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Diffstat (limited to 'vendor/tracing-subscriber/src/filter/layer_filters/mod.rs')
| -rw-r--r-- | vendor/tracing-subscriber/src/filter/layer_filters/mod.rs | 1135 |
1 files changed, 0 insertions, 1135 deletions
diff --git a/vendor/tracing-subscriber/src/filter/layer_filters/mod.rs b/vendor/tracing-subscriber/src/filter/layer_filters/mod.rs deleted file mode 100644 index 8949cfb5a..000000000 --- a/vendor/tracing-subscriber/src/filter/layer_filters/mod.rs +++ /dev/null @@ -1,1135 +0,0 @@ -//! ## Per-Layer Filtering -//! -//! Per-layer filters permit individual `Layer`s to have their own filter -//! configurations without interfering with other `Layer`s. -//! -//! This module is not public; the public APIs defined in this module are -//! re-exported in the top-level `filter` module. Therefore, this documentation -//! primarily concerns the internal implementation details. For the user-facing -//! public API documentation, see the individual public types in this module, as -//! well as the, see the `Layer` trait documentation's [per-layer filtering -//! section]][1]. -//! -//! ## How does per-layer filtering work? -//! -//! As described in the API documentation, the [`Filter`] trait defines a -//! filtering strategy for a per-layer filter. We expect there will be a variety -//! of implementations of [`Filter`], both in `tracing-subscriber` and in user -//! code. -//! -//! To actually *use* a [`Filter`] implementation, it is combined with a -//! [`Layer`] by the [`Filtered`] struct defined in this module. [`Filtered`] -//! implements [`Layer`] by calling into the wrapped [`Layer`], or not, based on -//! the filtering strategy. While there will be a variety of types that implement -//! [`Filter`], all actual *uses* of per-layer filtering will occur through the -//! [`Filtered`] struct. Therefore, most of the implementation details live -//! there. -//! -//! [1]: crate::layer#per-layer-filtering -//! [`Filter`]: crate::layer::Filter -use crate::{ - filter::LevelFilter, - layer::{self, Context, Layer}, - registry, -}; -use std::{ - any::TypeId, - cell::{Cell, RefCell}, - fmt, - marker::PhantomData, - ops::Deref, - sync::Arc, - thread_local, -}; -use tracing_core::{ - span, - subscriber::{Interest, Subscriber}, - Event, Metadata, -}; -pub mod combinator; - -/// A [`Layer`] that wraps an inner [`Layer`] and adds a [`Filter`] which -/// controls what spans and events are enabled for that layer. -/// -/// This is returned by the [`Layer::with_filter`] method. See the -/// [documentation on per-layer filtering][plf] for details. -/// -/// [`Filter`]: crate::layer::Filter -/// [plf]: crate::layer#per-layer-filtering -#[cfg_attr(docsrs, doc(cfg(feature = "registry")))] -#[derive(Clone)] -pub struct Filtered<L, F, S> { - filter: F, - layer: L, - id: MagicPlfDowncastMarker, - _s: PhantomData<fn(S)>, -} - -/// Uniquely identifies an individual [`Filter`] instance in the context of -/// a [`Subscriber`]. -/// -/// When adding a [`Filtered`] [`Layer`] to a [`Subscriber`], the [`Subscriber`] -/// generates a `FilterId` for that [`Filtered`] layer. The [`Filtered`] layer -/// will then use the generated ID to query whether a particular span was -/// previously enabled by that layer's [`Filter`]. -/// -/// **Note**: Currently, the [`Registry`] type provided by this crate is the -/// **only** [`Subscriber`] implementation capable of participating in per-layer -/// filtering. Therefore, the `FilterId` type cannot currently be constructed by -/// code outside of `tracing-subscriber`. In the future, new APIs will be added to `tracing-subscriber` to -/// allow non-Registry [`Subscriber`]s to also participate in per-layer -/// filtering. When those APIs are added, subscribers will be responsible -/// for generating and assigning `FilterId`s. -/// -/// [`Filter`]: crate::layer::Filter -/// [`Subscriber`]: tracing_core::Subscriber -/// [`Layer`]: crate::layer::Layer -/// [`Registry`]: crate::registry::Registry -#[cfg(feature = "registry")] -#[cfg_attr(docsrs, doc(cfg(feature = "registry")))] -#[derive(Copy, Clone)] -pub struct FilterId(u64); - -/// A bitmap tracking which [`FilterId`]s have enabled a given span or -/// event. -/// -/// This is currently a private type that's used exclusively by the -/// [`Registry`]. However, in the future, this may become a public API, in order -/// to allow user subscribers to host [`Filter`]s. -/// -/// [`Registry`]: crate::Registry -/// [`Filter`]: crate::layer::Filter -#[derive(Default, Copy, Clone, Eq, PartialEq)] -pub(crate) struct FilterMap { - bits: u64, -} - -/// The current state of `enabled` calls to per-layer filters on this -/// thread. -/// -/// When `Filtered::enabled` is