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use crate::{
field::RecordFields,
fmt::{format, FormatEvent, FormatFields, MakeWriter, TestWriter},
layer::{self, Context},
registry::{self, LookupSpan, SpanRef},
};
use format::{FmtSpan, TimingDisplay};
use std::{any::TypeId, cell::RefCell, fmt, io, marker::PhantomData, ops::Deref, time::Instant};
use tracing_core::{
field,
span::{Attributes, Current, Id, Record},
Event, Metadata, Subscriber,
};
/// A [`Layer`] that logs formatted representations of `tracing` events.
///
/// ## Examples
///
/// Constructing a layer with the default configuration:
///
/// ```rust
/// use tracing_subscriber::{fmt, Registry};
/// use tracing_subscriber::prelude::*;
///
/// let subscriber = Registry::default()
/// .with(fmt::Layer::default());
///
/// tracing::subscriber::set_global_default(subscriber).unwrap();
/// ```
///
/// Overriding the layer's behavior:
///
/// ```rust
/// use tracing_subscriber::{fmt, Registry};
/// use tracing_subscriber::prelude::*;
///
/// let fmt_layer = fmt::layer()
/// .with_target(false) // don't include event targets when logging
/// .with_level(false); // don't include event levels when logging
///
/// let subscriber = Registry::default().with(fmt_layer);
/// # tracing::subscriber::set_global_default(subscriber).unwrap();
/// ```
///
/// Setting a custom event formatter:
///
/// ```rust
/// use tracing_subscriber::fmt::{self, format, time};
/// use tracing_subscriber::prelude::*;
///
/// let fmt = format().with_timer(time::Uptime::default());
/// let fmt_layer = fmt::layer()
/// .event_format(fmt)
/// .with_target(false);
/// # let subscriber = fmt_layer.with_subscriber(tracing_subscriber::registry::Registry::default());
/// # tracing::subscriber::set_global_default(subscriber).unwrap();
/// ```
///
/// [`Layer`]: super::layer::Layer
#[cfg_attr(docsrs, doc(cfg(all(feature = "fmt", feature = "std"))))]
#[derive(Debug)]
pub struct Layer<
S,
N = format::DefaultFields,
E = format::Format<format::Full>,
W = fn() -> io::Stdout,
> {
make_writer: W,
fmt_fields: N,
fmt_event: E,
fmt_span: format::FmtSpanConfig,
is_ansi: bool,
log_internal_errors: bool,
_inner: PhantomData<fn(S)>,
}
impl<S> Layer<S> {
/// Returns a new [`Layer`][self::Layer] with the default configuration.
pub fn new() -> Self {
Self::default()
}
}
// This needs to be a seperate impl block because they place different bounds on the type parameters.
impl<S, N, E, W> Layer<S, N, E, W>
where
S: Subscriber + for<'a> LookupSpan<'a>,
N: for<'writer> FormatFields<'writer> + 'static,
W: for<'writer> MakeWriter<'writer> + 'static,
{
/// Sets the [event formatter][`FormatEvent`] that the layer being built will
/// use to format events.
///
/// The event formatter may be any type implementing the [`FormatEvent`]
/// trait, which is implemented for all functions taking a [`FmtContext`], a
/// [`Writer`], and an [`Event`].
///
/// # Examples
///
/// Setting a type implementing [`FormatEvent`] as the formatter:
/// ```rust
/// use tracing_subscriber::fmt::{self, format};
///
/// let layer = fmt::layer()
/// .event_format(format().compact());
/// # // this is necessary for type inference.
/// # use tracing_subscriber::Layer as _;
/// # let _ = layer.with_subscriber(tracing_subscriber::registry::Registry::default());
/// ```
/// [`FormatEvent`]: format::FormatEvent
/// [`Event`]: tracing::Event
/// [`Writer`]: format::Writer
pub fn event_format<E2>(self, e: E2) -> Layer<S, N, E2, W>
where
E2: FormatEvent<S, N> + 'static,
{
Layer {
fmt_fields: self.fmt_fields,
fmt_event: e,
fmt_span: self.fmt_span,
make_writer: self.make_writer,
is_ansi: self.is_ansi,
log_internal_errors: self.log_internal_errors,
_inner: self._inner,
}
}
/// Updates the event formatter by applying a function to the existing event formatter.
///
/// This sets the event formatter that the layer being built will use to record fields.
///
/// # Examples
///
/// Updating an event formatter:
///
/// ```rust
/// let layer = tracing_subscriber::fmt::layer()
/// .map_event_format(|e| e.compact());
/// # // this is necessary for type inference.
/// # use tracing_subscriber::Layer as _;
/// # let _ = layer.with_subscriber(tracing_subscriber::registry::Registry::default());
/// ```
pub fn map_event_format<E2>(self, f: impl FnOnce(E) -> E2) -> Layer<S, N, E2, W>
where
E2: FormatEvent<S, N> + 'static,
{
Layer {
fmt_fields: self.fmt_fields,
fmt_event: f(self.fmt_event),
fmt_span: self.fmt_span,
make_writer: self.make_writer,
is_ansi: self.is_ansi,
log_internal_errors: self.log_internal_errors,
_inner: self._inner,
}
}
}
// This needs to be a seperate impl block because they place different bounds on the type parameters.
impl<S, N, E, W> Layer<S, N, E, W> {
/// Sets the [`MakeWriter`] that the layer being built will use to write events.
///
/// # Examples
///
/// Using `stderr` rather than `stdout`:
///
/// ```rust
/// use std::io;
/// use tracing_subscriber::fmt;
///
/// let layer = fmt::layer()
/// .with_writer(io::stderr);
/// # // this is necessary for type inference.
