

        public event EventHandler TailPinned
        { 
            add
            { 
                this.store.LogManagement.TailPinned += value; 
            }
 
            remove
            {
                this.store.LogManagement.TailPinned -= value;
            } 
        }
 
        public void AdvanceBaseSequenceNumber( 
            SequenceNumber newBaseSequenceNumber)
        { 
            this.store.ValidateSequenceNumber(
                ref newBaseSequenceNumber,
                SequenceNumberConstraint.Arbitrary,
                "newBaseSequenceNumber"); 

            ulong newBaseLsn = newBaseSequenceNumber.High; 
 
            EnsureMarshalContext();
 
            UnsafeNativeMethods.AdvanceLogBaseSync(this.marshalContext,
                                                   ref newBaseLsn,
                                                   0);
        } 

        public SequenceNumber Append( 
            ArraySegment data, 
            SequenceNumber nextUndoRecord,
            SequenceNumber previousRecord, 
            RecordAppendOptions recordAppendOptions)
        {
            return Append(new ArraySegment[] { data },
                          nextUndoRecord, 
                          previousRecord,
                          recordAppendOptions); 
        } 

 
        public SequenceNumber Append(
            ArraySegment data,
            SequenceNumber nextUndoRecord,
            SequenceNumber previousRecord, 
            RecordAppendOptions recordAppendOptions,
            ReservationCollection reservations) 
        { 
            return Append(new ArraySegment[] { data },
                          nextUndoRecord, 
                          previousRecord,
                          recordAppendOptions,
                          reservations);
        } 

        public SequenceNumber Append( 
            IList> data, 
            SequenceNumber userRecord,
            SequenceNumber previousRecord, 
            RecordAppendOptions recordAppendOptions)
        {
            return Append(
                data, 
                userRecord,
                previousRecord, 
                recordAppendOptions, 
                null);
        } 

        public SequenceNumber Append(
            IList> data,
            SequenceNumber userRecord, 
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions, 
            ReservationCollection reservations) 
        {
            long totalRecordSize; 
            LogReservationCollection lrc;

            if ((this.store.Access & FileAccess.Write) == 0)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.NotSupported(SR.NotSupported_ReadOnly));
            } 
 
            if(recordAppendOptions > (RecordAppendOptions.ForceAppend | RecordAppendOptions.ForceFlush) ||
               recordAppendOptions < RecordAppendOptions.None) 
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("recordAppendOptions"));
            }
 
            this.store.ValidateSequenceNumber(
                ref userRecord, 
                SequenceNumberConstraint.Arbitrary, 
                "userRecord");
            this.store.ValidateSequenceNumber( 
                ref previousRecord,
                SequenceNumberConstraint.Arbitrary,
                "previousRecord");
 
            totalRecordSize = ValidateData(data);
            lrc = ValidateReservationCollection(reservations); 
 
            EnsureMarshalContext();
 
            LogReserveAndAppendState state = new LogReserveAndAppendState();

            state.RecordSequence = this;
            state.Data = data; 
            state.TotalRecordSize = totalRecordSize;
            state.UserLsn = userRecord.High; 
            state.PreviousLsn = previousRecord.High; 
            state.RecordAppendOptions = recordAppendOptions;
            state.ReservationCollection = lrc; 

            state.Start();

            return new SequenceNumber(state.ResultLsn); 
        }
 
        public IAsyncResult BeginAppend( 
            ArraySegment data,
            SequenceNumber nextUndoRecord, 
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions,
            AsyncCallback callback,
            object state) 
        {
            return BeginAppend(new ArraySegment[] { data }, 
                               nextUndoRecord, 
                               previousRecord,
                               recordAppendOptions, 
                               callback,
                               state);
        }
 
