Struct tracing_core::Metadata [−][src]
Metadata describing a span or event.
All spans and events have the following metadata:
- A name, represented as a static string.
- A target, a string that categorizes part of the system where the span
or event occurred. The
tracing
macros default to using the module path where the span or event originated as the target, but it may be overridden. - A verbosity level.
- The names of the fields defined by the span or event.
- Whether the metadata corresponds to a span or event.
In addition, the following optional metadata describing the source code location where the span or event originated may be provided:
- The file name
- The line number
- The module path
Metadata is used by Subscriber
s 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 ofMetadata
cannot be compared directly, they provide a methodid
, returning an opaque callsite identifier which uniquely identifies the callsite where the metadata originated. This can be used to determine if twoMetadata
correspond to the same callsite.
Implementations
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
) -> Self
[src]
name: &'static str,
target: &'a str,
level: Level,
file: Option<&'a str>,
line: Option<u32>,
module_path: Option<&'a str>,
fields: FieldSet,
kind: Kind
) -> Self
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
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,
[src]
T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
[src]
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
[src]
T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
[src]
impl<T> From<T> for T
[src]
impl<T, U> Into<U> for T where
U: From<T>,
[src]
U: From<T>,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
[src]
U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
[src]
impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
[src]
U: TryFrom<T>,