Is newly added Timer thread safe?

AlexanderRC
11 Jul 2014, 16:41

RE:

AlexanderRC said:

2) Can I call Timer.Start with some "zero" value for the Timer to be invoked as soon as possible?

Timer.Start(new TimeSpan(1)) seems to be instant.

Spotware
11 Jul 2014, 16:45

RE:

Hi AlexanderRC. 

1) can I call Timer.Start() from non-main cBot thread?

No, it's not thread safe

2) Can I call Timer.Start with some "zero" value for the Timer to be invoked as soon as possible?

No, it will stop timer instead, otherwise it would mean smth like infinite calls of OnTimer method. In case you want to call OnTimer as soon as possible pass interval equal to one millisecond

        private void ExecuteOnTimerASAP()
        {
            Timer.Start(TimeSpan.FromMilliseconds(1));
        }

        protected override void OnTimer()
        {
            Timer.Stop();
            //your code
        }

3) Can I call safely call Timer.Stop() from within OnTimer()?

Yes, you can safely call Stop() in OnTimer()

AlexanderRC
11 Jul 2014, 21:53

No, it will stop timer instead, otherwise it would mean smth like infinite calls of OnTimer method. In case you want to call OnTimer as soon as possible pass interval equal to one millisecond

Where does the one millisecond requirement come from? If OnTimer() handler takes more time than the Timer interval, will the handler be called second time simultaneously?

Are there any solution to pass "work objects" (Open/Close/Modify position) from arbitrary thread to "main" thread?

Spotware
14 Jul 2014, 10:21 ( Updated at: 21 Dec 2023, 09:20 )

Next OnTimer invocation will be scheduled after current OnTimer invocation will be finished. Please have a look at the following example:

Are there any solution to pass "work objects" (Open/Close/Modify position) from arbitrary thread to "main" thread?

You can put code that works with API objects to actions queue and invoke actions from it in OnTimer handler. In such case actions will be invoked in main thread. Example:

using System;
using System.Collections.Concurrent;
using System.Linq;
using System.Threading;
using cAlgo.API;

namespace cAlgo
{
    [Robot(TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
    public class MultiThreadexample : Robot
    {
        private readonly ConcurrentQueue<Action> _actionsQueue = new ConcurrentQueue<Action>();

        protected override void OnStart()
        {
            Timer.Start(new TimeSpan(1));//start timer with minimal interval

            var thread = new Thread(SeparateThreadHandler);
            thread.Start();
        }
        
        private void SeparateThreadHandler()
        {
            try
            {
                //perform some actions in separate thread:
                Thread.Sleep(10000);

                //scedule action to be invoked in main thread:
                _actionsQueue.Enqueue(() =>
                    {
                        //the following code will be invoked in main thread:
                        
                        var position = Positions.FirstOrDefault(p => p.TradeType == TradeType.Buy);
                        if (position != null)
                            ModifyPosition(position, Symbol.Bid - 10 * Symbol.PipSize, position.TakeProfit);
                    });
            }
            catch (Exception) 
            {
                //you must always catch exceptions from separate thread
            }
        }

        protected override void OnTimer()
        {
            Action action;
            while (_actionsQueue.TryDequeue(out action))
            {
                action();
            }
        }
    }
}

We plan to add method BeginInvokeOnMainThread in the future. It will simplify the above example.

AlexanderRC
14 Jul 2014, 11:35

RE:

Next OnTimer invocation will be scheduled after current OnTimer invocation will be finished

Good to know that this behavior is by design. That may have fired back on me if it was not always the case.

I have employed similar approach with work item queue where actual work is happening in OnTimer() (and previously in tick/market data updates subscribed to all possible symbols to get into main thread as frequently as possible).

Too sad there are no immediate "jump" into the main thread. I have to wait for the next Timer tick to occur.

We plan to add method BeginInvokeOnMainThread in the future. It will simplify the above example.

It would be great if BeginInvokeOnMainThread() passes execution instantly to the main thread instead of waiting for the next Timer tick to occur.

Spotware
14 Jul 2014, 13:00

RE: RE:

It would be great if BeginInvokeOnMainThread() passes execution instantly to the main thread instead of waiting for the next Timer tick to occur.

BeginInvokeOnMainThread method will execute action instantly if there is no any handler executing by main thread and there is no handlers in the queue. Otherwise it will be put in the queue.