Refactor to update state when cache or SLURM changes

Before this commit the new stayrtr state was only recalculated
when the validated cache changed.

This commit refactors the update loop and separates the actual
update from pulling the updated cache. The update is triggered
when the SLURM file changes _or_ when the validated cache changes.

Should fix cloudflare/gortr#95 and make
further changes that trigger an update when an update in the cache
has expired easier.

cmd/stayrtr/stayrtr.go

@@ -248,41 +248,12 @@ func (e IdenticalFile) Error() string {
 	return fmt.Sprintf("File %s is identical to the previous version", e.File)
 }
 
-func (s *state) updateFile(file string) error {
+// Update the state based on the current slurm file and data.
+func (s *state) updateFromNewState() error {
 	sessid, _ := s.server.GetSessionId(nil)
 
-	log.Debugf("Refreshing cache from %s", file)
-
-	s.lastts = time.Now().UTC()
-	data, code, lastrefresh, err := s.fetchConfig.FetchFile(file)
-	if err != nil {
-		return err
-	}
-	if lastrefresh {
-		LastRefresh.WithLabelValues(file).Set(float64(s.lastts.UnixNano() / 1e9))
-	}
-	if code != -1 {
-		RefreshStatusCode.WithLabelValues(file, fmt.Sprintf("%d", code)).Inc()
-	}
-
-	hsum, _ := checkFile(data)
-	if s.lasthash != nil {
-		cres := bytes.Compare(s.lasthash, hsum)
-		if cres == 0 {
-			return IdenticalFile{File: file}
-		}
-	}
-
-	s.lastchange = time.Now().UTC()
-	s.lastdata = data
-
-	vrplistjson, err := decodeJSON(s.lastdata)
-	if err != nil {
-		return err
-	}
-
 	if s.checktime {
-		buildtime, err := time.Parse(time.RFC3339, vrplistjson.Metadata.Buildtime)
+		buildtime, err := time.Parse(time.RFC3339, s.lastdata.Metadata.Buildtime)
 		if err != nil {
 			return err
 		}
@@ -292,7 +263,7 @@ func (s *state) updateFile(file string) error {
 		}
 	}
 
-	vrpsjson := vrplistjson.Data
+	vrpsjson := s.lastdata.Data
 	if s.slurm != nil {
 		kept, removed := s.slurm.FilterOnVRPs(vrpsjson)
 		asserted := s.slurm.AssertVRPs()
@@ -301,13 +272,9 @@ func (s *state) updateFile(file string) error {
 	}
 
 	vrps, count, countv4, countv6 := processData(vrpsjson)
-	if err != nil {
-		return err
-	}
 
-	log.Infof("New update (%v uniques, %v total prefixes). %v bytes. Updating sha256 hash %x -> %x",
-		len(vrps), count, len(s.lastconverted), s.lasthash, hsum)
-	s.lasthash = hsum
+	log.Infof("New update (%v uniques, %v total prefixes). %v bytes.",
+		len(vrps), count)
 
 	s.server.AddVRPs(vrps)
 
@@ -322,7 +289,7 @@ func (s *state) updateFile(file string) error {
 	s.exported = prefixfile.VRPList{
 		Metadata: prefixfile.MetaData{
 			Counts:    len(vrpsjson),
-			Buildtime: vrplistjson.Metadata.Buildtime,
+			Buildtime: s.lastdata.Metadata.Buildtime,
 		},
 		Data: vrpsjson,
 	}
@@ -339,16 +306,54 @@ func (s *state) updateFile(file string) error {
 				countv6_dup++
 			}
 		}
-		s.metricsEvent.UpdateMetrics(countv4, countv6, countv4_dup, countv6_dup, s.lastchange, s.lastts, file)
+		s.metricsEvent.UpdateMetrics(countv4, countv6, countv4_dup, countv6_dup, s.lastchange, s.lastts, *CacheBin)
 	}
+
 	return nil
 }
 
