MidInterpreter.GetMessageTemplate(int mid) is failing when calling Parse

[tjarnagin]

We are using the latest version - 6.1

When the controller sends a response, in this case MID 2, an exception is thrown:

Exception has been thrown by the target of an invocation. (mscorlib)

---

Program Location (Client side):

   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes, StackCrawlMark& stackMark)
   at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)
   at System.Activator.CreateInstance(Type type, Object[] args)
   at OpenProtocolInterpreter.MidInterpreter.<>c__DisplayClass13_0`1.<UseTemplate>b__0()
   at System.Lazy`1.CreateValue()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Lazy`1.get_Value()
   at OpenProtocolInterpreter.MidInterpreter.<>c__DisplayClass15_0.<GetMessageTemplate>b__0(Lazy`1 x)
   at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source, Func`2 predicate)
   at OpenProtocolInterpreter.MidInterpreter.GetMessageTemplate(Int32 mid)
   at OpenProtocolInterpreter.MidInterpreter.Parse(Byte[] package)
   at DesoutterActivityViewModel.OnDataReceived(Byte[] message)

---

ADDITIONAL INFORMATION:

Collection was modified; enumeration operation may not execute. (mscorlib)

---

Program Location (Client side):

   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Enumerator.MoveNext()
   at System.Linq.Enumerable.WhereEnumerableIterator`1.MoveNext()
   at OpenProtocolInterpreter.Messages.MessagesTemplate.FilterSelectedMids(IEnumerable`1 mids)
   at OpenProtocolInterpreter.Messages.MessagesTemplate.FilterSelectedMids(IEnumerable`1 mids)
   at OpenProtocolInterpreter.Communication.CommunicationMessages..ctor(IEnumerable`1 selectedMids)

[Rickedb]

Hello!

Are you using the same instance of MidInterpreter for many threads/drivers?
If yes, the mid interpreter is not thread-safe at the moment.

[tjarnagin]

Hi, No, we are not supporting multiple driver/controller interactions on the same instance. We are using a Nager.TcpClient which is subscribe/listen rather than polling the socket and so the client is pushing it’s DataReceived event. This is the same client version we have been using with your interpreter which was version 4.2. Tim Jarnagin From: Henrique Dal Bello ***@***.***> Sent: Tuesday, September 16, 2025 11:24 PM To: Rickedb/OpenProtocolInterpreter ***@***.***> Cc: Tim Jarnagin ***@***.***>; Author ***@***.***> Subject: Re: [Rickedb/OpenProtocolInterpreter] MidInterpreter.GetMessageTemplate(int mid) is failing when calling Parse (Issue #119) CAUTION: THIS EMAIL ORIGINATED OUTSIDE OF AEGIS [Image removed by sender.]Rickedb left a comment (Rickedb/OpenProtocolInterpreter#119)<#119 (comment)> Hello! Are you using the same instance of MidInterpreter for many threads/drivers? If yes, the mid interpreter is not thread-safe at the moment. — Reply to this email directly, view it on GitHub<#119 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AKBAONKR5GPRDLEVBI6FZ4L3TDH5NAVCNFSM6AAAAACGWNPLD2VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTGMBRGEZDMMRRGU>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[tjarnagin]

The exception is coming from the following line in:
internal void UseTemplate(IEnumerable types) where T : IMessagesTemplate
when the Lazy factory is creating the instance of the MID ( in this case MID 2 and I have seen the same on MID 4. I suspect all MIDs ):

(IMessagesTemplate)Activator.CreateInstance(type, [types])

** This is a single thread accessing the instance and there are no other threads accessing

[Rickedb]

I did reach the same point, however, its strange because the exception should happen only when someone modifies the list during the FirstOrDefault operation.
However, this is only modified when executing UseTemplate() via MidInterpreterMessagesExtensions extension methods.

How are you registering the mids you want to use/parse?

[tjarnagin]

Here how we are instantiating our interpreter:

        _messageInterpreter = new MidInterpreter().UseAllMessages(new Type[]
        {
            typeof(Mid0002),
            typeof(Mid0005),
            typeof(Mid0061),
            typeof(Mid0004),
            typeof(Mid0015),
            typeof(Mid0035),
            typeof(Mid1201),
            typeof(Mid1202),
        });

[tjarnagin]

Okay, I found that commit 435f729: #108 Mid0902 tests and implementation caused the issue.

Class MessageTemplate: FilterSelectedMids(IEnumerable mids) had ToList() removed so now it is removing from the same collection it is iterating over.

