[][src]Struct tracing::Metadata

pub struct Metadata<'a> { /* fields omitted */ }

Metadata describing a span or event.

All spans and events have the following metadata:

In addition, the following optional metadata describing the source code location where the span or event originated may be provided:

Metadata is used by Subscribers when filtering spans and events, and it may also be used as part of their data payload.

When created by the event! or span! macro, the metadata describing a particular event or span is constructed statically and exists as a single static instance. Thus, the overhead of creating the metadata is significantly lower than that of creating the actual span. Therefore, filtering is based on metadata, rather than on the constructed span.

Note: Although instances of Metadata cannot be compared directly, they provide a method id which returns an opaque callsite identifier which uniquely identifies the callsite where the metadata originated. This can be used for determining if two Metadata correspond to the same callsite.


impl<'a> Metadata<'a>[src]

pub const fn new(
    name: &'static str,
    target: &'a str,
    level: Level,
    file: Option<&'a str>,
    line: Option<u32>,
    module_path: Option<&'a str>,
    fields: FieldSet,
    kind: Kind
) -> Metadata<'a>

Construct new metadata for a span or event, with a name, target, level, field names, and optional source code location.

pub fn fields(&self) -> &FieldSet[src]

Returns the names of the fields on the described span or event.

pub fn level(&self) -> &Level[src]

Returns the level of verbosity of the described span or event.

pub fn name(&self) -> &'static str[src]

Returns the name of the span.

pub fn target(&self) -> &'a str[src]

Returns a string describing the part of the system where the span or event that this metadata describes occurred.

Typically, this is the module path, but alternate targets may be set when spans or events are constructed.

pub fn module_path(&self) -> Option<&'a str>[src]

Returns the path to the Rust module where the span occurred, or None if the module path is unknown.

pub fn file(&self) -> Option<&'a str>[src]

Returns the name of the source code file where the span occurred, or None if the file is unknown

pub fn line(&self) -> Option<u32>[src]

Returns the line number in the source code file where the span occurred, or None if the line number is unknown.

pub fn callsite(&self) -> Identifier[src]

Returns an opaque Identifier that uniquely identifies the callsite this Metadata originated from.

pub fn is_event(&self) -> bool[src]

Returns true if the callsite kind is Event.

pub fn is_span(&self) -> bool[src]

Return true if the callsite kind is Span.

Trait Implementations

impl<'a> Debug for Metadata<'a>[src]

Auto Trait Implementations

impl<'a> !RefUnwindSafe for Metadata<'a>

impl<'a> Send for Metadata<'a>

impl<'a> Sync for Metadata<'a>

impl<'a> Unpin for Metadata<'a>

impl<'a> !UnwindSafe for Metadata<'a>

Blanket Implementations

impl<T> Any for T where
    T: 'static + ?Sized

impl<T> Borrow<T> for T where
    T: ?Sized

impl<T> BorrowMut<T> for T where
    T: ?Sized

impl<T> From<T> for T[src]

impl<T, U> Into<U> for T where
    U: From<T>, 

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.