| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/tracing-core-0.1.31/src/metadata.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>metadata.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../tracing_core/index.html"><div class="logo-container"> |
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| <span id="1076">1076</span> |
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| <span id="1080">1080</span> |
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| <span id="1082">1082</span> |
| <span id="1083">1083</span> |
| <span id="1084">1084</span> |
| <span id="1085">1085</span> |
| <span id="1086">1086</span> |
| <span id="1087">1087</span> |
| <span id="1088">1088</span> |
| <span id="1089">1089</span> |
| <span id="1090">1090</span> |
| <span id="1091">1091</span> |
| <span id="1092">1092</span> |
| <span id="1093">1093</span> |
| <span id="1094">1094</span> |
| <span id="1095">1095</span> |
| <span id="1096">1096</span> |
| <span id="1097">1097</span> |
| <span id="1098">1098</span> |
| <span id="1099">1099</span> |
| <span id="1100">1100</span> |
| <span id="1101">1101</span> |
| <span id="1102">1102</span> |
| <span id="1103">1103</span> |
| <span id="1104">1104</span> |
| <span id="1105">1105</span> |
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| <span id="1107">1107</span> |
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| <span id="1110">1110</span> |
| <span id="1111">1111</span> |
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| <span id="1113">1113</span> |
| <span id="1114">1114</span> |
| <span id="1115">1115</span> |
| </pre><pre class="rust"><code><span class="doccomment">//! Metadata describing trace data. |
| </span><span class="kw">use super</span>::{callsite, field}; |
| <span class="kw">use </span><span class="kw">crate</span>::stdlib::{ |
| cmp, fmt, |
| str::FromStr, |
| sync::atomic::{AtomicUsize, Ordering}, |
| }; |
| |
| <span class="doccomment">/// Metadata describing a [span] or [event]. |
| /// |
| /// All spans and events have the following metadata: |
| /// - A [name], represented as a static string. |
| /// - A [target], a string that categorizes part of the system where the span |
| /// or event occurred. The `tracing` macros default to using the module |
| /// path where the span or event originated as the target, but it may be |
| /// overridden. |
| /// - A [verbosity level]. This determines how verbose a given span or event |
| /// is, and allows enabling or disabling more verbose diagnostics |
| /// situationally. See the documentation for the [`Level`] type for details. |
| /// - The names of the [fields] defined by the span or event. |
| /// - Whether the metadata corresponds to a span or event. |
| /// |
| /// In addition, the following optional metadata describing the source code |
| /// location where the span or event originated _may_ be provided: |
| /// - The [file name] |
| /// - The [line number] |
| /// - The [module path] |
| /// |
| /// Metadata is used by [`Subscriber`]s when filtering spans and events, and it |
| /// may also be used as part of their data payload. |
| /// |
| /// When created by the `event!` or `span!` macro, the metadata describing a |
| /// particular event or span is constructed statically and exists as a single |
| /// static instance. Thus, the overhead of creating the metadata is |
| /// _significantly_ lower than that of creating the actual span. Therefore, |
| /// filtering is based on metadata, rather than on the constructed span. |
| /// |
| /// ## Equality |
| /// |
| /// In well-behaved applications, two `Metadata` with equal |
| /// [callsite identifiers] will be equal in all other ways (i.e., have the same |
| /// `name`, `target`, etc.). Consequently, in release builds, [`Metadata::eq`] |
| /// *only* checks that its arguments have equal callsites. However, the equality |
| /// of `Metadata`'s other fields is checked in debug builds. |
| /// |
| /// [span]: super::span |
| /// [event]: super::event |
| /// [name]: Self::name |
| /// [target]: Self::target |
| /// [fields]: Self::fields |
| /// [verbosity level]: Self::level |
| /// [file name]: Self::file |
| /// [line number]: Self::line |
| /// [module path]: Self::module_path |
| /// [`Subscriber`]: super::subscriber::Subscriber |
| /// [callsite identifiers]: Self::callsite |
| </span><span class="kw">pub struct </span>Metadata<<span class="lifetime">'a</span>> { |
| <span class="doccomment">/// The name of the span described by this metadata. |
| </span>name: <span class="kw-2">&</span><span class="lifetime">'static </span>str, |
| |
| <span class="doccomment">/// The part of the system that the span that this metadata describes |
| /// occurred in. |
| </span>target: <span class="kw-2">&</span><span class="lifetime">'a </span>str, |
| |
| <span class="doccomment">/// The level of verbosity of the described span. |
| </span>level: Level, |
| |
| <span class="doccomment">/// The name of the Rust module where the span occurred, or `None` if this |
| /// could not be determined. |
| </span>module_path: <span class="prelude-ty">Option</span><<span class="kw-2">&</span><span class="lifetime">'a </span>str>, |
| |
| <span class="doccomment">/// The name of the source code file where the span occurred, or `None` if |
| /// this could not be determined. |
| </span>file: <span class="prelude-ty">Option</span><<span class="kw-2">&</span><span class="lifetime">'a </span>str>, |
| |
| <span class="doccomment">/// The line number in the source code file where the span occurred, or |
| /// `None` if this could not be determined. |
| </span>line: <span class="prelude-ty">Option</span><u32>, |
| |
| <span class="doccomment">/// The names of the key-value fields attached to the described span or |
| /// event. |
| </span>fields: field::FieldSet, |
| |
| <span class="doccomment">/// The kind of the callsite. |
| </span>kind: Kind, |
| } |
| |
| <span class="doccomment">/// Indicates whether the callsite is a span or event. |
| </span><span class="attribute">#[derive(Clone, Eq, PartialEq)] |
| </span><span class="kw">pub struct </span>Kind(u8); |
| |
| <span class="doccomment">/// Describes the level of verbosity of a span or event. |
| /// |
| /// # Comparing Levels |
| /// |
| /// `Level` implements the [`PartialOrd`] and [`Ord`] traits, allowing two |
| /// `Level`s to be compared to determine which is considered more or less |
| /// verbose. Levels which are more verbose are considered "greater than" levels |
| /// which are less verbose, with [`Level::ERROR`] considered the lowest, and |
| /// [`Level::TRACE`] considered the highest. |
| /// |
| /// For example: |
| /// ``` |
| /// use tracing_core::Level; |
| /// |
| /// assert!(Level::TRACE > Level::DEBUG); |
| /// assert!(Level::ERROR < Level::WARN); |
| /// assert!(Level::INFO <= Level::DEBUG); |
| /// assert_eq!(Level::TRACE, Level::TRACE); |
| /// ``` |
| /// |
| /// # Filtering |
| /// |
| /// `Level`s are typically used to implement filtering that determines which |
| /// spans and events are enabled. Depending on the use case, more or less |
| /// verbose diagnostics may be desired. For example, when running in |
| /// development, [`DEBUG`]-level traces may be enabled by default. When running in |
| /// production, only [`INFO`]-level and lower traces might be enabled. Libraries |
| /// may include very verbose diagnostics at the [`DEBUG`] and/or [`TRACE`] levels. |
| /// Applications using those libraries typically chose to ignore those traces. However, when |
| /// debugging an issue involving said libraries, it may be useful to temporarily |
