About transaction availability

[realLiangshiwei]

Mongo2Go is a great library, but we found some problems when using.

The document explains to use single server replica set mode to enable transactions, but after testing I think it is invalid.

Test code is very simple：

var runner = MongoDbRunner.Start(singleNodeReplSet: true, singleNodeReplSetWaitTimeout: 65535); // max timeout value

var client = new MongoClient(runner.ConnectionString);

using (var session = client.StartSession())
{
    session.StartTransaction();
}

The result:

I see that you use the transition to primary complete; database writes are now permitted message to determine whether the transaction is available, but this is not enough.

Mongo2Go/src/Mongo2Go/Helper/MongoDbProcessStarter.cs

Line 50 in 958b052

wrappedProcess.OutputDataReceived += (_, args) => replicaSetReady |= !string.IsNullOrWhiteSpace(args.Data) && args.Data.Contains(ReplicaSetReadyIdentifier);

This is the code for mongo driver to determine whether the transaction is available

https://github.com/mongodb/mongo-csharp-driver/blob/44fff3f7d618ade5eed7a3e874407ecbc231997c/src/MongoDB.Driver.Core/Core/Bindings/CoreSession.cs#L461

I think we can use the same logic

// wait until transaction is ready or until the timeout is reached
SpinWait.SpinUntil(() => client.Cluster.Description.Servers.Where(s => s.State == ServerState.Connected && s.IsDataBearing).Any(), TimeSpan.FromSeconds(singleNodeReplSetWaitTimeout));

Now, it works:

What do you think?

[JohannesHoppe]

👍

[JohannesHoppe]

New version released. Please try out Mongo2Go 2.2.13.