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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package autoexport // import "go.opentelemetry.io/contrib/exporters/autoexport"
import (
"context"
"errors"
"fmt"
"sync"
)
const otelExporterOTLPProtoEnvKey = "OTEL_EXPORTER_OTLP_PROTOCOL"
// registry maintains a map of exporter names to exporter factories
// func(context.Context) (T, error) that is safe for concurrent use by multiple
// goroutines without additional locking or coordination.
type registry[T any] struct {
mu sync.Mutex
names map[string]func(context.Context) (T, error)
}
var (
// errUnknownExporterProducer is returned when an unknown exporter name is used in
// the OTEL_*_EXPORTER or OTEL_METRICS_PRODUCERS environment variables.
errUnknownExporterProducer = errors.New("unknown exporter or metrics producer")
// errInvalidOTLPProtocol is returned when an invalid protocol is used in
// the OTEL_EXPORTER_OTLP_PROTOCOL environment variable.
errInvalidOTLPProtocol = errors.New("invalid OTLP protocol - should be one of ['grpc', 'http/protobuf']")
// errDuplicateRegistration is returned when an duplicate registration is detected.
errDuplicateRegistration = errors.New("duplicate registration")
)
// load returns tries to find the exporter factory with the key and
// then execute the factory, returning the created SpanExporter.
// errUnknownExporterProducer is returned if the registration is missing and the error from
// executing the factory if not nil.
func (r *registry[T]) load(ctx context.Context, key string) (T, error) {
r.mu.Lock()
defer r.mu.Unlock()
factory, ok := r.names[key]
if !ok {
var zero T
return zero, errUnknownExporterProducer
}
return factory(ctx)
}
// store sets the factory for a key if is not already in the registry. errDuplicateRegistration
// is returned if the registry already contains key.
func (r *registry[T]) store(key string, factory func(context.Context) (T, error)) error {
r.mu.Lock()
defer r.mu.Unlock()
if _, ok := r.names[key]; ok {
return fmt.Errorf("%w: %q", errDuplicateRegistration, key)
}
r.names[key] = factory
return nil
}
func must(err error) {
if err != nil {
panic(err)
}
}
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