Module opentelemetry::trace [−][src]
trace
only.Expand description
The trace
module includes types for tracking the progression of a single
request while it is handled by services that make up an application. A trace
is a tree of Span
s which are objects that represent the work being done
by individual services or components involved in a request as it flows
through a system. This module implements the OpenTelemetry trace
specification.
Getting Started
In application code:
use opentelemetry::{global, sdk::export::trace::stdout, trace::Tracer}; fn main() { // Create a new trace pipeline that prints to stdout let tracer = stdout::new_pipeline().install_simple(); tracer.in_span("doing_work", |cx| { // Traced app logic here... }); // Shutdown trace pipeline global::shutdown_tracer_provider(); }
In library code:
use opentelemetry::{global, trace::{Span, Tracer, TracerProvider}}; fn my_library_function() { // Use the global tracer provider to get access to the user-specified // tracer configuration let tracer_provider = global::tracer_provider(); // Get a tracer for this library let tracer = tracer_provider.get_tracer("my_name", Some(env!("CARGO_PKG_VERSION"))); // Create spans let mut span = tracer.start("doing_work"); // Do work... // End the span span.end(); }
Overview
The tracing API consists of a three main traits:
TracerProvider
s are the entry point of the API. They provide access toTracer
s.Tracer
s are types responsible for creatingSpan
s.Span
s provide the API to trace an operation.
Working with Async Runtimes
Exporting spans often involves sending data over a network or performing
other I/O tasks. OpenTelemetry allows you to schedule these tasks using
whichever runtime you area already using such as Tokio or async-std.
When using an async runtime it’s best to use the BatchSpanProcessor
where the spans will be sent in batches as opposed to being sent once ended,
which often ends up being more efficient.
Managing Active Spans
Spans can be marked as “active” for a given Context
, and all newly
created spans will automatically be children of the currently active span.
The active span for a given thread can be managed via get_active_span
and mark_span_as_active
.
use opentelemetry::{global, trace::{self, Span, StatusCode, Tracer, TracerProvider}}; fn may_error(rand: f32) { if rand < 0.5 { // Get the currently active span to record additional attributes, // status, etc. trace::get_active_span(|span| { span.set_status(StatusCode::Error, "value too small".into()); }); } } // Get a tracer let tracer = global::tracer("my_tracer"); // Create a span let span = tracer.start("parent_span"); // Mark the span as active let active = trace::mark_span_as_active(span); // Any span created here will be a child of `parent_span`... // Drop the guard and the span will no longer be active drop(active)
Additionally Tracer::with_span
and Tracer::in_span
can be used as shorthand to
simplify managing the parent context.
use opentelemetry::{global, trace::Tracer}; // Get a tracer let tracer = global::tracer("my_tracer"); // Use `in_span` to create a new span and mark it as the parent, dropping it // at the end of the block. tracer.in_span("parent_span", |cx| { // spans created here will be children of `parent_span` }); // Use `with_span` to mark a span as active for a given period. let span = tracer.start("parent_span"); tracer.with_span(span, |cx| { // spans created here will be children of `parent_span` });
Async active spans
Async spans can be propagated with TraceContextExt
and FutureExt
.
use opentelemetry::{Context, global, trace::{FutureExt, TraceContextExt, Tracer}}; async fn some_work() { } // Get a tracer let tracer = global::tracer("my_tracer"); // Start a span let span = tracer.start("my_span"); // Perform some async work with this span as the currently active parent. some_work().with_context(Context::current_with_span(span));
Structs
Event | A |
Link | During the |
NoopSpan | A no-op instance of a |
NoopSpanExporter | A no-op instance of an |
NoopTracer | A no-op instance of a |
NoopTracerProvider | A no-op instance of a |
SpanBuilder |
|
SpanContext | Immutable portion of a |
SpanId | SpanId is an 8-byte value which uniquely identifies a given span within a trace
The actual |
TraceFlags | Flags that can be set on a |
TraceId | TraceId is an 16-byte value which uniquely identifies a given trace
The actual |
TraceState | TraceState carries system-specific configuration data, represented as a list of key-value pairs. TraceState allows multiple tracing systems to participate in the same trace. |
Enums
SpanKind |
|
StatusCode | The |
TraceError | Errors returned by the trace API. |
TraceStateError | Error returned by |
Traits
FutureExt | Extension trait allowing futures, streams, and sinks to be traced with a span. |
IdGenerator | Interface for generating IDs |
Span | Interface for a single operation within a trace. |
TraceContextExt | Methods for storing and retrieving trace data in a context. |
Tracer | Interface for constructing |
TracerProvider | An interface to create |
Functions
get_active_span | Executes a closure with a reference to this thread’s current span. |
mark_span_as_active | Mark a given |
Type Definitions
TraceResult | Describe the result of operations in tracing API. |