A simple mutex POOL for a custom obj. Useful for templating data storage connector polls in a multi threaded way

mutex_pool.rs

#![feature(drop_types_in_const)]
use std::sync::{Mutex, MutexGuard};

#[macro_use]
extern crate lazy_static;

lazy_static! {
  static ref POOL: Mutex<Vec<Obj>> = Mutex::new(vec![]);
}

pub struct Obj;

fn get_pool<'a>() -> MutexGuard<'a, Vec<Obj>> {
        POOL.lock().unwrap()
}

impl Drop for Obj {
    fn drop(&mut self) {
        println!("dropping.");
        // println!("hangs here...");
        get_pool().push(Obj {});
        // println!("not here...");
    }
}

impl Obj {
    pub fn new() -> Obj {
        println!("initializing");
        let o = get_pool().pop();
        o.unwrap_or(Obj {})
    }
}

fn main() {
    Obj::new();
    Obj::new();
    println!("Now reaches this point.");
}