Impl FixedGrpcChannelTransport (#89)

* Make ClientBase abstract class

* Impl FixedGrpcChannelTransport.cs

Author: KirillKurdyukov

src/Ydb.Sdk/src/Transport/FixedGrpcChannelTransport.cs

@@ -0,0 +1,47 @@
+using Grpc.Core;
+using Grpc.Net.Client;
+using Microsoft.Extensions.Logging;
+
+namespace Ydb.Sdk.Transport;
+
+internal class FixedGrpcChannelTransport : GrpcTransport
+{
+    private readonly GrpcChannel _channel;
+
+    public FixedGrpcChannelTransport(
+        DriverConfig driverConfig,
+        ILogger logger
+    ) : base(
+        new DriverConfig(
+            endpoint: driverConfig.Endpoint,
+            database: driverConfig.Database,
+            customServerCertificate: driverConfig.CustomServerCertificate
+        ), logger
+    )
+    {
+        _channel = ChannelsCache.CreateChannel(Config.Endpoint, Config);
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        if (disposing)
+        {
+            _channel.Dispose();
+        }
+    }
+
+    protected override (string, GrpcChannel) GetChannel()
+    {
+        return (Config.Endpoint, _channel);
+    }
+
+    protected override void OnRpcError(string endpoint, RpcException e)
+    {
+        var status = e.Status;
+        if (e.Status.StatusCode != Grpc.Core.StatusCode.OK)
+        {
+            Logger.LogWarning("gRPC error {StatusCode}[{Detail}] on fixed channel {Endpoint}",
+                status.StatusCode, status.Detail, endpoint);
+        }
+    }
+}

src/Ydb.Sdk/src/GrpcTransport.cs renamed to src/Ydb.Sdk/src/Transport/GrpcTransport.cs

@@ -2,13 +2,13 @@
 using Grpc.Net.Client;
 using Microsoft.Extensions.Logging;
 
-namespace Ydb.Sdk;
+namespace Ydb.Sdk.Transport;
 
 // TODO Experimental [for Driver with fix call options]
 public abstract class GrpcTransport : IDisposable, IAsyncDisposable
 {
-    protected readonly ILogger Logger;
     protected readonly DriverConfig Config;
+    protected readonly ILogger Logger;
 
     internal GrpcTransport(DriverConfig driverConfig, ILogger logger)
     {