big_code_analysis_ast/

count.rs

// Metric counts (token, function, branch, argument, etc.) are stored as
// `usize` and crossed with `f64` averages, ratios, and Halstead scores
// across the cyclomatic / MI / Halstead computations. The `usize as f64`
// and `f64 as usize` casts are intentional and snapshot-anchored — every
// site is bounded by the count it came from. Allowing the lints at the
// module level keeps the metric arithmetic legible.
#![allow(
    clippy::cast_precision_loss,
    clippy::cast_possible_truncation,
    clippy::cast_sign_loss
)]
// Per-language metric and AST modules deliberately consume the macro-
// generated tree-sitter token enums via `use crate::*` and `use Foo::*`
// inside match expressions — explicit imports would list dozens of
// variants per arm and obscure the per-language token sets that are the
// point of these files. Allowed at the module level rather than per
// function so the per-language impl blocks stay readable.
#![allow(clippy::wildcard_imports, clippy::enum_glob_use)]

//! Node counting by kind or category, and the shared [`CountCollector`].

use num_format::{Locale, ToFormattedString};
use std::fmt;
use std::sync::{Arc, Mutex};

use crate::traits::{ParserTrait, Search};

/// Counts the types of nodes specified in the input slice and the
/// number of nodes in a code. Crate-internal walk core reached through
/// the `big_code_analysis::Ast::count` seam.
pub fn count<T: ParserTrait>(parser: &T, filters: &[String]) -> (usize, usize) {
    let filters = parser.filters(filters);
    let (mut good, mut total) = (0, 0);
    // The same shared walk as `find`, for the ancestor chain its
    // predicates read; this one only tallies, so the visit order it
    // imposes is incidental.
    parser.root().act_on_node(&mut |node, ancestors| {
        total += 1;
        good += usize::from(filters.any(node, ancestors));
    });
    (good, total)
}

/// Opaque, shareable collector that accumulates a [`Count`] across the
/// worker threads of a `big_code_analysis::ConcurrentRunner` walk.
///
/// Wraps the shared `Arc<Mutex<Count>>` behind a newtype so callers do
/// not handle the synchronization machinery directly. [`Clone`] is a
/// cheap reference-count bump, so each worker
/// can hold its own handle to the same tally while the config still
/// satisfies the `'static + Send + Sync` bound of
/// `big_code_analysis::ConcurrentRunner`. Recover the final tally with
/// [`CountCollector::into_count`] once every worker has joined.
#[derive(Debug, Clone)]
pub struct CountCollector(Arc<Mutex<Count>>);

impl CountCollector {
    /// Creates an empty collector.
    #[must_use]
    pub fn new() -> Self {
        Self(Arc::new(Mutex::new(Count::default())))
    }

    /// Creates a collector seeded with an existing tally.
    #[must_use]
    pub fn with_count(count: Count) -> Self {
        Self(Arc::new(Mutex::new(count)))
    }

    /// Add a per-file `(good, total)` tally into the shared collector.
    ///
    /// The aggregation is two monotonically-incremented counters, so a
    /// peer worker that panicked mid-update leaves at worst a slightly
    /// low tally — never an unsafe state. Recover the poisoned guard
    /// (issue #445) and clear the poison so this and later callers — and
    /// the collector's final [`CountCollector::into_count`] — degrade
    /// rather than cascade into a pool-wide abort the way `.unwrap()`
    /// would.
    pub fn add(&self, good: usize, total: usize) {
        let mut results = self.0.lock().unwrap_or_else(|poisoned| {
            self.0.clear_poison();
            poisoned.into_inner()
        });
        results.good += good;
        results.total += total;
    }

