This documentation is archived and is not being maintained.

BufferedStream Class

Adds a buffering layer to read and write operations on another stream. This class cannot be inherited.

Namespace:  System.IO
Assembly:  mscorlib (in mscorlib.dll)

'Declaration
<ComVisibleAttribute(True)> _
Public NotInheritable Class BufferedStream _
	Inherits Stream

The BufferedStream type exposes the following members.

  NameDescription
Public methodBufferedStream(Stream)Initializes a new instance of the BufferedStream class with a default buffer size of 4096 bytes.
Public methodBufferedStream(Stream, Int32)Initializes a new instance of the BufferedStream class with the specified buffer size.
Top

  NameDescription
Public propertyCanReadGets a value indicating whether the current stream supports reading. (Overrides Stream.CanRead.)
Public propertyCanSeekGets a value indicating whether the current stream supports seeking. (Overrides Stream.CanSeek.)
Public propertyCanTimeoutGets a value that determines whether the current stream can time out. (Inherited from Stream.)
Public propertyCanWriteGets a value indicating whether the current stream supports writing. (Overrides Stream.CanWrite.)
Public propertyLengthGets the stream length in bytes. (Overrides Stream.Length.)
Public propertyPositionGets the position within the current stream. (Overrides Stream.Position.)
Public propertyReadTimeoutGets or sets a value, in miliseconds, that determines how long the stream will attempt to read before timing out. (Inherited from Stream.)
Public propertyWriteTimeoutGets or sets a value, in miliseconds, that determines how long the stream will attempt to write before timing out. (Inherited from Stream.)
Top

  NameDescription
Public methodBeginReadBegins an asynchronous read operation. (Inherited from Stream.)
Public methodBeginWriteBegins an asynchronous write operation. (Inherited from Stream.)
Public methodCloseCloses the current stream and releases any resources (such as sockets and file handles) associated with the current stream. (Inherited from Stream.)
Public methodCopyTo(Stream)Reads the bytes from the current stream and writes them to the destination stream. (Inherited from Stream.)
Public methodCopyTo(Stream, Int32)Reads all the bytes from the current stream and writes them to a destination stream, using a specified buffer size. (Inherited from Stream.)
Public methodCreateObjRefCreates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject.)
Protected methodCreateWaitHandle Obsolete. Allocates a WaitHandle object. (Inherited from Stream.)
Public methodDisposeReleases all resources used by the Stream. (Inherited from Stream.)
Protected methodDispose(Boolean)Releases the unmanaged resources used by the Stream and optionally releases the managed resources. (Inherited from Stream.)
Public methodEndReadWaits for the pending asynchronous read to complete. (Inherited from Stream.)
Public methodEndWriteEnds an asynchronous write operation. (Inherited from Stream.)
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodFlushClears all buffers for this stream and causes any buffered data to be written to the underlying device. (Overrides Stream.Flush.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetLifetimeServiceRetrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodInitializeLifetimeServiceObtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodMemberwiseClone(Boolean)Creates a shallow copy of the current MarshalByRefObject object. (Inherited from MarshalByRefObject.)
Protected methodObjectInvariantInfrastructure. Provides support for a Contract. (Inherited from Stream.)
Public methodReadCopies bytes from the current buffered stream to an array. (Overrides Stream.Read(Byte(), Int32, Int32).)
Public methodReadByteReads a byte from the underlying stream and returns the byte cast to an int, or returns -1 if reading from the end of the stream. (Overrides Stream.ReadByte.)
Public methodSeekSets the position within the current buffered stream. (Overrides Stream.Seek(Int64, SeekOrigin).)
Public methodSetLengthSets the length of the buffered stream. (Overrides Stream.SetLength(Int64).)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodWriteCopies bytes to the buffered stream and advances the current position within the buffered stream by the number of bytes written. (Overrides Stream.Write(Byte(), Int32, Int32).)
Public methodWriteByteWrites a byte to the current position in the buffered stream. (Overrides Stream.WriteByte(Byte).)
Top

A buffer is a block of bytes in memory used to cache data, thereby reducing the number of calls to the operating system. Buffers improve read and write performance. A buffer can be used for either reading or writing, but never both simultaneously. The Read and Write methods of BufferedStream automatically maintain the buffer.

BufferedStream can be composed around certain types of streams. It provides implementations for reading and writing bytes to an underlying data source or repository. Use BinaryReader and BinaryWriter for reading and writing other data types. BufferedStream is designed to prevent the buffer from slowing down input and output when the buffer is not needed. If you always read and write for sizes greater than the internal buffer size, then BufferedStream might not even allocate the internal buffer. BufferedStream also buffers reads and writes in a shared buffer. It is assumed that you will almost always be doing a series of reads or writes, but rarely alternate between the two of them.

