allocation & perf improvements

metric/metric.go

@@ -59,13 +59,34 @@ func New(
 		mType: thisType,
 	}
 
-	m.tags = []byte{}
+	// pre-allocate exact size of the tags slice
+	taglen := 0
 	for k, v := range tags {
-		m.tags = append(m.tags, []byte(","+escaper.Replace(k))...)
+		taglen += 2 + len(escaper.Replace(k)) + len(escaper.Replace(v))
-		m.tags = append(m.tags, []byte("="+escaper.Replace(v))...)
 	}
+	m.tags = make([]byte, taglen)
 
 	i := 0
+	for k, v := range tags {
+		m.tags[i] = ','
+		i++
+		i += copy(m.tags[i:], escaper.Replace(k))
+		m.tags[i] = '='
+		i++
+		i += copy(m.tags[i:], escaper.Replace(v))
+	}
+
+	// pre-allocate capacity of the fields slice
+	fieldlen := 0
+	for k, _ := range fields {
+		// 10 bytes is completely arbitrary, but will at least prevent some
+		// amount of allocations. There's a small possibility this will create
+		// slightly more allocations for a metric that has many short fields.
+		fieldlen += len(k) + 10
+	}
+	m.fields = make([]byte, 0, fieldlen)
+
+	i = 0
 	for k, v := range fields {
 		if i != 0 {
 			m.fields = append(m.fields, ',')
@@ -138,7 +159,7 @@ func (m *metric) Point() *client.Point {
 }
 
 func (m *metric) String() string {
-	return string(m.Serialize())
+	return string(m.name) + string(m.tags) + " " + string(m.fields) + " " + string(m.t) + "\n"
 }
 
 func (m *metric) SetAggregate(b bool) {
@@ -154,24 +175,21 @@ func (m *metric) Type() telegraf.ValueType {
 }
 
 func (m *metric) Len() int {
-	return len(m.name) + len(m.tags) + 1 + len(m.fields) + 1 + len(m.t) + 1
+	// 3 is for 2 spaces surrounding the fields array + newline at the end.
+	return len(m.name) + len(m.tags) + len(m.fields) + len(m.t) + 3
 }
 
 func (m *metric) Serialize() []byte {
 	tmp := make([]byte, m.Len())
 	i := 0
-	copy(tmp[i:], m.name)
+	i += copy(tmp[i:], m.name)
-	i += len(m.name)
+	i += copy(tmp[i:], m.tags)
-	copy(tmp[i:], m.tags)
-	i += len(m.tags)
 	tmp[i] = ' '
 	i++
-	copy(tmp[i:], m.fields)
+	i += copy(tmp[i:], m.fields)
-	i += len(m.fields)
 	tmp[i] = ' '
 	i++
-	copy(tmp[i:], m.t)
+	i += copy(tmp[i:], m.t)
-	i += len(m.t)
 	tmp[i] = '\n'
 	return tmp
 }
@@ -307,12 +325,15 @@ func (m *metric) UnixNano() int64 {
 }
 
 func (m *metric) SetName(name string) {
+	m.hashID = 0
 	m.name = []byte(nameEscaper.Replace(name))
 }
 func (m *metric) SetPrefix(prefix string) {
+	m.hashID = 0
 	m.name = append([]byte(nameEscaper.Replace(prefix)), m.name...)
 }
 func (m *metric) SetSuffix(suffix string) {
+	m.hashID = 0
 	m.name = append(m.name, []byte(nameEscaper.Replace(suffix))...)
 }
 

metric/metric_benchmark_test.go

@@ -36,10 +36,9 @@ func BenchmarkNewMetric(b *testing.B) {
 	s = string(mt.String())
 }
 
-func BenchmarkNewMetricAndInspect(b *testing.B) {
+func BenchmarkTags(b *testing.B) {
-	var mt telegraf.Metric
 	for n := 0; n < b.N; n++ {
-		mt, _ = New("test_metric",
+		var mt, _ = New("test_metric",
 			map[string]string{
 				"test_tag_1": "tag_value_1",
 				"test_tag_2": "tag_value_2",
@@ -52,55 +51,32 @@ func BenchmarkNewMetricAndInspect(b *testing.B) {
 			},
 			time.Now(),
 		)
-		for k, v := range mt.Fields() {
-			s = k
-			I = v
-		}
-	}
-	s = mt.String()
-}
-
-func BenchmarkTags(b *testing.B) {
-	var mt, _ = New("test_metric",
-		map[string]string{
-			"test_tag_1": "tag_value_1",
-			"test_tag_2": "tag_value_2",
-			"test_tag_3": "tag_value_3",
-		},
-		map[string]interface{}{
-			"string_field": "string",
-			"int_field":    int64(1000),
-			"float_field":  float64(2.1),
-		},
-		time.Now(),
-	)
-	for n := 0; n < b.N; n++ {
 		tags = mt.Tags()
 	}
 	s = fmt.Sprint(tags)
 }
 
 func BenchmarkFields(b *testing.B) {
-	var mt, _ = New("test_metric",
-		map[string]string{
-			"test_tag_1": "tag_value_1",
-			"test_tag_2": "tag_value_2",
-			"test_tag_3": "tag_value_3",
-		},
-		map[string]interface{}{
-			"string_field": "string",
-			"int_field":    int64(1000),
-			"float_field":  float64(2.1),
-		},
-		time.Now(),
-	)
 	for n := 0; n < b.N; n++ {
+		var mt, _ = New("test_metric",
+			map[string]string{
+				"test_tag_1": "tag_value_1",
+				"test_tag_2": "tag_value_2",
+				"test_tag_3": "tag_value_3",
+			},
+			map[string]interface{}{
+				"string_field": "string",
+				"int_field":    int64(1000),
+				"float_field":  float64(2.1),
+			},
+			time.Now(),
+		)
 		fields = mt.Fields()
 	}
 	s = fmt.Sprint(fields)
 }
 
-func BenchmarkSerializeMetric(b *testing.B) {
+func BenchmarkString(b *testing.B) {
 	mt, _ := New("test_metric",
 		map[string]string{
 			"test_tag_1": "tag_value_1",
@@ -121,7 +97,7 @@ func BenchmarkSerializeMetric(b *testing.B) {
 	s = S
 }
 
-func BenchmarkSerializeMetricBytes(b *testing.B) {
+func BenchmarkSerialize(b *testing.B) {
 	mt, _ := New("test_metric",
 		map[string]string{
 			"test_tag_1": "tag_value_1",