    /// Consumes the collector, returning the accumulated [`Count`].
    ///
    /// Call this only after every worker sharing a clone of this
    /// collector has joined, so the underlying `Arc` reference count is
    /// back to one. Degrades rather than panics in the unlikely event
    /// that a worker panicked mid-update and poisoned the inner mutex
    /// (issue #445): the recovered guard still holds the fully-applied
    /// tally because the aggregation is two monotonically-incremented
    /// counters.
    ///
    /// If the `Arc` is unexpectedly **still shared**, a peer clone
    /// survived past this call — a worker failed to join — which is a
    /// caller-side coordination bug, not a recoverable runtime state.
    /// Another clone may still call [`CountCollector::add`] afterwards,
    /// so the value returned here is a **best-effort snapshot of a tally
    /// that is not yet final**, not the complete aggregate the
    /// `#[must_use]` return implies (issue #757). A `debug_assert!`
    /// trips loudly on this path so the coordination bug surfaces in
    /// debug and test builds; release builds still degrade to the
    /// snapshot rather than panicking, honoring the project's
    /// no-panic-in-production contract.
    #[must_use]
    pub fn into_count(self) -> Count {
        match Arc::try_unwrap(self.0) {
            Ok(mutex) => mutex
                .into_inner()
                .unwrap_or_else(std::sync::PoisonError::into_inner),
            Err(shared) => {
                // A still-shared `Arc` means a worker has not joined: the
                // returned tally is a non-final snapshot (issue #757).
                // Trip loudly in debug/test builds to expose the
                // coordination bug while release degrades gracefully.
                debug_assert!(
                    false,
                    "CountCollector::into_count called while the collector \
                     is still shared (a worker failed to join); the \
                     returned Count is a non-final snapshot"
                );
                let guard = shared
                    .lock()
                    .unwrap_or_else(std::sync::PoisonError::into_inner);
                Count {
                    good: guard.good,
                    total: guard.total,
                }
            }
        }
    }
}

impl Default for CountCollector {
    fn default() -> Self {
        Self::new()
    }
}

/// Count of different types of nodes in a code.
#[derive(Debug, Default)]
pub struct Count {
    /// The number of specific types of nodes searched in a code
    pub good: usize,
    /// The total number of nodes in a code
    pub total: usize,
}

impl fmt::Display for Count {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        writeln!(
            f,
            "Total nodes: {}",
            self.total.to_formatted_string(&Locale::en)
        )?;
        writeln!(
            f,
            "Found nodes: {}",
            self.good.to_formatted_string(&Locale::en)
        )?;
        // Guard the empty case: a zero-match `bca count` leaves the default
        // `Count { good: 0, total: 0 }`, and `0.0 / 0.0` is `NaN`, which would
        // render as the meaningless "Percentage: NaN%". Report 0% instead.
        let percentage = if self.total == 0 {
            0.0
        } else {
            (self.good as f64) / (self.total as f64) * 100.
        };
        write!(f, "Percentage: {percentage:.2}%")
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::thread;

    // Regression test for issue #445: a poisoned `stats` mutex must not
    // cascade into a pool-wide panic. A worker that panics while holding
    // the shared guard poisons the lock; `CountCollector::add` used to
    // re-panic on `.lock().unwrap()`. Verified by revert per
    // `.claude/rules/testing.md`: reverting the recovery makes this test
    // panic instead of applying the tally.
    #[test]
    fn add_degrades_on_poisoned_stats_mutex() {
        let stats = Arc::new(Mutex::new(Count::default()));

        // Poison the mutex: panic while holding the guard on a helper
        // thread, mirroring the dispatch_preproc #425 regression test.
        let poisoner = stats.clone();
        let handle = thread::spawn(move || {
            let _guard = poisoner.lock().expect("fresh mutex is unpoisoned");
            panic!("intentional panic to poison the stats mutex");
        });
        assert!(
            handle.join().is_err(),
            "poisoner thread should have panicked"
        );
        assert!(stats.is_poisoned(), "test setup failed to poison the mutex");

        // Adding into a poisoned collector must degrade (recover the
        // guard, clear the poison) rather than panic on `.lock()`.
        let collector = CountCollector(stats.clone());
        collector.add(2, 5);