called, the filter will set the bit -/// corresponding to its ID if the filter will disable the event/span being -/// filtered. When the event or span is recorded, the per-layer filter will -/// check its bit to determine if it disabled that event or span, and skip -/// forwarding the event or span to the inner layer if the bit is set. Once -/// a span or event has been skipped by a per-layer filter, it unsets its -/// bit, so that the `FilterMap` has been cleared for the next set of -/// `enabled` calls. -/// -/// FilterState is also read by the `Registry`, for two reasons: -/// -/// 1. When filtering a span, the Registry must store the `FilterMap` -/// generated by `Filtered::enabled` calls for that span as part of the -/// span's per-span data. This allows `Filtered` layers to determine -/// whether they had previously disabled a given span, and avoid showing it -/// to the wrapped layer if it was disabled. -/// -/// This allows `Filtered` layers to also filter out the spans they -/// disable from span traversals (such as iterating over parents, etc). -/// 2. If all the bits are set, then every per-layer filter has decided it -/// doesn't want to enable that span or event. In that case, the -/// `Registry`'s `enabled` method will return `false`, so that -/// recording a span or event can be skipped entirely. -#[derive(Debug)] -pub(crate) struct FilterState { - enabled: Cell<FilterMap>, - // TODO(eliza): `Interest`s should _probably_ be `Copy`. The only reason - // they're not is our Obsessive Commitment to Forwards-Compatibility. If - // this changes in tracing-core`, we can make this a `Cell` rather than - // `RefCell`... - interest: RefCell<Option<Interest>>, - - #[cfg(debug_assertions)] - counters: DebugCounters, -} - -/// Extra counters added to `FilterState` used only to make debug assertions. -#[cfg(debug_assertions)] -#[derive(Debug, Default)] -struct DebugCounters { - /// How many per-layer filters have participated in the current `enabled` - /// call? - in_filter_pass: Cell<usize>, - - /// How many per-layer filters have participated in the current `register_callsite` - /// call? - in_interest_pass: Cell<usize>, -} - -thread_local! { - pub(crate) static FILTERING: FilterState = FilterState::new(); -} - -/// Extension trait adding [combinators] for combining [`Filter`]. -/// -/// [combinators]: crate::filter::combinator -/// [`Filter`]: crate::layer::Filter -pub trait FilterExt<S>: layer::Filter<S> { - /// Combines this [`Filter`] with another [`Filter`] s so that spans and - /// events are enabled if and only if *both* filters return `true`. - /// - /// # Examples - /// - /// Enabling spans or events if they have both a particular target *and* are - /// above a certain level: - /// - /// ``` - /// use tracing_subscriber::{ - /// filter::{filter_fn, LevelFilter, FilterExt}, - /// prelude::*, - /// }; - /// - /// // Enables spans and events with targets starting with `interesting_target`: - /// let target_filter = filter_fn(|meta| { - /// meta.target().starts_with("interesting_target") - /// }); - /// - /// // Enables spans and events with levels `INFO` and below: - /// let level_filter = LevelFilter::INFO; - /// - /// // Combine the two filters together, returning a filter that only enables - /// // spans and events that *both* filters will enable: - /// let filter = target_filter.and(level_filter); - /// - /// tracing_subscriber::registry() - /// .with(tracing_subscriber::fmt::layer().with_filter(filter)) - /// .init(); - /// - /// // This event will *not* be enabled: - /// tracing::info!("an event with an uninteresting target"); - /// - /// // This event *will* be enabled: - /// tracing::info!(target: "interesting_target", "a very interesting event"); - /// - /// // This event will *not* be enabled: - /// tracing::debug!(target: "interesting_target", "interesting debug event..."); - /// ``` - /// - /// [`Filter`]: crate::layer::Filter - fn and<B>(self, other: B) -> combinator::And<Self, B, S> - where - Self: Sized, - B: layer::Filter<S>, - { - combinator::And::new(self, other) - } - - /// Combines two [`Filter`]s so that spans and events are enabled if *either* filter - /// returns `true`. - /// - /// # Examples - /// - /// Enabling spans and events at the `INFO` level and above, and all spans - /// and events with a particular target: - /// ``` - /// use tracing_subscriber::{ - /// filter::{filter_fn, LevelFilter, FilterExt}, - /// prelude::*, - /// }; - /// - /// // Enables spans and events with targets starting with `interesting_target`: - /// let target_filter = filter_fn(|meta| { - /// meta.target().starts_with("interesting_target") - /// }); - /// - /// // Enables spans and events with levels `INFO` and below: - /// let level_filter = LevelFilter::INFO; - /// - /// // Combine the two filters together so that a span or event is enabled - /// // if it is at INFO or lower, or if it has a target starting with - /// // `interesting_target`. - /// let filter = level_filter.or(target_filter); - /// - /// tracing_subscriber::registry() - /// .with(tracing_subscriber::fmt::layer().with_filter(filter)) - /// .init(); - /// - /// // This event will *not* be enabled: - /// tracing::debug!