Replace tag.NewKey calls with tag.MustNewKey where appropriate (#1146)

README.md

@@ -78,7 +78,7 @@ Package `tag` allows adding or modifying tags in the current context.
 
 [embedmd]:# (internal/readme/tags.go new)
 ```go
-ctx, err = tag.New(ctx,
+ctx, err := tag.New(ctx,
 	tag.Insert(osKey, "macOS-10.12.5"),
 	tag.Upsert(userIDKey, "cde36753ed"),
 )

examples/helloworld/main.go

@@ -54,10 +54,7 @@ func main() {
 
 	trace.ApplyConfig(trace.Config{DefaultSampler: trace.AlwaysSample()})
 
-	frontendKey, err = tag.NewKey("example.com/keys/frontend")
-	if err != nil {
-		log.Fatal(err)
-	}
+	frontendKey = tag.MustNewKey("example.com/keys/frontend")
 	videoSize = stats.Int64("example.com/measure/video_size", "size of processed videos", stats.UnitBytes)
 	view.SetReportingPeriod(2 * time.Second)
 

examples/quickstart/stats.go

@@ -56,7 +56,7 @@ var (
 
 // TagKeys for the stats quickstart.
 var (
-	keyMethod, _ = tag.NewKey("method")
+	keyMethod = tag.MustNewKey("method")
 )
 
 // Views for the stats quickstart.

internal/readme/README.md

@@ -1,6 +1,6 @@
 Use the following commands to regenerate the README.
 
 ```bash
-$ go get github.com/rakyll/embedmd
+$ GO11MODULE=off go get github.com/rakyll/embedmd
 $ embedmd -w ../../README.md
 ```

internal/readme/tags.go

@@ -24,17 +24,11 @@ import (
 func tagsExamples() {
 	ctx := context.Background()
 
-	osKey, err := tag.NewKey("example.com/keys/user-os")
-	if err != nil {
-		log.Fatal(err)
-	}
-	userIDKey, err := tag.NewKey("example.com/keys/user-id")
-	if err != nil {
-		log.Fatal(err)
-	}
+	osKey := tag.MustNewKey("example.com/keys/user-os")
+	userIDKey := tag.MustNewKey("example.com/keys/user-id")
 
 	// START new
-	ctx, err = tag.New(ctx,
+	ctx, err := tag.New(ctx,
 		tag.Insert(osKey, "macOS-10.12.5"),
 		tag.Upsert(userIDKey, "cde36753ed"),
 	)

plugin/ocgrpc/client_stats_handler_test.go

@@ -36,8 +36,8 @@ import (
 )
 
 func TestClientDefaultCollections(t *testing.T) {
-	k1, _ := tag.NewKey("k1")
-	k2, _ := tag.NewKey("k2")
+	k1 := tag.MustNewKey("k1")
+	k2 := tag.MustNewKey("k2")
 
 	type tagPair struct {
 		k tag.Key
@@ -340,7 +340,7 @@ func TestClientDefaultCollections(t *testing.T) {
 }
 
 func TestClientRecordExemplar(t *testing.T) {
-	key, _ := tag.NewKey("test_key")
+	key := tag.MustNewKey("test_key")
 	tagInfo := &stats.RPCTagInfo{FullMethodName: "/package.service/method"}
 	out := &stats.OutPayload{Length: 2000}
 	end := &stats.End{Error: nil}

plugin/ocgrpc/end_to_end_test.go

@@ -27,7 +27,7 @@ import (
 	"go.opencensus.io/tag"
 )
 
-var keyAccountId, _ = tag.NewKey("account_id")
+var keyAccountId = tag.MustNewKey("account_id")
 
 func TestEndToEnd_Single(t *testing.T) {
 	view.Register(ocgrpc.DefaultClientViews...)