| /// enable the more verbose traces. |
| /// |
| /// The [`LevelFilter`] type is provided to enable filtering traces by |
| /// verbosity. `Level`s can be compared against [`LevelFilter`]s, and |
| /// [`LevelFilter`] has a variant for each `Level`, which compares analogously |
| /// to that level. In addition, [`LevelFilter`] adds a [`LevelFilter::OFF`] |
| /// variant, which is considered "less verbose" than every other `Level`. This is |
| /// intended to allow filters to completely disable tracing in a particular context. |
| /// |
| /// For example: |
| /// ``` |
| /// use tracing_core::{Level, LevelFilter}; |
| /// |
| /// assert!(LevelFilter::OFF < Level::TRACE); |
| /// assert!(LevelFilter::TRACE > Level::DEBUG); |
| /// assert!(LevelFilter::ERROR < Level::WARN); |
| /// assert!(LevelFilter::INFO <= Level::DEBUG); |
| /// assert!(LevelFilter::INFO >= Level::INFO); |
| /// ``` |
| /// |
| /// ## Examples |
| /// |
| /// Below is a simple example of how a [`Subscriber`] could implement filtering through |
| /// a [`LevelFilter`]. When a span or event is recorded, the [`Subscriber::enabled`] method |
| /// compares the span or event's `Level` against the configured [`LevelFilter`]. |
| /// The optional [`Subscriber::max_level_hint`] method can also be implemented to allow spans |
| /// and events above a maximum verbosity level to be skipped more efficiently, |
| /// often improving performance in short-lived programs. |
| /// |
| /// ``` |
| /// use tracing_core::{span, Event, Level, LevelFilter, Subscriber, Metadata}; |
| /// # use tracing_core::span::{Id, Record, Current}; |
| /// |
| /// #[derive(Debug)] |
| /// pub struct MySubscriber { |
| /// /// The most verbose level that this subscriber will enable. |
| /// max_level: LevelFilter, |
| /// |
| /// // ... |
| /// } |
| /// |
| /// impl MySubscriber { |
| /// /// Returns a new `MySubscriber` which will record spans and events up to |
| /// /// `max_level`. |
| /// pub fn with_max_level(max_level: LevelFilter) -> Self { |
| /// Self { |
| /// max_level, |
| /// // ... |
| /// } |
| /// } |
| /// } |
| /// impl Subscriber for MySubscriber { |
| /// fn enabled(&self, meta: &Metadata<'_>) -> bool { |
| /// // A span or event is enabled if it is at or below the configured |
| /// // maximum level. |
| /// meta.level() <= &self.max_level |
| /// } |
| /// |
| /// // This optional method returns the most verbose level that this |
| /// // subscriber will enable. Although implementing this method is not |
| /// // *required*, it permits additional optimizations when it is provided, |
| /// // allowing spans and events above the max level to be skipped |
| /// // more efficiently. |
| /// fn max_level_hint(&self) -> Option<LevelFilter> { |
| /// Some(self.max_level) |
| /// } |
| /// |
| /// // Implement the rest of the subscriber... |
| /// fn new_span(&self, span: &span::Attributes<'_>) -> span::Id { |
| /// // ... |
| /// # drop(span); Id::from_u64(1) |
| /// } |
| |
| /// fn event(&self, event: &Event<'_>) { |
| /// // ... |
| /// # drop(event); |
| /// } |
| /// |
| /// // ... |
| /// # fn enter(&self, _: &Id) {} |
| /// # fn exit(&self, _: &Id) {} |
| /// # fn record(&self, _: &Id, _: &Record<'_>) {} |
| /// # fn record_follows_from(&self, _: &Id, _: &Id) {} |
| /// } |
| /// ``` |
| /// |
| /// It is worth noting that the `tracing-subscriber` crate provides [additional |
| /// APIs][envfilter] for performing more sophisticated filtering, such as |
| /// enabling different levels based on which module or crate a span or event is |
| /// recorded in. |
| /// |
| /// [`DEBUG`]: Level::DEBUG |
| /// [`INFO`]: Level::INFO |
| /// [`TRACE`]: Level::TRACE |
| /// [`Subscriber::enabled`]: crate::subscriber::Subscriber::enabled |
| /// [`Subscriber::max_level_hint`]: crate::subscriber::Subscriber::max_level_hint |
| /// [`Subscriber`]: crate::subscriber::Subscriber |
| /// [envfilter]: https://docs.rs/tracing-subscriber/latest/tracing_subscriber/filter/struct.EnvFilter.html |
| </span><span class="attribute">#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)] |
| </span><span class="kw">pub struct </span>Level(LevelInner); |
| |
| <span class="doccomment">/// A filter comparable to a verbosity [`Level`]. |
| /// |
| /// If a [`Level`] is considered less than a `LevelFilter`, it should be |
| /// considered enabled; if greater than or equal to the `LevelFilter`, |
| /// that level is disabled. See [`LevelFilter::current`] for more |
| /// details. |
| /// |
| /// Note that this is essentially identical to the `Level` type, but with the |
| /// addition of an [`OFF`] level that completely disables all trace |
| /// instrumentation. |
| /// |
| /// See the documentation for the [`Level`] type to see how `Level`s |
| /// and `LevelFilter`s interact. |
| /// |
| /// [`OFF`]: LevelFilter::OFF |
| </span><span class="attribute">#[repr(transparent)] |
| #[derive(Copy, Clone, Eq, PartialEq, Hash)] |
| </span><span class="kw">pub struct </span>LevelFilter(<span class="prelude-ty">Option</span><Level>); |
| |
| <span class="doccomment">/// Indicates that a string could not be parsed to a valid level. |
| </span><span class="attribute">#[derive(Clone, Debug)] |
| </span><span class="kw">pub struct </span>ParseLevelFilterError(()); |
| |
| <span class="kw">static </span>MAX_LEVEL: AtomicUsize = AtomicUsize::new(LevelFilter::OFF_USIZE); |
| |
| <span class="comment">// ===== impl Metadata ===== |
| |
| </span><span class="kw">impl</span><<span class="lifetime">'a</span>> Metadata<<span class="lifetime">'a</span>> { |
| <span class="doccomment">/// Construct new metadata for a span or event, with a name, target, level, field |
| /// names, and optional source code location. |
| </span><span class="kw">pub const fn </span>new( |
| name: <span class="kw-2">&</span><span class="lifetime">'static </span>str, |
| target: <span class="kw-2">&</span><span class="lifetime">'a </span>str, |
| level: Level, |
| file: <span class="prelude-ty">Option</span><<span class="kw-2">&</span><span class="lifetime">'a </span>str>, |
| line: <span class="prelude-ty">Option</span><u32>, |
| module_path: <span class="prelude-ty">Option</span><<span class="kw-2">&</span><span class="lifetime">'a </span>str>, |
| fields: field::FieldSet, |
| kind: Kind, |
| ) -> <span class="self">Self </span>{ |
| Metadata { |
| name, |
| target, |
| level, |
| module_path, |
| file, |
| line, |
| fields, |
| kind, |
| } |
| } |
| |
| <span class="doccomment">/// Returns the names of the fields on the described span or event. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>fields(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>field::FieldSet { |
| <span class="kw-2">&</span><span class="self">self</span>.fields |
| } |
| |
| <span class="doccomment">/// Returns the level of verbosity of the described span or event. |
| </span><span class="kw">pub fn </span>level(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>Level { |
| <span class="kw-2">&</span><span class="self">self</span>.level |
| } |
| |
| <span class="doccomment">/// Returns the name of the span. |
| </span><span class="kw">pub fn </span>name(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="lifetime">'static </span>str { |
| <span class="self">self</span>.name |
| } |
| |
| <span class="doccomment">/// Returns a string describing the part of the system where the span or |
| /// event that this metadata describes occurred. |
| /// |
| /// Typically, this is the module path, but alternate targets may be set |
| /// when spans or events are constructed. |
