Checkpoint

stats/timeseries.go

@@ -0,0 +1,105 @@
+package stats
+
+import (
+	"encoding/json"
+	"fmt"
+	"sync"
+	"time"
+)
+
+type timeseries struct {
+	sync.Mutex
+	now      time.Time
+	size     int
+	interval time.Duration
+	total    metric
+	samples  []metric
+}
+
+func (ts *timeseries) Reset() {
+	ts.total.Reset()
+	for _, s := range ts.samples {
+		s.Reset()
+	}
+}
+
+func (ts *timeseries) roll() {
+	t := time.Now()
+	roll := int((t.Round(ts.interval).Sub(ts.now.Round(ts.interval))) / ts.interval)
+	ts.now = t
+	n := len(ts.samples)
+	if roll <= 0 {
+		return
+	}
+	if roll >= len(ts.samples) {
+		ts.Reset()
+	} else {
+		for i := 0; i < roll; i++ {
+			tmp := ts.samples[n-1]
+			for j := n - 1; j > 0; j-- {
+				ts.samples[j] = ts.samples[j-1]
+			}
+			ts.samples[0] = tmp
+			ts.samples[0].Reset()
+		}
+		ts.total.Aggregate(roll, ts.samples)
+	}
+}
+
+func (ts *timeseries) Add(n float64) {
+	ts.Lock()
+	defer ts.Unlock()
+	ts.roll()
+	ts.total.Add(n)
+	ts.samples[0].Add(n)
+}
+
+func (ts *timeseries) MarshalJSON() ([]byte, error) {
+	ts.Lock()
+	defer ts.Unlock()
+	ts.roll()
+	return json.Marshal(struct {
+		Interval float64  `json:"interval"`
+		Total    Metric   `json:"total"`
+		Samples  []metric `json:"samples"`
+	}{float64(ts.interval) / float64(time.Second), ts.total, ts.samples})
+}
+
+func (ts *timeseries) String() string {
+	ts.Lock()
+	defer ts.Unlock()
+	ts.roll()
+	return ts.total.String()
+}
+
+func newTimeseries(builder func() metric, frame string) *timeseries {
+	var (
+		totalNum, intervalNum   int
+		totalUnit, intervalUnit rune
+	)
+	units := map[rune]time.Duration{
+		's': time.Second,
+		'm': time.Minute,
+		'h': time.Hour,
+		'd': time.Hour * 24,
+		'w': time.Hour * 24 * 7,
+		'M': time.Hour * 24 * 30,
+		'y': time.Hour * 24 * 365,
+	}
+	fmt.Sscanf(frame, "%d%c%d%c", &totalNum, &totalUnit, &intervalNum, &intervalUnit)
+	interval := units[intervalUnit] * time.Duration(intervalNum)
+	if interval == 0 {
+		interval = time.Minute
+	}
+	totalDuration := units[totalUnit] * time.Duration(totalNum)
+	if totalDuration == 0 {
+		totalDuration = interval * 15
+	}
+	n := int(totalDuration / interval)
+	samples := make([]metric, n, n)
+	for i := 0; i < n; i++ {
+		samples[i] = builder()
+	}
+	totalMetric := builder()
+	return &timeseries{interval: interval, total: totalMetric, samples: samples}
+}