        public IAsyncResult BeginAppend(
            ArraySegment data, 
            SequenceNumber nextUndoRecord, 
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions, 
            ReservationCollection reservations,
            AsyncCallback callback,
            object state)
        { 
            return BeginAppend(new ArraySegment[] { data },
                               nextUndoRecord, 
                               previousRecord, 
                               recordAppendOptions,
                               reservations, 
                               callback,
                               state);
        }
 
        public IAsyncResult BeginAppend(
            IList> data, 
            SequenceNumber userRecord, 
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions, 
            AsyncCallback callback,
            object state)
        {
            return BeginAppend( 
                data,
                userRecord, 
                previousRecord, 
                recordAppendOptions,
                null, 
                callback,
                state);
        }
 
        public IAsyncResult BeginAppend(
            IList> data, 
            SequenceNumber userRecord, 
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions, 
            ReservationCollection reservations,
            AsyncCallback callback,
            object state)
        { 
            long totalRecordSize;
            LogReservationCollection lrc; 
 
            if ((this.store.Access & FileAccess.Write) == 0)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.NotSupported(SR.NotSupported_ReadOnly));
            }

            if(recordAppendOptions > (RecordAppendOptions.ForceAppend | RecordAppendOptions.ForceFlush) || 
               recordAppendOptions < RecordAppendOptions.None)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("recordAppendOptions")); 
            }
 
            this.store.ValidateSequenceNumber(
                ref userRecord,
                SequenceNumberConstraint.Arbitrary,
                "userRecord"); 
            this.store.ValidateSequenceNumber(
                ref previousRecord, 
                SequenceNumberConstraint.Arbitrary, 
                "previousRecord");
 
            totalRecordSize = ValidateData(data);
            lrc = ValidateReservationCollection(reservations);

            EnsureMarshalContext(); 

            LogAppendAsyncResult result = new LogAppendAsyncResult(this, 
                                                                   callback, 
                                                                   state);
            result.Data = data; 
            result.TotalRecordSize = totalRecordSize;
            result.UserLsn = userRecord.High;
            result.PreviousLsn = previousRecord.High;
            result.RecordAppendOptions = recordAppendOptions; 
            result.ReservationCollection = lrc;
 
            result.Start(); 

            return result; 
        }

        public IAsyncResult BeginFlush(
            SequenceNumber sequenceNumber, 
            AsyncCallback callback,
            object state) 
        { 
            this.store.ValidateSequenceNumber(
                ref sequenceNumber, 
                SequenceNumberConstraint.Arbitrary,
                "sequenceNumber");

            EnsureMarshalContext(); 

            LogFlushAsyncResult flushResult = new LogFlushAsyncResult(this, 
                                                                      callback, 
                                                                      state);
            if (sequenceNumber == SequenceNumber.Invalid) 
            {
                flushResult.SequenceNumber = 0;
            }
            else 
            {
                flushResult.SequenceNumber = sequenceNumber.High; 
            } 

            flushResult.Start(); 
            return flushResult;
        }

        public IAsyncResult BeginReserveAndAppend( 
            ArraySegment data,
            SequenceNumber nextUndoRecord, 
            SequenceNumber previousRecord, 
            RecordAppendOptions recordAppendOptions,
            ReservationCollection reservationCollection, 
            long[] reservations,
            AsyncCallback callback,
            object state)
        { 
            return BeginReserveAndAppend(new ArraySegment[] { data },
                                         nextUndoRecord, 
                                         previousRecord, 
                                         recordAppendOptions,
                                         reservationCollection, 
                                         reservations,
                                         callback,
                                         state);
        } 

        public IAsyncResult BeginReserveAndAppend( 
            IList> data, 
            SequenceNumber userRecord,
            SequenceNumber previousRecord, 
            RecordAppendOptions recordAppendOptions,
            ReservationCollection reservationCollection,
            long[] reservations,
            AsyncCallback callback, 
            object state)
        { 
            long totalRecordSize; 
            LogReservationCollection lrc;
 
            this.store.ValidateSequenceNumber(
                ref userRecord,
                SequenceNumberConstraint.Arbitrary,
                "userRecord"); 
            this.store.ValidateSequenceNumber(
                ref previousRecord, 
                SequenceNumberConstraint.Arbitrary, 
                "previousRecord");
 
            if (reservationCollection == null)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("reservationCollection"));
            } 
            if (reservations == null)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("reservations")); 
            }
            ValidateReservations(reservations); 

            totalRecordSize = ValidateData(data);
            lrc = ValidateReservationCollection(reservationCollection);
 