| </span><span class="kw">pub fn </span>target(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="lifetime">'a </span>str { |
| <span class="self">self</span>.target |
| } |
| |
| <span class="doccomment">/// Returns the path to the Rust module where the span occurred, or |
| /// `None` if the module path is unknown. |
| </span><span class="kw">pub fn </span>module_path(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><<span class="kw-2">&</span><span class="lifetime">'a </span>str> { |
| <span class="self">self</span>.module_path |
| } |
| |
| <span class="doccomment">/// Returns the name of the source code file where the span |
| /// occurred, or `None` if the file is unknown |
| </span><span class="kw">pub fn </span>file(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><<span class="kw-2">&</span><span class="lifetime">'a </span>str> { |
| <span class="self">self</span>.file |
| } |
| |
| <span class="doccomment">/// Returns the line number in the source code file where the span |
| /// occurred, or `None` if the line number is unknown. |
| </span><span class="kw">pub fn </span>line(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><u32> { |
| <span class="self">self</span>.line |
| } |
| |
| <span class="doccomment">/// Returns an opaque `Identifier` that uniquely identifies the callsite |
| /// this `Metadata` originated from. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>callsite(<span class="kw-2">&</span><span class="self">self</span>) -> callsite::Identifier { |
| <span class="self">self</span>.fields.callsite() |
| } |
| |
| <span class="doccomment">/// Returns true if the callsite kind is `Event`. |
| </span><span class="kw">pub fn </span>is_event(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.kind.is_event() |
| } |
| |
| <span class="doccomment">/// Return true if the callsite kind is `Span`. |
| </span><span class="kw">pub fn </span>is_span(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.kind.is_span() |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>> fmt::Debug <span class="kw">for </span>Metadata<<span class="lifetime">'a</span>> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="kw">let </span><span class="kw-2">mut </span>meta = f.debug_struct(<span class="string">"Metadata"</span>); |
| meta.field(<span class="string">"name"</span>, <span class="kw-2">&</span><span class="self">self</span>.name) |
| .field(<span class="string">"target"</span>, <span class="kw-2">&</span><span class="self">self</span>.target) |
| .field(<span class="string">"level"</span>, <span class="kw-2">&</span><span class="self">self</span>.level); |
| |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(path) = <span class="self">self</span>.module_path() { |
| meta.field(<span class="string">"module_path"</span>, <span class="kw-2">&</span>path); |
| } |
| |
| <span class="kw">match </span>(<span class="self">self</span>.file(), <span class="self">self</span>.line()) { |
| (<span class="prelude-val">Some</span>(file), <span class="prelude-val">Some</span>(line)) => { |
| meta.field(<span class="string">"location"</span>, <span class="kw-2">&</span><span class="macro">format_args!</span>(<span class="string">"{}:{}"</span>, file, line)); |
| } |
| (<span class="prelude-val">Some</span>(file), <span class="prelude-val">None</span>) => { |
| meta.field(<span class="string">"file"</span>, <span class="kw-2">&</span><span class="macro">format_args!</span>(<span class="string">"{}"</span>, file)); |
| } |
| |
| <span class="comment">// Note: a line num with no file is a kind of weird case that _probably_ never occurs... |
| </span>(<span class="prelude-val">None</span>, <span class="prelude-val">Some</span>(line)) => { |
| meta.field(<span class="string">"line"</span>, <span class="kw-2">&</span>line); |
| } |
| (<span class="prelude-val">None</span>, <span class="prelude-val">None</span>) => {} |
| }; |
| |
| meta.field(<span class="string">"fields"</span>, <span class="kw-2">&</span><span class="macro">format_args!</span>(<span class="string">"{}"</span>, <span class="self">self</span>.fields)) |
| .field(<span class="string">"callsite"</span>, <span class="kw-2">&</span><span class="self">self</span>.callsite()) |
| .field(<span class="string">"kind"</span>, <span class="kw-2">&</span><span class="self">self</span>.kind) |
| .finish() |
| } |
| } |
| |
| <span class="kw">impl </span>Kind { |
| <span class="kw">const </span>EVENT_BIT: u8 = <span class="number">1 </span><< <span class="number">0</span>; |
| <span class="kw">const </span>SPAN_BIT: u8 = <span class="number">1 </span><< <span class="number">1</span>; |
| <span class="kw">const </span>HINT_BIT: u8 = <span class="number">1 </span><< <span class="number">2</span>; |
| |
| <span class="doccomment">/// `Event` callsite |
| </span><span class="kw">pub const </span>EVENT: Kind = Kind(<span class="self">Self</span>::EVENT_BIT); |
| |
| <span class="doccomment">/// `Span` callsite |
| </span><span class="kw">pub const </span>SPAN: Kind = Kind(<span class="self">Self</span>::SPAN_BIT); |
| |
| <span class="doccomment">/// `enabled!` callsite. [`Subscriber`][`crate::subscriber::Subscriber`]s can assume |
| /// this `Kind` means they will never recieve a |
| /// full event with this [`Metadata`]. |
| </span><span class="kw">pub const </span>HINT: Kind = Kind(<span class="self">Self</span>::HINT_BIT); |
| |
| <span class="doccomment">/// Return true if the callsite kind is `Span` |
| </span><span class="kw">pub fn </span>is_span(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.<span class="number">0 </span>& <span class="self">Self</span>::SPAN_BIT == <span class="self">Self</span>::SPAN_BIT |
| } |
| |
| <span class="doccomment">/// Return true if the callsite kind is `Event` |
| </span><span class="kw">pub fn </span>is_event(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.<span class="number">0 </span>& <span class="self">Self</span>::EVENT_BIT == <span class="self">Self</span>::EVENT_BIT |
| } |
| |
| <span class="doccomment">/// Return true if the callsite kind is `Hint` |
| </span><span class="kw">pub fn </span>is_hint(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.<span class="number">0 </span>& <span class="self">Self</span>::HINT_BIT == <span class="self">Self</span>::HINT_BIT |
| } |
| |
| <span class="doccomment">/// Sets that this `Kind` is a [hint](Self::HINT). |
| /// |
| /// This can be called on [`SPAN`](Self::SPAN) and [`EVENT`](Self::EVENT) |
| /// kinds to construct a hint callsite that also counts as a span or event. |
| </span><span class="kw">pub const fn </span>hint(<span class="self">self</span>) -> <span class="self">Self </span>{ |
| <span class="self">Self</span>(<span class="self">self</span>.<span class="number">0 </span>| <span class="self">Self</span>::HINT_BIT) |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Debug <span class="kw">for </span>Kind { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.write_str(<span class="string">"Kind("</span>)<span class="question-mark">?</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>has_bits = <span class="bool-val">false</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>write_bit = |name: <span class="kw-2">&</span>str| { |
| <span class="kw">if </span>has_bits { |
| f.write_str(<span class="string">" | "</span>)<span class="question-mark">?</span>; |
| } |
| f.write_str(name)<span class="question-mark">?</span>; |
| has_bits = <span class="bool-val">true</span>; |
| <span class="prelude-val">Ok</span>(()) |
| }; |
| |
