Struct Metadata 

pub struct Metadata { /* private fields */ }

Extensible message metadata: W3C-style trace context plus a small string baggage map. Empty by default and cheap to clone (the baggage map does not allocate until the first insert).

Implementations

impl Metadata

pub fn new() -> Self

An empty metadata map.

pub fn with_trace( trace_id: impl Into<String>, span_id: impl Into<String>, ) -> Self

Construct with a trace + span id.

pub fn trace_id(&self) -> Option<&str>

The W3C trace id, if set.

pub fn span_id(&self) -> Option<&str>

The current span id, if set.

pub fn set_trace_id(&mut self, trace_id: impl Into<String>)

Set the trace id.

pub fn set_span_id(&mut self, span_id: impl Into<String>)

Set the span id.

pub fn set_baggage(&mut self, key: impl Into<String>, value: impl Into<String>)

Insert a baggage key/value.

pub fn baggage(&self, key: &str) -> Option<&str>

Read a baggage value.

pub fn baggage_iter(&self) -> impl Iterator<Item = (&str, &str)>

Iterate baggage entries (e.g. to serialize on a remote hop).

pub fn is_empty(&self) -> bool

True if no trace context and no baggage are present.

Trait Implementations

impl Clone for Metadata

fn clone(&self) -> Metadata

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Metadata

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

Formats the value using the given formatter.

impl Default for Metadata

fn default() -> Metadata

Returns the “default value” for a type.

impl PartialEq for Metadata

fn eq(&self, other: &Metadata) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for Metadata

impl StructuralPartialEq for Metadata