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ch2-07-statistics.rs
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ch2-07-statistics.rs
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use std::sync::atomic::AtomicUsize;
use std::sync::atomic::AtomicU64;
use std::sync::atomic::Ordering::Relaxed;
use std::thread;
use std::time::Duration;
use std::time::Instant;
fn main() {
let num_done = &AtomicUsize::new(0);
let total_time = &AtomicU64::new(0);
let max_time = &AtomicU64::new(0);
thread::scope(|s| {
// Four background threads to process all 100 items, 25 each.
for t in 0..4 {
s.spawn(move || {
for i in 0..25 {
let start = Instant::now();
process_item(t * 25 + i); // Assuming this takes some time.
let time_taken = start.elapsed().as_micros() as u64;
num_done.fetch_add(1, Relaxed);
total_time.fetch_add(time_taken, Relaxed);
max_time.fetch_max(time_taken, Relaxed);
}
});
}
// The main thread shows status updates, every second.
loop {
let total_time = Duration::from_micros(total_time.load(Relaxed));
let max_time = Duration::from_micros(max_time.load(Relaxed));
let n = num_done.load(Relaxed);
if n == 100 { break; }
if n == 0 {
println!("Working.. nothing done yet.");
} else {
println!(
"Working.. {n}/100 done, {:?} average, {:?} peak",
total_time / n as u32,
max_time,
);
}
thread::sleep(Duration::from_secs(1));
}
});
println!("Done!");
}
fn process_item(_: usize) {
thread::sleep(Duration::from_millis(123));
}