Slate state when HttpClient reconnects

[VagnerGon]

When a connection is interrupted, the ping thread marks the RedisHost as unavailable. But, when the connection is restored, it does not update the Available property. It seems that the AsyncTcpClient recovers itself, marking the client as Connected, but the Available property is not updated.

Note that the TcpClient will have the IsConnected property as true, but the Available property will remain as false

BeetleX.Redis/src/RedisHost.cs

Lines 94 to 126 in df7fcaf

	public async Task<Result> Connect(RedisDB db, RedisClient client)
	{
	if (!client.TcpClient.IsConnected)
	{
	var connStatus = await client.TcpClient.Connect();
	if (connStatus.Connected)
	{
	this.Available = true;
	if (!string.IsNullOrEmpty(Password))
	{
	Commands.AUTH auth = new Commands.AUTH(Password);
	RedisRequest request = new RedisRequest(null, client, auth, typeof(string));
	var result = await request.Execute(db);
	if (result.ResultType == ResultType.DataError ||
	result.ResultType == ResultType.Error
	|| result.ResultType == ResultType.NetError)
	return result;
	}
	Commands.SELECT select = new Commands.SELECT(DB);
	var req = new RedisRequest(null, client, select, typeof(string));
	var t = req.Execute(db);
	t.Wait();
	return t.Result;
	}
	else
	{
	this.Available = false;
	return new Result { ResultType = ResultType.NetError, Messge = client.TcpClient.LastError.Message };
	}
	}
	return new Result { ResultType = ResultType.Simple, Messge = "Connected" };

Steps to reproduce:

• Host a local redis server
• Make a call (in my case, from an asp.net core controller), e.g. INFO. Everything works as expected.
• Now, shutdown the Redis instance
• Make the call again. It should throw an exception and the host marked as Available = false
• Start the Redis server again.
• Make the same call (aspnet server should not be rebooted).
• Exception is thrown as redis server is not available

The AsyncTcpClient changes to a Connected state, but the Available property is still false.

Changing the property before returning solved the issue for me:

this.Available = true;
return new Result { ResultType = ResultType.Simple, Messge = "Connected" }; 

[VagnerGon]

I think the cause is the parallel Ping from ReadHosts and WriteHosts.
Both will call Connect method, but one that fails may flag the mConnected field as false, while the second thread has set as true.

https://github.com/beetlex-io/BeetleX/blob/ce6f9d91394dbed5f28a66b9efbd9a87f9d32e23/src/BeetleX/Clients/Clients.cs#L1019-L1105

[beetlex-io]

thanks