LogRestartAreaEnumerator.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / WCF / Log / System / IO / Log / LogRestartAreaEnumerator.cs / 1305376 / LogRestartAreaEnumerator.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------
namespace System.IO.Log
{ 
    using System;
    using System.Collections; 
    using System.Collections.Generic; 
    using System.Runtime.InteropServices;
 

    // See the notes on LogLogRecordEnumerator for why this is
    // thread-safe: the same arguments apply here.
    // 
    class LogRestartAreaEnumerator : IEnumerator
    { 
        enum State 
        {
            BeforeFirst, 
            Valid,
            AfterLast,
            Disposed
        } 

        LogRecordSequence recordSequence; 
 
        State             state;
        object            syncRoot; 
        SafeReadContext   readContext;
        LogLogRecord      current;

        internal LogRestartAreaEnumerator(LogRecordSequence recordSequence) 
        {
            this.recordSequence = recordSequence; 
 
            this.syncRoot = new object();
            this.state = State.BeforeFirst; 
        }

        object IEnumerator.Current
        { 
            get
            { 
                return this.Current; 
            }
        } 

        public LogRecord Current
        {
            get 
            {
                lock(this.syncRoot) 
                { 
                    if (this.state == State.Disposed)
#pragma warning suppress 56503 
                         throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ObjectDisposed());

// IEnumerable interface contract for "current" member can throw InvalidOperationException. Suppressing this warning.
 
                    if (this.state == State.BeforeFirst)
#pragma warning suppress 56503 
                         throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.EnumNotStarted()); 
                    if (this.state == State.AfterLast)
#pragma warning suppress 56503 
                         throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.EnumEnded());

                    return this.current;
                } 
            }
        } 
 
        public void Dispose()
        { 
            lock(this.syncRoot)
            {
                if (this.current != null)
                { 
                    this.current.Detach();
                    this.current = null; 
                } 

                if ((this.readContext != null) && 
                    (!this.readContext.IsInvalid))
                {
                    this.readContext.Close();
                } 

                this.state = State.Disposed; 
            } 
        }
 
        public bool MoveNext()
        {
            lock(this.syncRoot)
            { 
                if (this.state == State.Disposed)
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ObjectDisposed()); 
                if (this.state == State.AfterLast) 
                    return false;
 
                if (this.readContext == null)
                {
                    return ReadRestartArea();
                } 
                else
                { 
                    if (this.current != null) 
                        this.current.Detach();
 
                    return ReadPreviousRestartArea();
                }
            }
        } 

        bool ReadRestartArea() 
        { 
            if (!((this.readContext == null || this.readContext.IsInvalid) && (this.current == 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 only call this for first record!"); 
            }
            unsafe 
            { 
                byte *readBuffer;
                int bufferLength; 
                ulong lsnRecord;

                if (!UnsafeNativeMethods.ReadLogRestartAreaSync(
                        this.recordSequence.MarshalContext, 
                        out readBuffer,
                        out bufferLength, 
                        out lsnRecord, 
                        out this.readContext))
                { 
                    this.state = State.AfterLast;
                    return false;
                }
 
                this.current = new LogLogRecord(
                    new SequenceNumber(lsnRecord), 
                    SequenceNumber.Invalid, 
                    SequenceNumber.Invalid,
                    readBuffer, 
                    bufferLength);

                this.state = State.Valid;
                return true; 
            }
        } 
 
        bool ReadPreviousRestartArea()
        { 
            if (this.readContext == null || this.readContext.IsInvalid)
            {
                // 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 only be called for records after the first!"); 
            } 
            unsafe
            { 
                byte *readBuffer;
                int bufferLength;
                ulong lsnRecord;
 
                if (!UnsafeNativeMethods.ReadPreviousLogRestartAreaSync(
                        this.readContext, 
                        out readBuffer, 
                        out bufferLength,
                        out lsnRecord)) 
                {
                    this.state = State.AfterLast;
                    return false;
                } 

                this.current = new LogLogRecord( 
                    new SequenceNumber(lsnRecord), 
                    SequenceNumber.Invalid,
                    SequenceNumber.Invalid, 
                    readBuffer,
                    bufferLength);

                this.state = State.Valid; 
                return true;
            } 
        } 

        public void Reset() 
        {
            lock (this.syncRoot)
            {
                if (this.state == State.Disposed) 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ObjectDisposed());
 
                if (this.current != null) 
                {
                    this.current.Detach(); 
                    this.current = null;
                }

                if ((this.readContext != null) && 
                    (!this.readContext.IsInvalid))
                { 
                    this.readContext.Close(); 
                    this.readContext = null;
                } 

                this.state = State.BeforeFirst;
            }
        } 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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LogRestartAreaEnumerator.cs source code in C# .NET

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