plugin/ocgrpc/server_stats_handler_test.go

@@ -32,8 +32,8 @@ import (
 )
 
 func TestServerDefaultCollections(t *testing.T) {
-	k1, _ := tag.NewKey("k1")
-	k2, _ := tag.NewKey("k2")
+	k1 := tag.MustNewKey("k1")
+	k2 := tag.MustNewKey("k2")
 
 	type tagPair struct {
 		k tag.Key
@@ -338,7 +338,7 @@ func newDistributionData(countPerBucket []int64, count int64, min, max, mean, su
 }
 
 func TestServerRecordExemplar(t *testing.T) {
-	key, _ := tag.NewKey("test_key")
+	key := tag.MustNewKey("test_key")
 	tagInfo := &stats.RPCTagInfo{FullMethodName: "/package.service/method"}
 	out := &stats.OutPayload{Length: 2000}
 	end := &stats.End{Error: nil}

plugin/ocgrpc/stats_common.go

@@ -61,14 +61,14 @@ var (
 // Server tags are applied to the context used to process each RPC, as well as
 // the measures at the end of each RPC.
 var (
-	KeyServerMethod, _ = tag.NewKey("grpc_server_method")
-	KeyServerStatus, _ = tag.NewKey("grpc_server_status")
+	KeyServerMethod = tag.MustNewKey("grpc_server_method")
+	KeyServerStatus = tag.MustNewKey("grpc_server_status")
 )
 
 // Client tags are applied to measures at the end of each RPC.
 var (
-	KeyClientMethod, _ = tag.NewKey("grpc_client_method")
-	KeyClientStatus, _ = tag.NewKey("grpc_client_status")
+	KeyClientMethod = tag.MustNewKey("grpc_client_method")
+	KeyClientStatus = tag.MustNewKey("grpc_client_status")
 )
 
 var (

plugin/ochttp/stats.go

@@ -92,38 +92,38 @@ var (
 	// The value of this tag can be controlled by the HTTP client, so you need
 	// to watch out for potentially generating high-cardinality labels in your
 	// metrics backend if you use this tag in views.
-	Host, _ = tag.NewKey("http.host")
+	Host = tag.MustNewKey("http.host")
 
 	// StatusCode is the numeric HTTP response status code,
 	// or "error" if a transport error occurred and no status code was read.
-	StatusCode, _ = tag.NewKey("http.status")
+	StatusCode = tag.MustNewKey("http.status")
 
 	// Path is the URL path (not including query string) in the request.
 	//
 	// The value of this tag can be controlled by the HTTP client, so you need
 	// to watch out for potentially generating high-cardinality labels in your
 	// metrics backend if you use this tag in views.
-	Path, _ = tag.NewKey("http.path")
+	Path = tag.MustNewKey("http.path")
 
 	// Method is the HTTP method of the request, capitalized (GET, POST, etc.).
-	Method, _ = tag.NewKey("http.method")
+	Method = tag.MustNewKey("http.method")
 
 	// KeyServerRoute is a low cardinality string representing the logical
 	// handler of the request. This is usually the pattern registered on the a
 	// ServeMux (or similar string).
-	KeyServerRoute, _ = tag.NewKey("http_server_route")
+	KeyServerRoute = tag.MustNewKey("http_server_route")
 )
 
 // Client tag keys.
 var (
 	// KeyClientMethod is the HTTP method, capitalized (i.e. GET, POST, PUT, DELETE, etc.).
-	KeyClientMethod, _ = tag.NewKey("http_client_method")
+	KeyClientMethod = tag.MustNewKey("http_client_method")
 	// KeyClientPath is the URL path (not including query string).
-	KeyClientPath, _ = tag.NewKey("http_client_path")
+	KeyClientPath = tag.MustNewKey("http_client_path")
 	// KeyClientStatus is the HTTP status code as an integer (e.g. 200, 404, 500.), or "error" if no response status line was received.
-	KeyClientStatus, _ = tag.NewKey("http_client_status")
+	KeyClientStatus = tag.MustNewKey("http_client_status")
 	// KeyClientHost is the value of the request Host header.
-	KeyClientHost, _ = tag.NewKey("http_client_host")
+	KeyClientHost = tag.MustNewKey("http_client_host")
 )
 
 // Default distributions used by views in this package.

