rawlinp commented on a change in pull request #6527:
URL: https://github.com/apache/trafficcontrol/pull/6527#discussion_r804124720
##########
File path: traffic_monitor/manager/monitorconfig.go
##########
@@ -337,6 +379,103 @@ func monitorConfigListen(
}
}
+// getCacheGroupsToPoll returns the name of this Traffic Monitor's cache group
+// and the set of cache groups it needs to poll.
+func getCacheGroupsToPoll(distributedPolling bool, hostname string, monitors
map[string]tc.TrafficMonitor,
+ caches map[string]tc.TrafficServer, allCacheGroups
map[string]tc.TMCacheGroup) (string, map[string]tc.TMCacheGroup, error) {
+ tmGroupSet := make(map[string]tc.TMCacheGroup)
+ cacheGroupSet := make(map[string]tc.TMCacheGroup)
+ tmGroupToPolledCacheGroups :=
make(map[string]map[string]tc.TMCacheGroup)
+ thisTMGroup := ""
+
+ for _, tm := range monitors {
+ if tm.HostName == hostname {
+ thisTMGroup = tm.Location
+ }
+ if tc.CacheStatusFromString(tm.ServerStatus) ==
tc.CacheStatusOnline {
+ tmGroupSet[tm.Location] = allCacheGroups[tm.Location]
+ if _, ok := tmGroupToPolledCacheGroups[tm.Location];
!ok {
+ tmGroupToPolledCacheGroups[tm.Location] =
make(map[string]tc.TMCacheGroup)
+ }
+ }
+ }
+ if thisTMGroup == "" {
+ return "", nil, fmt.Errorf("unable to find cache group for this
Traffic Monitor (%s) in monitoring config snapshot", hostname)
+ }
+
+ for _, c := range caches {
+ status := tc.CacheStatusFromString(c.ServerStatus)
+ if status == tc.CacheStatusOnline || status ==
tc.CacheStatusReported || status == tc.CacheStatusAdminDown {
+ cacheGroupSet[c.CacheGroup] =
allCacheGroups[c.CacheGroup]
+ }
+ }
+
+ if !distributedPolling {
+ return thisTMGroup, cacheGroupSet, nil
+ }
+
+ tmGroups := make([]string, 0, len(tmGroupSet))
+ for tg := range tmGroupSet {
+ tmGroups = append(tmGroups, tg)
+ }
+ sort.Strings(tmGroups)
+ cgs := make([]string, 0, len(cacheGroupSet))
+ for cg := range cacheGroupSet {
+ cgs = append(cgs, cg)
+ }
+ sort.Strings(cgs)
+ tmGroupCount := len(tmGroups)
+ var closest string
+ for tmi := 0; len(cgs) > 0; tmi = (tmi + 1) % tmGroupCount {
+ tmGroup := tmGroups[tmi]
+ closest, cgs = findAndRemoveClosestCachegroup(cgs,
allCacheGroups[tmGroup], allCacheGroups)
+ tmGroupToPolledCacheGroups[tmGroup][closest] =
allCacheGroups[closest]
+ }
+ return thisTMGroup, tmGroupToPolledCacheGroups[thisTMGroup], nil
+}
+
+func findAndRemoveClosestCachegroup(remainingCacheGroups []string, target
tc.TMCacheGroup, allCacheGroups map[string]tc.TMCacheGroup) (string, []string) {
+ shortestDistance := math.MaxFloat64
+ shortestIndex := -1
+ for i := 0; i < len(remainingCacheGroups); i++ {
+ distance := getDistance(target,
allCacheGroups[remainingCacheGroups[i]])
+ if distance < shortestDistance {
+ shortestDistance = distance
+ shortestIndex = i
+ }
+ }
+ closest := remainingCacheGroups[shortestIndex]
+ remainingCacheGroups = append(remainingCacheGroups[:shortestIndex],
remainingCacheGroups[shortestIndex+1:]...)
+ return closest, remainingCacheGroups
+}
+
+const meanEarthRadius = 6371.0
+const x = math.Pi / 180
+
+// toRadians converts degrees to radians.
+func toRadians(d float64) float64 {
+ return d * x
+}
+
+// getDistance gets the great circle distance in kilometers between x and y.
+func getDistance(x, y tc.TMCacheGroup) float64 {
Review comment:
Maybe? I basically just transliterated this from TR, which I assume is
correct because we've been using it for years.
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