            EnsureMarshalContext();
 
            LogAppendAsyncResult result = new LogAppendAsyncResult(this, 
                                                                   callback,
                                                                   state); 
            result.Data = data;
            result.TotalRecordSize = totalRecordSize;
            result.UserLsn = userRecord.High;
            result.PreviousLsn = previousRecord.High; 
            result.RecordAppendOptions = recordAppendOptions;
            result.ReservationCollection = lrc; 
            result.Reservations = reservations; 

            result.Start(); 

            return result;
        }
 
        public IAsyncResult BeginWriteRestartArea(
            ArraySegment data, 
            SequenceNumber newBaseSeqNum, 
            ReservationCollection reservation,
            AsyncCallback callback, 
            object state)
        {
            return BeginWriteRestartArea(new ArraySegment[] { data },
                                         newBaseSeqNum, 
                                         reservation,
                                         callback, 
                                         state); 
        }
 
        public IAsyncResult BeginWriteRestartArea(
            IList> data,
            SequenceNumber newBaseSeqNum,
            ReservationCollection reservationCollection, 
            AsyncCallback callback,
            object state) 
        { 
            long totalRecordSize;
            LogReservationCollection lrc; 

            this.store.ValidateSequenceNumber(
                ref newBaseSeqNum,
                SequenceNumberConstraint.Arbitrary, 
                "newBaseSeqNum");
 
            totalRecordSize = ValidateData(data); 
            lrc = ValidateReservationCollection(reservationCollection);
 
            EnsureMarshalContext();

            LogWriteRestartAreaAsyncResult result;
            result = new LogWriteRestartAreaAsyncResult(this, 
                                                        callback,
                                                        state); 
            result.Data = data; 
            result.TotalRecordSize = totalRecordSize;
            result.NewBaseLsn = newBaseSeqNum.High; 
            result.ReservationCollection = lrc;

            result.Start();
 
            return result;
        } 
 
        public ReservationCollection CreateReservationCollection()
        { 
            return new LogReservationCollection(this);
        }

        public void Dispose() 
        {
            if ((this.marshalContext != null) && 
                (!this.marshalContext.IsInvalid)) 
            {
                this.marshalContext.Close(); 
            }

            if (this.ownStore)
                this.store.Dispose(); 
        }
 
        public SequenceNumber EndAppend( 
            IAsyncResult result)
        { 
            LogAppendAsyncResult lar = result as LogAppendAsyncResult;
            if (lar == null)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.InvalidAsyncResult());
 
            // Having some reservations to make is a requirement of
            // calling BeginReserveAndAppend, so if we have some, we 
            // know this is not our AsyncResult. 
            //
            if (lar.Reservations != null) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.InvalidAsyncResult());

            lar.End();
 
            return new SequenceNumber(lar.ResultLsn);
        } 
 
        public SequenceNumber EndFlush(
            IAsyncResult result) 
        {
            LogFlushAsyncResult lar = result as LogFlushAsyncResult;
            if (lar == null)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.InvalidAsyncResult()); 

            lar.End(); 
 
            return new SequenceNumber(lar.ResultLsn);
        } 

        public SequenceNumber EndReserveAndAppend(
            IAsyncResult result)
        { 
            LogAppendAsyncResult lar = result as LogAppendAsyncResult;
            if (lar == null) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.InvalidAsyncResult()); 

