मैं केवल कुछ हफ्तों के लिए सी # का उपयोग कर रहा हूं लेकिन मुझे धागे में घटनाओं को कैसे आग लगाना है, इस सवाल का सामना करना पड़ा। बहुत से पूर्ण उदाहरण उपलब्ध नहीं हैं (कोई भी?) और विभिन्न विशेषज्ञों के सभी व्यक्तिगत टुकड़ों को समझना मुश्किल था। कुछ समय बाद मैंने अंततः कुछ ऐसा काम किया जो काम करता है, इसलिए मैं इस धागे पर अपने जैसे किसी भी नए आने वालों के लिए इसका पूरा उदाहरण साझा करना चाहता था। इसके अलावा मैं किसी भी विशेषज्ञ सलाह या आलोचना का स्वागत करता हूं क्योंकि मैं सी # के लिए काफी नया हूं और निश्चित रूप से इसमें सुधार किया जा सकता है।
यह एक पूर्ण उदाहरण है जिसमें 3 बटन और एक लंबवत ट्रैकबार के साथ एक छोटा सा रूप है, सभी डिफ़ॉल्ट नामों के साथ। डिज़ाइनर में फॉर्म बनाएं और इसे टेस्टवेन्ट क्लास के साथ ओवरराइट करें, फिर 3 बटन ऑनक्लिक ईवेंट को हुक करें। ट्रैकबार का उपयोग उस थ्रेड को चुनने के लिए किया जा सकता है जिसे आप बटन के माध्यम से किसी ईवेंट को आग लगाना चाहते हैं, और जब आप शून्य मुख्य() में numThreads को बदलते हैं तो स्वचालित रूप से स्केल हो जाएगा। बटन 2 थ्रेड को बंद करने के लिए एक ईवेंट भेजेगा।
माइवेन्ट क्लास का उपयोग IMyEventActions इंटरफ़ेस को लागू करने वाले किसी भी वर्ग के संयोजन के साथ किया जा सकता है। MyEvent का उपयोग करने वाली कक्षा स्वचालित रूप से ऑनर्सिंग हैप्डेन (...) में निकाल दी गई घटनाओं को प्राप्त करेगी। इसके अलावा, MyEvent को तत्काल कक्षा में अन्य कक्षाओं की घटनाओं की पुन: सदस्यता ले सकते हैं। फायरिंग घटनाओं को आसानी से MyEvent.Fire (...) विधि के माध्यम से हासिल किया जाता है।
// Create a designer form with 3 buttons and a vertical trackbar and overwrite
//it with "TestEvent" class near bottom of code, then hook up the buttons to
//button<1/2/3>_OnClick. Event Sibling Subscribing section explains why the
//first 4 event threads all fire at once.
using System;
using System.Windows.Forms;
using System.Threading;
using System.Collections.Generic;
using System.Runtime.InteropServices;
namespace TestingEventsApplication
{
using Extensions;
public delegate void OnSomethingHappenedDel(MyEventArgs e);
public delegate void EventMarshalDel(IMyEventActions sender, MyEventArgs e);
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Console.WriteLine("Thread Main is Thread#" + Thread.CurrentThread.ManagedThreadId);
//This controls how many threads we want to make for testing
int numThreads = 10;
QuickSync quickSync = new QuickSync();
MyThread[] myThreads = new MyThread[numThreads];
TestEvent GUI = new TestEvent(myThreads);
GUI.TrackbarVal = numThreads-1;
for (int i = 0; i < numThreads; i++)
{
myThreads[i] = new MyThread();
Thread thread = new Thread(delegate()
{
myThreads[i].Start(quickSync);
});
thread.Name = "Thread#" + thread.ManagedThreadId.ToString();
thread.IsBackground = true;
thread.Start();
while (!thread.IsAlive || !quickSync.Sync) { Thread.Sleep(1); }
myThreads[i].thread = thread;
Console.WriteLine(thread.Name + " is alive");
quickSync.Sync = false;
}
#region Event Sibling Subscribing
// ********* Event Sibling Subscribing *********
// Just for example, I will link Thread 0 to thread 1, then
// 1->2,2->3,3->4 so when thread 0 receives an event, so will
// thread 1, 2, 3, and 4 (Noncommutative.)
