MongoDB C++ driver handling replica set connection failures - c++

Question

So the mongo c++ documentation says
On a failover situation, expect at least one operation to return an
error (throw an exception) before the failover is complete. Operations
are not retried
Kind of annoying, but that leaves it up to me to handle a failed operation. Ideally I would just like the application to sleep for a few seconds (app is single threaded). And retry with the hopes that a new primary mongod is established. In the case of a second failure, well I take it the connection is truly messed up and I just want to thrown an exception.
Within my MongodbManager class this means all operations have this kind of double try/catch block set up. I was wondering if there is a more elegant solution?
Example method:
template <typename T>
std::string
MongoManager::insert(std::string ns, T object)
{
mongo::BSONObj = convertToBson(object);
std::string result;
try {
connection_->insert(ns, oo); //connection_ = shared_ptr<DBClientReplicaSet>
result = connection_->getLastError();
lastOpSucceeded_ = true;
}
catch (mongo::SocketException& ex)
{
lastOpSucceeded_ = false;
boost::this_thread::sleep( boost::posix_time::seconds(5) );
}
// try again?
if (!lastOpSucceeded_) {
try {
connection_->insert(ns, oo);
result = connection_->getLastError();
lastOpSucceeded_ = true;
}
catch (mongo::SocketException& ex)
{
//do some clean up, throw exception
}
}
return result;
}

Answer 1

That's indeed sort of how you need to handle it. Perhaps instead of having two try/catch blocks I would use the following strategy:
keep a count of how many times you have tried
create a while loop with as terminator (count < 5 && lastOpSucceeded)
and then sleep with pow(2,count) to sleep more in every iteration.
And then when all else fails, bail out.