            // Having some reservations to make is a requirement of 
            // calling BeginReserveAndAppend, so if we have none, we
            // know this is an AsyncResult for some OTHER method.
            //
            if (lar.Reservations == null) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.InvalidAsyncResult());
 
            lar.End(); 

            return new SequenceNumber(lar.ResultLsn); 
        }

        public SequenceNumber EndWriteRestartArea(
            IAsyncResult result) 
        {
            LogWriteRestartAreaAsyncResult lar = result as LogWriteRestartAreaAsyncResult; 
            if (lar == null) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.InvalidAsyncResult());
 
            lar.End();

            return new SequenceNumber(lar.ResultLsn);
        } 

        public SequenceNumber Flush() 
        { 
            return Flush(SequenceNumber.Invalid);
        } 

        public SequenceNumber Flush(SequenceNumber sequenceNumber)
        {
            this.store.ValidateSequenceNumber( 
                ref sequenceNumber,
                SequenceNumberConstraint.Arbitrary, 
                "sequenceNumber"); 

            ulong resultLsn; 
            ulong lsn;

             if (sequenceNumber == SequenceNumber.Invalid)
             { 
                 lsn = 0;
             } 
             else 
             {
                 lsn = sequenceNumber.High; 
             }

            EnsureMarshalContext();
            UnsafeNativeMethods.FlushLogToLsnSync(this.marshalContext, 
                                                  ref lsn,
                                                  out resultLsn); 
 
            return new SequenceNumber(resultLsn);
        } 

        public IEnumerable ReadLogRecords(
            SequenceNumber start,
            LogRecordEnumeratorType logRecordEnum) 
        {
            this.store.ValidateSequenceNumber( 
                ref start, 
                SequenceNumberConstraint.Arbitrary,
                "start"); 

            CLFS_CONTEXT_MODE mode;
            switch(logRecordEnum)
            { 
            case LogRecordEnumeratorType.User:
                mode = CLFS_CONTEXT_MODE.ClfsContextUndoNext; 
                break; 

            case LogRecordEnumeratorType.Previous: 
                mode = CLFS_CONTEXT_MODE.ClfsContextPrevious;
                break;

            case LogRecordEnumeratorType.Next: 
                mode = CLFS_CONTEXT_MODE.ClfsContextForward;
                break; 
 
            default:
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("logRecordEnum")); 
            }

            return new RecordEnumerable(this, mode, start.High);
        } 

        public IEnumerable ReadRestartAreas() 
        { 
            return new RestartAreaEnumerable(this);
        } 

        public SequenceNumber ReserveAndAppend(
            ArraySegment data,
            SequenceNumber nextUndoRecord, 
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions, 
            ReservationCollection reservationCollection, 
            params long[] reservations)
        { 
            return ReserveAndAppend(new ArraySegment[] { data },
                                    nextUndoRecord,
                                    previousRecord,
                                    recordAppendOptions, 
                                    reservationCollection,
                                    reservations); 
        } 

        public SequenceNumber ReserveAndAppend( 
            IList> data,
            SequenceNumber userRecord,
            SequenceNumber previousRecord,
            RecordAppendOptions recordAppendOptions, 
            ReservationCollection reservationCollection,
            params long[] reservations) 
        { 
            long totalRecordSize;
            LogReservationCollection lrc; 

            this.store.ValidateSequenceNumber(
                ref userRecord,
                SequenceNumberConstraint.Arbitrary, 
                "userRecord");
            this.store.ValidateSequenceNumber( 
                ref previousRecord, 
                SequenceNumberConstraint.Arbitrary,
                "previousRecord"); 

            totalRecordSize = ValidateData(data);
            lrc = ValidateReservationCollection(reservationCollection);
            if (lrc == null) 
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("reservationCollection")); 
            } 
            if (reservations == null)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("reservations"));
            }
            ValidateReservations(reservations);
 
            EnsureMarshalContext();
 
