Struct tracing_subscriber::fmt::Layer

pub struct Layer<S, N = DefaultFields, E = Format<Full>, W = fn() -> Stdout> { /* fields omitted */ }

A Layer that logs formatted representations of tracing events.

Examples

Constructing a default fmt subscriber via the Layer API:

use tracing_subscriber::{fmt, registry::Registry};
use tracing_subscriber::prelude::*;

let subscriber = fmt::Layer::default()
    .with_subscriber(Registry::default());

tracing::subscriber::set_global_default(subscriber).unwrap();

Methods

impl<S> Layer<S>

pub fn builder() -> LayerBuilder<S>

Returns a new LayerBuilder for configuring a Layer.

Trait Implementations

impl<S: Debug, N: Debug, E: Debug, W: Debug> Debug for Layer<S, N, E, W>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl<S> Default for Layer<S> where
    S: Subscriber + for<'a> LookupSpan<'a>, 

fn default() -> Self

Returns the "default value" for a type.

impl<S, N, E, W> 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: MakeWriter + 'static, 

fn new_span(&self, attrs: &Attributes, id: &Id, ctx: Context<S>)

Notifies this layer that a new span was constructed with the given Attributes and Id.

fn on_record(&self, id: &Id, values: &Record, ctx: Context<S>)

Notifies this layer that a span with the given Id recorded the given values.

fn on_event(&self, event: &Event, ctx: Context<S>)

Notifies this layer that an event has occurred.

unsafe fn downcast_raw(&self, id: TypeId) -> Option<*const ()>

fn register_callsite(&self, metadata: &'static Metadata<'static>) -> Interest

Registers a new callsite with this layer, returning whether or not the layer is interested in being notified about the callsite, similarly to [Subscriber::register_callsite].

fn enabled(&self, metadata: &Metadata, ctx: Context<S>) -> bool

Returns true if this layer is interested in a span or event with the given metadata in the current [Context], similarly to [Subscriber::enabled].

fn on_follows_from(&self, _span: &Id, _follows: &Id, _ctx: Context<S>)

Notifies this layer that a span with the ID span recorded that it follows from the span with the ID follows.

fn on_enter(&self, _id: &Id, _ctx: Context<S>)

Notifies this layer that a span with the given ID was entered.

fn on_exit(&self, _id: &Id, _ctx: Context<S>)

Notifies this layer that the span with the given ID was exited.

fn on_close(&self, _id: Id, _ctx: Context<S>)

Notifies this layer that the span with the given ID has been closed.

fn on_id_change(&self, _old: &Id, _new: &Id, _ctx: Context<S>)

Notifies this layer that a span ID has been cloned, and that the subscriber returned a different ID.

fn and_then<L>(self, layer: L) -> Layered<L, Self, S> where
    L: Layer<S>,
    Self: Sized, 

Composes this layer around the given Layer, returning a Layered struct implementing Layer.

fn with_subscriber(self, inner: S) -> Layered<Self, S> where
    Self: Sized, 

Composes this Layer with the given [Subscriber], returning a Layered struct that implements [Subscriber].