/// # use tracing_subscriber::Layer as _;
/// # let _ = layer.with_subscriber(tracing_subscriber::registry::Registry::default());
/// ```
pub fn with_writer<W2>(self, make_writer: W2) -> Layer<S, N, E, W2>
where
W2: for<'writer> MakeWriter<'writer> + 'static,
{
Layer {
fmt_fields: self.fmt_fields,
fmt_event: self.fmt_event,
fmt_span: self.fmt_span,
is_ansi: self.is_ansi,
log_internal_errors: self.log_internal_errors,
make_writer,
_inner: self._inner,
}
}
/// Borrows the [writer] for this [`Layer`].
///
/// [writer]: MakeWriter
pub fn writer(&self) -> &W {
&self.make_writer
}
/// Mutably borrows the [writer] for this [`Layer`].
///
/// This method is primarily expected to be used with the
/// [`reload::Handle::modify`](crate::reload::Handle::modify) method.
///
/// # Examples
///
/// ```
/// # use tracing::info;
/// # use tracing_subscriber::{fmt,reload,Registry,prelude::*};
/// # fn non_blocking<T: std::io::Write>(writer: T) -> (fn() -> std::io::Stdout) {
/// # std::io::stdout
/// # }
/// # fn main() {
/// let layer = fmt::layer().with_writer(non_blocking(std::io::stderr()));
/// let (layer, reload_handle) = reload::Layer::new(layer);
/// #
/// # // specifying the Registry type is required
/// # let _: &reload::Handle<fmt::Layer<Registry, _, _, _>, Registry> = &reload_handle;
/// #
/// info!("This will be logged to stderr");
/// reload_handle.modify(|layer| *layer.writer_mut() = non_blocking(std::io::stdout()));
/// info!("This will be logged to stdout");
/// # }
/// ```
///
/// [writer]: MakeWriter
pub fn writer_mut(&mut self) -> &mut W {
&mut self.make_writer
}
/// Sets whether this layer should use ANSI terminal formatting
/// escape codes (such as colors).
///
/// This method is primarily expected to be used with the
/// [`reload::Handle::modify`](crate::reload::Handle::modify) method when changing
/// the writer.
#[cfg(feature = "ansi")]
#[cfg_attr(docsrs, doc(cfg(feature = "ansi")))]
pub fn set_ansi(&mut self, ansi: bool) {
self.is_ansi = ansi;
}
/// Configures the layer to support [`libtest`'s output capturing][capturing] when used in
/// unit tests.
///
/// See [`TestWriter`] for additional details.
///
/// # Examples
///
/// Using [`TestWriter`] to let `cargo test` capture test output:
///
/// ```rust
/// use std::io;
/// use tracing_subscriber::fmt;
///
/// let layer = fmt::layer()
/// .with_test_writer();
/// # // this is necessary for type inference.
/// # use tracing_subscriber::Layer as _;
/// # let _ = layer.with_subscriber(tracing_subscriber::registry::Registry::default());
/// ```
/// [capturing]:
/// https://doc.rust-lang.org/book/ch11-02-running-tests.html#showing-function-output
/// [`TestWriter`]: super::writer::TestWriter
pub fn with_test_writer(self) -> Layer<S, N, E, TestWriter> {
Layer {
fmt_fields: self.fmt_fields,
fmt_event: self.fmt_event,
fmt_span: self.fmt_span,
is_ansi: self.is_ansi,
log_internal_errors: self.log_internal_errors,
make_writer: TestWriter::default(),
_inner: self._inner,
}
}
/// Enable ANSI terminal colors for formatted output.
#[cfg(feature = "ansi")]
#[cfg_attr(docsrs, doc(cfg(feature = "ansi")))]
pub fn with_ansi(self, ansi: bool) -> Self {
Self {
is_ansi: ansi,
..self
}
}
/// Sets whether to write errors from [`FormatEvent`] to the writer.
/// Defaults to true.
///
/// By default, `fmt::Layer` will write any `FormatEvent`-internal errors to
/// the writer. These errors are unlikely and will only occur if there is a
/// bug in the `FormatEvent` implementation or its dependencies.
///
/// If writing to the writer fails, the error message is printed to stderr
/// as a fallback.
///
/// [`FormatEvent`]: crate::fmt::FormatEvent
pub fn log_internal_errors(self, log_internal_errors: bool) -> Self {
Self {
log_internal_errors,
..self
}
}
/// Updates the [`MakeWriter`] by applying a function to the existing [`MakeWriter`].
///
/// This sets the [`MakeWriter`] that the layer being built will use to write events.
///
/// # Examples
///
/// Redirect output to stderr if level is <= WARN:
///
/// ```rust
/// use tracing::Level;
/// use tracing_subscriber::fmt::{self, writer::MakeWriterExt};
///
/// let stderr = std::io::stderr.with_max_level(Level::WARN);
/// let layer = fmt::layer()
/// .map_writer(move |w| stderr.or_else(w));
/// # // this is necessary for type inference.
/// # use tracing_subscriber::Layer as _;
/// # let _ = layer.with_subscriber(tracing_subscriber::registry::Registry::default());
/// ```
pub fn map_writer<W2>(self, f: impl FnOnce(W) -> W2) -> Layer<S, N, E, W2>
where
W2: for<'writer> MakeWriter<'writer> + 'static,
{
Layer {
fmt_fields: self.fmt_fields,
fmt_event: self.fmt_event,
fmt_span: self.fmt_span,
is_ansi: self.is_ansi,
log_internal_errors: self.log_internal_errors,
make_writer: f(self.make_writer),
_inner: self._inner,
}
}
}
impl<S, N, L, T, W> Layer<S, N, format::Format<L, T>, W>
where
N: for<'writer> FormatFields<'writer> + 'static,
{
/// Use the given [`timer`] for span and event timestamps.
///
/// See the [`time` module] for the provided timer implementations.
///
/// Note that using the `"time`"" feature flag enables the
/// additional time formatters [`UtcTime`] and [`LocalTime`], which use the
/// [`time` crate] to provide more sophisticated timestamp formatting
/// options.
