如何在C＃MongoDB驱动程序v2.0中获取连接状态？

Question

We are starting using new MongoDB driver v2 and we can't understand whether we are connected to the db or not.

Our repository code:

var client = new MongoClient("mongodb://{wrong-host}:{wrong-port}/{dbbname}");
var database = client.GetDatabase(url.DatabaseName);

Where wrong-host and wrong-port are invalid values.

First we thought that exception will be raised if no one is listening on specified address but driver doesn't throws.

Next step was to invoke method on the db:

var dbs = client.ListDatabasesAsync().Result.ToListAsync().Result;

Here we have freez for 30 seconds and than exception. It was not suitable for us to wait 30 seconds to get to know connected we are or not.

System.TimeoutException: A timeout occured after 30000ms selecting a server using CompositeServerSelector{ Selectors = ReadPreferenceServerSelector{ ReadPreference = { Mode = Primary, TagSets = [] } }, LatencyLimitingServerSelector{ AllowedLatencyRange = 00:00:00.0150000 } }. Client view of cluster state is { ClusterId : "1", Type : "Unknown", State : "Disconnected", Servers : [{ ServerId: "{ ClusterId : 1, EndPoint : "****" }", EndPoint: "****", State: "Disconnected", Type: "Unknown", HeartbeatException: "MongoDB.Driver.MongoConnectionException: An exception occurred while opening a connection to the server. ---> System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it ******

Finally we tried to set up different timeouts but nothing changed.

var client = new MongoClient(new MongoClientSettings
  { 
    SocketTimeout = TimeSpan.FromSeconds(1),
    MaxConnectionIdleTime = TimeSpan.FromSeconds(1),
    MaxConnectionLifeTime = TimeSpan.FromSeconds(1),
    ConnectTimeout = TimeSpan.FromSeconds(1),
    Servers = url.Servers
  });

So the question is how we could know whether we are connected to the mongo or not in short time interval ~(1-2) seconds?

[UPD]

Our current solution is:

private IMongoDatabase Connect(string connectionString, TimeSpan timeout)
{
  var url = MongoUrl.Create(connectionString);
  var client = new MongoClient(url);
  var db = client.GetDatabase(url.DatabaseName);
  var pingTask = db.RunCommandAsync<BsonDocument>(new BsonDocument("ping", 1));
  pingTask.Wait(timeout);
  if (pingTask.IsCompleted)
    log.InfoFormat("Connected to: {0}.", connectionString);
  else
    throw new TimeoutException(string.Format("Failed to connect to: {0}.", connectionString));

  return db;
}

usage

database = Connect(connectionString, TimeSpan.FromSeconds(1));

Answer 1

There is next workaround for this issue :

var client = new MongoClient(new MongoClientSettings
{
       Server = new MongoServerAddress("xxxx"),
       ClusterConfigurator = builder =>
       {
             builder.ConfigureCluster(settings => settings.With(serverSelectionTimeout: TimeSpan.FromSeconds(10)));
       }
});

Answer 2

With the new API :

         try
            {
                MongoClient client = new MongoClient("xxx"); 
                // if you're running localhost let the parameter empty
                var db = client.GetDatabase("dbName");
                var collection = db.GetCollection<BsonDocument>("collectionName");
                var filter1 = Builders<BsonDocument>.Filter.Empty;
                var filter = new BsonDocument();
                var count = 0;
                   using (var cursor = await collection.FindAsync(filter))
                    {
                      while (await cursor.MoveNextAsync())
                       {
                        var batch = cursor.Current;
                        foreach (var document in batch)
                        {
                          count++;
                        }
                       }
                    }
               MessageBox.Show(count.ToString());
            }
            catch(Exception ex)
            {
                MessageBox.Show(ex.Message);
            }