Platform dependency of thread management - C# Discussion Boards

c# language issue: when you need to serialize/deserialize a user defined Func/Action

7-Dec-20 21:04

See here: Sending email via GMail in C#/.NET using SmtpClient[^]

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Re: Send GMail

Richard Deeming7-Dec-20 21:55

Richard Deeming

7-Dec-20 21:55

Depending on your account settings, you may need to create an app password to allow your application to bypass 2SV:
Sign in with App Passwords - Google Account Help[^]

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BillWoodruff7-Dec-20 2:40

BillWoodruff

7-Dec-20 2:40

okay, we know that's not possible via the usual save/restore techniques for damn good reasons:

1) Func and Action (delegates) can have references to external objects/states the compiler can't resolve.

2) if that could be done, it would be an ideal way to insert/execute malicious code.

as i see it, now, that leaves two alternatives:

1) have some kind of plug-in architecture that exposes pre-defined delegates. but, that could also be vulnerable to security threats. more critical would be the delegates defined in the plug-in need for access/reference to the definitions/references of internal objects in the app it would manipulate.

2) a DSL/script-language that could be saved/restored as text, and then compiled via Roslyn reflection/emit, etc.

a concrete example of the type of Func i'd iike to save:

private static readonly Random rand = new Random();

private double IntensityFunc(Edge edge)
{
    var hour = DateTime.Now.Hour;

    if (hour > 3 && hour < 12) return edge.IntensityMin;

    if (hour > 22) return edge.IntensityMax;

    return rand.NextDouble() * (edge.IntensityMax - edge.IntensityMin) + edge.IntensityMin;
}

mini-example showing Node and Edge definitions, and Func usage:

// node or vertex
public class Node: INode // interface not shown 
{
        public Node(string name, int id)
        {
            Name = name;
            Id = id;
        }

	public string Name { set; get; }
	
	public string Id { set; get; }
}

// an edge describes a connection between two nodes
public class Edge: IEdge // interface not shown 
{
    public Edge(Node node1, Node node2, double intensity, double intensityMin = 0.0, double intensityMax = 0.0,
        Func<Edge, double> intensityFunc = null)
    {
        Node1 = node1;
        Node2 = node2;
        Intensity = intensity;
        IntensityMin = intensityMin;
        IntensityMax = intensityMax;
        IntensityFunc = intensityFunc;
    }

    public Node Node1 { set; get; }

    public Node Node2 { set; get; }

    public double Intensity { set; get; }

    public double IntensityMin { set; get; }

    public double IntensityMax { set; get; }

    public Func<Edge, double> IntensityFunc { set; get; }

    public double GetIntensity()
    {
        return IntensityFunc?.Invoke(this) ?? Intensity;
    }
}

// usage example
private void Form1_Load(object sender, EventArgs e)
{
    var Jack = new Node("Jack", 1);

    var Jill = new Node("Jill", 2);

    var JackToJill = new Edge(Jack, Jill, 50.0, 20.0, 80.0);

    var jintensity = JackToJill.Intensity;

    JackToJill.IntensityFunc = IntensityFunc;

    // test intensity func
    for (var i = 0; i < 20; i++)
    {
        var jintensity2 = JackToJill.GetIntensity();
        Console.WriteLine(jintensity2);
    }
}

private double IntensityFunc(Edge edge)
{
    var hour = DateTime.Now.Hour;

    if (hour > 3 && hour < 12) return edge.IntensityMin;

    if (hour > 22) return edge.IntensityMax;

    return rand.NextDouble() * (edge.IntensityMax - edge.IntensityMin) + edge.IntensityMin;
}

«One day it will have to be officially admitted that what we have christened reality is an even greater illusion than the world of dreams.» Salvador Dali

modified 7-Dec-20 18:15pm.

Platform dependency of thread management

Bernhard Hiller6-Dec-20 23:30

Bernhard Hiller

6-Dec-20 23:30

A Thread.Sleep(n) will pause the current thread for at least n milliseconds. But there are some caveats: Thread.Sleep(1) takes at least some 15 ms on "common" Windows 7/8/10 due to the "time slice" management of threads. In contrast, running the same code with mono on Linux, the sleep time may get close to 1 ms. I haven't found any information on Windows 10 IoT for that feature.
Already this simple example shows that Threads are dealt with differently depending on the underlying platform.
Where can I find more information on that feature?
The main interest is differences between Windows 10 Pro and Windows 10 IoT, but also information beyond that is appreciated.

