套接字中的BeginReceive（Byte（），Int32，Int32，SocketFlags，AsyncCallback，Object）和回调方法是什么？

Question

我在套接字编程方面很新。 因此，最近我被分配到一个使用vb.net进行套接字编程的任务，以找出为什么该程序分配了近20GB的物理内存。 但是由于我对Socket没有足够的了解，所以我深陷其中。 我发现程序中有BeginReceive()方法和EndReceive()方法作为回调位于程序中，当我搜索这些内容时，我发现一些信息应调用EndReceive()进行回调。 所以，我的问题是：

1. 我是否需要每次在BeginReceive()之后调用EndReceive()方法来清除缓冲区，以便清除内存分配？
2. 如果有人用简单的单词解释BeginReceive()和EndReceive()真正含义，我将不胜感激。

更新：请检查我在项目中找到的以下代码：

Public Sub Receive(ByVal client As Socket)

      Dim state As New StateObject
    state.workSocket = client


    Try
        If m_clientSocket.Connected Then

            client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, New AsyncCallback(AddressOf ReceiveCallback), state)
        Else
            Connect()
        End If

    Catch se As SocketException
        logstr = se.Message
        write_log(logstr, "Receive", "Receive")
    End Try
End Sub


 Public Sub ReceiveCallback(ByVal ar As IAsyncResult)


    Dim state As StateObject = CType(ar.AsyncState, StateObject)
    Dim client As Socket = state.workSocket
    Dim receiveData As String = ""
    Dim sendData As String = ""

    Dim bytesRead As Integer = client.EndReceive(ar)

    If bytesRead > 0 Then

        state.sb.Append(System.Text.Encoding.ASCII.GetString(state.buffer, 0, bytesRead))

        client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, New AsyncCallback(AddressOf ReceiveCallback), state)      

        receiveData = state.sb.ToString()

        Me.lsBulk.Items.Insert(0, receiveData)
        sendData = getReply(receiveData)
        write_log(Now.ToString & " : " & receiveData & vbCrLf, "bytesRead", "bytesRead")

        Try
            Dim objData As [Object] = sendData
            Dim byData As Byte() = System.Text.Encoding.ASCII.GetBytes(objData.ToString())
            If m_clientSocket IsNot Nothing Then
                m_clientSocket.Send(byData)
            End If

            write_log(Now.ToString & " : " & sendData & vbCrLf, "sendData", "sendData")
        Catch se As SocketException
            logstr = se.Message
            write_log(logstr, "WaitForData", "waitfordata")
        End Try

    Else

        receiveData = state.sb.ToString()


        If receiveData <> "" Then
            write_log(Now.ToString & " : " & receiveData & vbCrLf, "receiveData2", "receiveData2")
        End If


    End If
End Sub 

Answer 1

根据文档BeginReceive “开始从连接的Socket异步接收数据。”。 因此，以普通语言显示：在继续执行程序的同时开始接收数据。

在EndReceive的文档中，“回调方法必须接受BeginConnect方法返回的IAsyncResult作为参数。” 和“获取套接字后，您可以调用EndConnect方法来成功完成连接尝试。”

并且：“异步BeginReceive操作必须通过调用EndReceive方法来完成。通常，该方法由回调委托调用。”

所以，是的，你必须调用EndReceive得到的结果BeginReceive 。

另外，作为对第二个问题的回答：“要获取接收到的数据，请调用IAsyncResult的AsyncState方法，并提取包含在结果状态对象中的缓冲区。” 因此，结果将缓存在IAsyncResult对象中。 从那里提取它并摆脱对象，让GC收集它。

来源： BeginReceive ， EndReceive ， IAsyncResult 。