("an uninteresting event"); - /// - /// // This event *will* be enabled: - /// tracing::info!("an uninteresting INFO event"); - /// - /// // This event *will* be enabled: - /// tracing::info!(target: "interesting_target", "a very interesting event"); - /// - /// // This event *will* be enabled: - /// tracing::debug!(target: "interesting_target", "interesting debug event..."); - /// ``` - /// - /// Enabling a higher level for a particular target by using `or` in - /// conjunction with the [`and`] combinator: - /// - /// ``` - /// use tracing_subscriber::{ - /// filter::{filter_fn, LevelFilter, FilterExt}, - /// prelude::*, - /// }; - /// - /// // This filter will enable spans and events with targets beginning with - /// // `my_crate`: - /// let my_crate = filter_fn(|meta| { - /// meta.target().starts_with("my_crate") - /// }); - /// - /// let filter = my_crate - /// // Combine the `my_crate` filter with a `LevelFilter` to produce a - /// // filter that will enable the `INFO` level and lower for spans and - /// // events with `my_crate` targets: - /// .and(LevelFilter::INFO) - /// // If a span or event *doesn't* have a target beginning with - /// // `my_crate`, enable it if it has the `WARN` level or lower: - /// .or(LevelFilter::WARN); - /// - /// tracing_subscriber::registry() - /// .with(tracing_subscriber::fmt::layer().with_filter(filter)) - /// .init(); - /// ``` - /// - /// [`Filter`]: crate::layer::Filter - /// [`and`]: FilterExt::and - fn or<B>(self, other: B) -> combinator::Or<Self, B, S> - where - Self: Sized, - B: layer::Filter<S>, - { - combinator::Or::new(self, other) - } - - /// Inverts `self`, returning a filter that enables spans and events only if - /// `self` would *not* enable them. - fn not(self) -> combinator::Not<Self, S> - where - Self: Sized, - { - combinator::Not::new(self) - } - - /// [Boxes] `self`, erasing its concrete type. - /// - /// This is equivalent to calling [`Box::new`], but in method form, so that - /// it can be used when chaining combinator methods. - /// - /// # Examples - /// - /// When different combinations of filters are used conditionally, they may - /// have different types. For example, the following code won't compile, - /// since the `if` and `else` clause produce filters of different types: - /// - /// ```compile_fail - /// use tracing_subscriber::{ - /// filter::{filter_fn, LevelFilter, FilterExt}, - /// prelude::*, - /// }; - /// - /// let enable_bar_target: bool = // ... - /// # false; - /// - /// let filter = if enable_bar_target { - /// filter_fn(|meta| meta.target().starts_with("foo")) - /// // If `enable_bar_target` is true, add a `filter_fn` enabling - /// // spans and events with the target `bar`: - /// .or(filter_fn(|meta| meta.target().starts_with("bar"))) - /// .and(LevelFilter::INFO) - /// } else { - /// filter_fn(|meta| meta.target().starts_with("foo")) - /// .and(LevelFilter::INFO) - /// }; - /// - /// tracing_subscriber::registry() - /// .with(tracing_subscriber::fmt::layer().with_filter(filter)) - /// .init(); - /// ``` - /// - /// By using `boxed`, the types of the two different branches can be erased, - /// so the assignment to the `filter` variable is valid (as both branches - /// have the type `Box<dyn Filter<S> + Send + Sync + 'static>`). The - /// following code *does* compile: - /// - /// ``` - /// use tracing_subscriber::{ - /// filter::{filter_fn, LevelFilter, FilterExt}, - /// prelude::*, - /// }; - /// - /// let enable_bar_target: bool = // ... - /// # false; - /// - /// let filter = if enable_bar_target { - /// filter_fn(|meta| meta.target().starts_with("foo")) - /// .or(filter_fn(|meta| meta.target().starts_with("bar"))) - /// .and(LevelFilter::INFO) - /// // Boxing the filter erases its type, so both branches now - /// // have the same type. - /// .boxed() - /// } else { - /// filter_fn(|meta| meta.target().starts_with("foo")) - /// .and(LevelFilter::INFO) - /// .boxed() - /// }; - /// - /// tracing_subscriber::registry() - /// .with(tracing_subscriber::fmt::layer().with_filter(filter)) - /// .init(); - /// ``` - /// - /// [Boxes]: std::boxed - /// [`Box::new`]: std::boxed::Box::new - fn boxed(self) -> Box<dyn layer::Filter<S> + Send + Sync + 'static> - where - Self: Sized + Send + Sync + 