FileRecordSequence Constructors
Definition
Important
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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
The file specified by path
is not valid.
The file specified by path
cannot be found.
The request cannot be performed because of an unexpected I/O exception.
There is not enough memory to continue the execution of the program.
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.
Applies to
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
The file specified by path
is not valid.
The file specified by path
cannot be found.
The request cannot be performed because of an unexpected I/O exception.
There is not enough memory to continue the execution of the program.
Access for the specified log store is denied by the operating system.
Applies to
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
One or more of the parameters are out of the valid range.
The file specified by path
is not valid.
The file specified by path
cannot be found.
The request cannot be performed because of an unexpected I/O exception.
There is not enough memory to continue the execution of the program.
Access for the specified log store is denied by the operating system.