// Loops are perfectly acceptable and will not result in
// eternal events.
// e.g. 0->1 + 1->0 is OK, or 0->1 + 1->2 + 2->0... No problem.
if (numThreads > 0)
myThreads[0].Event.SubscribeMeTo(myThreads[1].Event);
//Recursively add thread 2
if (numThreads > 1)
myThreads[1].Event.SubscribeMeTo(myThreads[2].Event);
//Recursively add thread 3
if (numThreads > 2)
myThreads[2].Event.SubscribeMeTo(myThreads[3].Event);
//Recursively add thread 4
if (numThreads > 3)
myThreads[3].Event.SubscribeMeTo(myThreads[4].Event);
#endregion
Application.Run(GUI);
}
}
/// <summary>
/// Used to determine when a task is complete.
/// </summary>
public class QuickSync
{
public bool Sync
{
get
{
lock (this)
return sync;
}
set
{
lock (this)
sync = value;
}
}
private bool sync;
}
/// <summary>
/// A class representing the operating body of a Background thread.
/// Inherits IMyEventActions.
/// </summary>
/// <param name="m">a QuickSync boxed bool.</param>
public class MyThread : IMyEventActions
{
/// <summary>
/// An reference to the Thread object used by this thread.
/// </summary>
public Thread thread { get; set; }
/// <summary>
/// Tracks the MyEvent object used by the thread.
/// </summary>
public MyEvent Event { get; set;}
/// <summary>
/// Satisfies IMyEventActions and provides a method to implement
/// Event actions
/// </summary>
public void OnSomethingHappened(MyEventArgs e)
{
switch ((MyEventArgsFuncs)e.Function)
{
case MyEventArgsFuncs.Shutdown:
Console.WriteLine("Shutdown Event detected... " + Thread.CurrentThread.Name + " exiting");
Event.Close();
break;
case MyEventArgsFuncs.SomeOtherEvent:
Console.WriteLine("SomeOtherEvent Event detected on " + Thread.CurrentThread.Name);
break;
case MyEventArgsFuncs.TheLastEvent:
Console.WriteLine("TheLastEvent Event detected on " + Thread.CurrentThread.Name);
break;
}
}
/// <summary>
/// The method used by a thread starting delegate.
/// </summary>
public void Start(QuickSync quickSync)
{
//MyEvent inherits from Form which inherits from Control which is
//the key to this whole thing working. It is the BeginInvoke method
//of Control which allows us to marshal objects between threads,
//without it any event handlers would simply fire in the same thread
//which they were triggered. We don't want to see this form though
//so I've moved it off screen and out of the task bar
Event = new MyEvent();
Event.MyEventSender = this;
Event.SomethingHappened += new EventMarshalDel(Event.EventMarshal);
Event.FormBorderStyle = FormBorderStyle.FixedToolWindow;
Event.ShowInTaskbar = false;
Event.StartPosition = FormStartPosition.Manual;
Event.Location = new System.Drawing.Point(-10000, -10000);
Event.Size = new System.Drawing.Size(1, 1);
System.Windows.Forms.Application.Idle += new EventHandler(OnApplicationIdle);
quickSync.Sync = true;
Application.Run(Event);
}
/// <summary>
/// The operating body of the thread.
/// </summary>
private void OnApplicationIdle(object sender, EventArgs e)
{
while (this.AppStillIdle)
{
//Do your threads work here...
Console.Write(".");
Thread.Sleep(1000);
}
}
/// <summary>
/// Monitors the Threads msg procedure to make sure we handle messages.
