exclude bot commits from churn when `--no-bots` option is used (#1335)

* init

* fix

* review

* early exit in is_bot_commit

src/info/git/mod.rs

@@ -48,6 +48,8 @@ pub fn traverse_commit_graph(
 
     let (churn_thread, churn_tx) = get_churn_channel(
         repo,
+        &mailmap,
+        no_bots.clone(),
         &has_commit_graph_traversal_ended,
         &total_number_of_commits,
         max_churn_pool_size,
@@ -169,6 +171,8 @@ type ChurnPair = (NumberOfCommitsByFilepath, usize);
 
 fn get_churn_channel(
     repo: &gix::Repository,
+    mailmap: &gix::mailmap::Snapshot,
+    bot_regex_pattern: Option<MyRegex>,
     has_commit_graph_traversal_ended: &Arc<AtomicBool>,
     total_number_of_commits: &Arc<AtomicUsize>,
     max_churn_pool_size: Option<usize>,
@@ -176,6 +180,8 @@ fn get_churn_channel(
     let (tx, rx) = channel::<gix::hash::ObjectId>();
     let thread = std::thread::spawn({
         let repo = repo.clone();
+        let mailmap = mailmap.clone();
+        let bot_regex_pattern = bot_regex_pattern.clone();
         let has_commit_graph_traversal_ended = has_commit_graph_traversal_ended.clone();
         let total_number_of_commits = total_number_of_commits.clone();
         move || -> Result<_> {
@@ -183,6 +189,9 @@ fn get_churn_channel(
             let mut number_of_diffs_computed = 0;
             while let Ok(commit_id) = rx.recv() {
                 let commit = repo.find_object(commit_id)?.into_commit();
+                if is_bot_commit(&commit, &mailmap, bot_regex_pattern.as_ref())? {
+                    continue;
+                }
                 compute_diff_with_parent(&mut number_of_commits_by_file_path, &commit, &repo)?;
                 number_of_diffs_computed += 1;
                 if should_break(
@@ -272,6 +281,19 @@ fn compute_diff_with_parent(
     Ok(())
 }
 
+fn is_bot_commit(
+    commit: &Commit,
+    mailmap: &gix::mailmap::Snapshot,
+    bot_regex_pattern: Option<&MyRegex>,
+) -> Result<bool> {
+    if bot_regex_pattern.is_some() {
+        let sig = mailmap.resolve(commit.author()?);
+        Ok(is_bot(&sig.name, bot_regex_pattern))
+    } else {
+        Ok(false)
+    }
+}
+
 fn is_bot(author_name: &BString, bot_regex_pattern: Option<&MyRegex>) -> bool {
     bot_regex_pattern.map_or(false, |regex| {
         regex.0.is_match(author_name.to_str_lossy().as_ref())