Add GetLogger method to Tracer interface (#655)

interceptor/tracing_interceptor.go

@@ -30,6 +30,7 @@ import (
 	"go.temporal.io/sdk/activity"
 	"go.temporal.io/sdk/client"
 	"go.temporal.io/sdk/converter"
+	"go.temporal.io/sdk/log"
 	"go.temporal.io/sdk/workflow"
 )
 
@@ -41,6 +42,9 @@ const (
 // Tracer is an interface for tracing implementations as used by
 // NewTracingInterceptor. Most callers do not use this directly, but rather use
 // the opentracing or opentelemetry packages.
+//
+// All implementations must embed BaseTracer to safely
+// handle future changes.
 type Tracer interface {
 	// Options returns the options for the tracer. This is only called once on
 	// initialization.
@@ -61,8 +65,24 @@ type Tracer interface {
 
 	// StartSpan starts and returns a span with the given options.
 	StartSpan(*TracerStartSpanOptions) (TracerSpan, error)
+
+	// GetLogger returns a log.Logger which may include additional fields in its
+	// output in order to support correlation of tracing and log data.
+	GetLogger(log.Logger, TracerSpanRef) log.Logger
+
+	mustEmbedBaseTracer()
+}
+
+// BaseTracer is a default implementation of Tracer meant for embedding.
+type BaseTracer struct{}
+
+func (BaseTracer) GetLogger(logger log.Logger, ref TracerSpanRef) log.Logger {
+	return logger
 }
 
+//lint:ignore U1000 Ignore unused method; it is only required to implement the Tracer interface but will never be called.
+func (BaseTracer) mustEmbedBaseTracer() {}
+
 // TracerOptions are options returned from Tracer.Options.
 type TracerOptions struct {
 	// SpanContextKey provides a key to put a span on a context unrelated to how a
@@ -319,6 +339,13 @@ func (t *tracingWorkflowOutboundInterceptor) ExecuteLocalActivity(
 	return t.Next.ExecuteLocalActivity(ctx, activityType, args...)
 }
 
+func (t *tracingWorkflowOutboundInterceptor) GetLogger(ctx workflow.Context) log.Logger {
+	if span, _ := ctx.Value(t.root.options.SpanContextKey).(TracerSpan); span != nil {
+		t.root.tracer.GetLogger(t.Next.GetLogger(ctx), span)
+	}
+	return t.Next.GetLogger(ctx)
+}
+
 func (t *tracingWorkflowOutboundInterceptor) ExecuteChildWorkflow(
 	ctx workflow.Context,
 	childWorkflowType string,

opentelemetry/tracing_interceptor.go

@@ -72,7 +72,10 @@ type spanContextKey struct{}
 
 const defaultHeaderKey = "_tracer-data"
 
-type tracer struct{ options *TracerOptions }
+type tracer struct {
+	interceptor.BaseTracer
+	options *TracerOptions
+}
 
 // NewTracer creates a tracer with the given options. Most callers should use
 // NewTracingInterceptor instead.
@@ -100,7 +103,7 @@ func NewTracer(options TracerOptions) (interceptor.Tracer, error) {
 			return span
 		}
 	}
-	return &tracer{&options}, nil
+	return &tracer{options: &options}, nil
 }
 
 // NewTracingInterceptor creates an interceptor for setting on client options

opentracing/interceptor.go

@@ -54,7 +54,10 @@ type spanContextKey struct{}
 
 const defaultHeaderKey = "_tracer-data"
 
-type tracer struct{ options *TracerOptions }
+type tracer struct {
+	interceptor.BaseTracer
+	options *TracerOptions
+}
 
 // NewTracer creates a tracer with the given options. Most callers should use
 // NewInterceptor instead.
@@ -77,7 +80,7 @@ func NewTracer(options TracerOptions) (interceptor.Tracer, error) {
 			return t.StartSpan(operationName, opts...)
 		}
 	}
-	return &tracer{&options}, nil
+	return &tracer{options: &options}, nil
 }
 
 // NewTracingInterceptor creates an interceptor for setting on client options