/// </summary>
public bool AppStillIdle
{
get
{
Win32.NativeMessage msg;
return !Win32.PeekMessage(out msg, IntPtr.Zero, 0, 0, 0);
}
}
}
/// <summary>
/// Houses all of the plumbing necessary to fire cross thread events.
/// </summary>
public class MyEvent : System.Windows.Forms.Form
{
/// <summary>
/// A reference to the object using this MyEvent, used during recursion.
/// </summary>
public IMyEventActions MyEventSender { get; set; }
/// <summary>
/// Lock for somethingHappened delegate access.
/// </summary>
public readonly object someEventLock = new object();
/// <summary>
/// Public access to the event SomethingHappened with a locking
/// subscription mechanism for thread safety.
/// </summary>
public event EventMarshalDel SomethingHappened
{
add
{
lock (someEventLock)
somethingHappened += value;
}
remove
{
lock (someEventLock) //Contributes to preventing race condition
somethingHappened -= value;
}
}
/// <summary>
/// The trigger of MyEvent class.
/// </summary>
public void Fire(MyEventArgs e)
{
//After rigorous testing I found this was the simplest way to solve
//the classic event race condition. I rewired RaiseEvent and
//EventMarshal to increase race condition tendency, and began
//looping only iterating between 20 and 200 times I was able to
//observe the race condition every time, with this lock in place,
//I have iterated 10's of thousands of times without failure.
lock (someEventLock)
somethingHappened.RaiseEvent(MyEventSender, e);
Thread.Sleep(1); //Optional, may make things more fluid.
}
/// <summary>
/// The Event Marshal.
/// </summary>
public void EventMarshal(IMyEventActions sender, MyEventArgs e)
{
if (sender.Event.InvokeRequired)
//Without the lock in Fire() a race condition would occur
//here when one thread closes the MyEvent form and another
//tries to Invoke it.
sender.Event.BeginInvoke(
new OnSomethingHappenedDel(sender.OnSomethingHappened),
new object[] { e });
else
sender.OnSomethingHappened(e);
if (SiblingEvents.Count > 0) Recurs(e);
}
/// <summary>
/// Provides safe recursion and event propagation through siblings.
/// </summary>
public void Recurs(MyEventArgs e)
{
e.Event.Add(this);
foreach (MyEvent m in SiblingEvents)
lock (m.someEventLock) //Prevents Race with UnSubscribeMeTo()
if (!e.Event.Contains(m)) //Provides safety from Eternals
m.Fire(e);
}
/// <summary>
/// Adds sibling MyEvent classes which to fire synchronously.
/// </summary>
public void SubscribeMeTo(MyEvent m)
{
if (this != m) SiblingEvents.Add(m);
}
/// <summary>
/// Removes sibling MyEvent's.
/// </summary>
public void UnSubscribeMeTo(MyEvent m)
{
lock (m.someEventLock) //Prevents race condition with Recurs()
if (SiblingEvents.Contains(m)) SiblingEvents.Remove(m);
}
protected override void OnFormClosing(FormClosingEventArgs e)
{
SomethingHappened -= somethingHappened;
base.OnFormClosing(e);
}
/// <summary>
/// Delegate backing the SomethingHappened event.
/// </summary>
private EventMarshalDel somethingHappened;
/// <summary>
/// A list of siblings to Eventcast.
/// </summary>
private List<MyEvent> SiblingEvents = new List<MyEvent>();
}
/// <summary>
/// The interface used by MyThread to enlist OnSomethingHappened arbiter.
/// </summary>
public interface IMyEventActions
{
void OnSomethingHappened(MyEventArgs e);
MyEvent Event { get; set; }
}
public enum MyEventArgsFuncs : int
{
Shutdown = 0,
SomeOtherEvent,
TheLastEvent
};
/// <summary>
/// Uses a string-referable enum to target functions handled
/// by OnSomethingHappened.