'static, - { - Box::new(self) - } -} - -// === impl Filter === - -#[cfg(feature = "registry")] -#[cfg_attr(docsrs, doc(cfg(feature = "registry")))] -impl<S> layer::Filter<S> for LevelFilter { - fn enabled(&self, meta: &Metadata<'_>, _: &Context<'_, S>) -> bool { - meta.level() <= self - } - - fn callsite_enabled(&self, meta: &'static Metadata<'static>) -> Interest { - if meta.level() <= self { - Interest::always() - } else { - Interest::never() - } - } - - fn max_level_hint(&self) -> Option<LevelFilter> { - Some(*self) - } -} - -macro_rules! filter_impl_body { - () => { - #[inline] - fn enabled(&self, meta: &Metadata<'_>, cx: &Context<'_, S>) -> bool { - self.deref().enabled(meta, cx) - } - - #[inline] - fn callsite_enabled(&self, meta: &'static Metadata<'static>) -> Interest { - self.deref().callsite_enabled(meta) - } - - #[inline] - fn max_level_hint(&self) -> Option<LevelFilter> { - self.deref().max_level_hint() - } - }; -} - -#[cfg(feature = "registry")] -#[cfg_attr(docsrs, doc(cfg(feature = "registry")))] -impl<S> layer::Filter<S> for Arc<dyn layer::Filter<S> + Send + Sync + 'static> { - filter_impl_body!(); -} - -#[cfg(feature = "registry")] -#[cfg_attr(docsrs, doc(cfg(feature = "registry")))] -impl<S> layer::Filter<S> for Box<dyn layer::Filter<S> + Send + Sync + 'static> { - filter_impl_body!(); -} - -// === impl Filtered === - -impl<L, F, S> Filtered<L, F, S> { - /// Wraps the provided [`Layer`] so that it is filtered by the given - /// [`Filter`]. - /// - /// This is equivalent to calling the [`Layer::with_filter`] method. - /// - /// See the [documentation on per-layer filtering][plf] for details. - /// - /// [`Filter`]: crate::layer::Filter - /// [plf]: crate::layer#per-layer-filtering - pub fn new(layer: L, filter: F) -> Self { - Self { - layer, - filter, - id: MagicPlfDowncastMarker(FilterId::disabled()), - _s: PhantomData, - } - } - - #[inline(always)] - fn id(&self) -> FilterId { - debug_assert!( - !self.id.0.is_disabled(), - "a `Filtered` layer was used, but it had no `FilterId`; \ - was it registered with the subscriber?" - ); - self.id.0 - } - - fn did_enable(&self, f: impl FnOnce()) { - FILTERING.with(|filtering| filtering.did_enable(self.id(), f)) - } - - /// Borrows the [`Filter`](crate::layer::Filter) used by this layer. - pub fn filter(&self) -> &F { - &self.filter - } - - /// Mutably borrows the [`Filter`](crate::layer::Filter) used by this layer. - /// - /// When this layer can be mutably borrowed, this may be used to mutate the filter. - /// Generally, this will primarily be used with the - /// [`reload::Handle::modify`](crate::reload::Handle::modify) method. - /// - /// # Examples - /// - /// ``` - /// # use tracing::info; - /// # use tracing_subscriber::{filter,fmt,reload,Registry,prelude::*}; - /// # fn main() { - /// let filtered_layer = fmt::Layer::default().with_filter(filter::LevelFilter::WARN); - /// let (filtered_layer, reload_handle) = reload::Layer::new(filtered_layer); - /// # - /// # // specifying the Registry type is required - /// # let _: &reload::Handle<filter::Filtered<fmt::Layer<Registry>, - /// # filter::LevelFilter, Registry>,Registry> - /// # = &reload_handle; - /// # - /// info!("This will be ignored"); - /// reload_handle.modify(|layer| *layer.filter_mut() = filter::LevelFilter::INFO); - /// info!("This will be logged"); - /// # } - /// ``` - pub fn filter_mut(&mut self) -> &mut F { - &mut self.filter - } - - /// Borrows the inner [`Layer`] wrapped by this `Filtered` layer. - pub fn inner(&self) -> &L { - &self.layer - } - - /// Mutably borrows the inner [`Layer`] wrapped by this `Filtered` layer. - /// - /// This method is primarily expected to be used with the - /// [`reload::Handle::modify`](crate::reload::Handle::modify) method. - /// - /// # Examples - /// - /// ``` - /// # use tracing::info; - /// # use tracing_subscriber::{filter,fmt,reload,Registry,prelude::*}; - /// # fn non_blocking<T: std::io::Write>(writer: T) -> (fn() -> std::io::Stdout) { - /// # std::io::stdout - /// # } - /// # fn main() { - /// let filtered_layer = fmt::layer().with_writer(non_blocking(std::io::stderr())).with_filter(filter::LevelFilter::INFO); - /// let (filtered_layer, reload_handle) = reload::Layer::new(filtered_layer); - /// # - /// # // specifying the Registry type is required - /// # let _: &reload::Handle<filter::Filtered<fmt::Layer<Registry, _, _, fn() -> std::io::Stdout>, - /// # filter::LevelFilter, Registry>, Registry> - /// # = &reload_handle; - /// # - /// info!("This will be logged to stderr"); - /// reload_handle.modify(|layer| *layer.inner_mut().writer_mut() = non_blocking(std::io::stdout())); - /// info!