SimpleFileLog.cs source code in C# .NET

                        Code:
                         / WCF / WCF / 3.5.30729.1 / untmp / Orcas / SP / ndp / cdf / src / WCF / Log / System / IO / Log / SimpleFileLog.cs / 1 / SimpleFileLog.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------
namespace System.IO.Log
{ 
    using System;
    using System.Runtime.InteropServices; 
    using System.Runtime.InteropServices.ComTypes; 

    internal class SimpleFileLog 
    {
        SmuggledIUnknown smuggledLog;

        internal SimpleFileLog(string absolutePath, int size) 
        {
            // Open the log. 
            // First, we try to open an existing log-- if that doesn't 
            // work, we create a new one.
            // 
            bool loaded = false;
            ILog log = (ILog)new SimpleFileBasedLog();
            try
            { 
                if (File.Exists(absolutePath))
                { 
                    try 
                    {
                        IPersistFile ipf = (IPersistFile)log; 
                        ipf.Load(absolutePath, (int)STGM.ReadWrite);
                        loaded = true;
                    }
                    catch (FileNotFoundException) 
                    {
                        // File not found, create a new one. 
                    } 
                }
 
                if (!loaded)
                {
                    // File does not exist.  Attempt to create a new one,
                    // with the specified size. 
                    //
                    IFileBasedLogInit logInit = (IFileBasedLogInit)log; 
                    logInit.InitNew(absolutePath, size); 
                }
 
                log.SetAccessPolicyHint(RECORD_READING_POLICY.RANDOM);
                this.smuggledLog = new SmuggledIUnknown(log);
            }
            catch (COMException exception) 
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ConvertKnownException(exception)); 
            } 
            catch(FileNotFoundException)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SR.GetString(SR.Argument_FileNameInvalid)));
            }
            finally
            { 
                SafeRelease(log);
            } 
        } 

        static void SafeRelease(object obj) 
        {
            if (obj != null)
            {
                Marshal.FinalReleaseComObject(obj); 
            }
        } 
 
        internal void Close()
        { 

            if(!this.smuggledLog.IsInvalid)
            {
                ILog log = (ILog)(this.smuggledLog.Smuggle()); 
                try
                { 
                    this.smuggledLog.Close(); 
                }
                catch (COMException exception) 
                {
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ConvertKnownException(exception));
                }
                finally 
                {
                    SafeRelease(log); 
                } 
            }
        } 

        internal void TruncatePrefix(SequenceNumber seqNumber)
        {
            if(this.smuggledLog.IsInvalid) 
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ObjectDisposed()); 
            } 

            ILog log = (ILog)(this.smuggledLog.Smuggle()); 
            try
            {
                log.TruncatePrefix(seqNumber.High);
            } 
            catch (COMException exception)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ConvertKnownException(exception)); 
            }
            finally 
            {
                SafeRelease(log);
            }
        } 

        internal void Force(SequenceNumber seqNumber) 
        { 
            if(this.smuggledLog.IsInvalid)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ObjectDisposed());
            }

            ILog log = (ILog)(this.smuggledLog.Smuggle()); 
            try
            { 
                log.Force(seqNumber.High); 
            }
            catch (COMException exception) 
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ConvertKnownException(exception));
            }
            finally 
            {
                SafeRelease(log); 
            } 
        }
 
        internal void GetLogLimits(out SequenceNumber first, out SequenceNumber last)
        {
            ulong lsnfirst = 0;
            ulong lsnlast = 0; 

            if(this.smuggledLog.IsInvalid) 
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ObjectDisposed());
            } 

            ILog log = (ILog)(this.smuggledLog.Smuggle());
            try
            { 
                log.GetLogLimits(out lsnfirst, out lsnlast);
            } 
            catch (COMException exception) 
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ConvertKnownException(exception)); 
            }
            finally
            {
                SafeRelease(log); 
            }
 
            first = new SequenceNumber(lsnfirst); 
            last = new SequenceNumber(lsnlast);
        } 

        internal SequenceNumber AppendRecord(UnmanagedBlob[] data, bool fForceNow)
        {
            ulong recordLsn = 0; 

            if(this.smuggledLog.IsInvalid) 
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ObjectDisposed());
            } 

            ILog log = (ILog)(this.smuggledLog.Smuggle());
            try
            { 
                // Due to WinSE 184096 bug, we always do force flush as a work around. Ignoring fForceNow value...
                // If force flush is not done, the user will be able to read stale records after calling TruncatePrefix and 
                // the base lsn will not be updated to reflect the new lsn in TruncatePrefix call. 
                // This is a temporary work around fix and if txflog issue is fixed at a later date, we need to have a QFE
                // to use the user passed in fForceNow flag value to support buffering of log records. 
                // Related Bugs:
                //          WinSE: 184096
                //          Windows OS: 1729140
                //          MB: 57586 52216 

                log.AppendRecord(data, 
                                 data.Length, 
                                 true,
                                 out recordLsn); 
            }
            catch (COMException exception)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ConvertKnownException(exception)); 
            }
            finally 
            { 
                SafeRelease(log);
            } 

            return new SequenceNumber(recordLsn);
        }
 
        internal void ReadRecord(SequenceNumber seqNumtoRead, out byte[] record, out int recordSize, out SequenceNumber previous, out SequenceNumber next)
        { 
            ulong prevLsn = 0; 
            ulong nextLsn = 0;
            record = null; 
            recordSize = 0;

            if(this.smuggledLog.IsInvalid)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ObjectDisposed());
            } 
 
            ILog log = (ILog)(this.smuggledLog.Smuggle());
            try 
            {
                CoTaskMemHandle pData = null;
                try
                { 
                    log.ReadRecord(seqNumtoRead.High,
                                   out prevLsn, 
                                   out nextLsn, 
                                   out pData,
                                   out recordSize); 

                    record = new byte[recordSize];

                    Marshal.Copy(pData.DangerousGetHandle(), 
                                 record,
                                 0, 
                                 recordSize); 
                }
                catch (COMException exception) 
                {
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ConvertKnownException(exception));
                }
                finally 
                {
                    if (pData != null && !pData.IsInvalid) pData.Close(); 
                } 
            }
            finally 
            {
                SafeRelease(log);
            }
 
            previous = new SequenceNumber(prevLsn);
            next = new SequenceNumber(nextLsn); 
        } 

        internal void ReadRecordPrefix(SequenceNumber seqNumtoRead, out byte[] record, ref int cbData, out int recordSize, out SequenceNumber previous, out SequenceNumber next) 
        {
            ulong prevLsn = 0;
            ulong nextLsn = 0;
            record = null; 
            recordSize = 0;
 
            if(this.smuggledLog.IsInvalid) 
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ObjectDisposed()); 
            }

            ILog log = (ILog)(this.smuggledLog.Smuggle());
            try 
            {
                record = new byte[cbData]; 
                log.ReadRecordPrefix(seqNumtoRead.High, 
                                out prevLsn,
                                out nextLsn, 
                                record,
                                ref cbData,
                                out recordSize);
 
            }
            catch (COMException exception) 
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ConvertKnownException(exception));
            } 
            finally
            {
                SafeRelease(log);
            } 

            previous = new SequenceNumber(prevLsn); 
            next = new SequenceNumber(nextLsn); 
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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SimpleFileLog.cs source code in C# .NET

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