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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,170 @@ | ||
| use std::cell::RefCell; | ||
| use std::cmp::Ordering; | ||
| use std::collections::HashMap; | ||
| use std::sync::{Arc, Mutex, MutexGuard}; | ||
| use std::time::{Duration, SystemTime}; | ||
|
|
||
| use anyhow::Result; | ||
| use rand::Rng; | ||
|
|
||
| pub const HOUR: Duration = Duration::from_secs(3600); | ||
| #[derive(Debug, Clone)] | ||
| struct RelayStats { | ||
| pub failure_times: Vec<SystemTime>, | ||
| } | ||
|
|
||
| impl RelayStats { | ||
| fn new() -> RelayStats { | ||
| RelayStats { | ||
| failure_times: Vec::new(), | ||
| } | ||
| } | ||
|
|
||
| fn _clean(&mut self, retain: Duration) { | ||
| let count = self.failure_times.len(); | ||
| self.failure_times.retain(|t| { | ||
| t.elapsed().unwrap_or({ | ||
| log::warn!("the system experience system time error, ranker may malfunction."); | ||
| retain.saturating_add(Duration::from_secs(1)) | ||
| }) < retain | ||
| }); | ||
| log::trace!("cleaning {:?} entires", count - &self.failure_times.len()); | ||
| } | ||
|
|
||
| fn add_failure(&mut self, retain: Duration) { | ||
| self.failure_times.push(SystemTime::now()); | ||
| self._clean(retain); | ||
| } | ||
|
|
||
| fn failures_last(&self, period: Duration) -> Result<usize> { | ||
| let mut count = 0; | ||
| for failure_time in &self.failure_times { | ||
| if failure_time | ||
| .elapsed() | ||
| .map_err(|e| anyhow::anyhow!(e.to_string()))? | ||
| < period | ||
| { | ||
| break; | ||
| } | ||
| count += 1; | ||
| } | ||
| Ok(&self.failure_times.len() - count) | ||
| } | ||
|
|
||
| fn mean_failure_rate(&self, period: Duration) -> Result<f64> { | ||
| let failures = self.failures_last(period)?; | ||
|
|
||
| if failures == 0 { | ||
| return Ok(0.0); | ||
| } | ||
| Ok(failures as f64 / (period.as_secs_f64() / 3600.0)) | ||
| } | ||
| } | ||
|
|
||
| #[derive(Debug, Clone)] | ||
| pub struct RelayRanker { | ||
| domain_stats: Arc<Mutex<RefCell<HashMap<String, RelayStats>>>>, | ||
| max_duration: Duration, | ||
| } | ||
|
|
||
| impl RelayRanker { | ||
| pub fn new(retain: Duration) -> RelayRanker { | ||
| RelayRanker { | ||
| domain_stats: Arc::new(Mutex::new(RefCell::new(HashMap::new()))), | ||
| max_duration: retain, | ||
| } | ||
| } | ||
|
|
||
| pub fn downvote(&self, domain: impl Into<String>) -> Result<()> { | ||
| let guard = match self.domain_stats.lock() { | ||
| Ok(guard) => guard, | ||
| Err(_) => return Err(anyhow::anyhow!("failed to acquire lock")), | ||
| }; | ||
| let mut inner = guard.borrow_mut(); | ||
| let stats = inner.entry(domain.into()).or_insert(RelayStats::new()); | ||
| stats.add_failure(self.max_duration); | ||
| Ok(()) | ||
| } | ||
|
|
||
| pub fn reorder(&self, domains: &mut Vec<&str>) -> Result<()> { | ||
| let guard = match self.domain_stats.lock() { | ||
| Ok(guard) => guard, | ||
| Err(_) => return Err(anyhow::anyhow!("failed to acquire lock")), | ||
| }; | ||
|
|
||
| domains.sort_by(|a, b| { | ||
| let a_failure_rate = self._mean_failure_rate(*a, &guard).unwrap_or_default(); | ||
| let b_failure_rate = self._mean_failure_rate(*b, &guard).unwrap_or_default(); | ||
| if a_failure_rate == b_failure_rate { | ||
| let mut rng = rand::thread_rng(); | ||
| rng.gen::<bool>().cmp(&rng.gen::<bool>()) | ||
| } else { | ||
| a_failure_rate | ||
| .partial_cmp(&b_failure_rate) | ||
| .unwrap_or(Ordering::Equal) | ||
| } | ||
| }); | ||
| log::debug!("ranking system hint: {:?}", domains); | ||
| Ok(()) | ||
| } | ||
|
|
||
| fn _mean_failure_rate( | ||
| &self, | ||
| domain: impl Into<String>, | ||
| guard: &MutexGuard<'_, RefCell<HashMap<String, RelayStats>>>, | ||
| ) -> Result<f64> { | ||
| let inner = guard.borrow(); | ||
| if let Some(stats) = inner.get(&domain.into()) { | ||
| stats.mean_failure_rate(self.max_duration) | ||
| } else { | ||
| Ok(0.0) | ||
| } | ||
| } | ||
| } | ||
|
|
||
| #[cfg(test)] | ||
| mod tests { | ||
|
|
||
| use super::*; | ||
|
|
||
| #[test] | ||
| fn test_downvoted_at_last() { | ||
| let ranking_system = RelayRanker::new(HOUR); | ||
|
|
||
| let _ = ranking_system.downvote("bing.com"); | ||
| let mut domains = vec!["example.com", "bing.com", "google.com"]; | ||
| let _ = ranking_system.reorder(&mut domains); | ||
|
|
||
| assert_eq!(*domains.last().unwrap(), "bing.com"); | ||
| } | ||
|
|
||
| #[test] | ||
| fn test_order_by_failure_rate() { | ||
| let ranking_system = RelayRanker::new(HOUR); | ||
|
|
||
| let _ = ranking_system.downvote("bing.com"); | ||
| let _ = ranking_system.downvote("example.com"); | ||
| let _ = ranking_system.downvote("example.com"); | ||
|
|
||
| let mut domains = vec!["example.com", "bing.com", "google.com"]; | ||
| let _ = ranking_system.reorder(&mut domains); | ||
|
|
||
| assert_eq!(domains, vec!("google.com", "bing.com", "example.com")); | ||
| } | ||
|
|
||
| #[test] | ||
| fn test_rank_healing() { | ||
| let ranking_system = RelayRanker::new(HOUR); | ||
|
|
||
| let _ = ranking_system.downvote("bing.com"); | ||
|
|
||
| let binding = ranking_system.domain_stats.lock().unwrap(); | ||
| let mut inner = binding.borrow_mut(); | ||
| let ds = inner.get_mut("bing.com").unwrap(); | ||
| if let Some(first) = ds.failure_times.get_mut(0) { | ||
| *first = SystemTime::checked_sub(&SystemTime::now(), HOUR * 2).unwrap(); | ||
| } | ||
| let failure_rate = ds.mean_failure_rate(HOUR).unwrap(); | ||
| assert_eq!(failure_rate, 0.0); | ||
| } | ||
| } | ||
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