Execute request for each element in CSV, not per user - jmeter

Question

I'm using jMeter 3.2 to write some tests. I have a CSV file with test account info. Each row contains login info for a user. Each user needs to request a token that is used on later requests.
My test plan:
The get token request retrieves a token. The login requests logs in the user and returns another token. Select customer card selects a customer and returns the final token. The code for the postprocesser is (I'm not experienced in this, so any advice is appreciated):
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
// Check if our map already exists
if (props.get("map") == null) {
JSONObject obj = new JSONObject();
obj.put("${department}", new String(data));
log.info("Adding department to map. Department: ${department}. Token: " + new String(data));
props.put("map", obj.toJSONString());
} else {
// Retrieve the current map
map = props.get("map");
JSONParser parser = new JSONParser();
JSONObject jobj = (JSONObject) parser.parse(map);
// Add the new department (with it's token) to the map
jobj.put("${department}", new String(data));
log.info("Updating map for department. Department: ${department}. Token: " + new String(data));
props.put("map", jobj.toJSONString());
}
Attempt 1:
I'm setting up a once only controller to log in a user and retrieve the token.
Now lets say I have 10 lines in my CSV file but in my test I only want to use 3 users and loop 10 times. What happens is that 3 login requests are sent (one for each user). This works fine for the first iteration. At the 2. iteration the 3 threads will use row 4-6 which doesn't have a token and thereby fail.
Attempt 2:
I'm using an if controller to check whether the token has been set or not. I haven't got this working at all. I added a beanshell preprocessor to the controller where I attempt to retrieve the token. If it's null or empty I set the token variable to "". In the if controller I check for this value. But yeah. No luck yet.
Attempt 3
In Beanshell check if the token is created already. If not, call the test fragment that retrieves it. Unfortunately this seems not possible.
It might be worth noting that I store my tokens in a property, so that all threads can access it.
Please let me know if you need more information.

Answer 1

I figured out a solution. In essence what I tried to do is to store a token for each row in the data file.
I did this by creating a setUp Thread Group which is executed before other thread groups. In this I loop through the data and store a token for each. Now all other thread groups may access these as they run.