-func (s *state) updateSlurm(file string) error {
+func (s *state) updateFile(file string) (bool, error) {
+	log.Debugf("Refreshing cache from %s", file)
+
+	s.lastts = time.Now().UTC()
+	data, code, lastrefresh, err := s.fetchConfig.FetchFile(file)
+	if err != nil {
+		return false, err
+	}
+	if lastrefresh {
+		LastRefresh.WithLabelValues(file).Set(float64(s.lastts.UnixNano() / 1e9))
+	}
+	if code != -1 {
+		RefreshStatusCode.WithLabelValues(file, fmt.Sprintf("%d", code)).Inc()
+	}
+
+	hsum, _ := checkFile(data)
+	if s.lasthash != nil {
+		cres := bytes.Compare(s.lasthash, hsum)
+		if cres == 0 {
+			return false, IdenticalFile{File: file}
+		}
+	}
+
+	log.Infof("new cache file: Updating sha256 hash %x -> %x", s.lasthash, hsum)
+
+	vrplistjson, err := decodeJSON(data)
+	if err != nil {
+		return false, err
+	}
+
+	s.lasthash = hsum
+	s.lastchange = time.Now().UTC()
+	s.lastdata = vrplistjson
+
+	return true, nil
+}
+
+func (s *state) updateSlurm(file string) (bool, error) {
 	log.Debugf("Refreshing slurm from %v", file)
 	data, code, lastrefresh, err := s.fetchConfig.FetchFile(file)
 	if err != nil {
-		return err
+		return false, err
 	}
 	if lastrefresh {
 		LastRefresh.WithLabelValues(file).Set(float64(s.lastts.UnixNano() / 1e9))
@@ -361,10 +366,10 @@ func (s *state) updateSlurm(file string) error {
 
 	slurm, err := prefixfile.DecodeJSONSlurm(buf)
 	if err != nil {
-		return err
+		return false, err
 	}
 	s.slurm = slurm
-	return nil
+	return true, nil
 }
 
 func (s *state) routineUpdate(file string, interval int, slurmFile string) {
@@ -379,8 +384,10 @@ func (s *state) routineUpdate(file string, interval int, slurmFile string) {
 			log.Debug("Received HUP signal")
 		}
 		delay.Stop()
+		slurmNotPresentOrUpdated := false
 		if slurmFile != "" {
-			err := s.updateSlurm(slurmFile)
+			var err error
+			slurmNotPresentOrUpdated, err = s.updateSlurm(slurmFile)
 			if err != nil {
 				switch err.(type) {
 				case utils.HttpNotModified:
@@ -392,7 +399,7 @@ func (s *state) routineUpdate(file string, interval int, slurmFile string) {
 				}
 			}
 		}
-		err := s.updateFile(file)
+		cacheUpdated, err := s.updateFile(file)
 		if err != nil {
 			switch err.(type) {
 			case utils.HttpNotModified:
@@ -405,6 +412,15 @@ func (s *state) routineUpdate(file string, interval int, slurmFile string) {
 				log.Errorf("Error updating: %v", err)
 			}
 		}
+
+		// Only process the first time after there is either a cache or SLURM
+		// update.
+		if (cacheUpdated || slurmNotPresentOrUpdated) {
+			err := s.updateFromNewState()
+			if err != nil {
+				log.Errorf("Error updating from new state: %v", err)
+			}
+		}
 	}
 }
 
@@ -417,8 +433,7 @@ func (s *state) exporter(wr http.ResponseWriter, r *http.Request) {
 }
 
 type state struct {
-	lastdata      []byte
-	lastconverted []byte
+	lastdata      *prefixfile.VRPList
 	lasthash      []byte
 	lastchange    time.Time
 	lastts        time.Time
@@ -532,7 +547,7 @@ func main() {
 		log.Fatalf("Specify at least a bind address")
 	}
 
-	err := s.updateFile(*CacheBin)
+	_, err := s.updateFile(*CacheBin)
 	if err != nil {
 		switch err.(type) {
 		case utils.HttpNotModified:
@@ -548,7 +563,7 @@ func main() {
 
 	slurmFile := *Slurm
 	if slurmFile != "" {
-		err := s.updateSlurm(slurmFile)
+		_, err := s.updateSlurm(slurmFile)
 		if err != nil {
 			switch err.(type) {
 			case utils.HttpNotModified: