Asynchronous task constructors¶

PeriodicTask(action, periodMilliseconds, excutingNode) constructor

Create a PeriodicTask task that executes code at regular time intervals.

PeriodicTask(Action action, int periodMilliseconds, IUANode executingNode);

Arguments

action Action

Method or lambda expression to execute.

periodMilliseconds int

Period of time between one execution and the next.

executingNode IUANode

Node in which to execute the code.

Example

Below is an example where a myPeriodicTask task is created that executes the IncrementVariable() method every second (1000 milliseconds). The method increments the value of the variable1 variable by one unit each time it is executed.

public override void Start()
{
    myPeriodicTask = new PeriodicTask(IncrementVariable, 1000, LogicObject);
    myPeriodicTask.Start();
}

public override void Stop()
{
    myPeriodicTask.Dispose();
}

private void IncrementVariable()
{
    variable1.Value = variable1.Value + 1;
}

private PeriodicTask myPeriodicTask;

Note

in this example, the IncrementVariable() method has no PeriodicTask argument as the simplicity of its code does not require the task to be canceled.

DelayedTask(action, delayMilliseconds, executingNode) constructor

Creates a DelayedTask task that executes code after a desired time interval.

DelayedTask(Action action, int delayMilliseconds, IUANode executingNode);

Arguments

action Action

Method or lambda expression to execute.

delayMilliseconds int

Time after which the method or lambda expression is executed.

executingNode IUANode

Node in which to execute the code.

Example

Below is an example where a myDelayedTask task is created to execute the ResetLabelText() method after 10 seconds (10000 milliseconds). The method cancels the text of a label1 label.

public override void Start()
{
    myDelayedTask = new DelayedTask(ResetLabelText, 10000, LogicObject);
    myDelayedTask.Start();
}

public override void Stop()
{
    myDelayedTask.Dispose();
}

private void ResetLabelText()
{
    label1.Text = string.Empty;
}

private DelayedTask myDelayedTask;

Note

in this example, the ResetLabelText() method has no DelayedTask argument as the simplicity of its code does not require the task to be canceled.

LongRunningTask(action, executingNode) constructor

Creates a LongRunningTask task to execute time- or CPU-binding codes.

LongRunningTask(Action action, IUANode executingNode);

Arguments

action Action

Method or lambda expression to execute.

executingNode IUANode

Node in which to execute the code.

Example

Below is an example in which a myLongRunningTask task is created to process a CSV file using the ProcessCsvFile() method. This method has the task itself as argument, the status of which is checked using the IsCancellationRequested property after reading each row of the CSV file. In this way, the task can be canceled.

using namespace System.IO; // For using the StreamReader
class public override void Start()
{
    myLongRunningTask = new LongRunningTask(ProcessCSVFile, LogicObject);
    myLongRunningTask.Start();
}

public override void Stop()
{
    myLongRunningTask.Dispose();
}

private void ProcessCsvFile(LongRunningTask task)
{
    using (var reader = new StreamReader(pathToCsvFile))
    {
        while (!reader.EndOfStream)
        {
            // Check whether task cancellation has been requested
            if (task.IsCancellationRequested)
            {
                // Properly handle task cancellation here
                return;
            }

            string line = reader.ReadLine();
            // Process line
        }
    }
}

private LongRunningTask myLongRunningTask;