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json_decode.go
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/
json_decode.go
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// Copyright 2015 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package expfmt
import (
"encoding/json"
"fmt"
"io"
"sort"
"github.com/coreos/etcd/Godeps/_workspace/src/github.com/golang/protobuf/proto"
dto "github.com/coreos/etcd/Godeps/_workspace/src/github.com/prometheus/client_model/go"
"github.com/coreos/etcd/Godeps/_workspace/src/github.com/prometheus/common/model"
)
type json2Decoder struct {
dec *json.Decoder
fams []*dto.MetricFamily
}
func newJSON2Decoder(r io.Reader) Decoder {
return &json2Decoder{
dec: json.NewDecoder(r),
}
}
type histogram002 struct {
Labels model.LabelSet `json:"labels"`
Values map[string]float64 `json:"value"`
}
type counter002 struct {
Labels model.LabelSet `json:"labels"`
Value float64 `json:"value"`
}
func protoLabelSet(base, ext model.LabelSet) []*dto.LabelPair {
labels := base.Clone().Merge(ext)
delete(labels, model.MetricNameLabel)
names := make([]string, 0, len(labels))
for ln := range labels {
names = append(names, string(ln))
}
sort.Strings(names)
pairs := make([]*dto.LabelPair, 0, len(labels))
for _, ln := range names {
lv := labels[model.LabelName(ln)]
pairs = append(pairs, &dto.LabelPair{
Name: proto.String(ln),
Value: proto.String(string(lv)),
})
}
return pairs
}
func (d *json2Decoder) more() error {
var entities []struct {
BaseLabels model.LabelSet `json:"baseLabels"`
Docstring string `json:"docstring"`
Metric struct {
Type string `json:"type"`
Values json.RawMessage `json:"value"`
} `json:"metric"`
}
if err := d.dec.Decode(&entities); err != nil {
return err
}
for _, e := range entities {
f := &dto.MetricFamily{
Name: proto.String(string(e.BaseLabels[model.MetricNameLabel])),
Help: proto.String(e.Docstring),
Type: dto.MetricType_UNTYPED.Enum(),
Metric: []*dto.Metric{},
}
d.fams = append(d.fams, f)
switch e.Metric.Type {
case "counter", "gauge":
var values []counter002
if err := json.Unmarshal(e.Metric.Values, &values); err != nil {
return fmt.Errorf("could not extract %s value: %s", e.Metric.Type, err)
}
for _, ctr := range values {
f.Metric = append(f.Metric, &dto.Metric{
Label: protoLabelSet(e.BaseLabels, ctr.Labels),
Untyped: &dto.Untyped{
Value: proto.Float64(ctr.Value),
},
})
}
case "histogram":
var values []histogram002
if err := json.Unmarshal(e.Metric.Values, &values); err != nil {
return fmt.Errorf("could not extract %s value: %s", e.Metric.Type, err)
}
for _, hist := range values {
quants := make([]string, 0, len(values))
for q := range hist.Values {
quants = append(quants, q)
}
sort.Strings(quants)
for _, q := range quants {
value := hist.Values[q]
// The correct label is "quantile" but to not break old expressions
// this remains "percentile"
hist.Labels["percentile"] = model.LabelValue(q)
f.Metric = append(f.Metric, &dto.Metric{
Label: protoLabelSet(e.BaseLabels, hist.Labels),
Untyped: &dto.Untyped{
Value: proto.Float64(value),
},
})
}
}
default:
return fmt.Errorf("unknown metric type %q", e.Metric.Type)
}
}
return nil
}
// Decode implements the Decoder interface.
func (d *json2Decoder) Decode(v *dto.MetricFamily) error {
if len(d.fams) == 0 {
if err := d.more(); err != nil {
return err
}
}
*v = *d.fams[0]
d.fams = d.fams[1:]
return nil
}