Refactor directory structure

pkg/schema/float.go

@@ -0,0 +1,105 @@
+package schema
+
+import (
+	"errors"
+	"io"
+	"math"
+	"strconv"
+)
+
+// A custom float type is used so that (Un)MarshalJSON and
+// (Un)MarshalGQL can be overloaded and NaN/null can be used.
+// The default behaviour of putting every nullable value behind
+// a pointer has a bigger overhead.
+type Float float64
+
+var NaN Float = Float(math.NaN())
+var nullAsBytes []byte = []byte("null")
+
+func (f Float) IsNaN() bool {
+	return math.IsNaN(float64(f))
+}
+
+// NaN will be serialized to `null`.
+func (f Float) MarshalJSON() ([]byte, error) {
+	if f.IsNaN() {
+		return nullAsBytes, nil
+	}
+
+	return strconv.AppendFloat(make([]byte, 0, 10), float64(f), 'f', 2, 64), nil
+}
+
+// `null` will be unserialized to NaN.
+func (f *Float) UnmarshalJSON(input []byte) error {
+	s := string(input)
+	if s == "null" {
+		*f = NaN
+		return nil
+	}
+
+	val, err := strconv.ParseFloat(s, 64)
+	if err != nil {
+		return err
+	}
+	*f = Float(val)
+	return nil
+}
+
+// UnmarshalGQL implements the graphql.Unmarshaler interface.
+func (f *Float) UnmarshalGQL(v interface{}) error {
+	f64, ok := v.(float64)
+	if !ok {
+		return errors.New("invalid Float scalar")
+	}
+
+	*f = Float(f64)
+	return nil
+}
+
+// MarshalGQL implements the graphql.Marshaler interface.
+// NaN will be serialized to `null`.
+func (f Float) MarshalGQL(w io.Writer) {
+	if f.IsNaN() {
+		w.Write(nullAsBytes)
+	} else {
+		w.Write(strconv.AppendFloat(make([]byte, 0, 10), float64(f), 'f', 2, 64))
+	}
+}
+
+// Only used via REST-API, not via GraphQL.
+// This uses a lot less allocations per series,
+// but it turns out that the performance increase
+// from using this is not that big.
+func (s *Series) MarshalJSON() ([]byte, error) {
+	buf := make([]byte, 0, 512+len(s.Data)*8)
+	buf = append(buf, `{"hostname":"`...)
+	buf = append(buf, s.Hostname...)
+	buf = append(buf, '"')
+	if s.Id != nil {
+		buf = append(buf, `,"id":`...)
+		buf = strconv.AppendInt(buf, int64(*s.Id), 10)
+	}
+	if s.Statistics != nil {
+		buf = append(buf, `,"statistics":{"min":`...)
+		buf = strconv.AppendFloat(buf, s.Statistics.Min, 'f', 2, 64)
+		buf = append(buf, `,"avg":`...)
+		buf = strconv.AppendFloat(buf, s.Statistics.Avg, 'f', 2, 64)
+		buf = append(buf, `,"max":`...)
+		buf = strconv.AppendFloat(buf, s.Statistics.Max, 'f', 2, 64)
+		buf = append(buf, '}')
+	}
+	buf = append(buf, `,"data":[`...)
+	for i := 0; i < len(s.Data); i++ {
+		if i != 0 {
+			buf = append(buf, ',')
+		}
+
+		if s.Data[i].IsNaN() {
+			buf = append(buf, `null`...)
+		} else {
+			buf = strconv.AppendFloat(buf, float64(s.Data[i]), 'f', 2, 32)
+		}
+	}
+	buf = append(buf, ']', '}')
+	return buf, nil
+}