TraceContext class final

Identifies a span and the trace it belongs to.

Propagated across process boundaries — into an isolate, into an HTTP header, into a job queue — so that work performed elsewhere still joins the same trace.

Annotations

• @immutable

Constructors

TraceContext({required String traceId, required String spanId, String? parentSpanId, bool sampled = true, String? traceState})

Creates a trace context.

const

Properties

hashCode → int

The hash code for this object.

no setter, override

parentSpanId → String?

Identifier of the enclosing span, absent for a root span.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

sampled → bool

Whether this trace is being recorded.

final

spanId → String

Identifier of this span.

final

traceId → String

Identifier shared by every span in the run.

final

traceState → String?

The W3C tracestate header, carried through untouched.

final

Methods

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toHeaders() → Map<String, String>

The headers that continue this trace in an outgoing request.

toJson() → JsonMap

Serialises the context for propagation.

toString() → String

A string representation of this object.

override

toTraceParent() → String

Renders the context as a W3C traceparent header value.

Operators

operator ==(Object other) → bool

The equality operator.

override

Static Methods

fromHeaders(Map<String, String> headers) → TraceContext?

Reads a context from request headers, matching names case-insensitively.

fromJson(JsonMap json) → TraceContext

Restores a context produced by toJson.

fromTraceParent(String value, {String? traceState}) → TraceContext?

Parses a W3C traceparent header value, or returns null.