FileRecordSequence Constructors

Definition

Namespace:

System.IO.Log

Assembly:

System.IO.Log.dll

Initializes a new instance of the FileRecordSequence class.

Overloads

FileRecordSequence(String)	Initializes a new instance of the FileRecordSequence class with a specified file.
FileRecordSequence(String, FileAccess)	Initializes a new instance of the FileRecordSequence class with a specified file and an access mode.
FileRecordSequence(String, FileAccess, Int32)	Initializes a new instance of the FileRecordSequence class with a specified file, an access mode, and a file size.

FileRecordSequence(String)

Initializes a new instance of the FileRecordSequence class with a specified file.

public:
 FileRecordSequence(System::String ^ path);

public FileRecordSequence (string path);

new System.IO.Log.FileRecordSequence : string -> System.IO.Log.FileRecordSequence

Public Sub New (path As String)

Parameters

path

String

A relative or absolute path for the file that this FileRecordSequence instance will encapsulate.

Exceptions

ArgumentException

The file specified by path is not valid.

FileNotFoundException

The file specified by path cannot be found.

IOException

The request cannot be performed because of an unexpected I/O exception.

OutOfMemoryException

There is not enough memory to continue the execution of the program.

UnauthorizedAccessException

Access for the specified log store is denied by the operating system.

Examples

The following example creates a record sequence, appends record to it, reads the records, and finally disposes the sequence.

public class MyLog
{
    string logName = "test.log";
    FileRecordSequence sequence = null;
    bool delete = true;

    public MyLog()
    {
    // Create a FileRecordSequence.
        sequence = new FileRecordSequence(logName, FileAccess.ReadWrite);
    }

// Append records to the record sequence.
    public void AppendRecords()
    {
        Console.WriteLine("Appending Log Records...");
        SequenceNumber previous = SequenceNumber.Invalid;

        previous = sequence.Append(CreateData("Hello World!"), SequenceNumber.Invalid, SequenceNumber.Invalid, RecordAppendOptions.ForceFlush);
        previous = sequence.Append(CreateData("This is my first Logging App"), SequenceNumber.Invalid, SequenceNumber.Invalid, RecordAppendOptions.ForceFlush);
        previous = sequence.Append(CreateData("Using FileRecordSequence..."), SequenceNumber.Invalid, SequenceNumber.Invalid, RecordAppendOptions.ForceFlush);

        Console.WriteLine("Done...");
    }
    
// Read the records added to the log.
    public void ReadRecords()
    {
        Encoding enc = Encoding.Unicode;

        Console.WriteLine();

        Console.WriteLine("Reading Log Records...");
        try
        {
            foreach (LogRecord record in this.sequence.ReadLogRecords(this.sequence.BaseSequenceNumber, LogRecordEnumeratorType.Next))
            {
                byte[] data = new byte[record.Data.Length];
                record.Data.Read(data, 0, (int)record.Data.Length);
                string mystr = enc.GetString(data);
                Console.WriteLine("    {0}", mystr);
            }
        }
        catch (Exception e)
        {
            Console.WriteLine("Exception {0} {1}", e.GetType(), e.Message);
        }

        Console.WriteLine();
    }

// Dispose the record sequence and delete the log file.
    public void Cleanup()
    {
    // Dispose the sequence.
        sequence.Dispose();

    // Delete the log file.
        if (delete)
        {
            try
            {
                File.Delete(this.logName);
            }
            catch (Exception e)
            {
                Console.WriteLine("Exception {0} {1}", e.GetType(), e.Message);
            }
        }
    }

// Converts the given data to an Array of ArraySegment<byte>
    public static IList<ArraySegment<byte>> CreateData(string str)
    {
        Encoding enc = Encoding.Unicode;

        byte[] array = enc.GetBytes(str);

        ArraySegment<byte>[] segments = new ArraySegment<byte>[1];
        segments[0] = new ArraySegment<byte>(array);

        return Array.AsReadOnly<ArraySegment<byte>>(segments);
    }
}

class LogSample
{
    static void Main2(string[] args)
    {
        MyLog log = new MyLog();

        log.AppendRecords();
        log.ReadRecords();
        log.Cleanup();
    }
}

Public Class MyLog
    Private logName As String = "test.log"
    Private sequence As FileRecordSequence = Nothing
    Private delete As Boolean = True

    Public Sub New()
    ' Create a FileRecordSequence.
        sequence = New FileRecordSequence(logName, FileAccess.ReadWrite)
    End Sub

