Async Threads Tutorial
About
Ever wanted to make a seperate thread that doesn't run constantly in c# for a simple task, such as sending web requests or loading a file? Well, this will teach you how to do it without a BackGroundWorker! This will also teach you how to set control values from another thread safely.
Pre-Requisites
In order to use Threads and different Thread tasks, you will need to import these 2 classes into your project. At the top of your project, include these:
using System.Threading; using System.Threading.Tasks;
Step 1
First off, you will want to create a simple function with no paramters, like so:
private void doStuff()
{
}
This will be your thread, written as a method/function. Pretty simple, right? Inside of this method you will perform the code for your operation.
Step 2
Next, you will want to fill your thread with operations, so for instance:
private void doStuff()
{
WebClient client = new WebClient();
string resp = client.uploadString("http://www.examplesite.com/api_post.php", "GET", "user=zero&dev_id=00000000000");
}
Once you have what you want in there, its quite simple from here. In your control that handles starting the thread (like a button, or anything else) simply type this code out to execute the thread:
new Thread(new ThreadStart(doStuff)).Start();
When you click the button (or other control), it will run the thread once. If you need data that is retrieved within the thread, you can create a variable at the top of your class, and pass the data from the thread into the variable to be used elsewhere. You can get from controls in an async thread, but you cannot set values or properties to a control that is not on the thread. As for variables, you can access them from any thread.
Additional
So, let's say that you have a label that you want to set data to from a thread, but you keep getting an error in VS stating that you cannot set control values cross thread. You indeed can, but it takes a little extra work. For this we need to create a new function, and we need to do something called invoking. You can invoke control properties from another thread, but you cannot set them directly. Here is an example function that will set text onto a label from an async thread:
private void setLabelText(Label label, string text)
{
if (label.InvokeRequired)
{
MethodInvoker mi = new MethodInvoker(() => label.Text = text);
label.Invoke(mi);
}
}
With this function, you can set virtually any label on your form from an async thread. This is how it would be used in a thread:
private void doStuff()
{
WebClient client = new WebClient();
string resp = client.uploadString("http://www.examplesite.com/api_post.php", "GET", "user=zero&dev_id=00000000000");
setLabelText(yourLabelName, resp);
}
In this code snippet, we are taking the result of the webclient and invoking a text change on a label named "yourLabelName". This is how you set control properties from another thread the safe and efficient way!
Conclusion
Being able to create async threads on the fly is very simple, and extremely useful in many circumstances. It allows you to create heavy-loaded functions that once froze your program (such as offset searching for the PS3 Modders) that no longer damper the flow of your program, and still allow you to perform other tasks while the operation is being carried out! You can also make looping threads with this very easily, and it requires little work. This is far more efficient than creating a background worker to perform all your threaded tasks in my opinion, and a much better solution than that of using a timer.
I hope you guys take this knowledge and use it to better your programs! 🙂
Absolute Zero
