rusty-dynamic-loading.rs

extern crate dylib;
extern crate notify;

use dylib::DynamicLibrary;
use notify::Watcher;
use std::fs;
use std::mem::transmute;
use std::path::Path;
use std::sync::mpsc::channel;
use std::thread;
use std::time::Duration;

const LIB_PATH: &'static str = "../game/target/debug/libgame.so";

const FPS: u64 = 1;

fn main() {
    let mut lib = DynamicLibrary::open(Some(Path::new(LIB_PATH))).unwrap_or_else(|error| panic!("{}", error));
    let mut get_message: fn() -> &'static str = unsafe { transmute(lib.symbol::<usize>("get_message").unwrap()) };
    let mut needs_reload = false;

    let (ns, nr) = channel();
    let mut watcher = notify::new(ns).unwrap();
    watcher.watch(LIB_PATH).unwrap();

    let dur = Duration::from_millis(1000 / FPS);
    loop {
        thread::sleep(dur);

        if let Ok(ref event) = nr.try_recv() {
            if let Ok(ref op) = event.op {
                if op.contains(notify::op::REMOVE) {
                    watcher.watch(LIB_PATH).unwrap();
                } else {
                    needs_reload = true;
                }
            }
        }

        if needs_reload && fs::metadata(LIB_PATH).unwrap().len() > 0 {
            drop(lib);
            lib = DynamicLibrary::open(Some(Path::new(LIB_PATH))).unwrap_or_else(|error| panic!("{}", error));
            get_message = unsafe {
                transmute(lib.symbol::<usize>("get_message").unwrap())
            };
            needs_reload = false;
        }

        println!("message: {}", get_message());
    }
}