How to transfer data between threads?

Question

What are the ways to transfer data between threads in .NET? Currently, I can think of two things:

• Membervariables, for example. using the manufacturer-consumer template.
• Using the ParameterizedThreadStart delegate when starting a thread. (Works only once, not suitable for long desktop workflows).

When does the .NET Framework solve this problem? Maybe .NET already has a common producer-consumer pattern? Perhaps I can use Thread.GetData and Thread.SetData in some way?

Answer 1

As an alternative to Ash, consider the following example.

, : . , Receiver Processor, , . .

. , Receiver , . , . - .NET.

.

using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using System.Threading;
public class Packet
{
    public byte[] Buffer { get; private set; }
    public Packet(byte[] buffer)
    {
        Buffer = buffer;
    }
}
public class PacketEventArgs : EventArgs
{
    public Packet Packet { get; set; }
}
public class UdpState
{
    public UdpClient Client{get;set;}
    public IPEndPoint EndPoint{get;set;}
}
public class Receiver
{
    public event EventHandler<PacketEventArgs> PacketReceived;
    private Thread _thread;
    private ManualResetEvent _shutdownThread = new ManualResetEvent(false);
    public void Start() { _thread.Start(); }
    public void Stop() { _shutdownThread.Set(); }
    public Receiver()
    {
        _thread = new Thread(
            delegate() {
                // Create the client UDP socket.
                IPEndPoint endPoint = new IPEndPoint(IPAddress.Any, 5006);
                UdpClient client = new UdpClient( endPoint );
                // Receive the packets asynchronously.
                client.BeginReceive(
                    new AsyncCallback(OnPacketReceived),
                    new UdpState() { Client = client, EndPoint = endpoint });
                // Wait for the thread to end.
                _shutdownThread.WaitOne();
            }
        );
    }
    private void OnPacketReceived(IAsyncResult ar)
    {
        UdpState state = (UdpState)ar.AsyncState;
        IPEndPoint endPoint = state.EndPoint;
        byte[] bytes = state.Client.EndReceive(ar, ref endPoint);
        // Create the packet. 
        Packet packet = new Packet(bytes);
        // Notify any listeners.
        EventHandler<PacketEventArgs> handler = PacketReceived;
        if (handler != null) {
            handler(this, new PacketEventArgs() { Packet = packet });
        }
        // Read next packet.
        if (!_shutdownThread.WaitOne(0)) {
            state.Client.BeginReceive(
                new AsyncCallback(OnPacketReceived),
                state);
        }
    }
}
public class Processor
{
    private Thread _thread;
    private object _sync = new object();
    private ManualResetEvent _packetReceived = new ManualResetEvent(false);
    private ManualResetEvent _shutdownThread = new ManualResetEvent(false);
    private Queue<Packet> _packetQueue = new Queue<Packet>(); // shared data
    public void Start() { _thread.Start(); }
    public void Stop() { _shutdownThread.Set(); }
    public Processor()
    {
        _thread = new Thread(
            delegate() {
                WaitHandle[] handles = new WaitHandle[] {
                    _shutdownThread,
                    _packetReceived
                };

                while (!_shutdownThread.WaitOne(0)) {
                    switch (WaitHandle.WaitAny(handles)) {
                        case 0: // Shutdown Thread Event
                            break;
                        case 1: // Packet Received Event
                            _packetReceived.Reset();
                            ProcessPackets();
                            break;
                        default:
                            Stop();
                            break;
                    }
                }
            }
        );
    }
    private void ProcessPackets()
    {
        Queue<Packet> localPacketQueue = null;
        Queue<Packet> newPacketQueue = new Queue<Packet>();
        lock (_sync) {
            // Swap out the populated queue with the empty queue.
            localPacketQueue = _packetQueue;
            _packetQueue = newPacketQueue;
        }

        foreach (Packet packet in localPacketQueue) {
            Console.WriteLine(
                "Packet received with {0} bytes",
                packet.Buffer.Length );
        }
    }
    public void OnPacketReceived(object sender, PacketEventArgs e)
    {
        // NOTE:  This function executes on the Receiver thread.
        lock (_sync) {
            // Enqueue the packet.
            _packetQueue.Enqueue(e.Packet);
        }

        // Notify the Processor thread that a packet is available.
        _packetReceived.Set();
    }
}
static void Main()
{
    Receiver receiver = new Receiver();
    Processor processor = new Processor();

    receiver.PacketReceived += processor.OnPacketReceived;

    processor.Start();
    receiver.Start();

    Thread.Sleep(5000);

    receiver.Stop();
    processor.Stop();
}

, . .NET 3.5, UDP- 5006.

, ProcessPackets() OnPacketReceived() Processor. , OnPacketReceived() Receiver, Processor .

Answer 2

, , "sync". .

:

class DataClass{
    private object m_syncObject=new object();

    private string m_data;

    public string Data
    {
        get{
            lock(m_syncobject)
            {
                return m_data;
            }
        }
        set{
           lock(m_syncobject)
           {
                m_data=value;
           }

        }
    }
} 

DataClass() , . Data / .

Answer 3

, .

Answer 4

: "" ( "-" ), , , . , (, ), , ".Count", ( . Google).

:

class pseudoThreadsafeHuman{
   private object m_syncobject;
   public string firstName;
   public string lastName;

   public string fullName
   get{
        lock(m_syncobject)
        {
            return lastName & "," & firstName;
        }
    }
    set{
       lock(m_syncobject)
       {
            lastName = value.Split(",")[1];
            firstName = value.Split(",")[2];
       }
    }
}

- - :

public void isJohn(pseudoThreadSafeHuman currentPerson) {
    if currentPerson.firstName == "John"  
       {
         MessageBox.Show(currentPerson.fullName)
       }
}

firstName, lastName fullName - . - , "", if MessageBox.Show(). :

, getInitials (pseudoThreadSafeHuman currentPerson), :

public getInitials(pseudoThreadSafeHuman currentPerson)
   string initials = ""
   if currentPerson.firstName != "" {
     initials += currentPerson.firstName[0];  // crash here if firstName got changed to ""
   }
   if currentPerson.lastName != "" {
      initials += currentPerson.lastName[0];  // crash here if lastName got changed to ""
   }
}

. , # ( VB.Net), . , , . , -, - , synclock ( ).