An in-memory data store holds the course records used by the EzyTutors REST APIs. The service uses it instead of a database. section 3.1 section 3.0
use super::models::Course;
use std::sync::Mutex;
pub struct AppState {
pub health_check_response: String,
pub visit_count: Mutex<u32>,
pub courses: Mutex<Vec<Course>>, #1
}
The application state holds courses in a mutex-protected vector, allowing the service to share its store. section 3.2.3
The vector starts empty when the application state is created. The course data model is defined before the APIs that use the store. section 3.2.3 section 3.2.3