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Re: Platform dependency of thread management

Dave Kreskowiak7-Dec-20 3:59

Dave Kreskowiak

7-Dec-20 3:59

Worse yet, Thread.Sleep doesn't even guarantee that the thread will actually give up its time slice. If there are no other threads ready to run at the same priority, your Thread is not suspended.

T minimum time a Thread can "sleep" is dependent on the system timer and its resolution. The timer is dependent on hardware and O/S implementation. From the Sleep function[^] in the Win32 documentation:

Quote:
The system clock "ticks" at a constant rate. If dwMilliseconds is less than the resolution of the system clock, the thread may sleep for less than the specified length of time. If dwMilliseconds is greater than one tick but less than two, the wait can be anywhere between one and two ticks, and so on. To increase the accuracy of the sleep interval, call the timeGetDevCaps function to determine the supported minimum timer resolution and the timeBeginPeriod function to set the timer resolution to its minimum. Use caution when calling timeBeginPeriod, as frequent calls can significantly affect the system clock, system power usage, and the scheduler. If you call timeBeginPeriod, call it one time early in the application and be sure to call the timeEndPeriod function at the very end of the application.

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Dave Kreskowiak

C# NET. Framework program (area 2x)

Member 150126775-Dec-20 23:49

Re: C# NET. Framework program (area 2x)

5-Dec-20 23:49

I created a program

class Program
    {
        static void Main(string[] args)
        {
            double b;
            double h;

            Console.WriteLine("Basis: ");
            b= Convert.ToDouble(Console.ReadLine());

            Console.WriteLine("Height: ");
            h= Convert.ToDouble(Console.ReadLine());

            double area1 = Program.calcArea(b, h);
            Console.WriteLine("The area of triangle 1 is: ");
            Console.WriteLine(area1);
            Console.ReadLine();
        }

    public static double calcArea(double b, double h)
        {
            return b * h / 2;
        }
    }
}

It works, but I have to do it twice, what's the solution?

Richard MacCutchan6-Dec-20 1:28

Richard MacCutchan

6-Dec-20 1:28

Create a loop which runs twice. See for statement - C# reference | Microsoft Docs[^]

Re: C# NET. Framework program (area 2x)

BillWoodruff7-Dec-20 7:07

BillWoodruff

7-Dec-20 7:07

Console.WriteLine("Number of calculations: ");

ntries = Convert.ToInt32(Console.ReadLine());

for(int x = 0; x < ntries; x++)
{
     // get user input and calculate
}

«One day it will have to be officially admitted that what we have christened reality is an even greater illusion than the world of dreams.» Salvador Dali

Decimal numbers in NET. Framework

Member 150126775-Dec-20 2:48

Re: Decimal numbers in NET. Framework

5-Dec-20 2:48

Hello, I am creating a simple program in Framework to calculate the area of a triangle.

But the problem is, I can't enter a decimal number and the result is not a decimal number either. How should I solve this?

OriginalGriff5-Dec-20 2:53

C# NET. Framework program

5-Dec-20 2:53

Use decimal.TryParse[^] to convert it from a string to a decimal value.

Member 150126775-Dec-20 0:59

5-Dec-20 0:59

Hi, I'

modified 5-Dec-20 8:33am.

OriginalGriff5-Dec-20 1:17

5-Dec-20 1:17

Read the string into a variable.
Then use string.Substring[^] to break it into three strings: one fro the day, one for the month, and one for the year.
Hint:

string s = "01092000";
string month = s.Substring(2, 2);
...

Then use int.TryParse[^] to convert each part to a numeric value.
Hint:

int mon;
if (!int.TryParse(month, out mon))
    {
    ... Report problem to user ...
    return;
    }

Then use the DateTime constructor[^] to make a valid date

Member 150126775-Dec-20 1:26

5-Dec-20 1:26

Can you give me please the full code for the program? I don't understand programming

Ralf Meier5-Dec-20 1:31

Ralf Meier

5-Dec-20 1:31

Sorry ... but if you don't understand programming and you are also not willing to try something - what are you trying to achieve ?

Member 150126775-Dec-20 1:33

5-Dec-20 1:33

I missed some classes at school because I had corona. In those lessons they started programming, but I have never programmed. So I really don't know where to start.

OriginalGriff5-Dec-20 1:41

5-Dec-20 1:41

Then you go back to your teacher and you ask for help - he knows you had Covid-19, so he knows you weren't just sitting around playing video games during a lockdown when you should have been studying.

But us just giving you the code doesn't help you at all in the long term, it makes it a lot worse!

OriginalGriff5-Dec-20 1:37