ddtrace/tracer: add WithDebugStack StartOption to configure stack traces.

ddtrace/tracer/option.go

@@ -92,6 +92,10 @@ type config struct {
 	// tickChan specifies a channel which will receive the time every time the tracer must flush.
 	// It defaults to time.Ticker; replaced in tests.
 	tickChan <-chan time.Time
+
+	// noDebugStack disables the collection of debug stack traces globally. No traces reporting
+	// errors will record a stack trace when this option is set.
+	noDebugStack bool
 }
 
 // StartOption represents a function that can be provided as a parameter to Start.
@@ -249,6 +253,15 @@ func WithPrioritySampling() StartOption {
 	}
 }
 
+// WithDebugStack can be used to globally enable or disable the collection of stack traces when
+// spans finish with errors. It is enabled by default. This is a global version of the NoDebugStack
+// FinishOption.
+func WithDebugStack(enabled bool) StartOption {
+	return func(c *config) {
+		c.noDebugStack = !enabled
+	}
+}
+
 // WithDebugMode enables debug mode on the tracer, resulting in more verbose logging.
 func WithDebugMode(enabled bool) StartOption {
 	return func(c *config) {

ddtrace/tracer/span.go

@@ -66,6 +66,7 @@ type span struct {
 	TraceID  uint64             `msg:"trace_id"`          // identifier of the root span
 	ParentID uint64             `msg:"parent_id"`         // identifier of the span's direct parent
 	Error    int32              `msg:"error"`             // error status of the span; 0 means no errors
+	errCfg   errorConfig        `msg:"-"`                 // configuration for errors tracing
 
 	finished bool         `msg:"-"` // true if the span has been submitted to a tracer.
 	context  *spanContext `msg:"-"` // span propagation context
@@ -102,7 +103,7 @@ func (s *span) SetTag(key string, value interface{}) {
 	}
 	switch key {
 	case ext.Error:
-		s.setTagError(value, &errorConfig{})
+		s.setTagError(value, &s.errCfg)
 		return
 	}
 	if v, ok := value.(bool); ok {
@@ -260,7 +261,9 @@ func (s *span) setMetric(key string, v float64) {
 func (s *span) Finish(opts ...ddtrace.FinishOption) {
 	t := now()
 	if len(opts) > 0 {
-		var cfg ddtrace.FinishConfig
+		cfg := ddtrace.FinishConfig{
+			NoDebugStack: s.errCfg.noDebugStack,
+		}
 		for _, fn := range opts {
 			fn(&cfg)
 		}

ddtrace/tracer/tracer.go

@@ -264,6 +264,7 @@ func (t *tracer) StartSpan(operationName string, options ...ddtrace.StartSpanOpt
 		TraceID:  id,
 		Start:    startTime,
 		taskEnd:  startExecutionTracerTask(operationName),
+		errCfg:   errorConfig{noDebugStack: t.config.noDebugStack},
 	}
 	if context != nil {
 		// this is a child span

ddtrace/tracer/tracer_test.go

@@ -7,6 +7,7 @@ package tracer
 
 import (
 	"context"
+	"errors"
 	"io"
 	"io/ioutil"
 	"net/http"
@@ -59,7 +60,7 @@ loop:
 	}
 }
 
-// TestTracerFrenetic does frenetic testing in a scenario where the tracer is started
+// TestTracerCleanStop does frenetic testing in a scenario where the tracer is started
 // and stopped in parallel with spans being created.
 func TestTracerCleanStop(t *testing.T) {
 	if testing.Short() {
@@ -442,6 +443,19 @@ func TestTracerSpanGlobalTags(t *testing.T) {
 	assert.Equal("value", child.Meta["key"])
 }
 
+func TestTracerNoDebugStack(t *testing.T) {
+	assert := assert.New(t)
+	tracer := newTracer(WithDebugStack(false))
+	s := tracer.StartSpan("web.request").(*span)
+	err := errors.New("test error")
+	s.Finish(WithError(err))
+
+	assert.Equal(int32(1), s.Error)
+	assert.Equal("test error", s.Meta[ext.ErrorMsg])
+	assert.Equal("*errors.errorString", s.Meta[ext.ErrorType])
+	assert.Empty(s.Meta[ext.ErrorStack])
+}
+
 func TestNewSpan(t *testing.T) {
 	assert := assert.New(t)