tokio/tokio-trace/tests/subscriber.rs

#[macro_use]
extern crate tokio_trace;
mod support;

use self::support::*;
use tokio_trace::subscriber::with_default;
use tokio_trace::Level;

use std::sync::{
    atomic::{AtomicUsize, Ordering},
    Arc,
};

#[test]
fn filters_are_not_reevaluated_for_the_same_span() {
    // Asserts that the `span!` macro caches the result of calling
    // `Subscriber::enabled` for each span.
    let alice_count = Arc::new(AtomicUsize::new(0));
    let bob_count = Arc::new(AtomicUsize::new(0));
    let alice_count2 = alice_count.clone();
    let bob_count2 = bob_count.clone();

    let (subscriber, handle) = subscriber::mock()
        .with_filter(move |meta| match meta.name {
            "alice" => {
                alice_count2.fetch_add(1, Ordering::Relaxed);
                false
            }
            "bob" => {
                bob_count2.fetch_add(1, Ordering::Relaxed);
                true
            }
            _ => false,
        })
        .run_with_handle();

    with_default(subscriber, move || {
        // Enter "alice" and then "bob". The dispatcher expects to see "bob" but
        // not "alice."
        let mut alice = span!(Level::TRACE, "alice");
        let mut bob = alice.enter(|| {
            let mut bob = span!(Level::TRACE, "bob");
            bob.enter(|| ());
            bob
        });

        // The filter should have seen each span a single time.
        assert_eq!(alice_count.load(Ordering::Relaxed), 1);
        assert_eq!(bob_count.load(Ordering::Relaxed), 1);

        alice.enter(|| bob.enter(|| {}));

        // The subscriber should see "bob" again, but the filter should not have
        // been called.
        assert_eq!(alice_count.load(Ordering::Relaxed), 1);
        assert_eq!(bob_count.load(Ordering::Relaxed), 1);

        bob.enter(|| {});
        assert_eq!(alice_count.load(Ordering::Relaxed), 1);
        assert_eq!(bob_count.load(Ordering::Relaxed), 1);
    });
    handle.assert_finished();
}

#[test]
fn filters_are_reevaluated_for_different_call_sites() {
    // Asserts that the `span!` macro caches the result of calling
    // `Subscriber::enabled` for each span.
    let charlie_count = Arc::new(AtomicUsize::new(0));
    let dave_count = Arc::new(AtomicUsize::new(0));
    let charlie_count2 = charlie_count.clone();
    let dave_count2 = dave_count.clone();

    let subscriber = subscriber::mock()
        .with_filter(move |meta| {
            println!("Filter: {:?}", meta.name);
            match meta.name {
                "charlie" => {
                    charlie_count2.fetch_add(1, Ordering::Relaxed);
                    false
                }
                "dave" => {
                    dave_count2.fetch_add(1, Ordering::Relaxed);
                    true
                }
                _ => false,
            }
        })
        .run();

    with_default(subscriber, move || {
        // Enter "charlie" and then "dave". The dispatcher expects to see "dave" but
        // not "charlie."
        let mut charlie = span!(Level::TRACE, "charlie");
        let mut dave = charlie.enter(|| {
            let mut dave = span!(Level::TRACE, "dave");
            dave.enter(|| {});
            dave
        });

        // The filter should have seen each span a single time.
        assert_eq!(charlie_count.load(Ordering::Relaxed), 1);
        assert_eq!(dave_count.load(Ordering::Relaxed), 1);

        charlie.enter(|| dave.enter(|| {}));

        // The subscriber should see "dave" again, but the filter should not have
        // been called.
        assert_eq!(charlie_count.load(Ordering::Relaxed), 1);
        assert_eq!(dave_count.load(Ordering::Relaxed), 1);

        // A different span with the same name has a different call site, so it
        // should cause the filter to be reapplied.
        let mut charlie2 = span!(Level::TRACE, "charlie");
        charlie.enter(|| {});
        assert_eq!(charlie_count.load(Ordering::Relaxed), 2);
        assert_eq!(dave_count.load(Ordering::Relaxed), 1);

        // But, the filter should not be re-evaluated for the new "charlie" span
        // when it is re-entered.
        charlie2.enter(|| span!(Level::TRACE, "dave").enter(|| {}));
        assert_eq!(charlie_count.load(Ordering::Relaxed), 2);
        assert_eq!(dave_count.load(Ordering::Relaxed), 2);
    });
}

#[test]
fn filter_caching_is_lexically_scoped() {
    pub fn my_great_function() -> bool {
        span!(Level::TRACE, "emily").enter(|| true)
    }

    pub fn my_other_function() -> bool {
        span!(Level::TRACE, "frank").enter(|| true)
    }

    let count = Arc::new(AtomicUsize::new(0));
    let count2 = count.clone();

    let subscriber = subscriber::mock()
        .with_filter(move |meta| match meta.name {
            "emily" | "frank" => {
                count2.fetch_add(1, Ordering::Relaxed);
                true
            }
            _ => false,
        })
        .run();

    with_default(subscriber, || {
        // Call the function once. The filter should be re-evaluated.
        assert!(my_great_function());
        assert_eq!(count.load(Ordering::Relaxed), 1);

        // Call the function again. The cached result should be used.
        assert!(my_great_function());
        assert_eq!(count.load(Ordering::Relaxed), 1);

        assert!(my_other_function());
        assert_eq!(count.load(Ordering::Relaxed), 2);

        assert!(my_great_function());
        assert_eq!(count.load(Ordering::Relaxed), 2);

        assert!(my_other_function());
        assert_eq!(count.load(Ordering::Relaxed), 2);

        assert!(my_great_function());
        assert_eq!(count.load(Ordering::Relaxed), 2);
    });
}