Creates a temporary which is freed while still in use - rust

Question

I'm creating a small application that explores variable lifetimes and threads. I want to load in a file once, and then use its contents (in this case an audio file) in a separate channel. I am having issues with value lifetimes.
I'm almost certain the syntax is wrong for what I have so far (for creating a static variable), but I can't find any resources for File types and lifetimes. What I have thus far produces this error:
let file = &File::open("src/censor-beep-01.wav").unwrap();
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ creates a temporary which is freed while still in use
let x: &'static File = file;
------------- type annotation requires that borrow lasts for `'static`
The code I currently have is:
#![allow(dead_code)]
#![allow(unused_imports)]
#![allow(unused_must_use)]
#![allow(unused_variables)]
use std::io::{self, BufRead, BufReader, stdin, Read};
use std::sync::mpsc::{self, TryRecvError};
use std::thread;
use std::time::Duration;
use std::fs::File;
use std::rc::Rc;
use rodio::Source;
fn main() {
let file = &File::open("src/censor-beep-01.wav").unwrap();
let x: &'static File = file;
loop {
let (tx, rx) = mpsc::channel();
thread::spawn(move || loop {
let tmp = x;
let (stream, stream_handle) = rodio::OutputStream::try_default().unwrap();
let source = rodio::Decoder::new(BufReader::new(tmp)).unwrap();
stream_handle.play_raw(source.convert_samples());
match rx.try_recv() {
Ok(_) | Err(TryRecvError::Disconnected) => {
break;
}
Err(TryRecvError::Empty) => {
println!("z");
thread::sleep(Duration::from_millis(1000));
}
}
});
let mut line = String::new();
let stdin = io::stdin();
let _ = stdin.lock().read_line(&mut line);
let _ = tx.send(());
return;
}
}

Answer 1

You need to wrap the file with Arc and Mutex like Arc::new(Mutex::new(file)) and then clone the file before passing it to the thread.
Arc is used for reference counting, which is needed to share the target object (in your case it is a file) across the thread and Mutex is needed to access the target object synchronously.
sample code (I have simplified your code to make it more understandable):
let file = Arc::new(Mutex::new(File::open("src/censor-beep-01.wav").unwrap()));
loop {
let file = file.clone();
thread::spawn(move || loop {
let mut file_guard = match file.lock() {
Ok(guard) => guard,
Err(poison) => poison.into_inner()
};
let file = file_guard.deref();
// now you can pass above file object to BufReader like "BufReader::new(file)"
});
}
reason for creates a temporary which is freed while still in use error:
You have only stored the reference of the file without the actual file object. so, the object will be droped in that line itself.