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//! A `Layer` that enables or disables spans and events based on a set of //! filtering directives. // these are publicly re-exported, but the compiler doesn't realize // that for some reason. #[allow(unreachable_pub)] pub use self::{ directive::{Directive, ParseError}, field::BadName as BadFieldName, }; mod directive; mod field; use crate::{ filter::LevelFilter, layer::{Context, Layer}, sync::RwLock, }; use std::{cell::RefCell, collections::HashMap, env, error::Error, fmt, str::FromStr}; use tracing_core::{ callsite, field::Field, span, subscriber::{Interest, Subscriber}, Metadata, }; /// A [`Layer`] which filters spans and events based on a set of filter /// directives. /// /// # Directives /// /// A filter consists of one or more directives which match on [`Span`]s and [`Event`]s. /// Each directive may have a corresponding maximum verbosity [`level`] which /// enables (e.g., _selects for_) spans and events that match. Like `log`, /// `tracing` considers less exclusive levels (like `trace` or `info`) to be more /// verbose than more exclusive levels (like `error` or `warn`). /// /// The directive syntax is similar to that of [`env_logger`]'s. At a high level, the syntax for directives /// consists of several parts: /// /// ```text /// target[span{field=value}]=level /// ``` /// /// Each component (`target`, `span`, `field`, `value`, and `level`) will be covered in turn. /// /// - `target` matches the event or span's target. In general, this is the module path and/or crate name. /// Examples of targets `h2`, `tokio::net`, or `tide::server`. For more information on targets, /// please refer to [`Metadata`]'s documentation. /// - `span` matches on the span's name. If a `span` directive is provided alongside a `target`, /// the `span` directive will match on spans _within_ the `target`. /// - `field` matches on [fields] within spans. Field names can also be supplied without a `value` /// and will match on any [`Span`] or [`Event`] that has a field with that name. /// For example: `[span{field=\"value\"}]=debug`, `[{field}]=trace`. /// - `value` matches on the value of a span's field. If a value is a numeric literal or a bool, /// it will match _only_ on that value. Otherwise, this filter acts as a regex on /// the `std::fmt::Debug` output from the value. /// - `level` sets a maximum verbosity level accepted by this directive. /// /// ## Usage Notes /// /// - The portion of the directive which is included within the square brackets is `tracing`-specific. /// - Any portion of the directive can be omitted. /// - The sole exception are the `field` and `value` directives. If a `value` is provided, /// a `field` must _also_ be provided. However, the converse does not hold, as fields can /// be matched without a value. /// - If only a level is provided, it will set the maximum level for all `Span`s and `Event`s /// that are not enabled by other filters. /// - A directive without a level will enable anything that it matches. This is equivalent to `=trace`. /// /// ## Examples /// /// - `tokio::net=info` will enable all spans or events that: /// - have the `tokio::net` target, /// - at the level `info` or above. /// - `my_crate[span_a]=trace` will enable all spans and events that: /// - are within the `span_a` span or named `span_a` _if_ `span_a` has the target `my_crate`, /// - at the level `trace` or above. /// - `[span_b{name=\"bob\"}]` will enable all spans or event that: /// - have _any_ target, /// - are inside a span named `span_b`, /// - which has a field named `name` with value `bob`, /// - at _any_ level. /// /// [`Layer`]: ../layer/trait.Layer.html /// [`env_logger`]: https://docs.rs/env_logger/0.7.1/env_logger/#enabling-logging /// [`Span`]: ../../tracing_core/span/index.html /// [fields]: ../../tracing_core/struct.Field.html /// [`Event`]: ../../tracing_core/struct.Event.html /// [`level`]: ../../tracing_core/struct.Level.html /// [`Metadata`]: ../../tracing_core/struct.Metadata.html #[cfg(feature = "env-filter")] #[cfg_attr(docsrs, doc(cfg(feature = "env-filter")))] #[derive(Debug)] pub struct EnvFilter { statics: directive::Statics, dynamics: directive::Dynamics, has_dynamics: bool, by_id: RwLock<HashMap<span::Id, directive::SpanMatcher>>, by_cs: RwLock<HashMap<callsite::Identifier, directive::CallsiteMatcher>>, } thread_local! { static SCOPE: RefCell<Vec<LevelFilter>> = RefCell::new(Vec::new()); } type FieldMap<T> = HashMap<Field, T>; #[cfg(feature = "smallvec")] type FilterVec<T> = smallvec::SmallVec<[T; 8]>; #[cfg(not(feature = "smallvec"))] type FilterVec<T> = Vec<T>; /// Indicates that an error occurred while parsing a `EnvFilter` from an /// environment variable. #[derive(Debug)] pub struct FromEnvError { kind: ErrorKind, } #[derive(Debug)] enum ErrorKind { Parse(ParseError), Env(env::VarError), } impl EnvFilter { /// `RUST_LOG` is the default environment variable used by /// [`EnvFilter::from_default_env`] and [`EnvFilter::try_from_default_env`]. /// /// [`EnvFilter::from_default_env`]: #method.from_default_env /// [`EnvFilter::try_from_default_env`]: #method.try_from_default_env pub const DEFAULT_ENV: &'static str = "RUST_LOG"; /// Returns a new `EnvFilter` from the value of the `RUST_LOG` environment /// variable, ignoring any invalid filter directives. pub fn from_default_env() -> Self { Self::from_env(Self::DEFAULT_ENV) } /// Returns a new `EnvFilter` from the value of the given environment /// variable, ignoring any invalid filter directives. pub fn from_env<A: AsRef<str>>(env: A) -> Self { env::var(env.as_ref()).map(Self::new).unwrap_or_default() } /// Returns a new `EnvFilter` from the directives in the given string, /// ignoring any that are invalid. pub fn new<S: AsRef<str>>(dirs: S) -> Self { let directives = dirs.as_ref().split(',').filter_map(|s| match s.parse() { Ok(d) => Some(d), Err(err) => { eprintln!("ignoring `{}`: {}", s, err); None } }); Self::from_directives(directives) } /// Returns a new `EnvFilter` from the directives in the given string, /// or an error if any are invalid. pub fn try_new<S: AsRef<str>>(dirs: S) -> Result<Self, ParseError> { let directives = dirs .as_ref() .split(',') .map(|s| s.parse()) .collect::<Result<Vec<_>, _>>()?; Ok(Self::from_directives(directives)) } /// Returns a new `EnvFilter` from the value of the `RUST_LOG` environment /// variable, or an error if the environment variable contains any invalid /// filter directives. pub fn try_from_default_env() -> Result<Self, FromEnvError> { Self::try_from_env(Self::DEFAULT_ENV) } /// Returns a new `EnvFilter` from the value of the given environment /// variable, or an error if the environment variable is unset or contains /// any invalid filter directives. pub fn try_from_env<A: AsRef<str>>(env: A) -> Result<Self, FromEnvError> { env::var(env.as_ref())?.parse().map_err(Into::into) } /// Add a filtering directive to this `EnvFilter`. /// /// The added directive will be used in addition to any previously set /// directives, either added using this method or provided when the filter /// is constructed. /// /// Filters may be created from may be [`LevelFilter`]s, which will /// enable all traces at or below a certain verbosity level, or /// parsed from a string specifying a directive. /// /// If a filter directive is inserted that matches exactly the same spans /// and events as a previous filter, but sets a different level for those /// spans and events, the previous directive is overwritten. /// /// [`LevelFilter`]: struct.LevelFilter.html /// /// # Examples /// ```rust /// use tracing_subscriber::filter::{EnvFilter, LevelFilter}; /// let mut filter = EnvFilter::from_default_env() /// .add_directive(LevelFilter::INFO.into()); /// ``` /// ```rust /// use tracing_subscriber::filter::{EnvFilter, Directive}; /// /// # fn try_mk_filter() -> Result<(), Box<dyn ::std::error::Error>> { /// let mut filter = EnvFilter::try_from_default_env()? /// .add_directive("my_crate::module=trace".parse()?) /// .add_directive("my_crate::my_other_module::something=info".parse()?); /// # Ok(()) /// # } /// ``` pub fn add_directive(mut self, directive: Directive) -> Self { if let Some(stat) = directive.to_static() { self.statics.add(stat) } else { self.has_dynamics = true; self.dynamics.add(directive); } self } fn from_directives(directives: impl IntoIterator<Item = Directive>) -> Self { let (dynamics, mut statics) = Directive::make_tables(directives); let has_dynamics = !dynamics.is_empty(); if statics.is_empty() && !has_dynamics { statics.add(directive::StaticDirective::default()); } Self { statics, dynamics, has_dynamics, by_id: RwLock::new(HashMap::new()), by_cs: RwLock::new(HashMap::new()), } } fn cares_about_span(&self, span: &span::Id) -> bool { let spans = try_lock!(self.by_id.read(), else return false); spans.contains_key(span) } fn base_interest(&self) -> Interest { if self.has_dynamics { Interest::sometimes() } else { Interest::never() } } } impl<S: Subscriber> Layer<S> for EnvFilter { fn register_callsite(&self, metadata: &'static Metadata<'static>) -> Interest { if self.has_dynamics && metadata.is_span() { // If this metadata describes a span, first, check if there is a // dynamic filter that should be constructed for it. If so, it // should always be enabled, since it influences filtering. if let Some(matcher) = self.dynamics.matcher(metadata) { let mut by_cs = try_lock!(self.by_cs.write(), else return self.base_interest()); by_cs.insert(metadata.callsite(), matcher); return Interest::always(); } } // Otherwise, check if any of our static filters enable this metadata. if self.statics.enabled(metadata) { Interest::always() } else { self.base_interest() } } fn enabled(&self, metadata: &Metadata<'_>, _: Context<'_, S>) -> bool { let level = metadata.level(); // is it possible for a dynamic filter directive to enable this event? // if not, we can avoid the thread local access + iterating over the // spans in the current scope. if self.has_dynamics && self.dynamics.max_level >= *level { let enabled_by_scope = SCOPE.with(|scope| { for filter in scope.borrow().iter() { if filter >= level { return true; } } false }); if enabled_by_scope { return true; } } // is it possible for a static filter directive to enable this event? if self.statics.max_level >= *level { // Otherwise, fall back to checking if the callsite is // statically enabled. // TODO(eliza): we *might* want to check this only if the `log` // feature is enabled, since if this is a `tracing` event with a // real callsite, it would already have been statically enabled... return self.statics.enabled(metadata); } false } fn new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, _: Context<'_, S>) { let by_cs = try_lock!(self.by_cs.read()); if let Some(cs) = by_cs.get(&attrs.metadata().callsite()) { let span = cs.to_span_match(attrs); try_lock!(self.by_id.write()).insert(id.clone(), span); } } fn on_record(&self, id: &span::Id, values: &span::Record<'_>, _: Context<'_, S>) { if let Some(span) = try_lock!(self.by_id.read()).get(id) { span.record_update(values); } } fn on_enter(&self, id: &span::Id, _: Context<'_, S>) { // XXX: This is where _we_ could push IDs to the stack instead, and use // that to allow changing the filter while a span is already entered. // But that might be much less efficient... if let Some(span) = try_lock!(self.by_id.read()).get(id) { SCOPE.with(|scope| scope.borrow_mut().push(span.level())); } } fn on_exit(&self, id: &span::Id, _: Context<'_, S>) { if self.cares_about_span(id) { SCOPE.with(|scope| scope.borrow_mut().pop()); } } fn on_close(&self, id: span::Id, _: Context<'_, S>) { // If we don't need to acquire a write lock, avoid doing so. if !self.cares_about_span(&id) { return; } let mut spans = try_lock!(self.by_id.write()); spans.remove(&id); } } impl FromStr for EnvFilter { type Err = ParseError; fn from_str(spec: &str) -> Result<Self, Self::Err> { Self::try_new(spec) } } impl<S> From<S> for EnvFilter where S: AsRef<str>, { fn from(s: S) -> Self { Self::new(s) } } impl Default for EnvFilter { fn default() -> Self { Self::from_directives(std::iter::empty()) } } impl fmt::Display for EnvFilter { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { let mut statics = self.statics.iter(); let wrote_statics = if let Some(next) = statics.next() { fmt::Display::fmt(next, f)?; for directive in statics { write!(f, ",{}", directive)?; } true } else { false }; let mut dynamics = self.dynamics.iter(); if let Some(next) = dynamics.next() { if wrote_statics { f.write_str(",")?; } fmt::Display::fmt(next, f)?; for directive in dynamics { write!(f, ",{}", directive)?; } } Ok(()) } } // ===== impl FromEnvError ===== impl From<ParseError> for FromEnvError { fn from(p: ParseError) -> Self { Self { kind: ErrorKind::Parse(p), } } } impl From<env::VarError> for FromEnvError { fn from(v: env::VarError) -> Self { Self { kind: ErrorKind::Env(v), } } } impl fmt::Display for FromEnvError { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { match self.kind { ErrorKind::Parse(ref p) => p.fmt(f), ErrorKind::Env(ref e) => e.fmt(f), } } } impl Error for FromEnvError { fn source(&self) -> Option<&(dyn Error + 'static)> { match self.kind { ErrorKind::Parse(ref p) => Some(p), ErrorKind::Env(ref e) => Some(e), } } } #[cfg(test)] mod tests { use super::*; use tracing_core::field::FieldSet; use tracing_core::*; struct NoSubscriber; impl Subscriber for NoSubscriber { #[inline] fn register_callsite(&self, _: &'static Metadata<'static>) -> subscriber::Interest { subscriber::Interest::always() } fn new_span(&self, _: &span::Attributes<'_>) -> span::Id { span::Id::from_u64(0xDEAD) } fn event(&self, _event: &Event<'_>) {} fn record(&self, _span: &span::Id, _values: &span::Record<'_>) {} fn record_follows_from(&self, _span: &span::Id, _follows: &span::Id) {} #[inline] fn enabled(&self, _metadata: &Metadata<'_>) -> bool { true } fn enter(&self, _span: &span::Id) {} fn exit(&self, _span: &span::Id) {} } struct Cs; impl Callsite for Cs { fn set_interest(&self, _interest: Interest) {} fn metadata(&self) -> &Metadata<'_> { unimplemented!() } } #[test] fn callsite_enabled_no_span_directive() { let filter = EnvFilter::new("app=debug").with_subscriber(NoSubscriber); static META: &Metadata<'static> = &Metadata::new( "mySpan", "app", Level::TRACE, None, None, None, FieldSet::new(&[], identify_callsite!(&Cs)), Kind::SPAN, ); let interest = filter.register_callsite(META); assert!(interest.is_never()); } #[test] fn callsite_off() { let filter = EnvFilter::new("app=off").with_subscriber(NoSubscriber); static META: &Metadata<'static> = &Metadata::new( "mySpan", "app", Level::ERROR, None, None, None, FieldSet::new(&[], identify_callsite!(&Cs)), Kind::SPAN, ); let interest = filter.register_callsite(&META); assert!(interest.is_never()); } #[test] fn callsite_enabled_includes_span_directive() { let filter = EnvFilter::new("app[mySpan]=debug").with_subscriber(NoSubscriber); static META: &Metadata<'static> = &Metadata::new( "mySpan", "app", Level::TRACE, None, None, None, FieldSet::new(&[], identify_callsite!(&Cs)), Kind::SPAN, ); let interest = filter.register_callsite(&META); assert!(interest.is_always()); } #[test] fn callsite_enabled_includes_span_directive_field() { let filter = EnvFilter::new("app[mySpan{field=\"value\"}]=debug").with_subscriber(NoSubscriber); static META: &Metadata<'static> = &Metadata::new( "mySpan", "app", Level::TRACE, None, None, None, FieldSet::new(&["field"], identify_callsite!(&Cs)), Kind::SPAN, ); let interest = filter.register_callsite(&META); assert!(interest.is_always()); } #[test] fn callsite_enabled_includes_span_directive_multiple_fields() { let filter = EnvFilter::new("app[mySpan{field=\"value\",field2=2}]=debug") .with_subscriber(NoSubscriber); static META: &Metadata<'static> = &Metadata::new( "mySpan", "app", Level::TRACE, None, None, None, FieldSet::new(&["field"], identify_callsite!(&Cs)), Kind::SPAN, ); let interest = filter.register_callsite(&META); assert!(interest.is_never()); } #[test] fn roundtrip() { let f1: EnvFilter = "[span1{foo=1}]=error,[span2{bar=2 baz=false}],crate2[{quux=\"quuux\"}]=debug" .parse() .unwrap(); let f2: EnvFilter = format!("{}", f1).parse().unwrap(); assert_eq!(f1.statics, f2.statics); assert_eq!(f1.dynamics, f2.dynamics); } }