("This will be logged to stdout"); - /// # } - /// ``` - /// - /// [subscriber]: Subscribe - pub fn inner_mut(&mut self) -> &mut L { - &mut self.layer - } -} - -impl<S, L, F> Layer<S> for Filtered<L, F, S> -where - S: Subscriber + for<'span> registry::LookupSpan<'span> + 'static, - F: layer::Filter<S> + 'static, - L: Layer<S>, -{ - fn on_layer(&mut self, subscriber: &mut S) { - self.id = MagicPlfDowncastMarker(subscriber.register_filter()); - self.layer.on_layer(subscriber); - } - - // TODO(eliza): can we figure out a nice way to make the `Filtered` layer - // not call `is_enabled_for` in hooks that the inner layer doesn't actually - // have real implementations of? probably not... - // - // it would be cool if there was some wild rust reflection way of checking - // if a trait impl has the default impl of a trait method or not, but that's - // almsot certainly impossible...right? - - fn register_callsite(&self, metadata: &'static Metadata<'static>) -> Interest { - let interest = self.filter.callsite_enabled(metadata); - - // If the filter didn't disable the callsite, allow the inner layer to - // register it — since `register_callsite` is also used for purposes - // such as reserving/caching per-callsite data, we want the inner layer - // to be able to perform any other registration steps. However, we'll - // ignore its `Interest`. - if !interest.is_never() { - self.layer.register_callsite(metadata); - } - - // Add our `Interest` to the current sum of per-layer filter `Interest`s - // for this callsite. - FILTERING.with(|filtering| filtering.add_interest(interest)); - - // don't short circuit! if the stack consists entirely of `Layer`s with - // per-layer filters, the `Registry` will return the actual `Interest` - // value that's the sum of all the `register_callsite` calls to those - // per-layer filters. if we returned an actual `never` interest here, a - // `Layered` layer would short-circuit and not allow any `Filtered` - // layers below us if _they_ are interested in the callsite. - Interest::always() - } - - fn enabled(&self, metadata: &Metadata<'_>, cx: Context<'_, S>) -> bool { - let cx = cx.with_filter(self.id()); - let enabled = self.filter.enabled(metadata, &cx); - FILTERING.with(|filtering| filtering.set(self.id(), enabled)); - - if enabled { - // If the filter enabled this metadata, ask the wrapped layer if - // _it_ wants it --- it might have a global filter. - self.layer.enabled(metadata, cx) - } else { - // Otherwise, return `true`. The _per-layer_ filter disabled this - // metadata, but returning `false` in `Layer::enabled` will - // short-circuit and globally disable the span or event. This is - // *not* what we want for per-layer filters, as other layers may - // still want this event. Returning `true` here means we'll continue - // asking the next layer in the stack. - // - // Once all per-layer filters have been evaluated, the `Registry` - // at the root of the stack will return `false` from its `enabled` - // method if *every* per-layer filter disabled this metadata. - // Otherwise, the individual per-layer filters will skip the next - // `new_span` or `on_event` call for their layer if *they* disabled - // the span or event, but it was not globally disabled. - true - } - } - - fn on_new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, cx: Context<'_, S>) { - self.did_enable(|| { - let cx = cx.with_filter(self.id()); - self.filter.on_new_span(attrs, id, cx.clone()); - self.layer.on_new_span(attrs, id, cx); - }) - } - - #[doc(hidden)] - fn max_level_hint(&self) -> Option<LevelFilter> { - self.filter.max_level_hint() - } - - fn on_record(&self, span: &span::Id, values: &span::Record<'_>, cx: Context<'_, S>) { - if let Some(cx) = cx.if_enabled_for(span, self.id()) { - self.filter.on_record(span, values, cx.clone()); - self.layer.on_record(span, values, cx) - } - } - - fn on_follows_from(&self, span: &span::Id, follows: &span::Id, cx: Context<'_, S>) { - // only call `on_follows_from` if both spans are enabled by us - if cx.is_enabled_for(span, self.id()) && cx.is_enabled_for(follows, self.id()) { - self.layer - .on_follows_from(span, follows, cx.with_filter(self.id())) - } - } - - fn on_event(&self, event: &Event<'_>, cx: Context<'_, S>) { - self.did_enable(|| { - self.layer.on_event(event, cx.with_filter(self.id())); - }) - } - - fn on_enter(&self, id: &span::Id, cx: Context<'_, S>) { - if let Some(cx) = cx.if_enabled_for(id, self.id()) { - self.filter.on_enter(id, cx.clone()); - self.layer.on_enter(id, cx); - } - } - - fn on_exit(&self, id: &span::Id, cx: Context<'_, S>) { - if let Some(cx) = cx.if_enabled_for(id, self.id()) { - self.filter.on_exit(id, cx.clone()); - self.layer.on_exit(id, cx); - } - } - - fn on_close(&self, id: span::Id, cx: Context<'_, S>) { - if let