            LogReserveAndAppendState state = new LogReserveAndAppendState(); 

            state.RecordSequence = this; 
            state.Data = data;
            state.TotalRecordSize = totalRecordSize;
            state.UserLsn = userRecord.High;
            state.PreviousLsn = previousRecord.High; 
            state.RecordAppendOptions = recordAppendOptions;
            state.ReservationCollection = lrc; 
            state.Reservations = reservations; 

            state.Start(); 

            return new SequenceNumber(state.ResultLsn);
        }
 
        public void SetLastRecord(
            SequenceNumber sequenceNumber) 
        { 
            this.store.ValidateSequenceNumber(
                ref sequenceNumber, 
                SequenceNumberConstraint.Arbitrary,
                "sequenceNumber");

            ulong lsn = sequenceNumber.High; 

            try 
            { 
                EnsureMarshalContext();
                UnsafeNativeMethods.TruncateLogSync(this.marshalContext, 
                                                                        ref lsn);
            }
            catch(EntryPointNotFoundException)
            { 
                // CLFS API for SetEndOfLog doesn;t update the client marshaling area and directly
                // uses the log handle. The client marshalling and kernal stats becomes out of [....] 
                // and will cause subsequent appends to fail. 
                // Work around - Invalidate the client marshall area. Call SetEndOfLog.
                // Subsequent Append calls will create a new marshalling context. 

                InvalidateMarshalContext();
                UnsafeNativeMethods.SetEndOfLogSync(this.store.Handle,
                                                    ref lsn); 
            }
        } 
 
        public SequenceNumber WriteRestartArea(
            ArraySegment data) 
        {
            return WriteRestartArea(new ArraySegment[] { data });
        }
 
        public SequenceNumber WriteRestartArea(
            IList> data) 
        { 
            return WriteRestartArea(data, SequenceNumber.Invalid);
        } 

        public SequenceNumber WriteRestartArea(
            ArraySegment data,
            SequenceNumber newBaseSeqNum) 
        {
            return WriteRestartArea(new ArraySegment[] { data }, 
                                    newBaseSeqNum); 
        }
 
        public SequenceNumber WriteRestartArea(
            IList> data,
            SequenceNumber newBaseSeqNum)
        { 
            return WriteRestartArea(data, newBaseSeqNum, null);
        } 
 
        public SequenceNumber WriteRestartArea(
            ArraySegment data, 
            SequenceNumber newBaseSeqNum,
            ReservationCollection reservations)
        {
            return WriteRestartArea(new ArraySegment[] { data }, 
                                    newBaseSeqNum,
                                    reservations); 
        } 

        public SequenceNumber WriteRestartArea( 
            IList> data,
            SequenceNumber newBaseSeqNum,
            ReservationCollection reservationCollection)
        { 
            long totalRecordSize;
            LogReservationCollection lrc; 
 
            this.store.ValidateSequenceNumber(
                ref newBaseSeqNum, 
                SequenceNumberConstraint.Arbitrary,
                "newBaseSeqNum");

            totalRecordSize = ValidateData(data); 
            lrc = ValidateReservationCollection(reservationCollection);
 
            EnsureMarshalContext(); 

            LogWriteRestartAreaState state = new LogWriteRestartAreaState(); 

            state.RecordSequence = this;
            state.Data = data;
            state.TotalRecordSize = totalRecordSize; 
            state.ReservationCollection = lrc;
            state.NewBaseLsn = newBaseSeqNum.High; 
 
            state.Start();
 
            return new SequenceNumber(state.ResultLsn);
        }

        void EnsureMarshalContext() 
        {
            // NOTE: Simple synchronization here may cause problems. I 
            //       am counting on the unfairness of the lock object to 
            //       make this fast enough.
            // 
            lock(this.store.SyncRoot)
            {
                if ((this.marshalContext != null) &&
                    (!this.marshalContext.IsInvalid)) 
                {
                    return; 
                } 

