Avoid learning the same job multiple times

src/bin/server/worker.rs

@@ -2,39 +2,25 @@ use super::{QueueItem, QueueItemKind};
 
 use crate::rla;
 use crate::rla::ci::{self, BuildCommit, CiPlatform};
-use std::collections::VecDeque;
+use std::collections::{HashSet, VecDeque};
+use std::hash::Hash;
 use std::path::PathBuf;
 use std::str;
 
-// We keep track of the last several unique job IDs. This is because
-// Azure sends us a notification for every individual builder's
-// state (around 70 notifications/job as of this time), but we want
-// to only process a given job once.
-//
-// You might ask -- why is this not a HashSet/HashMap? That would
-// also work, but be a little more complicated to remove things
-// from. We would need to keep track of order somehow to remove the
-// oldest job ID. An attempt at such an API was tried in PR #29, but
-// ultimately scrapped as too complicated.
-//
-// We keep few enough elements in this "set" that a Vec isn't too bad.
-//
-// Note: Don't update this number too high, as we O(n) loop through it on every
-// notification from GitHub (twice).
-const KEEP_IDS: usize = 16;
-
 pub struct Worker {
     debug_post: Option<(String, u32)>,
     index_file: PathBuf,
     index: rla::Index,
     extract_config: rla::extract::Config,
     github: rla::github::Client,
     queue: crossbeam::channel::Receiver<QueueItem>,
-    notified: VecDeque<u64>,
     ci: Box<dyn CiPlatform + Send>,
     repo: String,
     secondary_repos: Vec<String>,
     query_builds_from_primary_repo: bool,
+
+    recently_notified: RecentlySeen<u64>,
+    recently_learned: RecentlySeen<String>,
 }
 
 impl Worker {
@@ -66,12 +52,14 @@ impl Worker {
             index_file,
             extract_config: Default::default(),
             github: rla::github::Client::new()?,
-            notified: VecDeque::new(),
             queue,
             ci,
             repo,
             secondary_repos,
             query_builds_from_primary_repo,
+
+            recently_notified: RecentlySeen::new(32),
+            recently_learned: RecentlySeen::new(256),
         })
     }
 
@@ -133,10 +121,6 @@ impl Worker {
 
         info!("started processing");
 
-        if self.notified.contains(&build_id) {
-            info!("ignoring recently notified build");
-            return Ok(());
-        }
         let query_from = if self.query_builds_from_primary_repo {
             &self.repo
         } else {
@@ -160,14 +144,7 @@ impl Worker {
 
         // Avoid processing the same build multiple times.
         if !outcome.is_passed() {
-            info!("preparing report");
-            self.report_failed(build.as_ref())?;
-
-            info!("marked as notified");
-            self.notified.push_front(build_id);
-            if self.notified.len() > KEEP_IDS {
-                self.notified.pop_back();
-            }
+            self.report_failed(build_id, build.as_ref())?;
         }
         if build.pr_number().is_none() && build.branch_name() == "auto" {
             info!("learning from the log");
@@ -179,8 +156,13 @@ impl Worker {
         Ok(())
     }
 
-    fn report_failed(&mut self, build: &dyn rla::ci::Build) -> rla::Result<()> {
-        debug!("Preparing report...");
+    fn report_failed(&mut self, build_id: u64, build: &dyn rla::ci::Build) -> rla::Result<()> {
+        if self.recently_notified.recently_witnessed(&build_id) {
+            info!("avoided reporting recently notified build");
+            return Ok(());
+        }
+
+        info!("preparing report");
 
         let job = match build.jobs().iter().find(|j| j.outcome().is_failed()) {
             Some(job) => *job,
@@ -301,6 +283,9 @@ impl Worker {
 [I'm a bot](https://github.com/rust-lang/rust-log-analyzer)! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact **`@rust-lang/infra`**. ([Feature Requests](https://github.com/rust-lang/rust-log-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3Afeature-request))
         "#, opening = opening, html_url = job.html_url(), log_url = pretty_log_url, raw_log_url = raw_log_url, log = extracted))?;
 
+        info!("marked build {} as recently notified", build_id);
+        self.recently_notified.store(build_id);
+
         Ok(())
     }
 
@@ -310,6 +295,11 @@ impl Worker {
                 continue;
             }
 
+            if self.recently_learned.recently_witnessed(&job.id()) {
+                info!("Skipped already processed {}", job);
+                return Ok(());
+            }
+
             debug!("Processing {}...", job);
 
             match ci::download_log(self.ci.as_ref(), *job, self.github.internal()) {
@@ -320,6 +310,7 @@ impl Worker {
                             1,
                         );
                     }
+                    self.recently_learned.store(job.id());
                 }
                 None => {
                     warn!(
@@ -341,3 +332,70 @@ impl Worker {
         Ok(())
     }
 }
+
+/// Keeps track of the recently seen IDs for both the failed build reports and the learned jobs.
+/// Only the most recent IDs are stored, to avoid growing the memory usage endlessly.
+///
+/// Internally this uses both an HashSet to provide fast lookups and a VecDeque to know which old
+/// jobs needs to be removed.
+struct RecentlySeen<T: Clone + Eq + Hash> {
+    size: usize,
+    lookup: HashSet<T>,
+    removal: VecDeque<T>,
+}
+
+impl<T: Clone + Eq + Hash> RecentlySeen<T> {
+    fn new(size: usize) -> Self {
+        Self {
+            size,
+            lookup: HashSet::with_capacity(size),
+            removal: VecDeque::with_capacity(size),
+        }
+    }
+
+    fn recently_witnessed(&self, key: &T) -> bool {
+        self.lookup.contains(key)
+    }
+
+    fn store(&mut self, key: T) {
+        if self.lookup.contains(&key) {
+            return;
+        }
+        if self.removal.len() >= self.size {
+            if let Some(item) = self.removal.pop_back() {
+                self.lookup.remove(&item);
+            }
+        }
+        self.lookup.insert(key.clone());
+        self.removal.push_front(key);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_recently_seen() {
+        let mut recently = RecentlySeen::new(2);
+
+        assert!(!recently.recently_witnessed(&0));
+        assert!(!recently.recently_witnessed(&1));
+        assert!(!recently.recently_witnessed(&2));
+
+        recently.store(0);
+        assert!(recently.recently_witnessed(&0));
+        assert!(!recently.recently_witnessed(&1));
+        assert!(!recently.recently_witnessed(&2));
+
+        recently.store(1);
+        assert!(recently.recently_witnessed(&0));
+        assert!(recently.recently_witnessed(&1));
+        assert!(!recently.recently_witnessed(&2));
+
+        recently.store(2);
+        assert!(!recently.recently_witnessed(&0));
+        assert!(recently.recently_witnessed(&1));
+        assert!(recently.recently_witnessed(&2));
+    }
+}