Unify the Config type across instrumentation (#226)

* Initial idea to abstract Config internally

* Add Propagator to Config

* Test the Config.Copy method

* Add test for WithSpan

* Fix nil Config bug for mergedSpanStartOptions

* Move WithTracerProvider test to option_test

* Fix lint issues

go.mod

@@ -8,4 +8,5 @@ require (
 	go.opentelemetry.io/otel v1.2.0
 	go.opentelemetry.io/otel/exporters/jaeger v1.2.0
 	go.opentelemetry.io/otel/sdk v1.2.0
+	go.opentelemetry.io/otel/trace v1.2.0
 )

instrumentation/github.com/syndtr/goleveldb/leveldb/splunkleveldb/config.go

@@ -17,35 +17,38 @@ package splunkleveldb
 import (
 	"context"
 
-	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/codes"
 	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
 	"go.opentelemetry.io/otel/trace"
 
-	splunkotel "github.com/signalfx/splunk-otel-go"
+	"github.com/signalfx/splunk-otel-go/instrumentation/internal"
 )
 
 // instrumentationName is the instrumentation library identifier for a Tracer.
 const instrumentationName = "github.com/signalfx/splunk-otel-go/instrumentation/github.com/syndtr/goleveldb/leveldb/splunkleveldb"
 
 // config contains tracing configuration options.
 type config struct {
-	ctx              context.Context
-	tracer           trace.Tracer
-	defaultStartOpts []trace.SpanStartOption
+	*internal.Config
+
+	ctx context.Context
 }
 
 func newConfig(options ...Option) *config {
 	c := config{
-		defaultStartOpts: []trace.SpanStartOption{
-			trace.WithAttributes(
-				semconv.DBSystemKey.String("leveldb"),
-				semconv.NetTransportInProc,
-			),
-			// From the specification: span kind MUST always be CLIENT.
-			trace.WithSpanKind(trace.SpanKindClient),
-		},
+		Config: internal.NewConfig(instrumentationName, internal.OptionFunc(
+			func(c *internal.Config) {
+				c.DefaultStartOpts = []trace.SpanStartOption{
+					trace.WithAttributes(
+						semconv.DBSystemKey.String("leveldb"),
+						semconv.NetTransportInProc,
+					),
+					// From the specification: span kind MUST always be CLIENT.
+					trace.WithSpanKind(trace.SpanKindClient),
+				}
+			}),
+		),
+		ctx: context.Background(),
 	}
 
 	for _, o := range options {
@@ -54,95 +57,32 @@ func newConfig(options ...Option) *config {
 		}
 	}
 
-	if c.tracer == nil {
-		c.tracer = otel.Tracer(
-			instrumentationName,
-			trace.WithInstrumentationVersion(splunkotel.Version()),
-			trace.WithSchemaURL(semconv.SchemaURL),
-		)
-	}
-
-	if c.ctx == nil {
-		c.ctx = context.Background()
-	}
-
 	return &c
 }
 
-// resolveTracer returns an OTel tracer from the appropriate TracerProvider.
-//
-// If the passed context contains a span, the TracerProvider that created the
-// tracer that created that span will be used. Otherwise, the TracerProvider
-// from c is used.
-func (c *config) resolveTracer() trace.Tracer {
-	// There is a possibility that the config was not created with newConfig,
-	// try to handle this situation gracefully.
-	if c == nil {
-		return otel.Tracer(
-			instrumentationName,
-			trace.WithInstrumentationVersion(splunkotel.Version()),
-			trace.WithSchemaURL(semconv.SchemaURL),
-		)
-	}
-
-	if span := trace.SpanFromContext(c.ctx); span.SpanContext().IsValid() {
-		return span.TracerProvider().Tracer(
-			instrumentationName,
-			trace.WithInstrumentationVersion(splunkotel.Version()),
-			trace.WithSchemaURL(semconv.SchemaURL),
-		)
-	}
-
-	if c.tracer == nil {
-		return otel.Tracer(
-			instrumentationName,
-			trace.WithInstrumentationVersion(splunkotel.Version()),
-			trace.WithSchemaURL(semconv.SchemaURL),
-		)
-	}
-	return c.tracer
+// Option applies options to a configuration.
+type Option interface {
+	apply(*config)
 }
 
-func (c *config) mergedSpanStartOptions(opts ...trace.SpanStartOption) []trace.SpanStartOption {
-	if c == nil {
-		if len(opts) == 0 {
-			return nil
-		}
-	} else {
-		if len(opts)+len(c.defaultStartOpts) == 0 {
-			return nil
-		}
-	}
-
-	var merged []trace.SpanStartOption
-	if c == nil || len(c.defaultStartOpts) == 0 {
-		merged = make([]trace.SpanStartOption, len(opts))
-		copy(merged, opts)
-	} else {
-		merged = make([]trace.SpanStartOption, len(c.defaultStartOpts)+len(opts))
-		copy(merged, c.defaultStartOpts)
-		copy(merged[len(c.defaultStartOpts):], opts)
-	}
-	return merged
+type optConv struct {
+	iOpt internal.Option
 }
 
-// withSpan wraps the function f with a span.
-func (c *config) withSpan(name string, f func() error, opts ...trace.SpanStartOption) error {
-	sso := c.mergedSpanStartOptions(opts...)
-	_, span := c.resolveTracer().Start(c.ctx, name, sso...)
-	err := f()
-	if err != nil {
-		span.RecordError(err)
-		span.SetStatus(codes.Error, err.Error())
-	}
-	span.End()
+func (o optConv) apply(c *config) {
+	o.iOpt.Apply(c.Config)
+}
 
-	return err
+// WithTracerProvider returns an Option that sets the TracerProvider used with
+// this instrumentation library.
+func WithTracerProvider(tp trace.TracerProvider) Option {
+	return optConv{iOpt: internal.WithTracerProvider(tp)}
 }
 
-// Option applies options to a configuration.
-type Option interface {
-	apply(*config)
+// WithAttributes returns an Option that appends attr to the attributes set
+// for every span created with this instrumentation library.
+func WithAttributes(attr []attribute.KeyValue) Option {
+	return optConv{iOpt: internal.WithAttributes(attr)}
 }
 
 type optionFunc func(*config)
@@ -151,17 +91,6 @@ func (o optionFunc) apply(c *config) {
 	o(c)
 }
 
-// WithTracerProvider returns an Option that sets the TracerProvider used with
-// this instrumentation library.
-func WithTracerProvider(tp trace.TracerProvider) Option {
-	return optionFunc(func(c *config) {
-		c.tracer = tp.Tracer(
-			instrumentationName,
-			trace.WithInstrumentationVersion(splunkotel.Version()),
-		)
-	})
-}
-
 // WithContext returns an Option that sets the Context used with this
 // instrumentation library by default. This is used to pass context of any
 // existing trace to the instrumentation.
@@ -170,14 +99,3 @@ func WithContext(ctx context.Context) Option {
 		c.ctx = ctx
 	})
 }
-
-// WithAttributes returns an Option that appends attr to the attributes set
-// for every span created with this instrumentation library.
-func WithAttributes(attr []attribute.KeyValue) Option {
-	return optionFunc(func(c *config) {
-		c.defaultStartOpts = append(
-			c.defaultStartOpts,
-			trace.WithAttributes(attr...),
-		)
-	})
-}