Remove error return type from metric.New method (influxdata#9116)

* Remove error return type from metric.New method.

* Formatting changes for linter + gofmt

* Additional linter fixes.

* More linter fixes.

* Linter fix.

* address comments

agent/accumulator.go

@@ -90,10 +90,7 @@ func (ac *accumulator) addFields(
 	tp telegraf.ValueType,
 	t ...time.Time,
 ) {
-	m, err := metric.New(measurement, tags, fields, ac.getTime(t), tp)
-	if err != nil {
-		return
-	}
+	m := metric.New(measurement, tags, fields, ac.getTime(t), tp)
 	if m := ac.maker.MakeMetric(m); m != nil {
 		ac.metrics <- m
 	}

metric/metric.go

@@ -24,7 +24,7 @@ func New(
 	fields map[string]interface{},
 	tm time.Time,
 	tp ...telegraf.ValueType,
-) (telegraf.Metric, error) {
+) telegraf.Metric {
 	var vtype telegraf.ValueType
 	if len(tp) > 0 {
 		vtype = tp[0]
@@ -60,7 +60,7 @@ func New(
 		}
 	}
 
-	return m, nil
+	return m
 }
 
 // FromMetric returns a deep copy of the metric with any tracking information

metric/metric_test.go

@@ -20,8 +20,7 @@ func TestNewMetric(t *testing.T) {
 		"usage_idle": float64(99),
 		"usage_busy": float64(1),
 	}
-	m, err := New("cpu", tags, fields, now)
-	require.NoError(t, err)
+	m := New("cpu", tags, fields, now)
 
 	require.Equal(t, "cpu", m.Name())
 	require.Equal(t, tags, m.Tags())
@@ -38,10 +37,7 @@ func baseMetric() telegraf.Metric {
 	}
 	now := time.Now()
 
-	m, err := New("cpu", tags, fields, now)
-	if err != nil {
-		panic(err)
-	}
+	m := New("cpu", tags, fields, now)
 	return m
 }
 
@@ -176,7 +172,7 @@ func TestTagList_Sorted(t *testing.T) {
 
 func TestEquals(t *testing.T) {
 	now := time.Now()
-	m1, err := New("cpu",
+	m1 := New("cpu",
 		map[string]string{
 			"host": "localhost",
 		},
@@ -185,9 +181,8 @@ func TestEquals(t *testing.T) {
 		},
 		now,
 	)
-	require.NoError(t, err)
 
-	m2, err := New("cpu",
+	m2 := New("cpu",
 		map[string]string{
 			"host": "localhost",
 		},
@@ -196,7 +191,6 @@ func TestEquals(t *testing.T) {
 		},
 		now,
 	)
-	require.NoError(t, err)
 
 	lhs := m1.(*metric)
 	require.Equal(t, lhs, m2)
@@ -208,7 +202,7 @@ func TestEquals(t *testing.T) {
 }
 
 func TestHashID(t *testing.T) {
-	m, _ := New(
+	m := New(
 		"cpu",
 		map[string]string{
 			"datacenter": "us-east-1",
@@ -241,7 +235,7 @@ func TestHashID(t *testing.T) {
 }
 
 func TestHashID_Consistency(t *testing.T) {
-	m, _ := New(
+	m := New(
 		"cpu",
 		map[string]string{
 			"datacenter": "us-east-1",
@@ -255,7 +249,7 @@ func TestHashID_Consistency(t *testing.T) {
 	)
 	hash := m.HashID()
 
-	m2, _ := New(
+	m2 := New(
 		"cpu",
 		map[string]string{
 			"datacenter": "us-east-1",
@@ -274,7 +268,7 @@ func TestHashID_Consistency(t *testing.T) {
 }
 
 func TestHashID_Delimiting(t *testing.T) {
-	m1, _ := New(
+	m1 := New(
 		"cpu",
 		map[string]string{
 			"a": "x",
@@ -286,7 +280,7 @@ func TestHashID_Delimiting(t *testing.T) {
 		},
 		time.Now(),
 	)
-	m2, _ := New(
+	m2 := New(
 		"cpu",
 		map[string]string{
 			"a": "xbycz",
@@ -328,8 +322,7 @@ func TestValueType(t *testing.T) {
 	fields := map[string]interface{}{
 		"value": float64(42),
 	}
-	m, err := New("cpu", tags, fields, now, telegraf.Gauge)
-	assert.NoError(t, err)
+	m := New("cpu", tags, fields, now, telegraf.Gauge)
 
 	assert.Equal(t, telegraf.Gauge, m.Type())
 }

metric/series_grouper.go

@@ -50,18 +50,14 @@ func (g *SeriesGrouper) Add(
 	}
 	sort.Slice(taglist, func(i, j int) bool { return taglist[i].Key < taglist[j].Key })
 
