1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
use std::collections::{HashMap, HashSet, VecDeque}; use std::hash::Hash; use std::sync::mpsc; use std::sync::{Arc, RwLock}; use std::thread; pub fn run<A, B, F: FnMut(A) -> Result<(B, Vec<A>), Box<dyn std::error::Error + Send>>>( first_job: A, mut perform: F, ) -> Result<HashMap<A, B>, Box<dyn std::error::Error + Send>> where A: 'static + Clone + Eq + Hash + Send + Sync, B: 'static + Clone + Send, F: 'static + Send + Copy, { let mut pending = HashSet::<A>::new(); let queue = Arc::new(RwLock::new(VecDeque::new())); let (tx, rx) = mpsc::channel(); pending.insert(first_job.clone()); queue.write().unwrap().push_back(first_job); let _ = (0..4).map(|_| { let tx2 = tx.clone(); let pending2 = pending.clone(); let queue2 = queue.clone(); thread::spawn(move || loop { match queue2.write().unwrap().pop_front() { Some(job) => tx2.send((job.clone(), perform(job))).unwrap(), None if pending2.is_empty() => return, None => thread::yield_now() } }) }).collect::<Vec<_>>(); let mut results = HashMap::<A, B>::default(); while let Ok((job, result)) = rx.recv() { let (result, new_jobs) = result?; pending.remove(&job); results.insert(job, result); for job in new_jobs { if !results.contains_key(&job) { pending.insert(job.clone()); queue.write().unwrap().push_back(job); } } if pending.is_empty() { break; } } Ok(results) } #[test] fn test_queue() { let result = run(1, |num| match num { 1 => Ok(("one", vec![2])), 2 => Ok(("two", vec![])), _ => Err(Box::new(std::io::Error::new( std::io::ErrorKind::Other, "Error", ))), }) .unwrap(); assert_eq!(result.get(&1), Some(&"one")); assert_eq!(result.get(&2), Some(&"two")); let result = run(1, |num| match num { 1 => Ok((num, vec![ 1, 2, 3, 4, 5, 6, 7 ])), _ => Ok((num, vec![])) }) .unwrap(); assert_eq!(result.get(&1), Some(&1)); assert_eq!(result.get(&2), Some(&2)); assert_eq!(result.get(&3), Some(&3)); assert_eq!(result.get(&4), Some(&4)); assert_eq!(result.get(&5), Some(&5)); assert_eq!(result.get(&6), Some(&6)); assert_eq!(result.get(&7), Some(&7)); assert_eq!(result.get(&8), None); let result = run(1, |num| match num { 1 => Ok(("one", vec![2])), 2 => Ok(("two", vec![])), _ => Ok(("", vec![])), }); assert_eq!(result.unwrap().get(&1), Some(&"one")); let result = run("one", |num| Ok((num, vec![]))); assert_eq!(result.unwrap().get(&"one"), Some(&"one")); let result = run(1, |num| match num { 1 => Ok(("one", vec![2])), _ => Err(Box::new(std::io::Error::new( std::io::ErrorKind::Other, "Error", ))), }); assert_eq!(result.is_err(), true); }