/rust/registry/src/index.crates.io-1949cf8c6b5b557f/tracing-subscriber-0.3.20/src/util.rs

Source
//! Extension traits and other utilities to make working with subscribers more
//! ergonomic.
use core::fmt;
#[cfg(feature = "std")]
use std::error::Error;
use tracing_core::dispatcher::{self, Dispatch};
#[cfg(feature = "tracing-log")]
use tracing_log::AsLog;

/// Extension trait adding utility methods for subscriber initialization.
///
/// This trait provides extension methods to make configuring and setting a
/// [default subscriber] more ergonomic. It is automatically implemented for all
/// types that can be converted into a [trace dispatcher]. Since `Dispatch`
/// implements `From<T>` for all `T: Subscriber`, all `Subscriber`
/// implementations will implement this extension trait as well. Types which
/// can be converted into `Subscriber`s, such as builders that construct a
/// `Subscriber`, may implement `Into<Dispatch>`, and will also receive an
/// implementation of this trait.
///
/// [default subscriber]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html#setting-the-default-subscriber
/// [trace dispatcher]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html
pub trait SubscriberInitExt
where
    Self: Into<Dispatch>,
{
    /// Sets `self` as the [default subscriber] in the current scope, returning a
    /// guard that will unset it when dropped.
    ///
    /// If the "tracing-log" feature flag is enabled, this will also initialize
    /// a [`log`] compatibility layer. This allows the subscriber to consume
    /// `log::Record`s as though they were `tracing` `Event`s.
    ///
    /// [default subscriber]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html#setting-the-default-subscriber
    /// [`log`]: https://crates.io/log
    #[cfg(feature = "std")]
    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    fn set_default(self) -> dispatcher::DefaultGuard {
        #[cfg(feature = "tracing-log")]
        let _ = tracing_log::LogTracer::init();

        dispatcher::set_default(&self.into())
    }

    /// Attempts to set `self` as the [global default subscriber] in the current
    /// scope, returning an error if one is already set.
    ///
    /// If the "tracing-log" feature flag is enabled, this will also attempt to
    /// initialize a [`log`] compatibility layer. This allows the subscriber to
    /// consume `log::Record`s as though they were `tracing` `Event`s.
    ///
    /// This method returns an error if a global default subscriber has already
    /// been set, or if a `log` logger has already been set (when the
    /// "tracing-log" feature is enabled).
    ///
    /// [global default subscriber]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html#setting-the-default-subscriber
    /// [`log`]: https://crates.io/log
    fn try_init(self) -> Result<(), TryInitError> {
        dispatcher::set_global_default(self.into()).map_err(TryInitError::new)?;

        // Since we are setting the global default subscriber, we can
        // opportunistically go ahead and set its global max level hint as
        // the max level for the `log` crate as well. This should make
        // skipping `log` diagnostics much faster.
        #[cfg(feature = "tracing-log")]
        tracing_log::LogTracer::builder()
            // Note that we must call this *after* setting the global default
            // subscriber, so that we get its max level hint.
            .with_max_level(tracing_core::LevelFilter::current().as_log())
            .init()
            .map_err(TryInitError::new)?;

        Ok(())
    }

    /// Attempts to set `self` as the [global default subscriber] in the current
    /// scope, panicking if this fails.
    ///
    /// If the "tracing-log" feature flag is enabled, this will also attempt to
    /// initialize a [`log`] compatibility layer. This allows the subscriber to
    /// consume `log::Record`s as though they were `tracing` `Event`s.
    ///
    /// This method panics if a global default subscriber has already been set,
    /// or if a `log` logger has already been set (when the "tracing-log"
    /// feature is enabled).
    ///
    /// [global default subscriber]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html#setting-the-default-subscriber
    /// [`log`]: https://crates.io/log
    fn init(self) {
        self.try_init()
            .expect("failed to set global default subscriber")
    }
}

impl<T> SubscriberInitExt for T where T: Into<Dispatch> {}

/// Error returned by [`try_init`](SubscriberInitExt::try_init) if a global default subscriber could not be initialized.
pub struct TryInitError {
    #[cfg(feature = "std")]
    inner: Box<dyn Error + Send + Sync + 'static>,

    #[cfg(not(feature = "std"))]
    _p: (),
}

// ==== impl TryInitError ====

impl TryInitError {
    #[cfg(feature = "std")]
    fn new(e: impl Into<Box<dyn Error + Send + Sync + 'static>>) -> Self {
        Self { inner: e.into() }
    }

    #[cfg(not(feature = "std"))]
    fn new<T>(_: T) -> Self {
        Self { _p: () }
    }
}

impl fmt::Debug for TryInitError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        #[cfg(feature = "std")]
        {
            fmt::Debug::fmt(&self.inner, f)
        }

        #[cfg(not(feature = "std"))]
        {
            f.write_str("TryInitError(())")
        }
    }
}

impl fmt::Display for TryInitError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        #[cfg(feature = "std")]
        {
            fmt::Display::fmt(&self.inner, f)
        }

        #[cfg(not(feature = "std"))]
        {
            f.write_str("failed to set global default subscriber")
        }
    }
}

#[cfg(feature = "std")]
impl Error for TryInitError {
    fn source(&self) -> Option<&(dyn Error + 'static)> {
        self.inner.source()
    }
}

Line	Count	Source
1		//! Extension traits and other utilities to make working with subscribers more
2		//! ergonomic.
3		use core::fmt;
4		#[cfg(feature = "std")]
5		use std::error::Error;
6		use tracing_core::dispatcher::{self, Dispatch};
7		#[cfg(feature = "tracing-log")]
8		use tracing_log::AsLog;
9
10		/// Extension trait adding utility methods for subscriber initialization.
11		///
12		/// This trait provides extension methods to make configuring and setting a
13		/// [default subscriber] more ergonomic. It is automatically implemented for all
14		/// types that can be converted into a [trace dispatcher]. Since `Dispatch`
15		/// implements `From<T>` for all `T: Subscriber`, all `Subscriber`
16		/// implementations will implement this extension trait as well. Types which
17		/// can be converted into `Subscriber`s, such as builders that construct a
18		/// `Subscriber`, may implement `Into<Dispatch>`, and will also receive an
19		/// implementation of this trait.
20		///
21		/// [default subscriber]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html#setting-the-default-subscriber
22		/// [trace dispatcher]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html
23		pub trait SubscriberInitExt
24		where
25		Self: Into<Dispatch>,
26		{
27		/// Sets `self` as the [default subscriber] in the current scope, returning a
28		/// guard that will unset it when dropped.
29		///
30		/// If the "tracing-log" feature flag is enabled, this will also initialize
31		/// a [`log`] compatibility layer. This allows the subscriber to consume
32		/// `log::Record`s as though they were `tracing` `Event`s.
33		///
34		/// [default subscriber]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html#setting-the-default-subscriber
35		/// [`log`]: https://crates.io/log
36		#[cfg(feature = "std")]
37		#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
38	0	fn set_default(self) -> dispatcher::DefaultGuard {
39		#[cfg(feature = "tracing-log")]
40		let _ = tracing_log::LogTracer::init();
41
42	0	dispatcher::set_default(&self.into())
43	0	} Unexecuted instantiation: <tracing_subscriber::layer::layered::Layered<tracing_tree::HierarchicalLayer<tracing_subscriber::fmt::writer::TestWriter>, tracing_subscriber::registry::sharded::Registry> as tracing_subscriber::util::SubscriberInitExt>::set_default Unexecuted instantiation: <_ as tracing_subscriber::util::SubscriberInitExt>::set_default
44
45		/// Attempts to set `self` as the [global default subscriber] in the current
46		/// scope, returning an error if one is already set.
47		///
48		/// If the "tracing-log" feature flag is enabled, this will also attempt to
49		/// initialize a [`log`] compatibility layer. This allows the subscriber to
50		/// consume `log::Record`s as though they were `tracing` `Event`s.
51		///
52		/// This method returns an error if a global default subscriber has already
53		/// been set, or if a `log` logger has already been set (when the
54		/// "tracing-log" feature is enabled).
55		///
56		/// [global default subscriber]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html#setting-the-default-subscriber
57		/// [`log`]: https://crates.io/log
58	0	fn try_init(self) -> Result<(), TryInitError> {
59	0	dispatcher::set_global_default(self.into()).map_err(TryInitError::new)?;
60
61		// Since we are setting the global default subscriber, we can
62		// opportunistically go ahead and set its global max level hint as
63		// the max level for the `log` crate as well. This should make
64		// skipping `log` diagnostics much faster.
65		#[cfg(feature = "tracing-log")]
66		tracing_log::LogTracer::builder()
67		// Note that we must call this after setting the global default
68		// subscriber, so that we get its max level hint.
69		.with_max_level(tracing_core::LevelFilter::current().as_log())
70		.init()
71		.map_err(TryInitError::new)?;
72
73	0	Ok(())
74	0	}
75
76		/// Attempts to set `self` as the [global default subscriber] in the current
77		/// scope, panicking if this fails.
78		///
79		/// If the "tracing-log" feature flag is enabled, this will also attempt to
80		/// initialize a [`log`] compatibility layer. This allows the subscriber to
81		/// consume `log::Record`s as though they were `tracing` `Event`s.
82		///
83		/// This method panics if a global default subscriber has already been set,
84		/// or if a `log` logger has already been set (when the "tracing-log"
85		/// feature is enabled).
86		///
87		/// [global default subscriber]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html#setting-the-default-subscriber
88		/// [`log`]: https://crates.io/log
89	0	fn init(self) {
90	0	self.try_init()
91	0	.expect("failed to set global default subscriber")
92	0	}
93		}
94
95		impl<T> SubscriberInitExt for T where T: Into<Dispatch> {}
96
97		/// Error returned by [`try_init`](SubscriberInitExt::try_init) if a global default subscriber could not be initialized.
98		pub struct TryInitError {
99		#[cfg(feature = "std")]
100		inner: Box<dyn Error + Send + Sync + 'static>,
101
102		#[cfg(not(feature = "std"))]
103		_p: (),
104		}
105
106		// ==== impl TryInitError ====
107
108		impl TryInitError {
109		#[cfg(feature = "std")]
110	0	fn new(e: impl Into<Box<dyn Error + Send + Sync + 'static>>) -> Self {
111	0	Self { inner: e.into() }
112	0	}
113
114		#[cfg(not(feature = "std"))]
115		fn new<T>(_: T) -> Self {
116		Self { _p: () }
117		}
118		}
119
120		impl fmt::Debug for TryInitError {
121	0	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
122		#[cfg(feature = "std")]
123		{
124	0	fmt::Debug::fmt(&self.inner, f)
125		}
126
127		#[cfg(not(feature = "std"))]
128		{
129		f.write_str("TryInitError(())")
130		}
131	0	}
132		}
133
134		impl fmt::Display for TryInitError {
135	0	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
136		#[cfg(feature = "std")]
137		{
138	0	fmt::Display::fmt(&self.inner, f)
139		}
140
141		#[cfg(not(feature = "std"))]
142		{
143		f.write_str("failed to set global default subscriber")
144		}
145	0	}
146		}
147
148		#[cfg(feature = "std")]
149		impl Error for TryInitError {
150	0	fn source(&self) -> Option<&(dyn Error + 'static)> {
151	0	self.inner.source()
152	0	}
153		}

Coverage Report

Created: 2025-10-10 07:05