///
/// [`timer`]: super::time::FormatTime
/// [`time` module]: mod@super::time
/// [`UtcTime`]: super::time::UtcTime
/// [`LocalTime`]: super::time::LocalTime
/// [`time` crate]: https://docs.rs/time/0.3
pub fn with_timer<T2>(self, timer: T2) -> Layer<S, N, format::Format<L, T2>, W> {
Layer {
fmt_event: self.fmt_event.with_timer(timer),
fmt_fields: self.fmt_fields,
fmt_span: self.fmt_span,
make_writer: self.make_writer,
is_ansi: self.is_ansi,
log_internal_errors: self.log_internal_errors,
_inner: self._inner,
}
}
/// Do not emit timestamps with spans and event.
pub fn without_time(self) -> Layer<S, N, format::Format<L, ()>, W> {
Layer {
fmt_event: self.fmt_event.without_time(),
fmt_fields: self.fmt_fields,
fmt_span: self.fmt_span.without_time(),
make_writer: self.make_writer,
is_ansi: self.is_ansi,
log_internal_errors: self.log_internal_errors,
_inner: self._inner,
}
}
/// Configures how synthesized events are emitted at points in the [span
/// lifecycle][lifecycle].
///
/// The following options are available:
///
/// - `FmtSpan::NONE`: No events will be synthesized when spans are
/// created, entered, exited, or closed. Data from spans will still be
/// included as the context for formatted events. This is the default.
/// - `FmtSpan::NEW`: An event will be synthesized when spans are created.
/// - `FmtSpan::ENTER`: An event will be synthesized when spans are entered.
/// - `FmtSpan::EXIT`: An event will be synthesized when spans are exited.
/// - `FmtSpan::CLOSE`: An event will be synthesized when a span closes. If
/// [timestamps are enabled][time] for this formatter, the generated
/// event will contain fields with the span's _busy time_ (the total
/// time for which it was entered) and _idle time_ (the total time that
/// the span existed but was not entered).
/// - `FmtSpan::ACTIVE`: Events will be synthesized when spans are entered
/// or exited.
/// - `FmtSpan::FULL`: Events will be synthesized whenever a span is
/// created, entered, exited, or closed. If timestamps are enabled, the
/// close event will contain the span's busy and idle time, as
/// described above.
///
/// The options can be enabled in any combination. For instance, the following
/// will synthesize events whenever spans are created and closed:
///
/// ```rust
/// use tracing_subscriber::fmt;
/// use tracing_subscriber::fmt::format::FmtSpan;
///
/// let subscriber = fmt()
/// .with_span_events(FmtSpan::NEW | FmtSpan::CLOSE)
/// .finish();
/// ```
///
/// Note that the generated events will only be part of the log output by
/// this formatter; they will not be recorded by other `Subscriber`s or by
/// `Layer`s added to this subscriber.
///
/// [lifecycle]: https://docs.rs/tracing/latest/tracing/span/index.html#the-span-lifecycle
/// [time]: Layer::without_time()
pub fn with_span_events(self, kind: FmtSpan) -> Self {
Layer {
fmt_span: self.fmt_span.with_kind(kind),
..self
}
}
/// Sets whether or not an event's target is displayed.
pub fn with_target(self, display_target: bool) -> Layer<S, N, format::Format<L, T>, W> {
Layer {
fmt_event: self.fmt_event.with_target(display_target),
..self
}
}
/// Sets whether or not an event's [source code file path][file] is
/// displayed.
///
/// [file]: tracing_core::Metadata::file
pub fn with_file(self, display_filename: bool) -> Layer<S, N, format::Format<L, T>, W> {
Layer {
fmt_event: self.fmt_event.with_file(display_filename),
..self
}
}
/// Sets whether or not an event's [source code line number][line] is
/// displayed.
///
/// [line]: tracing_core::Metadata::line
pub fn with_line_number(
self,
display_line_number: bool,
) -> Layer<S, N, format::Format<L, T>, W> {
Layer {
fmt_event: self.fmt_event.with_line_number(display_line_number),
..self
}
}
/// Sets whether or not an event's level is displayed.
pub fn with_level(self, display_level: bool) -> Layer<S, N, format::Format<L, T>, W> {
Layer {
fmt_event: self.fmt_event.with_level(display_level),
..self
}
}
/// Sets whether or not the [thread ID] of the current thread is displayed
/// when formatting events.
///
/// [thread ID]: std::thread::ThreadId
pub fn with_thread_ids(self, display_thread_ids: bool) -> Layer<S, N, format::Format<L, T>, W> {
Layer {
fmt_event: self.fmt_event.with_thread_ids(display_thread_ids),
..self
}
}
/// Sets whether or not the [name] of the current thread is displayed
/// when formatting events.
///
/// [name]: std::thread#naming-threads
pub fn with_thread_names(
self,
display_thread_names: bool,
) -> Layer<S, N, format::Format<L, T>, W> {
Layer {
fmt_event: self.fmt_event.with_thread_names(display_thread_names),
..self
}
}
/// Sets the layer being built to use a [less verbose formatter][super::format::Compact].
pub fn compact(self) -> Layer<S, N, format::Format<format::Compact, T>, W>
where
N: for<'writer> FormatFields<'writer> + 'static,
{
Layer {
fmt_event: self.fmt_event.compact(),
fmt_fields: self.fmt_fields,
fmt_span: self.fmt_span,
make_writer: self.make_writer,
is_ansi: self.is_ansi,
log_internal_errors: self.log_internal_errors,
_inner: self._inner,
}
}
/// Sets the layer being built to use an [excessively pretty, human-readable formatter](crate::fmt::format::Pretty).
#[cfg(feature = "ansi")]
#[cfg_attr(docsrs, doc(cfg(feature = "ansi")))]
pub fn pretty(self) -> Layer<S, format::Pretty, format::Format<format::Pretty, T>, W> {
Layer {
fmt_event: self.fmt_event.pretty(),
fmt_fields: format::Pretty::default(),
fmt_span: self.fmt_span,
make_writer: self.make_writer,
is_ansi: self.is_ansi,
log_internal_errors: self.log_internal_errors,
_inner: self._inner,
}
}
/// Sets the layer being built to use a [JSON formatter][super::format::Json].