stats/benchmark_test.go

@@ -65,14 +65,14 @@ func BenchmarkRecord8_Parallel(b *testing.B) {
 
 func BenchmarkRecord8_8Tags(b *testing.B) {
 	ctx := context.Background()
-	key1, _ := tag.NewKey("key1")
-	key2, _ := tag.NewKey("key2")
-	key3, _ := tag.NewKey("key3")
-	key4, _ := tag.NewKey("key4")
-	key5, _ := tag.NewKey("key5")
-	key6, _ := tag.NewKey("key6")
-	key7, _ := tag.NewKey("key7")
-	key8, _ := tag.NewKey("key8")
+	key1 := tag.MustNewKey("key1")
+	key2 := tag.MustNewKey("key2")
+	key3 := tag.MustNewKey("key3")
+	key4 := tag.MustNewKey("key4")
+	key5 := tag.MustNewKey("key5")
+	key6 := tag.MustNewKey("key6")
+	key7 := tag.MustNewKey("key7")
+	key8 := tag.MustNewKey("key8")
 
 	tag.New(ctx,
 		tag.Insert(key1, "value"),

stats/record_test.go

@@ -42,8 +42,8 @@ var (
 )
 
 func TestRecordWithAttachments(t *testing.T) {
-	k1, _ := tag.NewKey("k1")
-	k2, _ := tag.NewKey("k2")
+	k1 := tag.MustNewKey("k1")
+	k2 := tag.MustNewKey("k2")
 	distribution := view.Distribution(5, 10)
 	m := stats.Int64("TestRecordWithAttachments/m1", "", stats.UnitDimensionless)
 	v := &view.View{

stats/view/benchmark_test.go

@@ -26,16 +26,17 @@ import (
 )
 
 var (
-	m     = stats.Float64("m", "", "")
-	k1, _ = tag.NewKey("k1")
-	k2, _ = tag.NewKey("k2")
-	k3, _ = tag.NewKey("k3")
-	k4, _ = tag.NewKey("k4")
-	k5, _ = tag.NewKey("k5")
-	k6, _ = tag.NewKey("k6")
-	k7, _ = tag.NewKey("k7")
-	k8, _ = tag.NewKey("k8")
-	view  = &View{
+	m  = stats.Float64("m", "", "")
+	k1 = tag.MustNewKey("k1")
+	k2 = tag.MustNewKey("k2")
+	k3 = tag.MustNewKey("k3")
+	k4 = tag.MustNewKey("k4")
+	k5 = tag.MustNewKey("k5")
+	k6 = tag.MustNewKey("k6")
+	k7 = tag.MustNewKey("k7")
+	k8 = tag.MustNewKey("k8")
+
+	view = &View{
 		Measure:     m,
 		Aggregation: Distribution(1, 2, 3, 4, 5, 6, 7, 8, 9, 10),
 		TagKeys:     []tag.Key{k1, k2},

stats/view/collector_test.go

@@ -29,18 +29,9 @@ func TestEncodeDecodeTags(t *testing.T) {
 		want map[tag.Key][]byte
 	}
 
-	k1, err := tag.NewKey("/encodedecodetest/k1")
-	if err != nil {
-		t.Fatal(err)
-	}
-	k2, err := tag.NewKey("/encodedecodetest/k2")
-	if err != nil {
-		t.Fatal(err)
-	}
-	k3, err := tag.NewKey("/encodedecodetest/k3")
-	if err != nil {
-		t.Fatal(err)
-	}
+	k1 = tag.MustNewKey("/encodedecodetest/k1")
+	k2 = tag.MustNewKey("/encodedecodetest/k2")
+	k3 = tag.MustNewKey("/encodedecodetest/k3")
 
 	ctx1, _ := tag.New(ctx)
 	ctx2, _ := tag.New(ctx, tag.Insert(k2, "v2"))

stats/view/view_test.go

@@ -29,9 +29,9 @@ import (
 )
 
 func Test_View_MeasureFloat64_AggregationDistribution(t *testing.T) {
-	k1, _ := tag.NewKey("k1")
-	k2, _ := tag.NewKey("k2")
-	k3, _ := tag.NewKey("k3")
+	k1 := tag.MustNewKey("k1")
+	k2 := tag.MustNewKey("k2")
+	k3 := tag.MustNewKey("k3")
 	agg1 := Distribution(2)
 	m := stats.Int64("Test_View_MeasureFloat64_AggregationDistribution/m1", "", stats.UnitDimensionless)
 	view1 := &View{
@@ -199,9 +199,9 @@ func Test_View_MeasureFloat64_AggregationDistribution(t *testing.T) {
 }
 
 func Test_View_MeasureFloat64_AggregationSum(t *testing.T) {
-	k1, _ := tag.NewKey("k1")
-	k2, _ := tag.NewKey("k2")
-	k3, _ := tag.NewKey("k3")