The following code example shows how to use the BufferedStream class over the NetworkStream class to increase the performance of certain I/O operations. Start the server on a remote computer before starting the client. Specify the remote computer name as a command-line argument when starting the client. Vary the dataArraySize and streamBufferSize constants to view their effect on performance.


' Compile using /r:System.dll.
Imports Microsoft.VisualBasic
Imports System
Imports System.IO
Imports System.Globalization
Imports System.Net
Imports System.Net.Sockets

Public Class Client 

    Const dataArraySize As Integer    =   100
    Const streamBufferSize As Integer =  1000
    Const numberOfLoops As Integer    = 10000

    Shared Sub Main(args As String()) 

        ' Check that an argument was specified when the 
        ' program was invoked.
        If args.Length = 0 Then
            Console.WriteLine("Error: The name of the host " & _
                "computer must be specified when the program " & _ 
                "is invoked.")
            Return
        End If

        Dim remoteName As String = args(0)

        ' Create the underlying socket and connect to the server.
        Dim clientSocket As New Socket(AddressFamily.InterNetwork, _
            SocketType.Stream, ProtocolType.Tcp)

        clientSocket.Connect(New IPEndPoint( _
            Dns.Resolve(remoteName).AddressList(0), 1800))

        Console.WriteLine("Client is connected." & vbCrLf)

        ' Create a NetworkStream that owns clientSocket and then 
        ' create a BufferedStream on top of the NetworkStream.
        Dim netStream As New NetworkStream(clientSocket, True)
        Dim bufStream As New _
            BufferedStream(netStream, streamBufferSize)

        Try
            ' Check whether the underlying stream supports seeking.
            If bufStream.CanSeek Then
                Console.WriteLine("NetworkStream supports" & _
                    "seeking." & vbCrLf)
            Else
                Console.WriteLine("NetworkStream does not " & _
                    "support seeking." & vbCrLf)
            End If

            ' Send and receive data.
            If bufStream.CanWrite Then
                SendData(netStream, bufStream)
            End If            
            If bufStream.CanRead Then
                ReceiveData(netStream, bufStream)
            End If
        Finally

            ' When bufStream is closed, netStream is in turn 
            ' closed, which in turn shuts down the connection 
            ' and closes clientSocket.
            Console.WriteLine(vbCrLf & "Shutting down the connection.")
            bufStream.Close()
        End Try
    End Sub

    Shared Sub SendData(netStream As Stream, bufStream As Stream)

        Dim startTime As DateTime 
        Dim networkTime As Double, bufferedTime As Double 

        ' Create random data to send to the server.
        Dim dataToSend(dataArraySize - 1) As Byte
        Dim randomGenerator As New Random()
        randomGenerator.NextBytes(dataToSend)

        ' Send the data using the NetworkStream.
        Console.WriteLine("Sending data using NetworkStream.")
        startTime = DateTime.Now
        For i As Integer = 1 To numberOfLoops
            netStream.Write(dataToSend, 0, dataToSend.Length)
        Next i
        networkTime = DateTime.Now.Subtract(startTime).TotalSeconds
        Console.WriteLine("{0} bytes sent in {1} seconds." & vbCrLf, _
            numberOfLoops * dataToSend.Length, _
            networkTime.ToString("F1"))

        ' Send the data using the BufferedStream.
        Console.WriteLine("Sending data using BufferedStream.")
        startTime = DateTime.Now
        For i As Integer = 1 To numberOfLoops
            bufStream.Write(dataToSend, 0, dataToSend.Length)
        Next i

        bufStream.Flush()
        bufferedTime = DateTime.Now.Subtract(startTime).TotalSeconds
        Console.WriteLine("{0} bytes sent In {1} seconds." & vbCrLf, _
            numberOfLoops * dataToSend.Length, _
            bufferedTime.ToString("F1"))

        ' Print the ratio of write times.
        Console.Write("Sending data using the buffered " & _
            "network stream was {0}", _
            (networkTime/bufferedTime).ToString("P0"))
        If bufferedTime < networkTime Then
            Console.Write(" faster")
        Else
            Console.Write(" slower")
        End If
        Console.WriteLine(" than using the network stream alone.")
    End Sub

    Shared Sub ReceiveData(netStream As Stream, bufStream As Stream)

        Dim startTime As DateTime 
        Dim networkTime As Double, bufferedTime As Double = 0

        Dim bytesReceived As Integer = 0
        Dim receivedData(dataArraySize - 1) As Byte

