thread safe variables in method

December 5th, 2018, 11:41 AM

Hello community,

I request support for the following problems:

1. I want to use a counter in a method. This does not yet work thread safe.
Sample 1a would be encapsulated but does not return a correct value.
Sample 1b works, but is not thread-safe (==> Sample2)

2. How can I use predecessor values in a method?
Sample 3 shows that no previous value is determined with this procedure.
Analog Sample 1b I can initialize the series outside the method; this solution is also not thread safe.

I gave the examples because I want to simplify my request.

I make 5 calculations with different values, but they always have the same conditions.
This requires a TickCounter and a previous value.

That's why I want to do the calculations in a method, using thread-safe variables.
My programming example shows that reusing a variable does not work if it is initialized outside the method.
I would have to use 5 variables or series for my 5 calculations, so that the method actually makes no sense.
Finally, methods should simplify the code and "save" variables.

There are suggestions on how I can solve the problem?

Thank you!
Best
user10

PS: Are there any examples of function programming in the forum; I did not find any.

Code

                            
namespace NinjaTrader.NinjaScript.Strategies

{

    public class TestFunktionen : Strategy

    {

        private SMA SMA1;

        private int barCounter;

        private int barCounterFuncIn;

        private int barCounterFuncIn1;

        private int barCounterFuncIn2;

        

        private int funktionsValue;

        private int funktionsValue1;

        private int funktionsValue2;

        

        protected override void OnStateChange()

        {

            #region notrelevant

            

            if (State == State.SetDefaults)

            {

                Calculate    = Calculate.OnEachTick;

            }

            else if (State == State.Configure)

            {

                AddDataSeries(Data.BarsPeriodType.Minute, 1);

            }

            else if (State == State.DataLoaded)

            {                

            }

            #endregion

        }

        protected override void OnBarUpdate()

        {

            // OnBarUpdate

            barCounter++;

            

            // Funktionen

            funktionsValue = barCounterF();

            funktionsValue1 = barCounterThread();

            funktionsValue2 = barCounterPrevious();

            

            Print (Time[0]     

            + "  barCounterF   " + funktionsValue 

            + "  barCounterThread   " + funktionsValue1 

            + "  barCounterPrevious   " + funktionsValue2    

            + "  barCounter   " + barCounter);

        }



            public int barCounterF()                    // Sample 1

            {

//                int counter = 0;                // Sample a    

//                return counter;                // returns 1

                

                barCounterFuncIn++;            // Sample b

                return barCounterFuncIn;        // not thread-safe

            }

    

            public int barCounterThread()                // Sample 2

            {

                barCounterFuncIn +=2;

                return barCounterFuncIn;           // not thread-safe

            }

            

            public int barCounterPrevious()        // Sample 3

            {

                Series <int> barCounterSeries = new Series<int> (this);

                barCounterFuncIn2++;

                barCounterSeries[0] = barCounterFuncIn2;

                

//                return barCounterFuncIn2;        // correct

                return barCounterSeries[0];        // correct

//                return barCounterSeries[1];        // ==> 0 ==> no previous Value

            }

December 5th, 2018, 02:19 PM

It’s simple to make a part of your code single threaded.

Add a class member first:

private static object lockObject = new object();

And then in your code where you want to make single threaded do this:

lock(lockObject)
{
// do your work here - threadsafe
}

If you only want to make an increment safe you do not need the above. You can do it in a simple command like this

return Interlocked.Increment(ref COUNTER);

December 5th, 2018, 03:42 PM

Hello LukePoga,

Thanks for the hint.
In the meantime, I've learned that threadsafe is probably the wrong name.

I calculate values in periods whose beginning and end are indefinite. At the end of the period I would like to do another calculation;
because the condition is wrong at this time, I need to access the predecessor value.
In real-time operation, this condition is true for one bar, but the condition should only be true for a tick to execute the calculation once.
These 5 calculations are performed with different values and periods and all five should access one method.

I understand that I can initialize variables and series outside the method.
Then both the counter and the return of the previous value will work.

In my example barCounterF () and barCounterThread () I increase the same variable barCounterFuncIn once by 1 and once by 2 and return it.
Although I assign a different variable (functionValue1 and functionValue2) to the respective return value, the methods influence each other.

If I change the barCounterThread () method to another variable e.g. assigning barCounterFuncIn1, both methods provide the correct result.

I added the code for verification.

If I want to simplify my code, this must not happen. It also makes no sense to use exactly the variables and series that I would have to use without any method.

Where is my mistake?

Best
user10

thread safe variables in method

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thread safe variables in method