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https://github.com/tokio-rs/tracing.git
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f42e7e6dd2
## Motivation Allow filter layers to filter on the contents of events (see #2007). ## Solution This branch adds a new `Subscriber::event_enabled` method, taking an `Event` and returning `bool`. This is called before the `Subscriber::event` method, and if it returns `false`, `Subscriber::event` is not called. For simple subscriber (e.g. not using `Layer`s), the `event_enabled` method is not particulary necessary, as the subscriber can just skip the `event` call. However, this branch also adds a new `Layer::event_enabled` method, with the signature: ```rust fn event_enabled(&self, event: &Event<'_>, ctx: Context<'_, S>) -> bool; ``` This is called before `Layer::on_event`, and if `event_enabled` returns `false`, `on_event` is not called (nor is `Subscriber::event`). This allows filter `Layer`s to filter out an `Event` based on its fields. Closes #2007
82 lines
2.2 KiB
Rust
82 lines
2.2 KiB
Rust
#![cfg(feature = "registry")]
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use std::sync::{Arc, Mutex};
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use tracing::{subscriber::with_default, Event, Metadata, Subscriber};
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use tracing_subscriber::{layer::Context, prelude::*, registry, Layer};
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struct TrackingLayer {
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enabled: bool,
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event_enabled_count: Arc<Mutex<usize>>,
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event_enabled: bool,
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on_event_count: Arc<Mutex<usize>>,
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}
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impl<C> Layer<C> for TrackingLayer
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where
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C: Subscriber + Send + Sync + 'static,
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{
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fn enabled(&self, _metadata: &Metadata<'_>, _ctx: Context<'_, C>) -> bool {
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self.enabled
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}
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fn event_enabled(&self, _event: &Event<'_>, _ctx: Context<'_, C>) -> bool {
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*self.event_enabled_count.lock().unwrap() += 1;
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self.event_enabled
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}
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fn on_event(&self, _event: &Event<'_>, _ctx: Context<'_, C>) {
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*self.on_event_count.lock().unwrap() += 1;
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}
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}
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#[test]
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fn event_enabled_is_only_called_once() {
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let event_enabled_count = Arc::new(Mutex::default());
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let count = event_enabled_count.clone();
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let subscriber = registry().with(TrackingLayer {
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enabled: true,
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event_enabled_count,
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event_enabled: true,
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on_event_count: Arc::new(Mutex::default()),
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});
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with_default(subscriber, || {
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tracing::error!("hiya!");
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});
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assert_eq!(1, *count.lock().unwrap());
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}
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#[test]
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fn event_enabled_not_called_when_not_enabled() {
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let event_enabled_count = Arc::new(Mutex::default());
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let count = event_enabled_count.clone();
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let subscriber = registry().with(TrackingLayer {
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enabled: false,
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event_enabled_count,
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event_enabled: true,
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on_event_count: Arc::new(Mutex::default()),
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});
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with_default(subscriber, || {
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tracing::error!("hiya!");
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});
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assert_eq!(0, *count.lock().unwrap());
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}
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#[test]
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fn event_disabled_does_disable_event() {
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let on_event_count = Arc::new(Mutex::default());
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let count = on_event_count.clone();
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let subscriber = registry().with(TrackingLayer {
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enabled: true,
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event_enabled_count: Arc::new(Mutex::default()),
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event_enabled: false,
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on_event_count,
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});
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with_default(subscriber, || {
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tracing::error!("hiya!");
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});
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assert_eq!(0, *count.lock().unwrap());
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}
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