-	var err error
 	id := groupID(g.hashSeed, measurement, taglist, tm)
-	metric := g.metrics[id]
-	if metric == nil {
-		metric, err = New(measurement, tags, map[string]interface{}{field: fieldValue}, tm)
-		if err != nil {
-			return err
-		}
-		g.metrics[id] = metric
-		g.ordered = append(g.ordered, metric)
+	m := g.metrics[id]
+	if m == nil {
+		m = New(measurement, tags, map[string]interface{}{field: fieldValue}, tm)
+		g.metrics[id] = m
+		g.ordered = append(g.ordered, m)
 	} else {
-		metric.AddField(field, fieldValue)
+		m.AddField(field, fieldValue)
 	}
 	return nil
 }

metric/series_grouper_test.go

@@ -6,7 +6,7 @@ import (
 	"time"
 )
 
-var m, _ = New(
+var m = New(
 	"mymetric",
 	map[string]string{
 		"host":        "host.example.com",

metric/tracking_test.go

@@ -16,10 +16,7 @@ func mustMetric(
 	tm time.Time,
 	tp ...telegraf.ValueType,
 ) telegraf.Metric {
-	m, err := New(name, tags, fields, tm, tp...)
-	if err != nil {
-		panic("mustMetric")
-	}
+	m := New(name, tags, fields, tm, tp...)
 	return m
 }
 

models/buffer_test.go

@@ -34,17 +34,14 @@ func Metric() telegraf.Metric {
 }
 
 func MetricTime(sec int64) telegraf.Metric {
-	m, err := metric.New(
+	m := metric.New(
 		"cpu",
 		map[string]string{},
 		map[string]interface{}{
 			"value": 42.0,
 		},
 		time.Unix(sec, 0),
 	)
-	if err != nil {
-		panic(err)
-	}
 	return m
 }
 

models/filter_test.go

@@ -15,11 +15,10 @@ func TestFilter_ApplyEmpty(t *testing.T) {
 	require.NoError(t, f.Compile())
 	require.False(t, f.IsActive())
 
-	m, err := metric.New("m",
+	m := metric.New("m",
 		map[string]string{},
 		map[string]interface{}{"value": int64(1)},
 		time.Now())
-	require.NoError(t, err)
 	require.True(t, f.Select(m))
 }
 
@@ -37,11 +36,10 @@ func TestFilter_ApplyTagsDontPass(t *testing.T) {
 	require.NoError(t, f.Compile())
 	require.True(t, f.IsActive())
 
-	m, err := metric.New("m",
+	m := metric.New("m",
 		map[string]string{"cpu": "cpu-total"},
 		map[string]interface{}{"value": int64(1)},
 		time.Now())
-	require.NoError(t, err)
 	require.False(t, f.Select(m))
 }
 
@@ -53,14 +51,13 @@ func TestFilter_ApplyDeleteFields(t *testing.T) {
 	require.NoError(t, f.Compile())
 	require.True(t, f.IsActive())
 
-	m, err := metric.New("m",
+	m := metric.New("m",
 		map[string]string{},
 		map[string]interface{}{
 			"value":  int64(1),
 			"value2": int64(2),
 		},
 		time.Now())
-	require.NoError(t, err)
 	require.True(t, f.Select(m))
 	f.Modify(m)
 	require.Equal(t, map[string]interface{}{"value2": int64(2)}, m.Fields())
@@ -74,14 +71,13 @@ func TestFilter_ApplyDeleteAllFields(t *testing.T) {
 	require.NoError(t, f.Compile())
 	require.True(t, f.IsActive())
 
-	m, err := metric.New("m",
+	m := metric.New("m",
 		map[string]string{},
 		map[string]interface{}{
 			"value":  int64(1),
 			"value2": int64(2),
 		},
 		time.Now())
-	require.NoError(t, err)
 	require.True(t, f.Select(m))
 	f.Modify(m)
 	require.Len(t, m.FieldList(), 0)
@@ -332,14 +328,13 @@ func TestFilter_TagDrop(t *testing.T) {
 }
 
 func TestFilter_FilterTagsNoMatches(t *testing.T) {
-	m, err := metric.New("m",
+	m := metric.New("m",
 		map[string]string{
 			"host":  "localhost",
 			"mytag": "foobar",
 		},
 		map[string]interface{}{"value": int64(1)},
 		time.Now())
-	require.NoError(t, err)
 	f := Filter{
 		TagExclude: []string{"nomatch"},
 	}
@@ -361,14 +356,13 @@ func TestFilter_FilterTagsNoMatches(t *testing.T) {
 }
 
 func TestFilter_FilterTagsMatches(t *testing.T) {
-	m, err := metric.New("m",
+	m := metric.New("m",
 		map[string]string{
 			"host":  "localhost",
 			"mytag": "foobar",
 		},
 		map[string]interface{}{"value": int64(1)},
 		time.Now())
-	require.NoError(t, err)
 	f := Filter{
 		TagExclude: []string{"ho*"},
 	}
@@ -379,14 +373,13 @@ func TestFilter_FilterTagsMatches(t *testing.T) {
 		"mytag": "foobar",
 	}, m.Tags())
 
-	m, err = metric.New("m",
+	m = metric.New("m",
 		map[string]string{
 			"host":  "localhost",
 			"mytag": "foobar",
 		},
 		map[string]interface{}{"value": int64(1)},
 		time.Now())
-	require.NoError(t, err)
 	f = Filter{
 		TagInclude: []string{"my*"},
 	}