+	k1 := tag.MustNewKey("k1")
+	k2 := tag.MustNewKey("k2")
+	k3 := tag.MustNewKey("k3")
 	m := stats.Int64("Test_View_MeasureFloat64_AggregationSum/m1", "", stats.UnitDimensionless)
 	view, err := newViewInternal(&View{TagKeys: []tag.Key{k1, k2}, Measure: m, Aggregation: Sum()})
 	if err != nil {
@@ -315,8 +315,8 @@ func Test_View_MeasureFloat64_AggregationSum(t *testing.T) {
 }
 
 func TestCanonicalize(t *testing.T) {
-	k1, _ := tag.NewKey("k1")
-	k2, _ := tag.NewKey("k2")
+	k1 := tag.MustNewKey("k1")
+	k2 := tag.MustNewKey("k2")
 	m := stats.Int64("TestCanonicalize/m1", "desc desc", stats.UnitDimensionless)
 	v := &View{TagKeys: []tag.Key{k2, k1}, Measure: m, Aggregation: Sum()}
 	err := v.canonicalize()
@@ -338,9 +338,9 @@ func TestCanonicalize(t *testing.T) {
 }
 
 func TestViewSortedKeys(t *testing.T) {
-	k1, _ := tag.NewKey("a")
-	k2, _ := tag.NewKey("b")
-	k3, _ := tag.NewKey("c")
+	k1 := tag.MustNewKey("a")
+	k2 := tag.MustNewKey("b")
+	k3 := tag.MustNewKey("c")
 	ks := []tag.Key{k1, k3, k2}
 
 	m := stats.Int64("TestViewSortedKeys/m1", "", stats.UnitDimensionless)

stats/view/view_to_metric_test.go

@@ -111,9 +111,9 @@ func init() {
 }
 
 func initTags() {
-	tk1, _ = tag.NewKey("k1")
-	tk2, _ = tag.NewKey("k2")
-	tk3, _ = tag.NewKey("k3")
+	tk1 = tag.MustNewKey("k1")
+	tk2 = tag.MustNewKey("k2")
+	tk3 = tag.MustNewKey("k3")
 	tk1v1 = tag.Tag{Key: tk1, Value: v1}
 	tk2v2 = tag.Tag{Key: tk2, Value: v2}
 

stats/view/worker_test.go

@@ -124,8 +124,8 @@ func Test_Worker_RecordFloat64(t *testing.T) {
 	someError := errors.New("some error")
 	m := stats.Float64("Test_Worker_RecordFloat64/MF1", "desc MF1", "unit")
 
-	k1, _ := tag.NewKey("k1")
-	k2, _ := tag.NewKey("k2")
+	k1 := tag.MustNewKey("k1")
+	k2 := tag.MustNewKey("k2")
 	ctx, err := tag.New(context.Background(),
 		tag.Insert(k1, "v1"),
 		tag.Insert(k2, "v2"),

tag/example_test.go

@@ -37,15 +37,14 @@ func ExampleNewKey() {
 	_ = key // use key
 }
 
+func ExampleMustNewKey() {
+	key := tag.MustNewKey("example.com/keys/user-os")
+	_ = key // use key
+}
+
 func ExampleNew() {
-	osKey, err := tag.NewKey("example.com/keys/user-os")
-	if err != nil {
-		log.Fatal(err)
-	}
-	userIDKey, err := tag.NewKey("example.com/keys/user-id")
-	if err != nil {
-		log.Fatal(err)
-	}
+	osKey := tag.MustNewKey("example.com/keys/user-os")
+	userIDKey := tag.MustNewKey("example.com/keys/user-id")
 
 	ctx, err := tag.New(ctx,
 		tag.Insert(osKey, "macOS-10.12.5"),

tag/key.go

@@ -21,16 +21,15 @@ type Key struct {
 }
 
 // NewKey creates or retrieves a string key identified by name.
-// Calling NewKey consequently with the same name returns the same key.
+// Calling NewKey more than once with the same name returns the same key.
 func NewKey(name string) (Key, error) {
 	if !checkKeyName(name) {
 		return Key{}, errInvalidKeyName
 	}
 	return Key{name: name}, nil
 }
 
-// MustNewKey creates or retrieves a string key identified by name.
-// An invalid key name raises a panic.
+// MustNewKey returns a key with the given name, and panics if name is an invalid key name.
 func MustNewKey(name string) Key {
 	k, err := NewKey(name)
 	if err != nil {