///
/// The full format includes fields from all entered spans.
///
/// # Example Output
///
/// ```ignore,json
/// {"timestamp":"Feb 20 11:28:15.096","level":"INFO","target":"mycrate","fields":{"message":"some message", "key": "value"}}
/// ```
///
/// # Options
///
/// - [`Layer::flatten_event`] can be used to enable flattening event fields into the root
/// object.
///
/// [`Layer::flatten_event`]: Layer::flatten_event()
#[cfg(feature = "json")]
#[cfg_attr(docsrs, doc(cfg(feature = "json")))]
pub fn json(self) -> Layer<S, format::JsonFields, format::Format<format::Json, T>, W> {
Layer {
fmt_event: self.fmt_event.json(),
fmt_fields: format::JsonFields::new(),
fmt_span: self.fmt_span,
make_writer: self.make_writer,
// always disable ANSI escapes in JSON mode!
is_ansi: false,
log_internal_errors: self.log_internal_errors,
_inner: self._inner,
}
}
}
#[cfg(feature = "json")]
#[cfg_attr(docsrs, doc(cfg(feature = "json")))]
impl<S, T, W> Layer<S, format::JsonFields, format::Format<format::Json, T>, W> {
/// Sets the JSON layer being built to flatten event metadata.
///
/// See [`format::Json`][super::format::Json]
pub fn flatten_event(
self,
flatten_event: bool,
) -> Layer<S, format::JsonFields, format::Format<format::Json, T>, W> {
Layer {
fmt_event: self.fmt_event.flatten_event(flatten_event),
fmt_fields: format::JsonFields::new(),
..self
}
}
/// Sets whether or not the formatter will include the current span in
/// formatted events.
///
/// See [`format::Json`][super::format::Json]
pub fn with_current_span(
self,
display_current_span: bool,
) -> Layer<S, format::JsonFields, format::Format<format::Json, T>, W> {
Layer {
fmt_event: self.fmt_event.with_current_span(display_current_span),
fmt_fields: format::JsonFields::new(),
..self
}
}
/// Sets whether or not the formatter will include a list (from root to leaf)
/// of all currently entered spans in formatted events.
///
/// See [`format::Json`][super::format::Json]
pub fn with_span_list(
self,
display_span_list: bool,
) -> Layer<S, format::JsonFields, format::Format<format::Json, T>, W> {
Layer {
fmt_event: self.fmt_event.with_span_list(display_span_list),
fmt_fields: format::JsonFields::new(),
..self
}
}
}
impl<S, N, E, W> Layer<S, N, E, W> {
/// Sets the field formatter that the layer being built will use to record
/// fields.
pub fn fmt_fields<N2>(self, fmt_fields: N2) -> Layer<S, N2, E, W>
where
N2: for<'writer> FormatFields<'writer> + 'static,
{
Layer {
fmt_event: self.fmt_event,
fmt_fields,
fmt_span: self.fmt_span,
make_writer: self.make_writer,
is_ansi: self.is_ansi,
log_internal_errors: self.log_internal_errors,
_inner: self._inner,
}
}
/// Updates the field formatter by applying a function to the existing field formatter.
///
/// This sets the field formatter that the layer being built will use to record fields.
///
/// # Examples
///
/// Updating a field formatter:
///
/// ```rust
/// use tracing_subscriber::field::MakeExt;
/// let layer = tracing_subscriber::fmt::layer()
/// .map_fmt_fields(|f| f.debug_alt());
/// # // this is necessary for type inference.
/// # use tracing_subscriber::Layer as _;
/// # let _ = layer.with_subscriber(tracing_subscriber::registry::Registry::default());
/// ```
pub fn map_fmt_fields<N2>(self, f: impl FnOnce(N) -> N2) -> Layer<S, N2, E, W>
where
N2: for<'writer> FormatFields<'writer> + 'static,
{
Layer {
fmt_event: self.fmt_event,
fmt_fields: f(self.fmt_fields),
fmt_span: self.fmt_span,
make_writer: self.make_writer,
is_ansi: self.is_ansi,
log_internal_errors: self.log_internal_errors,
_inner: self._inner,
}
}
}
impl<S> Default for Layer<S> {
fn default() -> Self {
Layer {
fmt_fields: format::DefaultFields::default(),
fmt_event: format::Format::default(),
fmt_span: format::FmtSpanConfig::default(),
make_writer: io::stdout,
is_ansi: cfg!(feature = "ansi"),
log_internal_errors: false,
_inner: PhantomData,
}
}
}
impl<S, N, E, W> Layer<S, N, E, W>
where
S: Subscriber + for<'a> LookupSpan<'a>,
N: for<'writer> FormatFields<'writer> + 'static,
E: FormatEvent<S, N> + 'static,
W: for<'writer> MakeWriter<'writer> + 'static,
{
#[inline]
fn make_ctx<'a>(&'a self, ctx: Context<'a, S>, event: &'a Event<'a>) -> FmtContext<'a, S, N> {
FmtContext {
ctx,
fmt_fields: &self.fmt_fields,
event,
}
}
}
/// A formatted representation of a span's fields stored in its [extensions].
///
/// Because `FormattedFields` is generic over the type of the formatter that
/// produced it, multiple versions of a span's formatted fields can be stored in
/// the [`Extensions`][extensions] type-map. This means that when multiple
/// formatters are in use, each can store its own formatted representation
/// without conflicting.
///
/// [extensions]: crate::registry::Extensions
#[derive(Default)]
pub struct FormattedFields<E: ?Sized> {
_format_fields: PhantomData<fn(E)>,
was_ansi: bool,
/// The formatted fields of a span.
pub fields: String,
}
impl<E: ?Sized> FormattedFields<E> {
/// Returns a new `FormattedFields`.
pub fn new(fields: String) -> Self {
Self {
fields,
was_ansi: false,
_format_fields: PhantomData,
}
}
/// Returns a new [`format::Writer`] for writing to this `FormattedFields`.
///
/// The returned [`format::Writer`] can be used with the
/// [`FormatFields::format_fields`] method.
pub fn as_writer(&mut self) -> format::Writer<'_> {
format::Writer::new(&mut self.fields).with_ansi(self.was_ansi)
}
}
impl<E: ?Sized> fmt::Debug for FormattedFields<E> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("FormattedFields")
.field("fields", &self.fields)
.field("formatter", &format_args!("{}", std::any::type_name::<E>()))
.field("was_ansi", &self.was_ansi)
.finish()
}
}
impl<E: ?Sized> fmt::Display for FormattedFields<E> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Display::fmt(&self.fields, f)
}
}
impl<E: ?Sized> Deref for FormattedFields<E> {
type Target = String;
fn deref(&self) -> &Self::Target {
&self.fields
}
}
// === impl FmtLayer ===
macro_rules! with_event_from_span {
($id:ident, $span:ident, $($field:literal = $value:expr),*, |$event:ident| $code:block) => {
let meta = $span.metadata();
let cs = meta.callsite();
let fs = field::FieldSet::new(&[$($field),*], cs);
#[allow(unused)]
let mut iter = fs.iter();
let v = [$(
(&iter.next().unwrap(), Some(&$value as &dyn field::Value)),
)*];
let vs = fs.value_set(&v);
let $event = Event::new_child_of($id, meta, &vs);
$code
};
}
impl<S, N, E, W> layer::Layer<S> for Layer<S, N, E, W>
where
S: Subscriber + for<'a> LookupSpan<'a>,
N: for<'writer> FormatFields<'writer> + 'static,
E: FormatEvent<S, N> + 'static,
W: for<'writer> MakeWriter<'writer> + 'static,
{
fn on_new_span(&self, attrs: &Attributes<'_>, id: &Id, ctx: Context<'_, S>) {
let span = ctx.span(id).expect("Span not found, this is a bug");
let mut extensions = span.extensions_mut();
if extensions.get_mut::<FormattedFields<N>>().is_none() {
let mut fields = FormattedFields::<N>::new(String::new());
if self
.fmt_fields
.format_fields(fields.as_writer().with_ansi(self.is_ansi), attrs)
.is_ok()
{
fields.was_ansi = self.is_ansi;
extensions.insert(fields);
} else {
eprintln!(
"[tracing-subscriber] Unable to format the following event, ignoring: {:?}",
attrs
);
}
}
if self.fmt_span.fmt_timing
&& self.fmt_span.trace_close()
&& extensions.get_mut::<Timings>().is_none()
{
extensions.insert(Timings::new());
}
if self.fmt_span.trace_new() {
with_event_from_span!(id, span, "message" = "new", |event| {
drop(extensions);
drop(span);
self.on_event(&event, ctx);
});
}
}
fn on_record(&self, id: &Id, values: &Record<'_>, ctx: Context<'_, S>) {
let span = ctx.span(id).expect("Span not found, this is a bug");
let mut extensions = span.extensions_mut();
if let Some(fields) = extensions.get_mut::<FormattedFields<N>>() {
let _ = self.fmt_fields.add_fields(fields, values);
return;
}
let mut fields = FormattedFields::<N>::new(String::new());
if self
.fmt_fields
.format_fields(fields.as_writer().with_ansi(self.is_ansi), values)
.is_ok()
{
fields.was_ansi = self.is_ansi;
extensions.insert(fields);
}
}
fn on_enter(&self, id: &Id, ctx: Context<'_, S>) {
if self.fmt_span.trace_enter() || self.fmt_span.trace_close() && self.fmt_span.fmt_timing {
let span = ctx.span(id).expect("Span not found, this is a bug");
let mut extensions = span.extensions_mut();
if let Some(timings) = extensions.get_mut::<Timings>() {
let now = Instant::now();
timings.idle += (now - timings.last).as_nanos() as u64;
timings.last = now;
}
if self.fmt_span.trace_enter() {
with_event_from_span!(id, span, "message" = "enter", |event| {
drop(extensions);
drop(span);
self.on_event(&event, ctx);
});
}
}
}
fn on_exit(&self, id: &Id, ctx: Context<'_, S>) {
if self.fmt_span.trace_exit() || self.fmt_span.trace_close() && self.fmt_span.fmt_timing {
let span = ctx.span(id).expect("Span not found, this is a bug");
let mut extensions = span.extensions_mut();
if let Some(timings) = extensions.get_mut::<Timings>() {
let now = Instant::now();
timings.busy += (now - timings.last).as_nanos() as u64;
timings.last = now;
}
if self.fmt_span.trace_exit() {
with_event_from_span!(id, span, "message" = "exit", |event| {
drop(extensions);
drop(span);
self.on_event(&event, ctx);
});
}
}
}
fn on_close(&self, id: Id, ctx: Context<'_, S>) {
if self.fmt_span.trace_close() {
let span = ctx.span(&id).expect("Span not found, this is a bug");
let extensions = span.extensions();
if let Some(timing) = extensions.get::<Timings>() {
let Timings {
busy,
mut idle,
last,
} = *timing;
idle += (Instant::now() - last).as_nanos() as u64;
let t_idle = field::display(TimingDisplay(idle));
let t_busy = field::display(TimingDisplay(busy));
with_event_from_span!(
id,
span,
"message" = "close",
"time.busy" = t_busy,
"time.idle" = t_idle,
|event| {
drop(extensions);
drop(span);
self.on_event(&event, ctx);
}
);
} else {
with_event_from_span!(id, span, "message" = "close", |event| {
drop(extensions);
drop(span);
self.on_event(&event, ctx);
});
}
}
}
fn on_event(&self, event: &Event<'_>, ctx: Context<'_, S>) {
thread_local! {
static BUF: RefCell<String> = RefCell::new(String::new());
}
BUF.with(|buf| {
let borrow = buf.try_borrow_mut();
let mut a;
let mut b;
let mut buf = match borrow {
Ok(buf) => {
a = buf;
&mut *a
}
_ => {
b = String::new();
&mut b
}
};
let ctx = self.make_ctx(ctx, event);
if self
.fmt_event
.format_event(
&ctx,
format::Writer::new(&mut buf).with_ansi(self.is_ansi),
event,
)
.is_ok()
{
let mut writer = self.make_writer.make_writer_for(event.metadata());
let res = io::Write::write_all(&mut writer, buf.as_bytes());
if self.log_internal_errors {
if let Err(e) = res {
eprintln!("[tracing-subscriber] Unable to write an event to the Writer for this Subscriber! Error: {}\n", e);
}
}
} else if self.log_internal_errors {
let err_msg = format!("Unable to format the following event. Name: {}; Fields: {:?}\n",
event.metadata().name(), event.fields());
let mut writer = self.make_writer.make_writer_for(event.metadata());
let res = io::Write::write_all(&mut writer, err_msg.as_bytes());
if let Err(e) = res {
eprintln!("[tracing-subscriber] Unable to write an \"event formatting error\" to the Writer for this Subscriber! Error: {}\n", e);
}
}
buf.clear();
});
}
unsafe fn downcast_raw(&self, id: TypeId) -> Option<*const ()> {
// This `downcast_raw` impl allows downcasting a `fmt` layer to any of
// its components (event formatter, field formatter, and `MakeWriter`)
// as well as to the layer's type itself. The potential use-cases for
// this *may* be somewhat niche, though...