| <span class="kw">if </span><span class="self">self</span>.is_event() { |
| write_bit(<span class="string">"EVENT"</span>)<span class="question-mark">?</span>; |
| } |
| |
| <span class="kw">if </span><span class="self">self</span>.is_span() { |
| write_bit(<span class="string">"SPAN"</span>)<span class="question-mark">?</span>; |
| } |
| |
| <span class="kw">if </span><span class="self">self</span>.is_hint() { |
| write_bit(<span class="string">"HINT"</span>)<span class="question-mark">?</span>; |
| } |
| |
| <span class="comment">// if none of the expected bits were set, something is messed up, so |
| // just print the bits for debugging purposes |
| </span><span class="kw">if </span>!has_bits { |
| <span class="macro">write!</span>(f, <span class="string">"{:#b}"</span>, <span class="self">self</span>.<span class="number">0</span>)<span class="question-mark">?</span>; |
| } |
| |
| f.write_str(<span class="string">")"</span>) |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>> Eq <span class="kw">for </span>Metadata<<span class="lifetime">'a</span>> {} |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>> PartialEq <span class="kw">for </span>Metadata<<span class="lifetime">'a</span>> { |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>eq(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span><span class="self">Self</span>) -> bool { |
| <span class="kw">if </span>core::ptr::eq(<span class="kw-2">&</span><span class="self">self</span>, <span class="kw-2">&</span>other) { |
| <span class="bool-val">true |
| </span>} <span class="kw">else if </span><span class="macro">cfg!</span>(not(debug_assertions)) { |
| <span class="comment">// In a well-behaving application, two `Metadata` can be assumed to |
| // be totally equal so long as they share the same callsite. |
| </span><span class="self">self</span>.callsite() == other.callsite() |
| } <span class="kw">else </span>{ |
| <span class="comment">// However, when debug-assertions are enabled, do not assume that |
| // the application is well-behaving; check every field of `Metadata` |
| // for equality. |
| |
| // `Metadata` is destructured here to ensure a compile-error if the |
| // fields of `Metadata` change. |
| </span><span class="kw">let </span>Metadata { |
| name: lhs_name, |
| target: lhs_target, |
| level: lhs_level, |
| module_path: lhs_module_path, |
| file: lhs_file, |
| line: lhs_line, |
| fields: lhs_fields, |
| kind: lhs_kind, |
| } = <span class="self">self</span>; |
| |
| <span class="kw">let </span>Metadata { |
| name: rhs_name, |
| target: rhs_target, |
| level: rhs_level, |
| module_path: rhs_module_path, |
| file: rhs_file, |
| line: rhs_line, |
| fields: rhs_fields, |
| kind: rhs_kind, |
| } = <span class="kw-2">&</span>other; |
| |
| <span class="comment">// The initial comparison of callsites is purely an optimization; |
| // it can be removed without affecting the overall semantics of the |
| // expression. |
| </span><span class="self">self</span>.callsite() == other.callsite() |
| && lhs_name == rhs_name |
| && lhs_target == rhs_target |
| && lhs_level == rhs_level |
| && lhs_module_path == rhs_module_path |
| && lhs_file == rhs_file |
| && lhs_line == rhs_line |
| && lhs_fields == rhs_fields |
| && lhs_kind == rhs_kind |
| } |
| } |
| } |
| |
| <span class="comment">// ===== impl Level ===== |
| |
| </span><span class="kw">impl </span>Level { |
| <span class="doccomment">/// The "error" level. |
| /// |
| /// Designates very serious errors. |
| </span><span class="kw">pub const </span>ERROR: Level = Level(LevelInner::Error); |
| <span class="doccomment">/// The "warn" level. |
| /// |
| /// Designates hazardous situations. |
| </span><span class="kw">pub const </span>WARN: Level = Level(LevelInner::Warn); |
| <span class="doccomment">/// The "info" level. |
| /// |
| /// Designates useful information. |
| </span><span class="kw">pub const </span>INFO: Level = Level(LevelInner::Info); |
| <span class="doccomment">/// The "debug" level. |
| /// |
| /// Designates lower priority information. |
| </span><span class="kw">pub const </span>DEBUG: Level = Level(LevelInner::Debug); |
| <span class="doccomment">/// The "trace" level. |
| /// |
| /// Designates very low priority, often extremely verbose, information. |
| </span><span class="kw">pub const </span>TRACE: Level = Level(LevelInner::Trace); |
| |
| <span class="doccomment">/// Returns the string representation of the `Level`. |
| /// |
| /// This returns the same string as the `fmt::Display` implementation. |
| </span><span class="kw">pub fn </span>as_str(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="lifetime">'static </span>str { |
| <span class="kw">match </span><span class="kw-2">*</span><span class="self">self </span>{ |
| Level::TRACE => <span class="string">"TRACE"</span>, |
| Level::DEBUG => <span class="string">"DEBUG"</span>, |
| Level::INFO => <span class="string">"INFO"</span>, |
| Level::WARN => <span class="string">"WARN"</span>, |
| Level::ERROR => <span class="string">"ERROR"</span>, |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Display <span class="kw">for </span>Level { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="kw">match </span><span class="kw-2">*</span><span class="self">self </span>{ |
| Level::TRACE => f.pad(<span class="string">"TRACE"</span>), |
| Level::DEBUG => f.pad(<span class="string">"DEBUG"</span>), |
| Level::INFO => f.pad(<span class="string">"INFO"</span>), |
| Level::WARN => f.pad(<span class="string">"WARN"</span>), |
| Level::ERROR => f.pad(<span class="string">"ERROR"</span>), |
| } |
| } |
| } |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| #[cfg_attr(docsrs, doc(cfg(feature = <span class="string">"std"</span>)))] |
| </span><span class="kw">impl </span><span class="kw">crate</span>::stdlib::error::Error <span class="kw">for </span>ParseLevelError {} |
| |
| <span class="kw">impl </span>FromStr <span class="kw">for </span>Level { |
| <span class="kw">type </span><span class="prelude-val">Err </span>= ParseLevelError; |
| <span class="kw">fn </span>from_str(s: <span class="kw-2">&</span>str) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>, ParseLevelError> { |
| s.parse::<usize>() |
| .map_err(|<span class="kw">_</span>| ParseLevelError { _p: () }) |
| .and_then(|num| <span class="kw">match </span>num { |
| <span class="number">1 </span>=> <span class="prelude-val">Ok</span>(Level::ERROR), |
| <span class="number">2 </span>=> <span class="prelude-val">Ok</span>(Level::WARN), |
| <span class="number">3 </span>=> <span class="prelude-val">Ok</span>(Level::INFO), |
| <span class="number">4 </span>=> <span class="prelude-val">Ok</span>(Level::DEBUG), |
| <span class="number">5 </span>=> <span class="prelude-val">Ok</span>(Level::TRACE), |
| <span class="kw">_ </span>=> <span class="prelude-val">Err</span>(ParseLevelError { _p: () }), |
| }) |
| .or_else(|<span class="kw">_</span>| <span class="kw">match </span>s { |
| s <span class="kw">if </span>s.eq_ignore_ascii_case(<span class="string">"error"</span>) => <span class="prelude-val">Ok</span>(Level::ERROR), |
| s <span class="kw">if </span>s.eq_ignore_ascii_case(<span class="string">"warn"</span>) => <span class="prelude-val">Ok</span>(Level::WARN), |
| s <span class="kw">if </span>s.eq_ignore_ascii_case(<span class="string">"info"</span>) => <span class="prelude-val">Ok</span>(Level::INFO), |
| s <span class="kw">if </span>s.eq_ignore_ascii_case(<span class="string">"debug"</span>) => <span class="prelude-val">Ok</span>(Level::DEBUG), |
