third_party/rust_crates/vendor/tracing-subscriber/tests/reload.rs

use std::sync::atomic::{AtomicUsize, Ordering};
use tracing_core::{
    span::{Attributes, Id, Record},
    subscriber::Interest,
    Event, Metadata, Subscriber,
};
use tracing_subscriber::{layer, prelude::*, reload::*};

pub struct NopSubscriber;

impl Subscriber for NopSubscriber {
    fn register_callsite(&self, _: &'static Metadata<'static>) -> Interest {
        Interest::never()
    }

    fn enabled(&self, _: &Metadata<'_>) -> bool {
        false
    }

    fn new_span(&self, _: &Attributes<'_>) -> Id {
        Id::from_u64(1)
    }

    fn record(&self, _: &Id, _: &Record<'_>) {}
    fn record_follows_from(&self, _: &Id, _: &Id) {}
    fn event(&self, _: &Event<'_>) {}
    fn enter(&self, _: &Id) {}
    fn exit(&self, _: &Id) {}
}

#[test]
fn reload_handle() {
    static FILTER1_CALLS: AtomicUsize = AtomicUsize::new(0);
    static FILTER2_CALLS: AtomicUsize = AtomicUsize::new(0);

    enum Filter {
        One,
        Two,
    }

    impl<S: Subscriber> tracing_subscriber::Layer<S> for Filter {
        fn register_callsite(&self, m: &Metadata<'_>) -> Interest {
            println!("REGISTER: {:?}", m);
            Interest::sometimes()
        }

        fn enabled(&self, m: &Metadata<'_>, _: layer::Context<'_, S>) -> bool {
            println!("ENABLED: {:?}", m);
            match self {
                Filter::One => FILTER1_CALLS.fetch_add(1, Ordering::SeqCst),
                Filter::Two => FILTER2_CALLS.fetch_add(1, Ordering::SeqCst),
            };
            true
        }
    }
    fn event() {
        tracing::trace!("my event");
    }

    let (layer, handle) = Layer::new(Filter::One);

    let subscriber = tracing_core::dispatcher::Dispatch::new(layer.with_subscriber(NopSubscriber));

    tracing_core::dispatcher::with_default(&subscriber, || {
        assert_eq!(FILTER1_CALLS.load(Ordering::SeqCst), 0);
        assert_eq!(FILTER2_CALLS.load(Ordering::SeqCst), 0);

        event();

        assert_eq!(FILTER1_CALLS.load(Ordering::SeqCst), 1);
        assert_eq!(FILTER2_CALLS.load(Ordering::SeqCst), 0);

        handle.reload(Filter::Two).expect("should reload");

        event();

        assert_eq!(FILTER1_CALLS.load(Ordering::SeqCst), 1);
        assert_eq!(FILTER2_CALLS.load(Ordering::SeqCst), 1);
    })
}