public override async Task <long> LogKV(Memory <byte> key, Memory <byte> value, bool isDeleted)
{
var c = GetChannelWriter();
var tcs = new TaskCompletionSource <long>();
var po = new PutOperation();
po.LoggingCompleted = tcs;
po.Key = key;
po.Value = value;
po.Deleted = isDeleted;
await c.WriteAsync(po);
var off = await po.LoggingCompleted.Task;
return(off);
}