| s <span class="kw">if </span>s.eq_ignore_ascii_case(<span class="string">"trace"</span>) => <span class="prelude-val">Ok</span>(Level::TRACE), |
| <span class="kw">_ </span>=> <span class="prelude-val">Err</span>(ParseLevelError { _p: () }), |
| }) |
| } |
| } |
| |
| <span class="attribute">#[repr(usize)] |
| #[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)] |
| </span><span class="kw">enum </span>LevelInner { |
| <span class="doccomment">/// The "trace" level. |
| /// |
| /// Designates very low priority, often extremely verbose, information. |
| </span>Trace = <span class="number">0</span>, |
| <span class="doccomment">/// The "debug" level. |
| /// |
| /// Designates lower priority information. |
| </span>Debug = <span class="number">1</span>, |
| <span class="doccomment">/// The "info" level. |
| /// |
| /// Designates useful information. |
| </span>Info = <span class="number">2</span>, |
| <span class="doccomment">/// The "warn" level. |
| /// |
| /// Designates hazardous situations. |
| </span>Warn = <span class="number">3</span>, |
| <span class="doccomment">/// The "error" level. |
| /// |
| /// Designates very serious errors. |
| </span>Error = <span class="number">4</span>, |
| } |
| |
| <span class="comment">// === impl LevelFilter === |
| |
| </span><span class="kw">impl </span>From<Level> <span class="kw">for </span>LevelFilter { |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>from(level: Level) -> <span class="self">Self </span>{ |
| <span class="self">Self</span>::from_level(level) |
| } |
| } |
| |
| <span class="kw">impl </span>From<<span class="prelude-ty">Option</span><Level>> <span class="kw">for </span>LevelFilter { |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>from(level: <span class="prelude-ty">Option</span><Level>) -> <span class="self">Self </span>{ |
| <span class="self">Self</span>(level) |
| } |
| } |
| |
| <span class="kw">impl </span>From<LevelFilter> <span class="kw">for </span><span class="prelude-ty">Option</span><Level> { |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>from(filter: LevelFilter) -> <span class="self">Self </span>{ |
| filter.into_level() |
| } |
| } |
| |
| <span class="kw">impl </span>LevelFilter { |
| <span class="doccomment">/// The "off" level. |
| /// |
| /// Designates that trace instrumentation should be completely disabled. |
| </span><span class="kw">pub const </span>OFF: LevelFilter = LevelFilter(<span class="prelude-val">None</span>); |
| <span class="doccomment">/// The "error" level. |
| /// |
| /// Designates very serious errors. |
| </span><span class="kw">pub const </span>ERROR: LevelFilter = LevelFilter::from_level(Level::ERROR); |
| <span class="doccomment">/// The "warn" level. |
| /// |
| /// Designates hazardous situations. |
| </span><span class="kw">pub const </span>WARN: LevelFilter = LevelFilter::from_level(Level::WARN); |
| <span class="doccomment">/// The "info" level. |
| /// |
| /// Designates useful information. |
| </span><span class="kw">pub const </span>INFO: LevelFilter = LevelFilter::from_level(Level::INFO); |
| <span class="doccomment">/// The "debug" level. |
| /// |
| /// Designates lower priority information. |
| </span><span class="kw">pub const </span>DEBUG: LevelFilter = LevelFilter::from_level(Level::DEBUG); |
| <span class="doccomment">/// The "trace" level. |
| /// |
| /// Designates very low priority, often extremely verbose, information. |
| </span><span class="kw">pub const </span>TRACE: LevelFilter = LevelFilter(<span class="prelude-val">Some</span>(Level::TRACE)); |
| |
| <span class="doccomment">/// Returns a `LevelFilter` that enables spans and events with verbosity up |
| /// to and including `level`. |
| </span><span class="kw">pub const fn </span>from_level(level: Level) -> <span class="self">Self </span>{ |
| <span class="self">Self</span>(<span class="prelude-val">Some</span>(level)) |
| } |
| |
| <span class="doccomment">/// Returns the most verbose [`Level`] that this filter accepts, or `None` |
| /// if it is [`OFF`]. |
| /// |
| /// [`OFF`]: LevelFilter::OFF |
| </span><span class="kw">pub const fn </span>into_level(<span class="self">self</span>) -> <span class="prelude-ty">Option</span><Level> { |
| <span class="self">self</span>.<span class="number">0 |
| </span>} |
| |
| <span class="comment">// These consts are necessary because `as` casts are not allowed as |
| // match patterns. |
| </span><span class="kw">const </span>ERROR_USIZE: usize = LevelInner::Error <span class="kw">as </span>usize; |
| <span class="kw">const </span>WARN_USIZE: usize = LevelInner::Warn <span class="kw">as </span>usize; |
| <span class="kw">const </span>INFO_USIZE: usize = LevelInner::Info <span class="kw">as </span>usize; |
| <span class="kw">const </span>DEBUG_USIZE: usize = LevelInner::Debug <span class="kw">as </span>usize; |
| <span class="kw">const </span>TRACE_USIZE: usize = LevelInner::Trace <span class="kw">as </span>usize; |
| <span class="comment">// Using the value of the last variant + 1 ensures that we match the value |
| // for `Option::None` as selected by the niche optimization for |
| // `LevelFilter`. If this is the case, converting a `usize` value into a |
| // `LevelFilter` (in `LevelFilter::current`) will be an identity conversion, |
| // rather than generating a lookup table. |
| </span><span class="kw">const </span>OFF_USIZE: usize = LevelInner::Error <span class="kw">as </span>usize + <span class="number">1</span>; |
| |
| <span class="doccomment">/// Returns a `LevelFilter` that matches the most verbose [`Level`] that any |
| /// currently active [`Subscriber`] will enable. |
| /// |
| /// User code should treat this as a *hint*. If a given span or event has a |
| /// level *higher* than the returned `LevelFilter`, it will not be enabled. |
| /// However, if the level is less than or equal to this value, the span or |
| /// event is *not* guaranteed to be enabled; the subscriber will still |
| /// filter each callsite individually. |
| /// |
| /// Therefore, comparing a given span or event's level to the returned |
| /// `LevelFilter` **can** be used for determining if something is |
| /// *disabled*, but **should not** be used for determining if something is |
| /// *enabled*. |
| /// |
| /// [`Level`]: super::Level |
| /// [`Subscriber`]: super::Subscriber |
| </span><span class="attribute">#[inline(always)] |
| </span><span class="kw">pub fn </span>current() -> <span class="self">Self </span>{ |
| <span class="kw">match </span>MAX_LEVEL.load(Ordering::Relaxed) { |
| <span class="self">Self</span>::ERROR_USIZE => <span class="self">Self</span>::ERROR, |
| <span class="self">Self</span>::WARN_USIZE => <span class="self">Self</span>::WARN, |
| <span class="self">Self</span>::INFO_USIZE => <span class="self">Self</span>::INFO, |
| <span class="self">Self</span>::DEBUG_USIZE => <span class="self">Self</span>::DEBUG, |
| <span class="self">Self</span>::TRACE_USIZE => <span class="self">Self</span>::TRACE, |
| <span class="self">Self</span>::OFF_USIZE => <span class="self">Self</span>::OFF, |
| <span class="attribute">#[cfg(debug_assertions)] |
| </span>unknown => <span class="macro">unreachable!</span>( |
| <span class="string">"/!\\ `LevelFilter` representation seems to have changed! /!\\ \n\ |
| This is a bug (and it's pretty bad). Please contact the `tracing` \ |
| maintainers. Thank you and I'm sorry.\n \ |
| The offending repr was: {:?}"</span>, |
| unknown, |
| ), |
| <span class="attribute">#[cfg(not(debug_assertions))] |
| </span><span class="kw">_ </span>=> <span class="kw">unsafe </span>{ |
| <span class="comment">// Using `unreachable_unchecked` here (rather than |
| // `unreachable!()`) is necessary to ensure that rustc generates |
| // an identity conversion from integer -> discriminant, rather |
| // than generating a lookup table. We want to ensure this |
| // function is a single `mov` instruction (on x86) if at all |
| // possible, because it is called *every* time a span/event |
| // callsite is hit; and it is (potentially) the only code in the |
| // hottest path for skipping a majority of callsites when level |
| // filtering is in use. |
| // |
| // safety: This branch is only truly unreachable if we guarantee |
| // that no values other than the possible enum discriminants |
| // will *ever* be present. The `AtomicUsize` is initialized to |
| // the `OFF` value. It is only set by the `set_max` function, |
| // which takes a `LevelFilter` as a parameter. This restricts |
| // the inputs to `set_max` to the set of valid discriminants. |
| // Therefore, **as long as `MAX_VALUE` is only ever set by |
| // `set_max`**, this is safe. |
| </span><span class="kw">crate</span>::stdlib::hint::unreachable_unchecked() |
| }, |
| } |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>set_max(LevelFilter(level): LevelFilter) { |
| <span class="kw">let </span>val = <span class="kw">match </span>level { |
| <span class="prelude-val">Some</span>(Level(level)) => level <span class="kw">as </span>usize, |
| <span class="prelude-val">None </span>=> <span class="self">Self</span>::OFF_USIZE, |
| }; |
| |
| <span class="comment">// using an AcqRel swap ensures an ordered relationship of writes to the |
| // max level. |
| </span>MAX_LEVEL.swap(val, Ordering::AcqRel); |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Display <span class="kw">for </span>LevelFilter { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="kw">match </span><span class="kw-2">*</span><span class="self">self </span>{ |
| LevelFilter::OFF => f.pad(<span class="string">"off"</span>), |
| LevelFilter::ERROR => f.pad(<span class="string">"error"</span>), |
| LevelFilter::WARN => f.pad(<span class="string">"warn"</span>), |
| LevelFilter::INFO => f.pad(<span class="string">"info"</span>), |
| LevelFilter::DEBUG => f.pad(<span class="string">"debug"</span>), |
| LevelFilter::TRACE => f.pad(<span class="string">"trace"</span>), |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Debug <span class="kw">for </span>LevelFilter { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="kw">match </span><span class="kw-2">*</span><span class="self">self </span>{ |
| LevelFilter::OFF => f.pad(<span class="string">"LevelFilter::OFF"</span>), |
| LevelFilter::ERROR => f.pad(<span class="string">"LevelFilter::ERROR"</span>), |
| LevelFilter::WARN => f.pad(<span class="string">"LevelFilter::WARN"</span>), |
| LevelFilter::INFO => f.pad(<span class="string">"LevelFilter::INFO"</span>), |
| LevelFilter::DEBUG => f.pad(<span class="string">"LevelFilter::DEBUG"</span>), |
| LevelFilter::TRACE => f.pad(<span class="string">"LevelFilter::TRACE"</span>), |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>FromStr <span class="kw">for </span>LevelFilter { |
| <span class="kw">type </span><span class="prelude-val">Err </span>= ParseLevelFilterError; |
| <span class="kw">fn </span>from_str(from: <span class="kw-2">&</span>str) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>, <span class="self">Self</span>::Err> { |
| from.parse::<usize>() |
| .ok() |
| .and_then(|num| <span class="kw">match </span>num { |
| <span class="number">0 </span>=> <span class="prelude-val">Some</span>(LevelFilter::OFF), |
| <span class="number">1 </span>=> <span class="prelude-val">Some</span>(LevelFilter::ERROR), |
| <span class="number">2 </span>=> <span class="prelude-val">Some</span>(LevelFilter::WARN), |
| <span class="number">3 </span>=> <span class="prelude-val">Some</span>(LevelFilter::INFO), |
| <span class="number">4 </span>=> <span class="prelude-val">Some</span>(LevelFilter::DEBUG), |
| <span class="number">5 </span>=> <span class="prelude-val">Some</span>(LevelFilter::TRACE), |
| <span class="kw">_ </span>=> <span class="prelude-val">None</span>, |
| }) |
| .or_else(|| <span class="kw">match </span>from { |
| <span class="string">"" </span>=> <span class="prelude-val">Some</span>(LevelFilter::ERROR), |
| s <span class="kw">if </span>s.eq_ignore_ascii_case(<span class="string">"error"</span>) => <span class="prelude-val">Some</span>(LevelFilter::ERROR), |
| s <span class="kw">if </span>s.eq_ignore_ascii_case(<span class="string">"warn"</span>) => <span class="prelude-val">Some</span>(LevelFilter::WARN), |
| s <span class="kw">if </span>s.eq_ignore_ascii_case(<span class="string">"info"</span>) => <span class="prelude-val">Some</span>(LevelFilter::INFO), |
| s <span class="kw">if </span>s.eq_ignore_ascii_case(<span class="string">"debug"</span>) => <span class="prelude-val">Some</span>(LevelFilter::DEBUG), |
| s <span class="kw">if </span>s.eq_ignore_ascii_case(<span class="string">"trace"</span>) => <span class="prelude-val">Some</span>(LevelFilter::TRACE), |
| s <span class="kw">if </span>s.eq_ignore_ascii_case(<span class="string">"off"</span>) => <span class="prelude-val">Some</span>(LevelFilter::OFF), |
| <span class="kw">_ </span>=> <span class="prelude-val">None</span>, |
| }) |
| .ok_or(ParseLevelFilterError(())) |
| } |
| } |
| |
| <span class="doccomment">/// Returned if parsing a `Level` fails. |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>ParseLevelError { |
| _p: (), |
| } |
| |
| <span class="kw">impl </span>fmt::Display <span class="kw">for </span>ParseLevelError { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.pad( |
| <span class="string">"error parsing level: expected one of \"error\", \"warn\", \ |
| \"info\", \"debug\", \"trace\", or a number 1-5"</span>, |
| ) |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Display <span class="kw">for </span>ParseLevelFilterError { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.pad( |
| <span class="string">"error parsing level filter: expected one of \"off\", \"error\", \ |
| \"warn\", \"info\", \"debug\", \"trace\", or a number 0-5"</span>, |
| ) |
| } |
| } |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| </span><span class="kw">impl </span>std::error::Error <span class="kw">for </span>ParseLevelFilterError {} |
| |
| <span class="comment">// ==== Level and LevelFilter comparisons ==== |
| |
| // /!\ BIG, IMPORTANT WARNING /!\ |
| // Do NOT mess with these implementations! They are hand-written for a reason! |
| // |
| // Since comparing `Level`s and `LevelFilter`s happens in a *very* hot path |
| // (potentially, every time a span or event macro is hit, regardless of whether |
| // or not is enabled), we *need* to ensure that these comparisons are as fast as |
| // possible. Therefore, we have some requirements: |
| // |
| // 1. We want to do our best to ensure that rustc will generate integer-integer |
| // comparisons wherever possible. |
| // |
| // The derived `Ord`/`PartialOrd` impls for `LevelFilter` will not do this, |
| // because `LevelFilter`s are represented by `Option<Level>`, rather than as |
| // a separate `#[repr(usize)]` enum. This was (unfortunately) necessary for |
| // backwards-compatibility reasons, as the `tracing` crate's original |
| // version of `LevelFilter` defined `const fn` conversions between `Level`s |
| // and `LevelFilter`, so we're stuck with the `Option<Level>` repr. |
| // Therefore, we need hand-written `PartialOrd` impls that cast both sides of |
| // the comparison to `usize`s, to force the compiler to generate integer |
