Web UI -- persistent stats by writing them into stats.json at exit

stats.go

@@ -2,12 +2,14 @@ package main
 
 import (
 	"bufio"
+	"encoding/json"
 	"io/ioutil"
 	"log"
 	"net"
 	"net/http"
 	"net/url"
 	"os"
+	"path/filepath"
 	"strconv"
 	"strings"
 	"syscall"
@@ -33,31 +35,41 @@ const (
 	processingTimeCount  = `coredns_dns_request_duration_seconds_count`
 )
 
+var entryWhiteList = map[string]bool{
+	totalRequests:        true,
+	filteredTotal:        true,
+	filteredSafebrowsing: true,
+	filteredSafesearch:   true,
+	filteredParental:     true,
+	processingTimeSum:    true,
+	processingTimeCount:  true,
+}
+
 type periodicStats struct {
-	entries    statsEntries
-	lastRotate time.Time // last time this data was rotated
+	Entries    statsEntries
+	LastRotate time.Time // last time this data was rotated
 }
 
 type stats struct {
-	perSecond periodicStats
-	perMinute periodicStats
-	perHour   periodicStats
-	perDay    periodicStats
+	PerSecond periodicStats
+	PerMinute periodicStats
+	PerHour   periodicStats
+	PerDay    periodicStats
 
-	lastSeen statsEntry
+	LastSeen statsEntry
 }
 
 var statistics stats
 
 func initPeriodicStats(periodic *periodicStats) {
-	periodic.entries = statsEntries{}
+	periodic.Entries = statsEntries{}
 }
 
 func init() {
-	initPeriodicStats(&statistics.perSecond)
-	initPeriodicStats(&statistics.perMinute)
-	initPeriodicStats(&statistics.perHour)
-	initPeriodicStats(&statistics.perDay)
+	initPeriodicStats(&statistics.PerSecond)
+	initPeriodicStats(&statistics.PerMinute)
+	initPeriodicStats(&statistics.PerHour)
+	initPeriodicStats(&statistics.PerDay)
 }
 
 func runStatsCollectors() {
@@ -85,37 +97,29 @@ func isConnRefused(err error) bool {
 	return false
 }
 
-func statsRotate(periodic *periodicStats, now time.Time) {
-	for key, values := range periodic.entries {
-		newValues := [statsHistoryElements]float64{}
-		for i := 1; i < len(values); i++ {
-			newValues[i] = values[i-1]
+func statsRotate(periodic *periodicStats, now time.Time, rotations int64) {
+	// calculate how many times we should rotate
+	for r := int64(0); r < rotations; r++ {
+		for key, values := range periodic.Entries {
+			newValues := [statsHistoryElements]float64{}
+			for i := 1; i < len(values); i++ {
+				newValues[i] = values[i-1]
+			}
+			periodic.Entries[key] = newValues
 		}
-		periodic.entries[key] = newValues
 	}
-	periodic.lastRotate = now
+	if rotations > 0 {
+		periodic.LastRotate = now
+	}
 }
 
 // called every second, accumulates stats for each second, minute, hour and day
 func collectStats() {
 	now := time.Now()
-	// rotate each second
-	// NOTE: since we are called every second, always rotate perSecond, otherwise aliasing problems cause the rotation to skip
-	if true {
-		statsRotate(&statistics.perSecond, now)
-	}
-	// if minute elapsed, rotate
-	if now.Sub(statistics.perMinute.lastRotate).Minutes() >= 1 {
-		statsRotate(&statistics.perMinute, now)
-	}
-	// if hour elapsed, rotate
-	if now.Sub(statistics.perHour.lastRotate).Hours() >= 1 {
-		statsRotate(&statistics.perHour, now)
-	}
-	// if day elapsed, rotate
-	if now.Sub(statistics.perDay.lastRotate).Hours()/24.0 >= 1 {
-		statsRotate(&statistics.perDay, now)
-	}
+	statsRotate(&statistics.PerSecond, now, int64(now.Sub(statistics.PerSecond.LastRotate)/time.Second))
+	statsRotate(&statistics.PerMinute, now, int64(now.Sub(statistics.PerMinute.LastRotate)/time.Minute))
+	statsRotate(&statistics.PerHour, now, int64(now.Sub(statistics.PerHour.LastRotate)/time.Hour))
+	statsRotate(&statistics.PerDay, now, int64(now.Sub(statistics.PerDay.LastRotate)/time.Hour/24))
 
 	// grab HTTP from prometheus
 	resp, err := client.Get("http://127.0.0.1:9153/metrics")
@@ -169,6 +173,11 @@ func collectStats() {
 			continue
 		}
 
+		// keys not in whitelist are not ok
+		if entryWhiteList[key] == false {
+			continue
+		}
+
 		got, ok := entry[key]
 		if ok {
 			value += got
@@ -177,16 +186,16 @@ func collectStats() {
 	}
 
 	// calculate delta
-	delta := calcDelta(entry, statistics.lastSeen)
+	delta := calcDelta(entry, statistics.LastSeen)
 
 	// apply delta to second/minute/hour/day
-	applyDelta(&statistics.perSecond, delta)
-	applyDelta(&statistics.perMinute, delta)
-	applyDelta(&statistics.perHour, delta)
-	applyDelta(&statistics.perDay, delta)
+	applyDelta(&statistics.PerSecond, delta)
+	applyDelta(&statistics.PerMinute, delta)
+	applyDelta(&statistics.PerHour, delta)
+	applyDelta(&statistics.PerDay, delta)
 
 	// save last seen
-	statistics.lastSeen = entry
+	statistics.LastSeen = entry
 }
 
 func calcDelta(current, seen statsEntry) statsEntry {
@@ -201,8 +210,50 @@ func calcDelta(current, seen statsEntry) statsEntry {
 
 func applyDelta(current *periodicStats, delta statsEntry) {
 	for key, deltaValue := range delta {
-		currentValues := current.entries[key]
+		currentValues := current.Entries[key]
 		currentValues[0] += deltaValue
-		current.entries[key] = currentValues
+		current.Entries[key] = currentValues
 	}
 }
+
+func loadStats() error {
+	statsFile := filepath.Join(config.ourBinaryDir, "stats.json")
+	if _, err := os.Stat(statsFile); os.IsNotExist(err) {
+		log.Printf("Stats JSON does not exist, skipping: %s", statsFile)
+		return nil
+	}
+	log.Printf("Loading JSON stats: %s", statsFile)
+	jsonText, err := ioutil.ReadFile(statsFile)
+	if err != nil {
+		log.Printf("Couldn't read JSON stats: %s", err)
+		return err
+	}
+	err = json.Unmarshal(jsonText, &statistics)
+	if err != nil {
+		log.Printf("Couldn't parse JSON stats: %s", err)
+		return err
+	}
+
+	return nil
+}
+
+func writeStats() error {
+	statsFile := filepath.Join(config.ourBinaryDir, "stats.json")
+	log.Printf("Writing JSON file: %s", statsFile)
+	json, err := json.MarshalIndent(statistics, "", "  ")
+	if err != nil {
+		log.Printf("Couldn't generate JSON: %s", err)
+		return err
+	}
+	err = ioutil.WriteFile(statsFile+".tmp", json, 0644)
+	if err != nil {
+		log.Printf("Couldn't write stats in JSON: %s", err)
+		return err
+	}
+	err = os.Rename(statsFile+".tmp", statsFile)
+	if err != nil {
+		log.Printf("Couldn't rename stats JSON: %s", err)
+		return err
+	}
+	return nil
+}