Some(cx) = cx.if_enabled_for(&id, self.id()) { - self.filter.on_close(id.clone(), cx.clone()); - self.layer.on_close(id, cx); - } - } - - // XXX(eliza): the existence of this method still makes me sad... - fn on_id_change(&self, old: &span::Id, new: &span::Id, cx: Context<'_, S>) { - if let Some(cx) = cx.if_enabled_for(old, self.id()) { - self.layer.on_id_change(old, new, cx) - } - } - - #[doc(hidden)] - #[inline] - unsafe fn downcast_raw(&self, id: TypeId) -> Option<*const ()> { - match id { - id if id == TypeId::of::<Self>() => Some(self as *const _ as *const ()), - id if id == TypeId::of::<L>() => Some(&self.layer as *const _ as *const ()), - id if id == TypeId::of::<F>() => Some(&self.filter as *const _ as *const ()), - id if id == TypeId::of::<MagicPlfDowncastMarker>() => { - Some(&self.id as *const _ as *const ()) - } - _ => self.layer.downcast_raw(id), - } - } -} - -impl<F, L, S> fmt::Debug for Filtered<F, L, S> -where - F: fmt::Debug, - L: fmt::Debug, -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_struct("Filtered") - .field("filter", &self.filter) - .field("layer", &self.layer) - .field("id", &self.id) - .finish() - } -} - -// === impl FilterId === - -impl FilterId { - const fn disabled() -> Self { - Self(std::u64::MAX) - } - - /// Returns a `FilterId` that will consider _all_ spans enabled. - pub(crate) const fn none() -> Self { - Self(0) - } - - pub(crate) fn new(id: u8) -> Self { - assert!(id < 64, "filter IDs may not be greater than 64"); - Self(1 << id as usize) - } - - /// Combines two `FilterId`s, returning a new `FilterId` that will match a - /// [`FilterMap`] where the span was disabled by _either_ this `FilterId` - /// *or* the combined `FilterId`. - /// - /// This method is called by [`Context`]s when adding the `FilterId` of a - /// [`Filtered`] layer to the context. - /// - /// This is necessary for cases where we have a tree of nested [`Filtered`] - /// layers, like this: - /// - /// ```text - /// Filtered { - /// filter1, - /// Layered { - /// layer1, - /// Filtered { - /// filter2, - /// layer2, - /// }, - /// } - /// ``` - /// - /// We want `layer2` to be affected by both `filter1` _and_ `filter2`. - /// Without combining `FilterId`s, this works fine when filtering - /// `on_event`/`new_span`, because the outer `Filtered` layer (`filter1`) - /// won't call the inner layer's `on_event` or `new_span` callbacks if it - /// disabled the event/span. - /// - /// However, it _doesn't_ work when filtering span lookups and traversals - /// (e.g. `scope`). This is because the [`Context`] passed to `layer2` - /// would set its filter ID to the filter ID of `filter2`, and would skip - /// spans that were disabled by `filter2`. However, what if a span was - /// disabled by `filter1`? We wouldn't see it in `new_span`, but we _would_ - /// see it in lookups and traversals...which we don't want. - /// - /// When a [`Filtered`] layer adds its ID to a [`Context`], it _combines_ it - /// with any previous filter ID that the context had, rather than replacing - /// it. That way, `layer2`'s context will check if a span was disabled by - /// `filter1` _or_ `filter2`. The way we do this, instead of representing - /// `FilterId`s as a number number that we shift a 1 over by to get a mask, - /// we just store the actual mask,so we can combine them with a bitwise-OR. - /// - /// For example, if we consider the following case (pretending that the - /// masks are 8 bits instead of 64 just so i don't have to write out a bunch - /// of extra zeroes): - /// - /// - `filter1` has the filter id 1 (`0b0000_0001`) - /// - `filter2` has the filter id 2 (`0b0000_0010`) - /// - /// A span that gets disabled by filter 1 would have the [`FilterMap`] with - /// bits `0b0000_0001`. - /// - /// If the `FilterId` was internally represented as `(bits to shift + 1), - /// when `layer2`'s [`Context`] checked if it enabled the span, it would - /// make the mask `0b0000_0010` (`1 << 1`). That bit would not be set in the - /// [`FilterMap`], so it would see that it _didn't_ disable the span. Which - /// is *true*, it just doesn't reflect the tree-like shape of the actual - /// subscriber. - /// - /// By having the IDs be masks instead of shifts, though, when the - /// [`Filtered`] with `filter2` gets the [`Context`] with `filter1`'s filter ID, - /// instead of replacing it, it ors them together: - /// - /// ```ignore - /// 0b0000_0001 | 0b0000_0010 == 0b0000_0011; - /// ``` - /// - /// We then test if the span was disabled by seeing if _any_ bits in the - /// mask are `1`: - /// - /// ```ignore - /// filtermap & mask != 0; - /// 0b0000_0001 & 0b0000_0011 != 0; - /// 0b0000_0001 != 0; - /// true; - /// ``` - /// - /// [`Context`]: crate::layer::Context - pub(crate) fn and(self, FilterId(other): Self) -> Self { - // If this mask is disabled, just return the other --- otherwise, we - // would always see that every span is disabled. - if self.0 == Self::disabled().0 { - return Self(other); - } - - Self(self.0 | other) - } - - fn is_disabled(self) -> bool { - self.0 == Self::disabled().0 - } -} - -impl fmt::Debug for FilterId { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - // don't print a giant set of the numbers 0..63 if the filter ID is disabled. - if self.0 == Self::disabled().0 { - return f - .debug_tuple("FilterId") - .field(&format_args!("DISABLED")) - .finish(); - } - - if f.alternate() { - f.debug_struct("FilterId") - .field("ids", &format_args!("{:?}", FmtBitset(self.0))) - .field("bits", &format_args!("{:b}", self.0)) - .finish() - } else { - f.debug_tuple("FilterId").field(&FmtBitset(self.0)).finish() - } - } -} - -impl fmt::Binary for FilterId { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_tuple("FilterId") - .field(&format_args!("{:b}", self.0)) - .finish() - } -} - -// === impl FilterExt === - -impl<F, S> FilterExt<S> for F where F: layer::Filter<S> {} - -// === impl FilterMap === - -impl FilterMap { - pub(crate) fn set(self, FilterId(mask): FilterId, enabled: bool) -> Self { - if mask == std::u64::MAX { - return self; - } - - if enabled { - Self { - bits: self.bits & (!mask), - } - } else { - Self { - bits: self.bits | mask, - } - } - } - - #[inline] - pub(crate) fn is_enabled(self, FilterId(mask): FilterId) -> bool { - self.bits & mask == 0 - } - - #[inline] - pub(crate) fn any_enabled(self) -> bool { - self.bits != std::u64::MAX - } -} - -impl fmt::Debug for FilterMap { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - let alt = f.alternate(); - let mut s = f.debug_struct("FilterMap"); - s.field("disabled_by", &format_args!("{:?}", &FmtBitset(self.bits))); - - if alt { - s.field("bits", &format_args!("{:b}", self.bits)); - } - - s.finish() - } -} - -impl fmt::Binary for FilterMap { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_struct("FilterMap") - .field("bits", &format_args!("{:b}", self.bits)) - .finish() - } -} - -// === impl FilterState === - -impl FilterState { - fn new() -> Self { - Self { - enabled: Cell::new(FilterMap::default()), - interest: RefCell::new(None), - - #[cfg(debug_assertions)] - counters: DebugCounters::default(), - } - } - - fn set(&self, filter: FilterId, enabled: bool) { - #[cfg(debug_assertions)] - { - let in_current_pass = self.counters.in_filter_pass.get(); - if in_current_pass == 0 { - debug_assert_eq!(self.enabled.get(), FilterMap::default()); - } - self.counters.in_filter_pass.set(in_current_pass + 1); - debug_assert_eq!( - self.counters.in_interest_pass.get(), - 0, - "if we are in or starting a filter pass, we must not be in an interest pass." - ) - } - - self.enabled.set(self.enabled.get().set(filter, enabled)) - } - - fn add_interest(&self, interest: Interest) { - let mut curr_interest = self.interest.borrow_mut(); - - #[cfg(debug_assertions)] - { - let in_current_pass = self.counters.in_interest_pass.get(); - if in_current_pass == 0 { - debug_assert!(curr_interest.is_none()); - } - self.counters.in_interest_pass.set(in_current_pass + 1); - } - - if let Some(curr_interest) = curr_interest.as_mut() { - if (curr_interest.is_always() && !interest.is_always()) - || (curr_interest.is_never() && !interest.is_never()) - { - *curr_interest = Interest::sometimes(); - } - // If the two interests are the same, do nothing. If the current - // interest is `sometimes`, stay sometimes. - } else { - *curr_interest = Some(interest); - } - } - - pub(crate) fn event_enabled() -> bool { - FILTERING - .try_with(|this| { - let enabled = this.enabled.get().any_enabled(); - #[cfg(debug_assertions)] - { - if this.counters.in_filter_pass.get() == 0 { - debug_assert_eq!(this.enabled.get(), FilterMap::default()); - } - - // Nothing enabled this event, we won't tick back down the - // counter in `did_enable`. Reset it. - if !enabled { - this.counters.in_filter_pass.set(0); - } - } - enabled - }) - .unwrap_or(true) - } - - /// Executes a closure if the filter with the provided ID did not disable - /// the current span/event. - /// - /// This is used to implement the `on_event` and `new_span` methods for - /// `Filtered`. - fn did_enable(&self, filter: FilterId, f: impl FnOnce()) { - let map = self.enabled.get(); - if map.is_enabled(filter) { - // If the filter didn't disable the current span/event, run the - // callback. - f(); - } else { - // Otherwise, if this filter _did_ disable the span or event - // currently being processed, clear its bit from this thread's - // `FilterState`. The bit has already been "consumed" by skipping - // this callback, and we need to ensure that the `FilterMap` for - // this thread is reset when the *next* `enabled` call occurs. - self.enabled.set(map.set(filter, true)); - } - #[cfg(debug_assertions)] - { - let in_current_pass = self.counters.in_filter_pass.get(); - if in_current_pass <= 1 { - debug_assert_eq!