| // compares. |
| // |
| // 2. The hottest `Level`/`LevelFilter` comparison, the one that happens every |
| // time a callsite is hit, occurs *within the `tracing` crate's macros*. |
| // This means that the comparison is happening *inside* a crate that |
| // *depends* on `tracing-core`, not in `tracing-core` itself. The compiler |
| // will only inline function calls across crate boundaries if the called |
| // function is annotated with an `#[inline]` attribute, and we *definitely* |
| // want the comparison functions to be inlined: as previously mentioned, they |
| // should compile down to a single integer comparison on release builds, and |
| // it seems really sad to push an entire stack frame to call a function |
| // consisting of one `cmp` instruction! |
| // |
| // Therefore, we need to ensure that all the comparison methods have |
| // `#[inline]` or `#[inline(always)]` attributes. It's not sufficient to just |
| // add the attribute to `partial_cmp` in a manual implementation of the |
| // trait, since it's the comparison operators (`lt`, `le`, `gt`, and `ge`) |
| // that will actually be *used*, and the default implementation of *those* |
| // methods, which calls `partial_cmp`, does not have an inline annotation. |
| // |
| // 3. We need the comparisons to be inverted. The discriminants for the |
| // `LevelInner` enum are assigned in "backwards" order, with `TRACE` having |
| // the *lowest* value. However, we want `TRACE` to compare greater-than all |
| // other levels. |
| // |
| // Why are the numeric values inverted? In order to ensure that `LevelFilter` |
| // (which, as previously mentioned, *has* to be internally represented by an |
| // `Option<Level>`) compiles down to a single integer value. This is |
| // necessary for storing the global max in an `AtomicUsize`, and for ensuring |
| // that we use fast integer-integer comparisons, as mentioned previously. In |
| // order to ensure this, we exploit the niche optimization. The niche |
| // optimization for `Option<{enum with a numeric repr}>` will choose |
| // `(HIGHEST_DISCRIMINANT_VALUE + 1)` as the representation for `None`. |
| // Therefore, the integer representation of `LevelFilter::OFF` (which is |
| // `None`) will be the number 5. `OFF` must compare higher than every other |
| // level in order for it to filter as expected. Since we want to use a single |
| // `cmp` instruction, we can't special-case the integer value of `OFF` to |
| // compare higher, as that will generate more code. Instead, we need it to be |
| // on one end of the enum, with `ERROR` on the opposite end, so we assign the |
| // value 0 to `ERROR`. |
| // |
| // This *does* mean that when parsing `LevelFilter`s or `Level`s from |
| // `String`s, the integer values are inverted, but that doesn't happen in a |
| // hot path. |
| // |
| // Note that we manually invert the comparisons by swapping the left-hand and |
| // right-hand side. Using `Ordering::reverse` generates significantly worse |
| // code (per Matt Godbolt's Compiler Explorer). |
| // |
| // Anyway, that's a brief history of why this code is the way it is. Don't |
| // change it unless you know what you're doing. |
| |
| </span><span class="kw">impl </span>PartialEq<LevelFilter> <span class="kw">for </span>Level { |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>eq(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>LevelFilter) -> bool { |
| <span class="self">self</span>.<span class="number">0 </span><span class="kw">as </span>usize == filter_as_usize(<span class="kw-2">&</span>other.<span class="number">0</span>) |
| } |
| } |
| |
| <span class="kw">impl </span>PartialOrd <span class="kw">for </span>Level { |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>partial_cmp(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>Level) -> <span class="prelude-ty">Option</span><cmp::Ordering> { |
| <span class="prelude-val">Some</span>(<span class="self">self</span>.cmp(other)) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>lt(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>Level) -> bool { |
| (other.<span class="number">0 </span><span class="kw">as </span>usize) < (<span class="self">self</span>.<span class="number">0 </span><span class="kw">as </span>usize) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>le(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>Level) -> bool { |
| (other.<span class="number">0 </span><span class="kw">as </span>usize) <= (<span class="self">self</span>.<span class="number">0 </span><span class="kw">as </span>usize) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>gt(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>Level) -> bool { |
| (other.<span class="number">0 </span><span class="kw">as </span>usize) > (<span class="self">self</span>.<span class="number">0 </span><span class="kw">as </span>usize) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>ge(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>Level) -> bool { |
| (other.<span class="number">0 </span><span class="kw">as </span>usize) >= (<span class="self">self</span>.<span class="number">0 </span><span class="kw">as </span>usize) |
| } |
| } |
| |
| <span class="kw">impl </span>Ord <span class="kw">for </span>Level { |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>cmp(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span><span class="self">Self</span>) -> cmp::Ordering { |
| (other.<span class="number">0 </span><span class="kw">as </span>usize).cmp(<span class="kw-2">&</span>(<span class="self">self</span>.<span class="number">0 </span><span class="kw">as </span>usize)) |
| } |
| } |
| |
| <span class="kw">impl </span>PartialOrd<LevelFilter> <span class="kw">for </span>Level { |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>partial_cmp(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>LevelFilter) -> <span class="prelude-ty">Option</span><cmp::Ordering> { |
| <span class="prelude-val">Some</span>(filter_as_usize(<span class="kw-2">&</span>other.<span class="number">0</span>).cmp(<span class="kw-2">&</span>(<span class="self">self</span>.<span class="number">0 </span><span class="kw">as </span>usize))) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>lt(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>LevelFilter) -> bool { |
| filter_as_usize(<span class="kw-2">&</span>other.<span class="number">0</span>) < (<span class="self">self</span>.<span class="number">0 </span><span class="kw">as </span>usize) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>le(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>LevelFilter) -> bool { |
| filter_as_usize(<span class="kw-2">&</span>other.<span class="number">0</span>) <= (<span class="self">self</span>.<span class="number">0 </span><span class="kw">as </span>usize) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>gt(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>LevelFilter) -> bool { |
| filter_as_usize(<span class="kw-2">&</span>other.<span class="number">0</span>) > (<span class="self">self</span>.<span class="number">0 </span><span class="kw">as </span>usize) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>ge(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>LevelFilter) -> bool { |
| filter_as_usize(<span class="kw-2">&</span>other.<span class="number">0</span>) >= (<span class="self">self</span>.<span class="number">0 </span><span class="kw">as </span>usize) |
| } |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>filter_as_usize(x: <span class="kw-2">&</span><span class="prelude-ty">Option</span><Level>) -> usize { |
