Should we register IClientApi as singleton?

[micdenny]

We are using this server-side and we're getting a lot of these thread-safety errors:

System.InvalidOperationException: Operations that change non-concurrent collections must have exclusive access. A concurrent update was performed on this collection and corrupted its state. The collection's state is no longer correct.
   at System.Collections.Generic.Dictionary`2.FindEntry(TKey key)
   at System.Collections.Generic.Dictionary`2.TryGetValue(TKey key, TValue& value)
   at OpenTl.Schema.Serialization.SerializationMap.TryGetSerializator(TypeInfo type, ISerializator& serializator)
   at OpenTl.Schema.Serialization.SerializationMap.GetSerializator(TypeInfo type)
   at OpenTl.Schema.Serialization.Serializators.ObjectTypes.IObjectSerializer.Deserialize(IByteBuffer buffer, SerializationMetadata typeMetadata)
   at OpenTl.Schema.Serialization.Serializators.ObjectTypes.IObjectSerializer.Deserialize(IByteBuffer buffer, SerializationMetadata typeMetadata)
   at OpenTl.Schema.Serialization.Serializators.ObjectTypes.VectorSerializer.Deserialize(IByteBuffer buffer, SerializationMetadata metadata)
   at OpenTl.Schema.Serialization.Serializators.ObjectTypes.IObjectSerializer.Deserialize(IByteBuffer buffer, SerializationMetadata typeMetadata)
   at OpenTl.ClientApi.MtProto.Layers.Messages.Adapters.RpcResultHandler.ChannelRead0(IChannelHandlerContext ctx, TRpcResult msg)
   at DotNetty.Transport.Channels.SimpleChannelInboundHandler`1.ChannelRead(IChannelHandlerContext ctx, Object msg)
   at DotNetty.Transport.Channels.AbstractChannelHandlerContext.InvokeChannelRead(Object msg)
--- End of stack trace from previous location where exception was thrown ---
   at OpenTl.ClientApi.MtProto.Services.RequestSenderService.SendRequestAsync[TResult](IRequest`1 request, CancellationToken cancellationToken)
   at OpenTl.ClientApi.Services.ContactsService.ImportContactsAsync(IReadOnlyList`1 contacts, CancellationToken cancellationToken)

DotNetty.Codecs.EncoderException: Exception of type 'DotNetty.Codecs.EncoderException' was thrown. ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at OpenTl.Schema.Serialization.SerializationMap.TryGetSerializator(TypeInfo type, ISerializator& serializator)
   at OpenTl.Schema.Serialization.SerializationMap.GetSerializator(TypeInfo type)
   at OpenTl.Schema.Serialization.Serializer.Serialize(Object obj, IByteBuffer buffer, SerializationMetadata metadata)
   at OpenTl.Schema.Serialization.Serializer.Serialize(Object obj)
   at OpenTl.ClientApi.MtProto.Layers.Secure.Codecs.SecureRequestEncoder.Encode(IChannelHandlerContext context, IObject message, IByteBuffer output)
   at DotNetty.Codecs.MessageToByteEncoder`1.WriteAsync(IChannelHandlerContext context, Object message)
   --- End of inner exception stack trace ---
   at OpenTl.ClientApi.MtProto.Layers.Top.Adapters.TopHandlerAdapter.SendInitConnectionRequest()
   at OpenTl.ClientApi.MtProto.Services.RequestSenderService.SendRequestAsync[TResult](IRequest`1 request, CancellationToken cancellationToken)
   at OpenTl.ClientApi.Services.ContactsService.ImportContactsAsync(IReadOnlyList`1 contacts, CancellationToken cancellationToken)

System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at System.Collections.Generic.LinkedList`1.Enumerator.MoveNext()
   at System.Linq.Enumerable.SelectEnumerableIterator`2.MoveNext()
   at OpenTl.ClientApi.MtProto.Layers.Top.Adapters.TopHandlerAdapter.SendInitConnectionRequest()
   at OpenTl.ClientApi.MtProto.Services.RequestSenderService.SendRequestAsync[TResult](IRequest`1 request, CancellationToken cancellationToken)
   at OpenTl.ClientApi.Services.ContactsService.ImportContactsAsync(IReadOnlyList`1 contacts, CancellationToken cancellationToken)

Does using the IClientApi as singleton resolve this thread-safety issues? maybe because some initialization are non thread-safe?

[vik-borisov]

Hi, @micdenny!

please write a test application with this exception. I think that this is a mistake.

[micdenny]

I will try, it’s hard to me understand what to mock in order to do a proper unit test, I will study your tests project and see if I can reproduce the exception.

[vik-borisov]

@micdenny A console application is sufficient

[micdenny]

Ok

[vik-borisov]

@micdenny Still relevant?

[micdenny]

yes, but need more time, I've scheduled this later

[vik-borisov]

@micdenny try to use new version