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// Copyright 2021 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
#![deny(missing_docs)]
//! Provides the `tracing::Subscriber` implementation that allows to publish `tracing` events to
//! Fuchsia Logging System.
//! This library isn't Fuchsia-specific and provides a general `tracing::Subscriber` that allows
//! the library to also be used in the host.
use tracing::Level;
use tracing_log::LogTracer;
#[cfg(target_os = "fuchsia")]
mod fuchsia;
#[cfg(target_os = "fuchsia")]
use self::fuchsia as implementation;
#[cfg(not(target_os = "fuchsia"))]
mod portable;
#[cfg(not(target_os = "fuchsia"))]
use self::portable as implementation;
pub use fidl_fuchsia_diagnostics::{Interest, Severity};
pub use implementation::*;
/// Trait that allows to convert a type into a `fidl_fuchsia_diagnostics::Severity`
pub trait IntoSeverity {
/// Returns a Severity.
fn into_severity(self) -> Severity;
}
impl IntoSeverity for Severity {
fn into_severity(self) -> Severity {
self
}
}
impl IntoSeverity for Level {
fn into_severity(self) -> Severity {
match self {
Level::TRACE => Severity::Trace,
Level::DEBUG => Severity::Debug,
Level::INFO => Severity::Info,
Level::WARN => Severity::Warn,
Level::ERROR => Severity::Error,
}
}
}
/// Logs emitted with the `log` crate will be ingested by the registered `Publisher`.
pub(crate) fn ingest_log_events() -> Result<(), PublishError> {
LogTracer::init()?;
Ok(())
}
/// Adds a panic hook which will log an `ERROR` log with the panic information.
pub(crate) fn install_panic_hook(prefix: Option<&'static str>) {
let previous_hook = std::panic::take_hook();
std::panic::set_hook(Box::new(move |info| {
let prefix = prefix.unwrap_or("PANIC");
tracing::error!({ %info }, "{prefix}");
previous_hook(info);
}));
}
/// Options to configure publishing. This is for initialization of logs, it's a superset of
/// `PublisherOptions`.
pub struct PublishOptions<'t> {
pub(crate) publisher: PublisherOptions<'t>,
pub(crate) ingest_log_events: bool,
pub(crate) install_panic_hook: bool,
pub(crate) panic_prefix: Option<&'static str>,
}
impl<'t> Default for PublishOptions<'t> {
fn default() -> Self {
Self {
publisher: PublisherOptions::default(),
ingest_log_events: true,
install_panic_hook: true,
panic_prefix: None,
}
}
}
impl<'t> PublishOptions<'t> {
/// Whether or not to install a panic hook which will log an ERROR whenever a panic happens.
///
/// Default: true.
pub fn install_panic_hook(mut self, enable: bool) -> Self {
self.install_panic_hook = enable;
self
}
/// Whether or not to ingest log events emitted by the `log` crate macros.
///
/// Default: true.
pub fn ingest_log_events(mut self, enable: bool) -> Self {
self.ingest_log_events = enable;
self
}
/// Override the default string prefix for a logged panic message.
pub fn panic_prefix(mut self, prefix: &'static str) -> Self {
self.panic_prefix = Some(prefix);
self
}
}
macro_rules! publisher_options {
($(($name:ident, $self:ident, $($self_arg:ident),*)),*) => {
$(
impl<'t> $name<'t> {
/// Sets the tags applied to all published events.
///
/// When set to an empty slice (the default), events are tagged with the moniker of
/// the component in which they are recorded.
///
/// Default: empty.
pub fn tags(mut $self, tags: &'t [&'t str]) -> Self {
let this = &mut $self$(.$self_arg)*;
this.tags = tags;
$self
}
/// Enable a metatag. It'll be applied to all published events.
///
/// Default: no metatags are enabled.
pub fn enable_metatag(mut $self, metatag: Metatag) -> Self {
let this = &mut $self$(.$self_arg)*;
this.metatags.insert(metatag);
$self
}
/// An interest filter to apply to messages published.
///
/// Default: EMPTY, which implies INFO.
pub fn minimum_severity(mut $self, severity: impl IntoSeverity) -> Self {
let this = &mut $self$(.$self_arg)*;
this.interest.min_severity = Some(severity.into_severity());
$self
}
}
)*
};
}
publisher_options!((PublisherOptions, self,), (PublishOptions, self, publisher));