| <span class="kw">match </span>x { |
| <span class="prelude-val">Some</span>(Level(f)) => <span class="kw-2">*</span>f <span class="kw">as </span>usize, |
| <span class="prelude-val">None </span>=> LevelFilter::OFF_USIZE, |
| } |
| } |
| |
| <span class="kw">impl </span>PartialEq<Level> <span class="kw">for </span>LevelFilter { |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>eq(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>Level) -> bool { |
| filter_as_usize(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>) == other.<span class="number">0 </span><span class="kw">as </span>usize |
| } |
| } |
| |
| <span class="kw">impl </span>PartialOrd <span class="kw">for </span>LevelFilter { |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>partial_cmp(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>LevelFilter) -> <span class="prelude-ty">Option</span><cmp::Ordering> { |
| <span class="prelude-val">Some</span>(<span class="self">self</span>.cmp(other)) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>lt(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>LevelFilter) -> bool { |
| filter_as_usize(<span class="kw-2">&</span>other.<span class="number">0</span>) < filter_as_usize(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>le(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>LevelFilter) -> bool { |
| filter_as_usize(<span class="kw-2">&</span>other.<span class="number">0</span>) <= filter_as_usize(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>gt(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>LevelFilter) -> bool { |
| filter_as_usize(<span class="kw-2">&</span>other.<span class="number">0</span>) > filter_as_usize(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>ge(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>LevelFilter) -> bool { |
| filter_as_usize(<span class="kw-2">&</span>other.<span class="number">0</span>) >= filter_as_usize(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>) |
| } |
| } |
| |
| <span class="kw">impl </span>Ord <span class="kw">for </span>LevelFilter { |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>cmp(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span><span class="self">Self</span>) -> cmp::Ordering { |
| filter_as_usize(<span class="kw-2">&</span>other.<span class="number">0</span>).cmp(<span class="kw-2">&</span>filter_as_usize(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>)) |
| } |
| } |
| |
| <span class="kw">impl </span>PartialOrd<Level> <span class="kw">for </span>LevelFilter { |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>partial_cmp(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>Level) -> <span class="prelude-ty">Option</span><cmp::Ordering> { |
| <span class="prelude-val">Some</span>((other.<span class="number">0 </span><span class="kw">as </span>usize).cmp(<span class="kw-2">&</span>filter_as_usize(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>))) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>lt(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>Level) -> bool { |
| (other.<span class="number">0 </span><span class="kw">as </span>usize) < filter_as_usize(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>le(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>Level) -> bool { |
| (other.<span class="number">0 </span><span class="kw">as </span>usize) <= filter_as_usize(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>gt(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>Level) -> bool { |
| (other.<span class="number">0 </span><span class="kw">as </span>usize) > filter_as_usize(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>ge(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span>Level) -> bool { |
| (other.<span class="number">0 </span><span class="kw">as </span>usize) >= filter_as_usize(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>) |
| } |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>tests { |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| <span class="kw">use </span><span class="kw">crate</span>::stdlib::mem; |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>level_from_str() { |
| <span class="macro">assert_eq!</span>(<span class="string">"error"</span>.parse::<Level>().unwrap(), Level::ERROR); |
| <span class="macro">assert_eq!</span>(<span class="string">"4"</span>.parse::<Level>().unwrap(), Level::DEBUG); |
| <span class="macro">assert!</span>(<span class="string">"0"</span>.parse::<Level>().is_err()) |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>filter_level_conversion() { |
| <span class="kw">let </span>mapping = [ |
| (LevelFilter::OFF, <span class="prelude-val">None</span>), |
| (LevelFilter::ERROR, <span class="prelude-val">Some</span>(Level::ERROR)), |
| (LevelFilter::WARN, <span class="prelude-val">Some</span>(Level::WARN)), |
| (LevelFilter::INFO, <span class="prelude-val">Some</span>(Level::INFO)), |
| (LevelFilter::DEBUG, <span class="prelude-val">Some</span>(Level::DEBUG)), |
| (LevelFilter::TRACE, <span class="prelude-val">Some</span>(Level::TRACE)), |
| ]; |
| <span class="kw">for </span>(filter, level) <span class="kw">in </span>mapping.iter() { |
| <span class="macro">assert_eq!</span>(filter.into_level(), <span class="kw-2">*</span>level); |
| <span class="kw">match </span>level { |
| <span class="prelude-val">Some</span>(level) => { |
| <span class="kw">let </span>actual: LevelFilter = (<span class="kw-2">*</span>level).into(); |
| <span class="macro">assert_eq!</span>(actual, <span class="kw-2">*</span>filter); |
| } |
| <span class="prelude-val">None </span>=> { |
| <span class="kw">let </span>actual: LevelFilter = <span class="prelude-val">None</span>.into(); |
| <span class="macro">assert_eq!</span>(actual, <span class="kw-2">*</span>filter); |
| } |
| } |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>level_filter_is_usize_sized() { |
| <span class="macro">assert_eq!</span>( |
| mem::size_of::<LevelFilter>(), |
| mem::size_of::<usize>(), |
| <span class="string">"`LevelFilter` is no longer `usize`-sized! global MAX_LEVEL may now be invalid!" |
| </span>) |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>level_filter_reprs() { |
| <span class="kw">let </span>mapping = [ |
| (LevelFilter::OFF, LevelInner::Error <span class="kw">as </span>usize + <span class="number">1</span>), |
| (LevelFilter::ERROR, LevelInner::Error <span class="kw">as </span>usize), |
| (LevelFilter::WARN, LevelInner::Warn <span class="kw">as </span>usize), |
| (LevelFilter::INFO, LevelInner::Info <span class="kw">as </span>usize), |
| (LevelFilter::DEBUG, LevelInner::Debug <span class="kw">as </span>usize), |
| (LevelFilter::TRACE, LevelInner::Trace <span class="kw">as </span>usize), |
| ]; |
| <span class="kw">for </span><span class="kw-2">&</span>(filter, expected) <span class="kw">in </span><span class="kw-2">&</span>mapping { |
| <span class="kw">let </span>repr = <span class="kw">unsafe </span>{ |
| <span class="comment">// safety: The entire purpose of this test is to assert that the |
| // actual repr matches what we expect it to be --- we're testing |
| // that *other* unsafe code is sound using the transmuted value. |
| // We're not going to do anything with it that might be unsound. |
| </span>mem::transmute::<LevelFilter, usize>(filter) |
| }; |
| <span class="macro">assert_eq!</span>(expected, repr, <span class="string">"repr changed for {:?}"</span>, filter) |
| } |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="tracing_core" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |