Struct tracing_subscriber::fmt::FmtContext

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

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 scope(&self) -> Scope<'_, S> where
    S: for<'lookup> LookupSpan<'lookup>, 

Returns an iterator over the stored data for all the spans in the current context, starting the root of the trace tree and ending with the current span.

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 mut dyn Write,
    fields: R
) -> Result

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

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

Record additional field(s) on an existing span.