match () {
_ if id == TypeId::of::<Self>() => Some(self as *const Self as *const ()),
_ if id == TypeId::of::<E>() => Some(&self.fmt_event as *const E as *const ()),
_ if id == TypeId::of::<N>() => Some(&self.fmt_fields as *const N as *const ()),
_ if id == TypeId::of::<W>() => Some(&self.make_writer as *const W as *const ()),
_ => None,
}
}
}
/// Provides the current span context to a formatter.
pub struct FmtContext<'a, S, N> {
pub(crate) ctx: Context<'a, S>,
pub(crate) fmt_fields: &'a N,
pub(crate) event: &'a Event<'a>,
}
impl<'a, S, N> fmt::Debug for FmtContext<'a, S, N> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("FmtContext").finish()
}
}
impl<'cx, 'writer, S, N> FormatFields<'writer> for FmtContext<'cx, S, N>
where
S: Subscriber + for<'lookup> LookupSpan<'lookup>,
N: FormatFields<'writer> + 'static,
{
fn format_fields<R: RecordFields>(
&self,
writer: format::Writer<'writer>,
fields: R,
) -> fmt::Result {
self.fmt_fields.format_fields(writer, fields)
}
}
impl<'a, S, N> FmtContext<'a, S, N>
where
S: Subscriber + for<'lookup> LookupSpan<'lookup>,
N: for<'writer> FormatFields<'writer> + 'static,
{
/// Visits every span in the current context with a closure.
///
/// The provided closure will be called first with the current span,
/// and then with that span's parent, and then that span's parent,
/// and so on until a root span is reached.
pub fn visit_spans<E, F>(&self, mut f: F) -> Result<(), E>
where
F: FnMut(&SpanRef<'_, S>) -> Result<(), E>,
{
// visit all the current spans
if let Some(scope) = self.event_scope() {
for span in scope.from_root() {
f(&span)?;
}
}
Ok(())
}
/// Returns metadata for the span with the given `id`, if it exists.
///
/// If this returns `None`, then no span exists for that ID (either it has
/// closed or the ID is invalid).
#[inline]
pub fn metadata(&self, id: &Id) -> Option<&'static Metadata<'static>>
where
S: for<'lookup> LookupSpan<'lookup>,
{
self.ctx.metadata(id)
}
/// Returns [stored data] for the span with the given `id`, if it exists.
///
/// If this returns `None`, then no span exists for that ID (either it has
/// closed or the ID is invalid).
///
/// [stored data]: crate::registry::SpanRef
#[inline]
pub fn span(&self, id: &Id) -> Option<SpanRef<'_, S>>
where
S: for<'lookup> LookupSpan<'lookup>,
{
self.ctx.span(id)
}
/// Returns `true` if an active span exists for the given `Id`.
#[inline]
pub fn exists(&self, id: &Id) -> bool
where
S: for<'lookup> LookupSpan<'lookup>,
{
self.ctx.exists(id)
}
/// Returns [stored data] for the span that the wrapped subscriber considers
/// to be the current.
///
/// If this returns `None`, then we are not currently within a span.
///
/// [stored data]: crate::registry::SpanRef
#[inline]
pub fn lookup_current(&self) -> Option<SpanRef<'_, S>>
where
S: for<'lookup> LookupSpan<'lookup>,
{
self.ctx.lookup_current()
}
/// Returns the current span for this formatter.
pub fn current_span(&self) -> Current {
self.ctx.current_span()
}
/// Returns [stored data] for the parent span of the event currently being
/// formatted.
///
/// If the event has a contextual parent, this will return the current span. If
/// the event has an explicit parent span, this will return that span. If
/// the event does not have a parent span, this will return `None`.
///
/// [stored data]: SpanRef
pub fn parent_span(&self) -> Option<SpanRef<'_, S>> {
self.ctx.event_span(self.event)
}
/// Returns an iterator over the [stored data] for all the spans in the
/// current context, starting with the specified span and ending with the
/// root of the trace tree and ending with the current span.
///
/// This is equivalent to the [`Context::span_scope`] method.
///
/// <div class="information">
/// <div class="tooltip ignore" style="">ⓘ<span class="tooltiptext">Note</span></div>
/// </div>
/// <div class="example-wrap" style="display:inline-block">
/// <pre class="ignore" style="white-space:normal;font:inherit;">
/// <strong>Note</strong>: Compared to <a href="#method.scope"><code>scope</code></a> this
/// returns the spans in reverse order (from leaf to root). Use
/// <a href="../registry/struct.Scope.html#method.from_root"><code>Scope::from_root</code></a>
/// in case root-to-leaf ordering is desired.