/// </summary>
public class MyEventArgs : EventArgs
{
public int Function { get; set; }
public List<MyEvent> Event = new List<MyEvent>();
public MyEventArgs(string s)
{
this.Function = (int)Enum.Parse(typeof(MyEventArgsFuncs), s);
}
}
/// <summary>
/// This is a form with 3 buttons and a trackbar on it.
/// </summary>
/// <param name="m">An array of MyThread objects.</param>
// Create a designer form with 3 buttons and a trackbar and overwrite it
// with this, then hook up the buttons to button<1/2/3>_OnClick.
public partial class TestEvent : Form
{
public TestEvent()
{
InitializeComponent();
}
public TestEvent(MyThread[] t)
: this()
{
myThreads = t;
}
/// <summary>
/// This button will fire a test event, which will write to the
/// console via OnSomethingHappened in another thread.
/// </summary>
private void button1_OnClick(object sender, EventArgs e)
{
Console.WriteLine("Firing SomeOtherEvent from Thread#" + Thread.CurrentThread.ManagedThreadId + " (Main)");
myThreads[TrackbarVal].Event.Fire(new MyEventArgs("SomeOtherEvent"));
}
/// <summary>
/// This button will fire an event, which remotely shut down the
/// myEvent form and kill the thread.
/// </summary>
private void button2_OnClick(object sender, EventArgs e)
{
Console.WriteLine("Firing Shutdown event from Thread#" + Thread.CurrentThread.ManagedThreadId + " (Main)");
myThreads[TrackbarVal].Event.Fire(new MyEventArgs("Shutdown"));
}
/// <summary>
/// This button will fire TheLastEvent, which will write to the
/// console via OnSomethingHappened in another thread.
/// </summary>
private void button3_OnClick(object sender, System.EventArgs e)
{
Console.WriteLine("Firing TheLastEvent from Thread#" + Thread.CurrentThread.ManagedThreadId + " (Main)");
myThreads[TrackbarVal].Event.Fire(new MyEventArgs("TheLastEvent"));
}
public int TrackbarVal
{
get { return this.trackBar1.Value; }
set { this.trackBar1.Maximum = value; }
}
private MyThread[] myThreads;
}
/// <summary>
/// Stores Win32 API's.
/// </summary>
public class Win32
{
/// <summary>
/// Used to determine if there are messages waiting
/// </summary>
[System.Security.SuppressUnmanagedCodeSecurity]
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("User32.dll", CharSet = CharSet.Auto, SetLastError = true)]
public static extern bool PeekMessage(out NativeMessage message, IntPtr handle, uint filterMin, uint filterMax, uint flags);
[StructLayout(LayoutKind.Sequential)]
public struct NativeMessage
{
public IntPtr handle;
public uint msg;
public IntPtr wParam;
public IntPtr lParam;
public uint time;
public System.Drawing.Point p;
}
}
}
namespace Extensions
{
using System;
using TestingEventsApplication;
/// <summary>
/// An extension method to null test for any OnSomethingHappened
/// event handlers.
/// </summary>
public static class Extension
{
public static void RaiseEvent(this EventMarshalDel @event, IMyEventActions sender, MyEventArgs e)
{
if (@event != null)
@event(sender, e);
}
}
}
क्या आप कृपया जानकारी को वापस मार्शल करने की आवश्यकता के लिए संदर्भ प्रदान कर सकते हैं, क्योंकि मुझे पता है कि क्रॉस प्रक्रिया और अपार्टमेंट के लिए मार्शलिंग की आवश्यकता है। अगर ये धागे एक ही प्रक्रिया में हैं तो मार्शल क्यों? (और कोई अपार्टमेंट नहीं है क्योंकि COM का उपयोग नहीं किया जा रहा है)। – bjan
मुझे मेरा जवाब यहां मिला है ** [यहां] (http://stackoverflow.com/questions/1361033/what-does-stathread-do) ** – bjan