                try 
                {
                    this.marshalContext =
                        UnsafeNativeMethods.CreateLogMarshallingArea(
                            this.store.Handle, 
                            IntPtr.Zero,
                            IntPtr.Zero, 
                            IntPtr.Zero, 
                            this.bufferSize,
                            this.writeBufferCount, 
                            DefaultReadBufferCount);
                }
                catch(InvalidOperationException )
                { 
                    if (this.store.Extents.Count == 0)
                    { 
                        throw DiagnosticUtility.ExceptionUtility.ThrowHelperError( 
                                        Error.InvalidOperation(SR.InvalidOperation_MustHaveExtents));
                    } 
                    else
                    {
                        throw;
                    } 
                }
            } 
        } 

        void InvalidateMarshalContext() 
        {
            lock(this.store.SyncRoot)
            {
                if(this.marshalContext != null) 
                {
                    this.marshalContext.Close(); 
                    this.marshalContext = null; 
                }
            } 
        }

        int GetBufferSize(int bufferSize)
        { 
            if (bufferSize > MaxBufferSize)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("bufferSize")); 
            }
 
            bufferSize += LogLogRecordHeader.Size;
            bufferSize = (bufferSize + CLFS_SECTOR_ALIGN) & ~CLFS_SECTOR_ALIGN;

            return bufferSize; 
        }
 
        long ValidateData(IList> data) 
        {
            if (data == null) 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentNull("data"));

            long dataLength = 0;
            for (int i = 0; i < data.Count; i++) 
            {
                ArraySegment segment = data[i]; 
 
                dataLength = checked(dataLength + segment.Count);
                if (dataLength > MaximumRecordLength) 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentInvalid(SR.LogRecSeq_Append_TooBig));
            }

            return dataLength + LogLogRecordHeader.Size; 
        }
 
        LogReservationCollection ValidateReservationCollection( 
            ReservationCollection reservations)
        { 
            LogReservationCollection lrc = null;
            if (reservations != null)
            {
                lrc = reservations as LogReservationCollection; 
                if (lrc == null)
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError( 
                                        Error.ArgumentInvalid(SR.LogRecSeq_InvalidReservationCollection)); 

                if (lrc.RecordSequence != this) 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(
                                        Error.ArgumentInvalid(SR.LogRecSeq_InvalidReservationCollection));
            }
 
            return lrc;
        } 
 
        void ValidateReservations(long[] reservations)
        { 
            foreach(long reservation in reservations)
            {
                if ((reservation < 0) || (reservation > MaximumRecordLength))
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ArgumentOutOfRange("reservations")); 
            }
        } 
 
        class RecordEnumerable : IEnumerable
        { 
            LogRecordSequence recordSequence;
            CLFS_CONTEXT_MODE mode;
            ulong             startLsn;
 
            internal RecordEnumerable(LogRecordSequence recordSequence,
                                      CLFS_CONTEXT_MODE mode, 
                                      ulong startLsn) 
            {
                this.recordSequence = recordSequence; 
                this.mode = mode;
                this.startLsn = startLsn;
            }
 
            IEnumerator IEnumerable.GetEnumerator()
            { 
                return this.GetEnumerator(); 
            }
 
            public IEnumerator GetEnumerator()
            {
                return new LogLogRecordEnumerator(this.recordSequence,
                                                  this.mode, 
                                                  this.startLsn);
            } 
        } 

        class RestartAreaEnumerable : IEnumerable 
        {
            LogRecordSequence recordSequence;

            internal RestartAreaEnumerable(LogRecordSequence recordSequence) 
            {
                this.recordSequence = recordSequence; 
            } 

            IEnumerator IEnumerable.GetEnumerator() 
            {
                return this.GetEnumerator();
            }
 
            public IEnumerator GetEnumerator()
            { 
                return new LogRestartAreaEnumerator(this.recordSequence); 
            }
        } 
    }
}

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

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