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105 lines
3.3 KiB
105 lines
3.3 KiB
Imports System
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Imports System.Collections.Generic
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Imports Xdr
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Namespace Rpc.TcpStreaming
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''' <summary>
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''' generator TCP messages with record mark
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''' http://tools.ietf.org/html/rfc5531#section-11
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''' </summary>
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Public Class TcpWriter
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Implements IByteWriter
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Private ReadOnly _maxBlock As Integer
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Private _pos As Long
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Private _currentBlock As Byte()
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Private _blocks As LinkedList(Of Byte())
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''' <summary>
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''' generator TCP messages with record mark
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''' </summary>
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''' <paramname="maxBlock">maximum block size in the TCP message</param>
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Public Sub New(ByVal maxBlock As Integer)
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_maxBlock = maxBlock
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_pos = 4
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_currentBlock = New Byte(_maxBlock - 1) {}
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_blocks = New LinkedList(Of Byte())()
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End Sub
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''' <summary>
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''' write array of bytes
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''' </summary>
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''' <paramname="buffer"></param>
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Public Sub Write(ByVal buffer As Byte()) Implements IByteWriter.Write
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Dim offset As Long = 0
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While True
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Dim len = buffer.LongLength - offset
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If len <= _maxBlock - _pos Then
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Array.Copy(buffer, offset, _currentBlock, _pos, len)
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_pos += len
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If _pos >= _maxBlock Then CreateNextBlock()
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Return
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End If
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Array.Copy(buffer, offset, _currentBlock, _pos, _maxBlock - _pos)
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offset += _maxBlock - _pos
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CreateNextBlock()
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End While
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End Sub
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''' <summary>
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''' write byte
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''' </summary>
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''' <paramname="b"></param>
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Public Sub Write(ByVal b As Byte) Implements IByteWriter.Write
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_currentBlock(_pos) = b
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_pos += 1
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If _pos >= _maxBlock Then CreateNextBlock()
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End Sub
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Private Sub CreateNextBlock()
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SetLenth(_currentBlock)
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_blocks.AddLast(_currentBlock)
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_currentBlock = New Byte(_maxBlock - 1) {}
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_pos = 4
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End Sub
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Private Sub SetLastBlock()
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Dim last = _blocks.Last
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If last Is Nothing Then Return
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Dim block = last.Value
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block(0) = CByte(block(0) Or &H80)
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End Sub
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Private Sub SetLenth(ByVal block As Byte())
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Dim len = block.Length - 4
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block(0) = CByte(len >> &H18 And &HfF)
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block(1) = CByte(len >> &H10 And &HfF)
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block(2) = CByte(len >> 8 And &HfF)
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block(3) = CByte(len And &HfF)
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End Sub
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''' <summary>
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''' create the TCP message (the original object is destroyed)
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''' </summary>
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''' <returns>blocks of TCP message</returns>
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Public Function Build() As LinkedList(Of Byte())
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If _pos <> 4 Then ' _currentBlock is not empty
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Dim shortBlock = New Byte(_pos - 1) {}
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Array.Copy(_currentBlock, shortBlock, _pos)
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SetLenth(shortBlock)
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_blocks.AddLast(shortBlock)
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_pos = 4
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End If
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SetLastBlock()
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Dim result = _blocks
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_currentBlock = Nothing
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_blocks = Nothing
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Return result
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End Function
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End Class
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End Namespace
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