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|
package metrics
import (
"context"
"fmt"
"net/http"
"sort"
"time"
)
// MetricsSummary holds a roll-up of metrics info for a given interval
type MetricsSummary struct {
Timestamp string
Gauges []GaugeValue
Points []PointValue
Counters []SampledValue
Samples []SampledValue
}
type GaugeValue struct {
Name string
Hash string `json:"-"`
Value float32
Labels []Label `json:"-"`
DisplayLabels map[string]string `json:"Labels"`
}
type PointValue struct {
Name string
Points []float32
}
type SampledValue struct {
Name string
Hash string `json:"-"`
*AggregateSample
Mean float64
Stddev float64
Labels []Label `json:"-"`
DisplayLabels map[string]string `json:"Labels"`
}
// deepCopy allocates a new instance of AggregateSample
func (source *SampledValue) deepCopy() SampledValue {
dest := *source
if source.AggregateSample != nil {
dest.AggregateSample = &AggregateSample{}
*dest.AggregateSample = *source.AggregateSample
}
return dest
}
// DisplayMetrics returns a summary of the metrics from the most recent finished interval.
func (i *InmemSink) DisplayMetrics(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
data := i.Data()
var interval *IntervalMetrics
n := len(data)
switch {
case n == 0:
return nil, fmt.Errorf("no metric intervals have been initialized yet")
case n == 1:
// Show the current interval if it's all we have
interval = data[0]
default:
// Show the most recent finished interval if we have one
interval = data[n-2]
}
return newMetricSummaryFromInterval(interval), nil
}
func newMetricSummaryFromInterval(interval *IntervalMetrics) MetricsSummary {
interval.RLock()
defer interval.RUnlock()
summary := MetricsSummary{
Timestamp: interval.Interval.Round(time.Second).UTC().String(),
Gauges: make([]GaugeValue, 0, len(interval.Gauges)),
Points: make([]PointValue, 0, len(interval.Points)),
}
// Format and sort the output of each metric type, so it gets displayed in a
// deterministic order.
for name, points := range interval.Points {
summary.Points = append(summary.Points, PointValue{name, points})
}
sort.Slice(summary.Points, func(i, j int) bool {
return summary.Points[i].Name < summary.Points[j].Name
})
for hash, value := range interval.Gauges {
value.Hash = hash
value.DisplayLabels = make(map[string]string)
for _, label := range value.Labels {
value.DisplayLabels[label.Name] = label.Value
}
value.Labels = nil
summary.Gauges = append(summary.Gauges, value)
}
sort.Slice(summary.Gauges, func(i, j int) bool {
return summary.Gauges[i].Hash < summary.Gauges[j].Hash
})
summary.Counters = formatSamples(interval.Counters)
summary.Samples = formatSamples(interval.Samples)
return summary
}
func formatSamples(source map[string]SampledValue) []SampledValue {
output := make([]SampledValue, 0, len(source))
for hash, sample := range source {
displayLabels := make(map[string]string)
for _, label := range sample.Labels {
displayLabels[label.Name] = label.Value
}
output = append(output, SampledValue{
Name: sample.Name,
Hash: hash,
AggregateSample: sample.AggregateSample,
Mean: sample.AggregateSample.Mean(),
Stddev: sample.AggregateSample.Stddev(),
DisplayLabels: displayLabels,
})
}
sort.Slice(output, func(i, j int) bool {
return output[i].Hash < output[j].Hash
})
return output
}
type Encoder interface {
Encode(interface{}) error
}
// Stream writes metrics using encoder.Encode each time an interval ends. Runs
// until the request context is cancelled, or the encoder returns an error.
// The caller is responsible for logging any errors from encoder.
func (i *InmemSink) Stream(ctx context.Context, encoder Encoder) {
interval := i.getInterval()
for {
select {
case <-interval.done:
summary := newMetricSummaryFromInterval(interval)
if err := encoder.Encode(summary); err != nil {
return
}
// update interval to the next one
interval = i.getInterval()
case <-ctx.Done():
return
}
}
}
|