/// </pre></div>
///
/// <div class="example-wrap" style="display:inline-block">
/// <pre class="ignore" style="white-space:normal;font:inherit;">
/// <strong>Note</strong>: This requires the wrapped subscriber to implement the
/// <a href="../registry/trait.LookupSpan.html"><code>LookupSpan</code></a> trait.
/// See the documentation on <a href="./struct.Context.html"><code>Context</code>'s
/// declaration</a> for details.
/// </pre></div>
///
/// [stored data]: crate::registry::SpanRef
pub fn span_scope(&self, id: &Id) -> Option<registry::Scope<'_, S>>
where
S: for<'lookup> LookupSpan<'lookup>,
{
self.ctx.span_scope(id)
}
/// Returns an iterator over the [stored data] for all the spans in the
/// event's span context, starting with its parent span and ending with the
/// root of the trace tree.
///
/// This is equivalent to calling the [`Context::event_scope`] method and
/// passing the event currently being formatted.
///
/// <div class="example-wrap" style="display:inline-block">
/// <pre class="ignore" style="white-space:normal;font:inherit;">
/// <strong>Note</strong>: Compared to <a href="#method.scope"><code>scope</code></a> this
/// returns the spans in reverse order (from leaf to root). Use
/// <a href="../registry/struct.Scope.html#method.from_root"><code>Scope::from_root</code></a>
/// in case root-to-leaf ordering is desired.
/// </pre></div>
///
/// <div class="example-wrap" style="display:inline-block">
/// <pre class="ignore" style="white-space:normal;font:inherit;">
/// <strong>Note</strong>: This requires the wrapped subscriber to implement the
/// <a href="../registry/trait.LookupSpan.html"><code>LookupSpan</code></a> trait.
/// See the documentation on <a href="./struct.Context.html"><code>Context</code>'s
/// declaration</a> for details.
/// </pre></div>
///
/// [stored data]: crate::registry::SpanRef
pub fn event_scope(&self) -> Option<registry::Scope<'_, S>>
where
S: for<'lookup> registry::LookupSpan<'lookup>,
{
self.ctx.event_scope(self.event)
}
/// Returns the [field formatter] configured by the subscriber invoking
/// `format_event`.
///
/// The event formatter may use the returned field formatter to format the
/// fields of any events it records.
///
/// [field formatter]: FormatFields
pub fn field_format(&self) -> &N {
self.fmt_fields
}
}
struct Timings {
idle: u64,
busy: u64,
last: Instant,
}
impl Timings {
fn new() -> Self {
Self {
idle: 0,
busy: 0,
last: Instant::now(),
}
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::fmt::{
self,
format::{self, test::MockTime, Format},
layer::Layer as _,
test::{MockMakeWriter, MockWriter},
time,
};
use crate::Registry;
use format::FmtSpan;
use regex::Regex;
use tracing::subscriber::with_default;
use tracing_core::dispatcher::Dispatch;
#[test]
fn impls() {
let f = Format::default().with_timer(time::Uptime::default());
let fmt = fmt::Layer::default().event_format(f);
let subscriber = fmt.with_subscriber(Registry::default());
let _dispatch = Dispatch::new(subscriber);
let f = format::Format::default();
let fmt = fmt::Layer::default().event_format(f);
let subscriber = fmt.with_subscriber(Registry::default());
let _dispatch = Dispatch::new(subscriber);
let f = format::Format::default().compact();
let fmt = fmt::Layer::default().event_format(f);
let subscriber = fmt.with_subscriber(Registry::default());
let _dispatch = Dispatch::new(subscriber);
}
#[test]
fn fmt_layer_downcasts() {
let f = format::Format::default();
let fmt = fmt::Layer::default().event_format(f);
let subscriber = fmt.with_subscriber(Registry::default());
let dispatch = Dispatch::new(subscriber);
assert!(dispatch.downcast_ref::<fmt::Layer<Registry>>().is_some());
}
#[test]
fn fmt_layer_downcasts_to_parts() {
let f = format::Format::default();
let fmt = fmt::Layer::default().event_format(f);
let subscriber = fmt.with_subscriber(Registry::default());
let dispatch = Dispatch::new(subscriber);
assert!(dispatch.downcast_ref::<format::DefaultFields>().is_some());
assert!(dispatch.downcast_ref::<format::Format>().is_some())
}
#[test]
fn is_lookup_span() {
fn assert_lookup_span<T: for<'a> crate::registry::LookupSpan<'a>>(_: T) {}
let fmt = fmt::Layer::default();
let subscriber = fmt.with_subscriber(Registry::default());
assert_lookup_span(subscriber)
}
fn sanitize_timings(s: String) -> String {
let re = Regex::new("time\\.(idle|busy)=([0-9.]+)[mµn]s").unwrap();
re.replace_all(s.as_str(), "timing").to_string()
}
#[test]
fn format_error_print_to_stderr() {
struct AlwaysError;
impl std::fmt::Debug for AlwaysError {
fn fmt(&self, _f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
Err(std::fmt::Error)
}
}
let make_writer = MockMakeWriter::default();
let subscriber = crate::fmt::Subscriber::builder()
.with_writer(make_writer.clone())
.with_level(false)
.with_ansi(false)
.with_timer(MockTime)
.finish();
with_default(subscriber, || {
tracing::info!(?AlwaysError);
});
let actual = sanitize_timings(make_writer.get_string());
// Only assert the start because the line number and callsite may change.
