' 导入命名空间
Imports System.IO
Imports System.IO.Log
Imports System.Collections.Generic
Imports System.Text


Namespace MyFileRecordSequence


Friend Class ReadRecordsSample
    Private Shared Function AppendRecord(ByVal sequence As IRecordSequence, ByVal message As String, ByVal user As SequenceNumber, ByVal previous As SequenceNumber) As SequenceNumber
        Dim data As New MemoryStream()
        Dim writer As New BinaryWriter(data)
        writer.Write(message)
        Dim segments() As ArraySegment(Of Byte)
        segments = New ArraySegment(Of Byte)(0){}
        segments(0) = New ArraySegment(Of Byte)(data.GetBuffer(), 0, CInt(Fix(data.Length)))
        Return sequence.Append(segments, user, previous,RecordAppendOptions.None)
    End Function
    Public Shared Sub Main(ByVal args() As String)
        Dim sequence As IRecordSequence
        sequence = New FileRecordSequence(args(0))
        Dim a, b, c, d As SequenceNumber
        a = AppendRecord(sequence, "This is record A", SequenceNumber.Invalid, SequenceNumber.Invalid)
        Console.WriteLine("Record A has sequence number System.IO.Log", a)
        b = AppendRecord(sequence, "This is record B", a, a)
        Console.WriteLine("Record B has sequence number System.IO.Log", b)
        c = AppendRecord(sequence, "This is record C", a, a)
        Console.WriteLine("Record C has sequence number System.IO.Log", c)
        d = AppendRecord(sequence, "This is record D", b, c)
        Console.WriteLine("Record D has sequence number System.IO.Log", d)
            For Each record In sequence.ReadLogRecords(a, LogRecordEnumeratorType.Next)
                Dim reader As New BinaryReader(record.Data)
                Console.WriteLine("System.IO.Log: T:System.IO.Log.IRecordSequence", record.SequenceNumber, reader.ReadString())
            Next record
            For Each record In sequence.ReadLogRecords(d, LogRecordEnumeratorType.User)
                Dim reader As New BinaryReader(record.Data)
                Console.WriteLine("System.IO.Log: T:System.IO.Log.IRecordSequence", record.SequenceNumber, reader.ReadString())
            Next record
            For Each record In sequence.ReadLogRecords(d, LogRecordEnumeratorType.Previous)
                Dim reader As New BinaryReader(record.Data)
                Console.WriteLine("System.IO.Log: T:System.IO.Log.IRecordSequence", record.SequenceNumber, reader.ReadString())
            Next record
    End Sub
End Class

' 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