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tracer_provider.go
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/
tracer_provider.go
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// Unless explicitly stated otherwise all files in this repository are licensed
// under the Apache License Version 2.0.
// This product includes software developed at Datadog (https://www.datadoghq.com/).
// Copyright 2023 Datadog, Inc.
// Package opentelemetry provides a wrapper on top of the Datadog tracer that can be used with OpenTelemetry.
// This feature is currently in beta.
// It also provides a wrapper around TracerProvider to propagate a list of tracer.StartOption
// that are specific to Datadog's APM product. To use it, simply call "NewTracerProvider".
//
// provider := opentelemetry.NewTracerProvider(tracer.WithService("opentelemetry_service"))
//
// When using Datadog, the OpenTelemetry span name is what is called operation name in Datadog's terms.
// Below is an example setting the tracer provider, initializing a tracer, and creating a span.
//
// otel.SetTracerProvider(opentelemetry.NewTracerProvider())
// tracer := otel.Tracer("")
// ctx, sp := tracer.Start(context.Background(), "span_name")
// yourCode(ctx)
// sp.End()
//
// Not every feature provided by OpenTelemetry is supported with this wrapper today.
// This package seeks to implement a minimal set of functions within
// the OpenTelemetry Tracing API (https://opentelemetry.io/docs/reference/specification/trace/api)
// to allow users to send traces to Datadog using existing OpenTelemetry code with minimal changes to the application.
// Span events (https://opentelemetry.io/docs/concepts/signals/traces/#span-events) are not supported at this time.
package opentelemetry
import (
"fmt"
"os"
"strings"
"sync"
"sync/atomic"
"time"
"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/internal"
"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
"gopkg.in/DataDog/dd-trace-go.v1/internal/log"
oteltrace "go.opentelemetry.io/otel/trace"
)
var _ oteltrace.TracerProvider = (*TracerProvider)(nil)
// TracerProvider provides implementation of OpenTelemetry TracerProvider interface.
// TracerProvider provides Tracers that are used by instrumentation code to
// trace computational workflows.
// WithInstrumentationVersion and WithSchemaURL TracerOptions are not supported.
type TracerProvider struct {
tracer *oteltracer
ddopts []tracer.StartOption
stopped uint32 // stopped indicates whether the tracerProvider has been shutdown.
sync.Once
}
// NewTracerProvider returns an instance of OpenTelemetry TracerProvider with Datadog Tracer start options.
// This allows propagation of the parameters to tracer.Start.
func NewTracerProvider(opts ...tracer.StartOption) *TracerProvider {
return &TracerProvider{ddopts: opts}
}
const (
w3cPropagator = "tracecontext"
genericHeaderPropagationStyle = "DD_TRACE_PROPAGATION_STYLE"
)
// Tracer returns an instance of OpenTelemetry Tracer and initializes Datadog Tracer.
// If the TracerProvider has already been shut down, this will return a no-op tracer.
func (p *TracerProvider) Tracer(_ string, _ ...oteltrace.TracerOption) oteltrace.Tracer {
if atomic.LoadUint32(&p.stopped) != 0 {
return &noopOteltracer{}
}
setW3CPropagationStyle("DD_TRACE_PROPAGATION_STYLE_INJECT",
"DD_PROPAGATION_STYLE_INJECT", genericHeaderPropagationStyle)
setW3CPropagationStyle("DD_TRACE_PROPAGATION_STYLE_EXTRACT",
"DD_PROPAGATION_STYLE_EXTRACT", genericHeaderPropagationStyle)
tracer.Start(p.ddopts...)
return &oteltracer{
Tracer: internal.GetGlobalTracer(),
provider: p,
}
}
func setW3CPropagationStyle(env ...string) {
for _, key := range env {
// if trace context propagation style was set but does not contain w3c propagator,
// append the w3c propagator
if v := os.Getenv(key); v != "" && !strings.Contains(v, w3cPropagator) {
style := fmt.Sprintf("%s,%s", v, w3cPropagator)
os.Setenv(key, style)
log.Info(fmt.Sprintf("W3C context propagation not enabled. "+
"Updating '%s' from '%s' to '%s'.", key, v, style))
return
}
}
// trace context propagation was not configured through environment variable,
// setting propagation style to tracecontext
if v := os.Getenv(genericHeaderPropagationStyle); v == "" {
log.Info(fmt.Sprintf("Trace context propagation style not configured. "+
"Setting '%s' to '%s'.", genericHeaderPropagationStyle, w3cPropagator))
os.Setenv(genericHeaderPropagationStyle, w3cPropagator)
}
}
// Shutdown stops the started tracer. Subsequent calls are valid but become no-op.
func (p *TracerProvider) Shutdown() error {
p.Once.Do(func() {
tracer.Stop()
atomic.StoreUint32(&p.stopped, 1)
})
return nil
}
// ForceFlush flushes any buffered traces. Flush is in effect only if a tracer
// is started.
func (p *TracerProvider) ForceFlush(timeout time.Duration, callback func(ok bool)) {
p.forceFlush(timeout, callback, tracer.Flush)
}
func (p *TracerProvider) forceFlush(timeout time.Duration, callback func(ok bool), flush func()) {
if atomic.LoadUint32(&p.stopped) != 0 {
log.Warn("Cannot perform (*TracerProvider).Flush since the tracer is already stopped.")
return
}
done := make(chan struct{})
go func() {
flush()
done <- struct{}{}
}()
for {
select {
case <-time.After(timeout):
callback(false)
return
case <-done:
callback(true)
return
}
}
}