let expected = concat!("Unable to format the following event. Name: event ", file!(), ":");
assert!(actual.as_str().starts_with(expected), "\nactual = {}\nshould start with expected = {}\n", actual, expected);
}
#[test]
fn format_error_ignore_if_log_internal_errors_is_false() {
struct AlwaysError;
impl std::fmt::Debug for AlwaysError {
fn fmt(&self, _f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
Err(std::fmt::Error)
}
}
let make_writer = MockMakeWriter::default();
let subscriber = crate::fmt::Subscriber::builder()
.with_writer(make_writer.clone())
.with_level(false)
.with_ansi(false)
.with_timer(MockTime)
.log_internal_errors(false)
.finish();
with_default(subscriber, || {
tracing::info!(?AlwaysError);
});
let actual = sanitize_timings(make_writer.get_string());
assert_eq!("", actual.as_str());
}
#[test]
fn synthesize_span_none() {
let make_writer = MockMakeWriter::default();
let subscriber = crate::fmt::Subscriber::builder()
.with_writer(make_writer.clone())
.with_level(false)
.with_ansi(false)
.with_timer(MockTime)
// check that FmtSpan::NONE is the default
.finish();
with_default(subscriber, || {
let span1 = tracing::info_span!("span1", x = 42);
let _e = span1.enter();
});
let actual = sanitize_timings(make_writer.get_string());
assert_eq!("", actual.as_str());
}
#[test]
fn synthesize_span_active() {
let make_writer = MockMakeWriter::default();
let subscriber = crate::fmt::Subscriber::builder()
.with_writer(make_writer.clone())
.with_level(false)
.with_ansi(false)
.with_timer(MockTime)
.with_span_events(FmtSpan::ACTIVE)
.finish();
with_default(subscriber, || {
let span1 = tracing::info_span!("span1", x = 42);
let _e = span1.enter();
});
let actual = sanitize_timings(make_writer.get_string());
assert_eq!(
"fake time span1{x=42}: tracing_subscriber::fmt::fmt_layer::test: enter\n\
fake time span1{x=42}: tracing_subscriber::fmt::fmt_layer::test: exit\n",
actual.as_str()
);
}
#[test]
fn synthesize_span_close() {
let make_writer = MockMakeWriter::default();
let subscriber = crate::fmt::Subscriber::builder()
.with_writer(make_writer.clone())
.with_level(false)
.with_ansi(false)
.with_timer(MockTime)
.with_span_events(FmtSpan::CLOSE)
.finish();
with_default(subscriber, || {
let span1 = tracing::info_span!("span1", x = 42);
let _e = span1.enter();
});
let actual = sanitize_timings(make_writer.get_string());
assert_eq!(
"fake time span1{x=42}: tracing_subscriber::fmt::fmt_layer::test: close timing timing\n",
actual.as_str()
);
}
#[test]
fn synthesize_span_close_no_timing() {
let make_writer = MockMakeWriter::default();
let subscriber = crate::fmt::Subscriber::builder()
.with_writer(make_writer.clone())
.with_level(false)
.with_ansi(false)
.with_timer(MockTime)
.without_time()
.with_span_events(FmtSpan::CLOSE)
.finish();
with_default(subscriber, || {
let span1 = tracing::info_span!("span1", x = 42);
let _e = span1.enter();
});
let actual = sanitize_timings(make_writer.get_string());
assert_eq!(
"span1{x=42}: tracing_subscriber::fmt::fmt_layer::test: close\n",
actual.as_str()
);
}
#[test]
fn synthesize_span_full() {
let make_writer = MockMakeWriter::default();
let subscriber = crate::fmt::Subscriber::builder()
.with_writer(make_writer.clone())
.with_level(false)
.with_ansi(false)
.with_timer(MockTime)
.with_span_events(FmtSpan::FULL)
.finish();
with_default(subscriber, || {
let span1 = tracing::info_span!("span1", x = 42);
let _e = span1.enter();
});
let actual = sanitize_timings(make_writer.get_string());
assert_eq!(
"fake time span1{x=42}: tracing_subscriber::fmt::fmt_layer::test: new\n\
fake time span1{x=42}: tracing_subscriber::fmt::fmt_layer::test: enter\n\
fake time span1{x=42}: tracing_subscriber::fmt::fmt_layer::test: exit\n\
fake time span1{x=42}: tracing_subscriber::fmt::fmt_layer::test: close timing timing\n",
actual.as_str()
);
}
#[test]
fn make_writer_based_on_meta() {
struct MakeByTarget {
make_writer1: MockMakeWriter,
make_writer2: MockMakeWriter,
}
impl<'a> MakeWriter<'a> for MakeByTarget {
type Writer = MockWriter;
fn make_writer(&'a self) -> Self::Writer {
self.make_writer1.make_writer()
}
fn make_writer_for(&'a self, meta: &Metadata<'_>) -> Self::Writer {
if meta.target() == "writer2" {
return self.make_writer2.make_writer();
}
self.make_writer()
}
}
let make_writer1 = MockMakeWriter::default();
let make_writer2 = MockMakeWriter::default();
let make_writer = MakeByTarget {
make_writer1: make_writer1.clone(),
make_writer2: make_writer2.clone(),
};
let subscriber = crate::fmt::Subscriber::builder()
.with_writer(make_writer)
.with_level(false)
.with_target(false)
.with_ansi(false)
.with_timer(MockTime)
.with_span_events(FmtSpan::CLOSE)
.finish();
with_default(subscriber, || {
let span1 = tracing::info_span!("writer1_span", x = 42);
let _e = span1.enter();
tracing::info!(target: "writer2", "hello writer2!");
let span2 = tracing::info_span!(target: "writer2", "writer2_span");
let _e = span2.enter();
tracing::warn!(target: "writer1", "hello writer1!");
});
let actual = sanitize_timings(make_writer1.get_string());
assert_eq!(
"fake time writer1_span{x=42}:writer2_span: hello writer1!\n\
fake time writer1_span{x=42}: close timing timing\n",
actual.as_str()
);
let actual = sanitize_timings(make_writer2.get_string());
assert_eq!(
"fake time writer1_span{x=42}: hello writer2!\n\
fake time writer1_span{x=42}:writer2_span: close timing timing\n",
actual.as_str()
);
}
}