        // The recovery clears the poison so later peers and the
        // collector's final `into_count()` see a usable, fully-applied
        // tally.
        assert!(
            !stats.is_poisoned(),
            "recovery should clear the poison flag"
        );
        let recovered = stats.lock().expect("poison cleared, lock must succeed");
        assert_eq!(
            (recovered.good, recovered.total),
            (2, 5),
            "the surviving worker's counts must still be applied"
        );
    }

    // `into_count` must surface the tally accumulated by every worker
    // sharing a clone of the collector, after they have all joined.
    #[test]
    fn into_count_returns_accumulated_tally() {
        let collector = CountCollector::new();

        let mut handles = Vec::new();
        for _ in 0..4 {
            let worker = collector.clone();
            handles.push(thread::spawn(move || {
                let mut guard = worker.0.lock().expect("fresh mutex is unpoisoned");
                guard.good += 1;
                guard.total += 10;
            }));
        }
        for handle in handles {
            handle.join().expect("worker thread must not panic");
        }

        let count = collector.into_count();
        assert_eq!(count.good, 4, "every worker's good count must be summed");
        assert_eq!(count.total, 40, "every worker's total count must be summed");
    }

    // `into_count` degrades to the recovered tally when the inner mutex
    // is poisoned, mirroring the #445 invariant for the extraction side.
    #[test]
    fn into_count_degrades_on_poisoned_mutex() {
        let collector = CountCollector::with_count(Count { good: 3, total: 7 });

        let poisoner = collector.clone();
        let handle = thread::spawn(move || {
            let _guard = poisoner.0.lock().expect("fresh mutex is unpoisoned");
            panic!("intentional panic to poison the collector mutex");
        });
        assert!(
            handle.join().is_err(),
            "poisoner thread should have panicked"
        );

        let count = collector.into_count();
        assert_eq!(count.good, 3, "poison recovery must preserve the tally");
        assert_eq!(count.total, 7, "poison recovery must preserve the tally");
    }

    // Regression test for issue #757: calling `into_count` while a peer
    // clone is still alive (a worker failed to join) is a coordination
    // bug that used to return a non-final snapshot silently. The
    // `debug_assert!` in the `Err(shared)` arm must trip loudly so the
    // misuse cannot masquerade as a final aggregate. Gated on
    // `debug_assertions`: `debug_assert!` is a no-op under `--release`,
    // where the call degrades to the snapshot instead of panicking.
    // Verified by revert per `.claude/rules/testing.md`: without the
    // `debug_assert!`, `into_count` returns normally and this test fails
    // (no panic), proving the assert is what makes the misuse loud.
    #[test]
    #[cfg(debug_assertions)]
    #[should_panic(expected = "still shared")]
    fn into_count_panics_in_debug_when_still_shared() {
        let collector = CountCollector::with_count(Count { good: 1, total: 2 });
        // Hold a live clone so the `Arc` strong count stays above one,
        // forcing `Arc::try_unwrap` down the still-shared `Err` arm.
        let _surviving_peer = collector.clone();
        let _ = collector.into_count();
    }

    // Regression test for issue #709: the default `Count { good: 0, total: 0 }`
    // (a zero-match `bca count` run) used to render "Percentage: NaN%" because
    // `0.0 / 0.0` is NaN. The empty case must report 0.00% instead.
    #[test]
    fn display_reports_zero_percent_for_empty_count() {
        let rendered = Count::default().to_string();
        assert!(
            rendered.contains("Percentage: 0.00%"),
            "empty Count must render 0.00%, got: {rendered}"
        );
        assert!(
            !rendered.contains("NaN"),
            "empty Count must not render NaN, got: {rendered}"
        );
    }

    // A non-empty Count still renders the true ratio (3/7 ≈ 42.86%), so the
    // zero-guard does not accidentally clamp populated tallies to 0%.
    #[test]
    fn display_reports_true_percentage_for_nonempty_count() {
        let rendered = Count { good: 3, total: 7 }.to_string();
        assert!(
            rendered.contains("Percentage: 42.86%"),
            "3/7 must render 42.86%, got: {rendered}"
        );
    }
}