cmd/ursrv: Filter out ancient versions from chart

cmd/ursrv/main.go

@@ -23,6 +23,7 @@ import (
 	"os"
 	"regexp"
 	"sort"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -900,7 +901,8 @@ func newDataHandler(db *sql.DB, w http.ResponseWriter, r *http.Request) {
 }
 
 func summaryHandler(db *sql.DB, w http.ResponseWriter, r *http.Request) {
-	s, err := getSummary(db)
+	min, _ := strconv.Atoi(r.URL.Query().Get("min"))
+	s, err := getSummary(db, min)
 	if err != nil {
 		log.Println("summaryHandler:", err)
 		http.Error(w, "Database Error", http.StatusInternalServerError)
@@ -1558,7 +1560,21 @@ func (s *summary) MarshalJSON() ([]byte, error) {
 	return json.Marshal(table)
 }
 
-func getSummary(db *sql.DB) (summary, error) {
+// filter removes versions that never reach the specified min count.
+func (s *summary) filter(min int) {
+	// We cheat and just remove the versions from the "index" and leave the
+	// data points alone. The version index is used to build the table when
+	// we do the serialization, so at that point the data points are
+	// filtered out as well.
+	for ver := range s.versions {
+		if s.max[ver] < min {
+			delete(s.versions, ver)
+			delete(s.max, ver)
+		}
+	}
+}
+
+func getSummary(db *sql.DB, min int) (summary, error) {
 	s := newSummary()
 
 	rows, err := db.Query(`SELECT Day, Version, Count FROM VersionSummary WHERE Day > now() - '2 year'::INTERVAL;`)
@@ -1589,6 +1605,7 @@ func getSummary(db *sql.DB) (summary, error) {
 		s.setCount(day.Format("2006-01-02"), ver, num)
 	}
 
+	s.filter(min)
 	return s, nil
 }