(self.enabled.get(), FilterMap::default()); - } - self.counters - .in_filter_pass - .set(in_current_pass.saturating_sub(1)); - debug_assert_eq!( - self.counters.in_interest_pass.get(), - 0, - "if we are in a filter pass, we must not be in an interest pass." - ) - } - } - - /// Clears the current in-progress filter state. - /// - /// This resets the [`FilterMap`] and current [`Interest`] as well as - /// clearing the debug counters. - pub(crate) fn clear_enabled() { - // Drop the `Result` returned by `try_with` --- if we are in the middle - // a panic and the thread-local has been torn down, that's fine, just - // ignore it ratehr than panicking. - let _ = FILTERING.try_with(|filtering| { - filtering.enabled.set(FilterMap::default()); - - #[cfg(debug_assertions)] - filtering.counters.in_filter_pass.set(0); - }); - } - - pub(crate) fn take_interest() -> Option<Interest> { - FILTERING - .try_with(|filtering| { - #[cfg(debug_assertions)] - { - if filtering.counters.in_interest_pass.get() == 0 { - debug_assert!(filtering.interest.try_borrow().ok()?.is_none()); - } - filtering.counters.in_interest_pass.set(0); - } - filtering.interest.try_borrow_mut().ok()?.take() - }) - .ok()? - } - - pub(crate) fn filter_map(&self) -> FilterMap { - let map = self.enabled.get(); - #[cfg(debug_assertions)] - { - if self.counters.in_filter_pass.get() == 0 { - debug_assert_eq!(map, FilterMap::default()); - } - } - - map - } -} -/// This is a horrible and bad abuse of the downcasting system to expose -/// *internally* whether a layer has per-layer filtering, within -/// `tracing-subscriber`, without exposing a public API for it. -/// -/// If a `Layer` has per-layer filtering, it will downcast to a -/// `MagicPlfDowncastMarker`. Since layers which contain other layers permit -/// downcasting to recurse to their children, this will do the Right Thing with -/// layers like Reload, Option, etc. -/// -/// Why is this a wrapper around the `FilterId`, you may ask? Because -/// downcasting works by returning a pointer, and we don't want to risk -/// introducing UB by constructing pointers that _don't_ point to a valid -/// instance of the type they claim to be. In this case, we don't _intend_ for -/// this pointer to be dereferenced, so it would actually be fine to return one -/// that isn't a valid pointer...but we can't guarantee that the caller won't -/// (accidentally) dereference it, so it's better to be safe than sorry. We -/// could, alternatively, add an additional field to the type that's used only -/// for returning pointers to as as part of the evil downcasting hack, but I -/// thought it was nicer to just add a `repr(transparent)` wrapper to the -/// existing `FilterId` field, since it won't make the struct any bigger. -/// -/// Don't worry, this isn't on the test. :) -#[derive(Clone, Copy)] -#[repr(transparent)] -struct MagicPlfDowncastMarker(FilterId); -impl fmt::Debug for MagicPlfDowncastMarker { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - // Just pretend that `MagicPlfDowncastMarker` doesn't exist for - // `fmt::Debug` purposes...if no one *sees* it in their `Debug` output, - // they don't have to know I thought this code would be a good idea. - fmt::Debug::fmt(&self.0, f) - } -} - -pub(crate) fn is_plf_downcast_marker(type_id: TypeId) -> bool { - type_id == TypeId::of::<MagicPlfDowncastMarker>() -} - -/// Does a type implementing `Subscriber` contain any per-layer filters? -pub(crate) fn subscriber_has_plf<S>(subscriber: &S) -> bool -where - S: Subscriber, -{ - (subscriber as &dyn Subscriber).is::<MagicPlfDowncastMarker>() -} - -/// Does a type implementing `Layer` contain any per-layer filters? -pub(crate) fn layer_has_plf<L, S>(layer: &L) -> bool -where - L: Layer<S>, - S: Subscriber, -{ - unsafe { - // Safety: we're not actually *doing* anything with this pointer --- we - // only care about the `Option`, which we're turning into a `bool`. So - // even if the layer decides to be evil and give us some kind of invalid - // pointer, we don't ever dereference it, so this is always safe. - layer.downcast_raw(TypeId::of::<MagicPlfDowncastMarker>()) - } - .is_some() -} - -struct FmtBitset(u64); - -impl fmt::Debug for FmtBitset { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - let mut set = f.debug_set(); - for bit in 0..64 { - // if the `bit`-th bit is set, add it to the debug set - if self.0 & (1 << bit) != 0 { - set.entry(&bit); - } - } - set.finish() - } -} |