Update Sampler descriptions (#511)

* update always and never sample descriptions

* fix typo

* rename always on / off sampler files, structs and variables to match

Co-authored-by: Rahul Patel <rahulpa@google.com>

api/trace/always_off_sampler.go

@@ -19,17 +19,17 @@ import (
 )
 
 const (
-	neverSamplerDescription = "NeverSampleSampler"
+	alwaysOffSamplerDescription = "AlwaysOffSampler"
 )
 
-var neverSampledecision = Decision{Sampled: false}
+var alwaysOffSamplerDecision = Decision{Sampled: false}
 
-type neverSampleSampler struct{}
+type alwaysOffSampler struct{}
 
 // ShouldSample implements Sampler interface.
 // It always returns a Decision with Sampled value set to false
 // and with Attributes set to an empty slice.
-func (ns neverSampleSampler) ShouldSample(
+func (ns alwaysOffSampler) ShouldSample(
 	_ core.SpanContext,
 	_ bool,
 	_ core.TraceID,
@@ -39,17 +39,17 @@ func (ns neverSampleSampler) ShouldSample(
 	_ []core.KeyValue,
 	_ []Link,
 ) Decision {
-	return neverSampledecision
+	return alwaysOffSamplerDecision
 }
 
 // Description implements Sampler interface.
 // It returns the description of this sampler.
-func (ns neverSampleSampler) Description() string {
+func (ns alwaysOffSampler) Description() string {
-	return neverSamplerDescription
+	return alwaysOffSamplerDescription
 }
 
-var _ Sampler = neverSampleSampler{}
+var _ Sampler = alwaysOffSampler{}
 
-func NeverSampleSampler() Sampler {
+func AlwaysOffSampler() Sampler {
-	return neverSampleSampler{}
+	return alwaysOffSampler{}
 }

api/trace/always_off_sampler_test.go

@@ -23,7 +23,7 @@ import (
 )
 
 func TestNeverSamperShouldSample(t *testing.T) {
-	gotD := NeverSampleSampler().ShouldSample(
+	gotD := AlwaysOffSampler().ShouldSample(
 		core.SpanContext{}, false, core.TraceID{}, core.SpanID{}, "span", SpanKindClient, []core.KeyValue{}, []Link{})
 	wantD := Decision{Sampled: false}
 	if diff := cmp.Diff(wantD, gotD); diff != "" {
@@ -31,9 +31,9 @@ func TestNeverSamperShouldSample(t *testing.T) {
 	}
 }
 
-func TestNeverSamplerDescription(t *testing.T) {
+func TestAlwaysOffSamplerDescription(t *testing.T) {
-	gotDesc := NeverSampleSampler().Description()
+	gotDesc := AlwaysOffSampler().Description()
-	wantDesc := neverSamplerDescription
+	wantDesc := alwaysOffSamplerDescription
 	if diff := cmp.Diff(wantDesc, gotDesc); diff != "" {
 		t.Errorf("Description: +got, -want%v", diff)
 	}

api/trace/always_on_sampler.go

@@ -19,17 +19,17 @@ import (
 )
 
 const (
-	alwaysSamplerDescription = "AlwaysSampleSampler"
+	alwaysOnSamplerDescription = "AlwaysOnSampler"
 )
 
-var alwaysSampleDecision = Decision{Sampled: true}
+var alwaysOnSamplerDecision = Decision{Sampled: true}
 
-type alwaysSampleSampler struct{}
+type alwaysOnSampler struct{}
 
 // ShouldSample implements Sampler interface.
 // It always returns a Decision with Sampled value set to true
 // and with Attributes set to an empty slice.
-func (as alwaysSampleSampler) ShouldSample(
+func (as alwaysOnSampler) ShouldSample(
 	_ core.SpanContext,
 	_ bool,
 	_ core.TraceID,
@@ -39,17 +39,17 @@ func (as alwaysSampleSampler) ShouldSample(
 	_ []core.KeyValue,
 	_ []Link,
 ) Decision {
-	return alwaysSampleDecision
+	return alwaysOnSamplerDecision
 }
 
 // Description implements Sampler interface.
 // It returns the description of this sampler.
-func (as alwaysSampleSampler) Description() string {
+func (as alwaysOnSampler) Description() string {
-	return alwaysSamplerDescription
+	return alwaysOnSamplerDescription
 }
 
-var _ Sampler = alwaysSampleSampler{}
+var _ Sampler = alwaysOnSampler{}
 
-func AlwaysSampleSampler() Sampler {
+func AlwaysOnSampler() Sampler {
-	return alwaysSampleSampler{}
+	return alwaysOnSampler{}
 }

api/trace/always_on_sampler_test.go

@@ -22,8 +22,8 @@ import (
 	"go.opentelemetry.io/otel/api/core"
 )
 
-func TestShouldSample(t *testing.T) {
+func TestAlwaysOnSamplerShouldSample(t *testing.T) {
-	gotD := AlwaysSampleSampler().ShouldSample(
+	gotD := AlwaysOnSampler().ShouldSample(
 		core.SpanContext{}, false, core.TraceID{}, core.SpanID{}, "span", SpanKindClient, []core.KeyValue{}, []Link{})
 	wantD := Decision{Sampled: true}
 	if diff := cmp.Diff(wantD, gotD); diff != "" {
@@ -31,9 +31,9 @@ func TestShouldSample(t *testing.T) {
 	}
 }
 
-func TestDescription(t *testing.T) {
+func TestAlwaysOnSamplerDescription(t *testing.T) {
-	gotDesc := AlwaysSampleSampler().Description()
+	gotDesc := AlwaysOnSampler().Description()
-	wantDesc := alwaysSamplerDescription
+	wantDesc := alwaysOnSamplerDescription
 	if diff := cmp.Diff(wantDesc, gotDesc); diff != "" {
 		t.Errorf("Description: +got, -want%v", diff)
 	}

sdk/trace/sampling.go

@@ -79,7 +79,7 @@ func (ps probabilitySampler) Description() string {
 
 // ProbabilitySampler samples a given fraction of traces. Fractions >= 1 will
 // always sample. If the parent span is sampled, then it's child spans will
-// automatically be sampled. Fractions <0 are treated as zero, but spans may
+// automatically be sampled. Fractions < 0 are treated as zero, but spans may
 // still be sampled if their parent is.
 func ProbabilitySampler(fraction float64) Sampler {
 	if fraction >= 1 {