' Append records to the record sequence.
    Public Sub AppendRecords()
        Console.WriteLine("Appending Log Records...")
        Dim previous As SequenceNumber = SequenceNumber.Invalid

        previous = sequence.Append(CreateData("Hello World!"), SequenceNumber.Invalid, SequenceNumber.Invalid, RecordAppendOptions.ForceFlush)
        previous = sequence.Append(CreateData("This is my first Logging App"), SequenceNumber.Invalid, SequenceNumber.Invalid, RecordAppendOptions.ForceFlush)
        previous = sequence.Append(CreateData("Using FileRecordSequence..."), SequenceNumber.Invalid, SequenceNumber.Invalid, RecordAppendOptions.ForceFlush)

        Console.WriteLine("Done...")
    End Sub

' Read the records added to the log. 
    Public Sub ReadRecords()
        Dim enc As Encoding = Encoding.Unicode

        Console.WriteLine()

        Console.WriteLine("Reading Log Records...")
        Try
            For Each record In Me.sequence.ReadLogRecords(Me.sequence.BaseSequenceNumber, LogRecordEnumeratorType.Next)
                Dim data(record.Data.Length - 1) As Byte
                record.Data.Read(data, 0, CInt(Fix(record.Data.Length)))
                Dim mystr As String = enc.GetString(data)
                Console.WriteLine("    {0}", mystr)
            Next record
        Catch e As Exception
            Console.WriteLine("Exception {0} {1}", e.GetType(), e.Message)
        End Try

        Console.WriteLine()
    End Sub

' Dispose the record sequence and delete the log file. 
    Public Sub Cleanup()
    ' Dispose the sequence.
        sequence.Dispose()

    ' Delete the log file.
        If delete Then
            Try
                File.Delete(Me.logName)
            Catch e As Exception
                Console.WriteLine("Exception {0} {1}", e.GetType(), e.Message)
            End Try
        End If
    End Sub

' Converts the given data to an Array of ArraySegment<byte> 
    Public Shared Function CreateData(ByVal str As String) As IList(Of ArraySegment(Of Byte))
        Dim enc As Encoding = Encoding.Unicode

        Dim array() As Byte = enc.GetBytes(str)

        Dim segments(0) As ArraySegment(Of Byte)
        segments(0) = New ArraySegment(Of Byte)(array)

        Return System.Array.AsReadOnly(Of ArraySegment(Of Byte))(segments)
    End Function
End Class

Friend Class LogSample
    Private Shared Sub Main2(ByVal args() As String)
        Dim log As New MyLog()

        log.AppendRecords()
        log.ReadRecords()
        log.Cleanup()
    End Sub
End Class

Remarks

This constructor creates read/write access to the file, and opens the file with share Read access. This means that requests to open the file for writing by this or another process fails until this FileRecordSequence instance has been disposed of, but read attempts will succeed. If path is not found, a new file is created with a size of 0 bytes.

FileRecordSequence(String, FileAccess)

Initializes a new instance of the FileRecordSequence class with a specified file and an access mode.

public:
 FileRecordSequence(System::String ^ path, System::IO::FileAccess access);

public FileRecordSequence (string path, System.IO.FileAccess access);

new System.IO.Log.FileRecordSequence : string * System.IO.FileAccess -> System.IO.Log.FileRecordSequence

Public Sub New (path As String, access As FileAccess)

Parameters

path

String

A relative or absolute path for the file that this FileRecordSequence instance will encapsulate.

access

FileAccess

A valid FileAccess value that controls the kind of access users have to a log file.

Exceptions

ArgumentException

The file specified by path is not valid.

FileNotFoundException

The file specified by path cannot be found.

IOException

The request cannot be performed because of an unexpected I/O exception.

OutOfMemoryException

There is not enough memory to continue the execution of the program.

UnauthorizedAccessException

Access for the specified log store is denied by the operating system.

FileRecordSequence(String, FileAccess, Int32)

Initializes a new instance of the FileRecordSequence class with a specified file, an access mode, and a file size.

public:
 FileRecordSequence(System::String ^ path, System::IO::FileAccess access, int size);

public FileRecordSequence (string path, System.IO.FileAccess access, int size);

new System.IO.Log.FileRecordSequence : string * System.IO.FileAccess * int -> System.IO.Log.FileRecordSequence

Public Sub New (path As String, access As FileAccess, size As Integer)

Parameters

path

String

A relative or absolute path for the file that this FileRecordSequence instance will encapsulate.

access

FileAccess

A valid FileAccess value that controls the kind of access users have to a log file.

size

Int32

The size of the log file to be opened.

Exceptions

ArgumentOutOfRangeException

One or more of the parameters are out of the valid range.

ArgumentException

The file specified by path is not valid.

FileNotFoundException

The file specified by path cannot be found.

IOException

The request cannot be performed because of an unexpected I/O exception.

OutOfMemoryException

There is not enough memory to continue the execution of the program.

UnauthorizedAccessException

Access for the specified log store is denied by the operating system.