Thread signaling basics

In C# how does one achieve thr开发者_高级运维ead signaling?

Here is a custom-made console application example for you. Not really a good real world scenario, but the usage of thread signaling is there.

using System;
using System.Threading;

class Program
{
    static void Main()
    {
        bool isCompleted = false;
        int diceRollResult = 0;

        // AutoResetEvent is one type of the WaitHandle that you can use for signaling purpose.
        AutoResetEvent waitHandle = new AutoResetEvent(false);

        Thread thread = new Thread(delegate() {
            Random random = new Random();
            int numberOfTimesToLoop = random.Next(1, 10);

            for (int i = 0; i < numberOfTimesToLoop - 1; i++) {
                diceRollResult = random.Next(1, 6);

                // Signal the waiting thread so that it knows the result is ready.
                waitHandle.Set();

                // Sleep so that the waiting thread have enough time to get the result properly - no race condition.
                Thread.Sleep(1000);
            }

            diceRollResult = random.Next(1, 6);
            isCompleted = true;

            // Signal the waiting thread so that it knows the result is ready.
            waitHandle.Set();
        });

        thread.Start();

        while (!isCompleted) {
            // Wait for signal from the dice rolling thread.
            waitHandle.WaitOne();
            Console.WriteLine("Dice roll result: {0}", diceRollResult);
        }

        Console.Write("Dice roll completed. Press any key to quit...");
        Console.ReadKey(true);
    }
}

The way this works in a nutshell.

1. AutoResetEvent waitHandle = new AutoResetEvent(false); --- The false means that that wait handle is unsignaled if a waitHandle.WaitOne() is called it will stop the thread.

2. The thread you want to wait for another event to complete add waitHandle.WaitOne();

3. In the thread that needs to be completed,at the end when completed add waitHandle.Set();

waitHandle.WaitOne(); Waits for signal

waitHandle.Set(); signals completion.

For understanding concepts like signaling, see Thread Synchronization which would be a good place to start.

It's got examples too. You can then drill down into specific .net types based on what you're trying to do.. signal between threads within a process or across processes etc..