Support for auto reconnect

[wereHamster]

It would be nice to have this option so that the driver automatically reconnects to the server if the connection goes down.

[gregwebs]

can you give more details on this? Is this an option that should be set?

[wereHamster]

Some other mongodb drivers have an option, called something like auto_reconnect, which will instruct the driver to automatically reconnect to the server if the connection goes down (due to server restart, or when a replica set elects a new master).

Examples from other drivers:

• http://api.mongodb.org/perl/current/MongoDB/Connection.html#auto_reconnect
• http://mongodb.github.io/node-mongodb-native/api-generated/server.html (search for auto_reconnect)
• The python driver automatically performs reconnects, but the user has to acknowledge reconnect attempts.

[gregwebs]

Why not always attempt to automatically re-connect? I am wondering if this is functionality that can be built into resource-pool rather than mongoDB. Probably should switch to resource-pool before trying to implement this.

[wereHamster]

Automatic reconnect by default? That would work for me as well :)

[gregwebs]

I saw this in my error logs:

PersistMongoDBError "ConnectionFailure <socket: 4>: hGetBuf: resource vanished (Connection reset by peer)"

Is that what you saw also? (Minus the Persist wrapper if you aren't using persistent)

[wereHamster]

I don't have access the the logs anymore. But the symptom was that after I restarted, the application didn't work anymore.

[gregwebs]

after you restarted the database?

[wereHamster]

Oh, I deleted too much text while editing the comment, should have read 'after I restarted mongodb, the app...'

[gregwebs]

I was easily able to write a one-off for mongodb-queue that does this

https://github.com/docmunch/haskell-mongodb-queue/blob/master/Database/MongoDB/Queue.hs#L158