first commit

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "loader"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "loader"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

src/lib.rs

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+pub use std::sync::mpsc::TryRecvError;
+use std::sync::mpsc::{self, Receiver};
+
+pub struct Loader<T> {
+    rx: Receiver<T>,
+}
+
+impl<T: Send + 'static> Loader<T> {
+    pub fn new<F: FnOnce() -> T + Send + 'static>(f: F) -> Loader<T> {
+        let (tx, rx) = mpsc::sync_channel(0);
+        std::thread::spawn(move || tx.send(f()).unwrap());
+        return Loader { rx };
+    }
+    #[inline(always)]
+    pub fn try_recv(&self) -> Result<T, TryRecvError> {
+        self.rx.try_recv()
+    }
+}

src/main.rs

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+use loader::{Loader, TryRecvError};
+use std::{
+    io::{self, stdout, Write},
+    num::IntErrorKind,
+    time::{Duration, Instant},
+};
+
+const FPS: u64 = 12;
+const NSPF: u64 = ((1.0 / FPS as f64) * 1.0e9) as u64;
+const FRAME_DUR: Duration = Duration::from_nanos(NSPF);
+
+fn main() {
+    let stdin = io::stdin();
+    loop {
+        print!("How many seconds: ");
+        stdout().flush().unwrap();
+        let mut input = String::new();
+        stdin.read_line(&mut input).unwrap();
+        let seconds: u64 = match input.strip_suffix("\n").unwrap_or(&input).parse() {
+            Ok(i) => i,
+            Err(e) if *e.kind() == IntErrorKind::Empty => break,
+            Err(e) => {
+                println!("Error parsing number: {:?}", e.kind());
+                continue;
+            }
+        };
+
+        let loader: Loader<String> = Loader::new(move || {
+            std::thread::sleep(Duration::from_secs(seconds));
+            return format!("Hello World {}", seconds);
+        });
+        let start = Instant::now();
+
+        let mut res = loader.try_recv();
+        while res == Err(TryRecvError::Empty) {
+            print!("\rWaiting... {:.2}s", start.elapsed().as_secs_f32());
+            std::io::stdout().flush().unwrap();
+            std::thread::sleep(FRAME_DUR);
+            res = loader.try_recv();
+        }
+
+        let elapsed = start.elapsed();
+        println!("\nDone! {:.2}s", elapsed.as_secs_f32());
+        println!("{}\n", res.unwrap());
+    }
+}