Can I persist state between Jenkins shared library calls?

Question

I would like to persist the state of some logic between calls in my Jenkins shared library. I don't want to pass in an object/map/... with the state in the arguments but use some kind of global variable/map for this. I failed with global varibales in the foobar.groovy below or use of environment variables. I found a work-around by creating a small helper class with a static map to store my data but this does not seem to be the right solution. Is there a cleaner way?

src/pkg/GlobalConfig.groovy

package pkg;

class GlobalConfig {
    // define a static map
    static Map data = new HashMap()
}

use map in shared library eg vars/foobar.groovy

import pkg.GlobalConfig
 
def do_something() {
    def data = pkg.GlobalConfig.data
    // do something with data
}

Answer 1

Define your global variables with the @groovy.transform.Field annotation.
Take a look at the Defining global variables section in the pipeline documentation.

foobar.groovy can look like:

import groovy.transform.Field

@Field
def data = [:]

def do_something() {
   // use data as is
}

From outside this file just use foobar.data .
Once the library is loaded the state will be persistent whenever you use it.