graph: Align time-series before grouping them.

[sysdb/webui.git] / graph / graph.go

diff --git a/graph/graph.go b/graph/graph.go
index 17de57d8e48552d4672d6883e064b68e9c476041..76c6eaf18f85a4a9f22b7f8af510462e33be584c 100644 (file)
--- a/graph/graph.go
+++ b/graph/graph.go
@@ -112,24 +112,63 @@ func (p *pl) addTimeseries(c *client.Client, metric Metric, verbose bool) error
        return nil
 }
 
-// sum is an aggregation function that adds ts2 to ts1.
-func sum(ts1, ts2 *sysdb.Timeseries) error {
-       if !ts1.Start.Equal(ts1.Start) || !ts1.End.Equal(ts2.End) {
-               return fmt.Errorf("Timeseries cover different ranges: [%s, %s] != [%s, %s]",
-                       ts1.Start, ts1.End, ts2.Start, ts2.End)
-       }
+// align aligns two timeseries such that start and end times and the step
+// sizes match.
+func align(ts1, ts2 *sysdb.Timeseries) error {
        if len(ts1.Data) != len(ts2.Data) {
-               return fmt.Errorf("Incompatible time-series: %v != %v", ts1.Data, ts2.Data)
+               return fmt.Errorf("mismatching data sources: %v != %v", ts1.Data, ts2.Data)
+       }
+
+       start := time.Time(ts1.Start)
+       if t := time.Time(ts2.Start); t.After(start) {
+               start = t
+       }
+       end := time.Time(ts1.End)
+       if t := time.Time(ts2.End); t.Before(end) {
+               end = t
+       }
+       if end.Before(start) {
+               return fmt.Errorf("non-overlapping ranges: [%v, %v] <-> [%v, %v]",
+                       ts1.Start, ts1.End, ts2.Start, ts2.End)
        }
 
+       range1 := time.Time(ts1.End).Sub(time.Time(ts1.Start))
+       range2 := time.Time(ts2.End).Sub(time.Time(ts2.Start))
        for name := range ts1.Data {
-               if len(ts1.Data[name]) != len(ts2.Data[name]) {
-                       return fmt.Errorf("Time-series %q is not aligned", name)
+               l1, l2 := len(ts1.Data[name]), len(ts2.Data[name])
+               if l1 <= 1 || l2 <= 1 {
+                       if l1 == l2 && range1 == range2 {
+                               continue
+                       }
+                       return fmt.Errorf("invalid value count for %q: %d != %d", name, l1, l2)
                }
+
+               step1, step2 := range1/time.Duration(l1-1), range2/time.Duration(l2-1)
+               if step1 != step2 || step1 <= 0 {
+                       return fmt.Errorf("mismatching steps sizes for %q: %v != %v", name, step1, step2)
+               }
+
+               for _, ts := range []*sysdb.Timeseries{ts1, ts2} {
+                       a := start.Sub(time.Time(ts.Start)) / step1
+                       b := end.Sub(time.Time(ts.Start)) / step1
+                       ts.Data[name] = ts.Data[name][a : b+1]
+               }
+       }
+
+       ts1.Start, ts2.Start = sysdb.Time(start), sysdb.Time(start)
+       ts1.End, ts2.End = sysdb.Time(end), sysdb.Time(end)
+       return nil
+}
+
+// sum is an aggregation function that adds ts2 to ts1. The timeseries will be
+// aligned.
+func sum(ts1, ts2 *sysdb.Timeseries) error {
+       if err := align(ts1, ts2); err != nil {
+               return fmt.Errorf("Incompatible time-series: %v", err)
+       }
+
+       for name := range ts1.Data {
                for i := range ts1.Data[name] {
-                       if !ts1.Data[name][i].Timestamp.Equal(ts2.Data[name][i].Timestamp) {
-                               return fmt.Errorf("Time-series %q is not aligned", name)
-                       }
                        ts1.Data[name][i].Value += ts2.Data[name][i].Value
                }
        }