        ' Receive data using the NetworkStream.
        Console.WriteLine("Receiving data using NetworkStream.")
        startTime = DateTime.Now
        While bytesReceived < numberOfLoops * receivedData.Length
            bytesReceived += netStream.Read( _
                receivedData, 0, receivedData.Length)
        End While
        networkTime = DateTime.Now.Subtract(startTime).TotalSeconds
        Console.WriteLine("{0} bytes received in {1} " & _
            "seconds." & vbCrLf, _
            bytesReceived.ToString(), _
            networkTime.ToString("F1"))

        ' Receive data using the BufferedStream.
        Console.WriteLine("Receiving data using BufferedStream.")
        bytesReceived = 0
        startTime = DateTime.Now

        Dim numBytesToRead As Integer = receivedData.Length
        Dim n As Integer
        Do While numBytesToRead > 0

            'Read my return anything from 0 to numBytesToRead
            n = bufStream.Read(receivedData, 0, receivedData.Length)
            'The end of the file is reached.
            If n = 0 Then
                Exit Do
            End If

            bytesReceived += n
            numBytesToRead -= n
        Loop

        bufferedTime = DateTime.Now.Subtract(startTime).TotalSeconds
        Console.WriteLine("{0} bytes received in {1} " & _
            "seconds." & vbCrLf, _
            bytesReceived.ToString(), _
            bufferedTime.ToString("F1"))

        ' Print the ratio of read times.
        Console.Write("Receiving data using the buffered " & _
            "network stream was {0}", _
            (networkTime/bufferedTime).ToString("P0"))
        If bufferedTime < networkTime Then
            Console.Write(" faster")
        Else
            Console.Write(" slower")
        End If
        Console.WriteLine(" than using the network stream alone.")
    End Sub
End Class



' Compile using /r:System.dll.
Imports Microsoft.VisualBasic
Imports System
Imports System.Net
Imports System.Net.Sockets

Public Class Server 

    Shared Sub Main() 

        ' This is a Windows Sockets 2 error code.
        Const WSAETIMEDOUT As Integer = 10060

        Dim serverSocket As Socket 
        Dim bytesReceived As Integer
        Dim totalReceived As Integer = 0
        Dim receivedData(2000000-1) As Byte

        ' Create random data to send to the client.
        Dim dataToSend(2000000-1) As Byte
        Dim randomGenerator As New Random()
        randomGenerator.NextBytes(dataToSend)

        Dim ipAddress As IPAddress = _
            Dns.Resolve(Dns.GetHostName()).AddressList(0)

        Dim ipEndpoint As New IPEndPoint(ipAddress, 1800)

        ' Create a socket and listen for incoming connections.
        Dim listenSocket As New Socket(AddressFamily.InterNetwork, _
            SocketType.Stream, ProtocolType.Tcp)

        Try
            listenSocket.Bind(ipEndpoint)
            listenSocket.Listen(1)

            ' Accept a connection and create a socket to handle it.
            serverSocket = listenSocket.Accept()
            Console.WriteLine("Server is connected." & vbCrLf)
        Finally
            listenSocket.Close()
        End Try

        Try
            ' Send data to the client.
            Console.Write("Sending data ... ")
            Dim bytesSent As Integer = serverSocket.Send( _
                dataToSend, 0, dataToSend.Length, SocketFlags.None)
            Console.WriteLine("{0} bytes sent." & vbCrLf, _
                bytesSent.ToString())

            ' Set the timeout for receiving data to 2 seconds.
            serverSocket.SetSocketOption(SocketOptionLevel.Socket, _
                SocketOptionName.ReceiveTimeout, 2000)

            ' Receive data from the client.
            Console.Write("Receiving data ... ")
            Try
                Do
                    bytesReceived = serverSocket.Receive( _
                        receivedData, 0, receivedData.Length, _
                        SocketFlags.None)
                    totalReceived += bytesReceived
                Loop While bytesReceived <> 0
            Catch e As SocketException
                If(e.ErrorCode = WSAETIMEDOUT)

                    ' Data was not received within the given time.
                    ' Assume that the transmission has ended.
                Else
                    Console.WriteLine("{0}: {1}" & vbCrLf, _
                        e.GetType().Name, e.Message)
                End If
            Finally
                Console.WriteLine("{0} bytes received." & vbCrLf, _
                    totalReceived.ToString())
            End Try
        Finally
            serverSocket.Shutdown(SocketShutdown.Both)
            Console.WriteLine("Connection shut down.")
            serverSocket.Close()
        End Try

    End Sub
End Class


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Show: