Is there a common way to recover from a connection error in MongoDB with the C# driver? Currently, my Windows service shuts down if MongoDB is turned off. I currently have my app structured like this at the start of my Windows service:
//Set up connections for Mongo
var con = new MongoConnectionStringBuilder(ConfigurationManager.ConnectionStrings["MongoDB"].ConnectionString);
var client = new MongoClient(con.ToString());
var server = client.GetServer();
var db = server.GetDatabase(con.DatabaseName);
I then inject the db object into my repositories.
I'm trying to find something like an event handler or a condition I could listen to in my whole application to prevent from crashing the entire service should mongo go down for some reason.
As suggested by the driver document, the MongoClient is added to manage Replica Set stuff, which earlier or later you will need. To avoid mass code refactoring then, you need to make better use of it now.
The MongoClient, which is thread-safe, have implemented the failover logic among replica set nodes already. It's supposed to be singleton along with your application domain. Thus you can inject the MongoClient, other than db (which is not even thread safe).
So always retry the GetServer() and GetDatabase() from MongoClient, and try/catch the exceptions produced by them would finally give you the available db object when MongoDB is online again.
The point is, MongoDB will not notify the clients about its online, so there's no such event to notify you, either. You'll have to keep trying in your client side until it's ok. And to avoid the exceptions to bring down your service, you'll have to catch them.
EDIT: I am wrong about the thread-safety according to the document. However, it doesn't change the fact you shouldn't store MongoDatabase for future migration to replica set.