Struct tracing_subscriber::fmt::FmtContext

pub struct FmtContext<'a, S, N> { /* private fields */ }

Available on crate features fmt and std only.

Provides the current span context to a formatter.

Implementations

impl<'a, S, N> FmtContext<'a, S, N>

where S: Subscriber + for<'lookup> LookupSpan<'lookup>, N: for<'writer> FormatFields<'writer> + 'static,

pub fn visit_spans<E, F>(&self, f: F) -> Result<(), E>

where F: FnMut(&SpanRef<'_, S>) -> Result<(), E>,

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 metadata(&self, id: &Id) -> Option<&'static Metadata<'static>>

where S: for<'lookup> LookupSpan<'lookup>,

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).

pub fn span(&self, id: &Id) -> Option<SpanRef<'_, S>>

where S: for<'lookup> LookupSpan<'lookup>,

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).

pub fn exists(&self, id: &Id) -> bool

where S: for<'lookup> LookupSpan<'lookup>,

Returns true if an active span exists for the given Id.

pub fn lookup_current(&self) -> Option<SpanRef<'_, S>>

where S: for<'lookup> LookupSpan<'lookup>,

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.

pub fn current_span(&self) -> Current

Returns the current span for this formatter.

pub fn parent_span(&self) -> Option<SpanRef<'_, S>>

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.

pub fn span_scope(&self, id: &Id) -> Option<Scope<'_, S>>

where S: for<'lookup> LookupSpan<'lookup>,

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.

Note: Compared to scope this
returns the spans in reverse order (from leaf to root). Use
Scope::from_root
in case root-to-leaf ordering is desired.

Note: This requires the wrapped subscriber to implement the
LookupSpan trait.
See the documentation on Context's
declaration for details.

pub fn event_scope(&self) -> Option<Scope<'_, S>>

where S: for<'lookup> LookupSpan<'lookup>,

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.

Note: Compared to scope this
returns the spans in reverse order (from leaf to root). Use
Scope::from_root
in case root-to-leaf ordering is desired.

Note: This requires the wrapped subscriber to implement the
LookupSpan trait.
See the documentation on Context's
declaration for details.

pub fn field_format(&self) -> &N

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.

Trait Implementations

impl<'a, S, N> Debug for FmtContext<'a, S, N>

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

Formats the value using the given formatter.

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: Writer<'writer>, fields: R ) -> Result

Format the provided fields to the provided Writer, returning a result.

fn add_fields( &self, current: &'writer mut FormattedFields<Self>, fields: &Record<'_> ) -> Result

Record additional field(s) on an existing span.