Struct tracing_core::Event

pub struct Event<'a> {
    fields: &'a ValueSet<'a>,
    metadata: &'static Metadata<'static>,
    parent: Parent,
}

Events represent single points in time where something occurred during the execution of a program.

An Event can be compared to a log record in unstructured logging, but with two key differences:

• Events exist within the context of a span. Unlike log lines, they may be located within the trace tree, allowing visibility into the temporal context in which the event occurred, as well as the source code location.
• Like spans, Events have structured key-value data known as fields, which may include textual message. In general, a majority of the data associated with an event should be in the event’s fields rather than in the textual message, as the fields are more structured.

Fields

fields: &'a ValueSet<'a>

metadata: &'static Metadata<'static>

parent: Parent

Implementations

impl<'a> Event<'a>

pub fn dispatch(metadata: &'static Metadata<'static>, fields: &'a ValueSet<'_>)

Constructs a new Event with the specified metadata and set of values, and observes it with the current subscriber.

pub fn new( metadata: &'static Metadata<'static>, fields: &'a ValueSet<'a>, ) -> Self

Returns a new Event in the current span, with the specified metadata and set of values.

pub fn new_child_of( parent: impl Into<Option<Id>>, metadata: &'static Metadata<'static>, fields: &'a ValueSet<'a>, ) -> Self

Returns a new Event as a child of the specified span, with the provided metadata and set of values.

pub fn child_of( parent: impl Into<Option<Id>>, metadata: &'static Metadata<'static>, fields: &'a ValueSet<'_>, )

Constructs a new Event with the specified metadata and set of values, and observes it with the current subscriber and an explicit parent.

pub fn record(&self, visitor: &mut dyn Visit)

Visits all the fields on this Event with the specified visitor.

pub fn fields(&self) -> Iter

Returns an iterator over the set of values on this Event.

pub fn metadata(&self) -> &'static Metadata<'static>

Returns metadata describing this Event.

pub fn is_root(&self) -> bool

Returns true if the new event should be a root.

pub fn is_contextual(&self) -> bool

Returns true if the new event’s parent should be determined based on the current context.

If this is true and the current thread is currently inside a span, then that span should be the new event’s parent. Otherwise, if the current thread is not inside a span, then the new event will be the root of its own trace tree.

pub fn parent(&self) -> Option<&Id>

Returns the new event’s explicitly-specified parent, if there is one.

Otherwise (if the new event is a root or is a child of the current span), returns None.

Trait Implementations

impl<'a> Debug for Event<'a>

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

Formats the value using the given formatter.