I altered this and the exception is gone.

[tjarnagin]

I posted our construction of the interpreter which is done in our class constructor. The error happens after connecting to the controller and the first MID response from the controller. No matter when that method is accessed you can't alter a collection while iterating it. Tim Jarnagin

…

-------- Original message -------- From: Henrique Dal Bello ***@***.***> Date: 9/17/25 9:14 PM (GMT-05:00) To: Rickedb/OpenProtocolInterpreter ***@***.***> Cc: Tim Jarnagin ***@***.***>, Author ***@***.***> Subject: Re: [Rickedb/OpenProtocolInterpreter] MidInterpreter.GetMessageTemplate(int mid) is failing when calling Parse (Issue #119) CAUTION: THIS EMAIL ORIGINATED OUTSIDE OF AEGIS [https://avatars.githubusercontent.com/u/9448672?s=20&v=4]Rickedb left a comment (Rickedb/OpenProtocolInterpreter#119)<#119 (comment)> I did reach the same point, however, its strange because the exception should happen only when someone modifies the list during the FirstOrDefault operation. However, this is only modified when executing UseTemplate() via MidInterpreterMessagesExtensions extension methods. How are you registering the mids you want to use/parse? — Reply to this email directly, view it on GitHub<#119 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AKBAONODXH3JQJBPTD6QPGD3TIBQRAVCNFSM6AAAAACGWNPLD2VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTGMBVGA2DCMJSGQ>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[tjarnagin]

To me this makes since when the error happens because of the lazy loading. It would not be hit until the first use of, in this case Communication message class, because that is when it is initialized and only then would it actually remove the mids not being used. I do love your choosing to use the Lazy structure by the way. This error would still happen without using Lazy and would just happen earlier. We are under a tight dead line to get our new project out to the customer. We added our use of MIDs 8, 9, 1201 and 1202 which is why we had to upgrade to 6.1 so I may need to alter your source on my end until a fix is in place in which case we would switch back to the NuGet. Tim Jarnagin

…

-------- Original message -------- From: Henrique Dal Bello ***@***.***> Date: 9/17/25 9:14 PM (GMT-05:00) To: Rickedb/OpenProtocolInterpreter ***@***.***> Cc: Tim Jarnagin ***@***.***>, Author ***@***.***> Subject: Re: [Rickedb/OpenProtocolInterpreter] MidInterpreter.GetMessageTemplate(int mid) is failing when calling Parse (Issue #119) CAUTION: THIS EMAIL ORIGINATED OUTSIDE OF AEGIS [https://avatars.githubusercontent.com/u/9448672?s=20&v=4]Rickedb left a comment (Rickedb/OpenProtocolInterpreter#119)<#119 (comment)> I did reach the same point, however, its strange because the exception should happen only when someone modifies the list during the FirstOrDefault operation. However, this is only modified when executing UseTemplate() via MidInterpreterMessagesExtensions extension methods. How are you registering the mids you want to use/parse? — Reply to this email directly, view it on GitHub<#119 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AKBAONODXH3JQJBPTD6QPGD3TIBQRAVCNFSM6AAAAACGWNPLD2VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTGMBVGA2DCMJSGQ>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[Rickedb]

Hi Tim,

Feel free to modify it and import to your project temporarily.
I'll be working on it in the next few days so we can fix that problem and upload the fixed version at NuGet.

[tjarnagin]

Awesome! Thank you Henrique. Tim Jarnagin From: Henrique Dal Bello ***@***.***> Sent: Thursday, September 18, 2025 5:34 PM To: Rickedb/OpenProtocolInterpreter ***@***.***> Cc: Tim Jarnagin ***@***.***>; Author ***@***.***> Subject: Re: [Rickedb/OpenProtocolInterpreter] MidInterpreter.GetMessageTemplate(int mid) is failing when calling Parse (Issue #119) CAUTION: THIS EMAIL ORIGINATED OUTSIDE OF AEGIS [Image removed by sender.]Rickedb left a comment (Rickedb/OpenProtocolInterpreter#119)<#119 (comment)> Hi Tim, Feel free to modify it and import to your project temporarily. I'll be working on it in the next few days so we can fix that problem and upload the fixed version at NuGet. — Reply to this email directly, view it on GitHub<#119 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AKBAONM7TFK53GF3L7YSFDD3TMQLPAVCNFSM6AAAAACGWNPLD2VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTGMBZG44TAMZSGU>. You are receiving this because you authored the thread.Message ID: ***@***.***>