Merge pull request #1663 from molecula/fully-disable-usage-endpoint

CORE-800 Disable /ui/usage endpoint completely when usage-duty-cycle is set to 0

api.go

@@ -910,6 +910,7 @@ type usageCache struct {
 	resetTrigger     chan bool
 	lastCalcDuration time.Duration
 	waitMultiplier   float64
+	disable          bool
 
 	muCalculate sync.Mutex
 	muAssign    sync.Mutex
@@ -962,6 +963,11 @@ func (api *API) Usage(ctx context.Context, remote bool) (map[string]NodeUsage, e
 	span, _ := tracing.StartSpanFromContext(ctx, "API.Usage")
 	defer span.Finish()
 
+	if api.usageCache.disable {
+		resp := make(map[string]NodeUsage)
+		return resp, nil
+	}
+
 	if api.usageCache.lastCalcDuration < usageCacheMinDuration {
 		err := api.ResetUsageCache()
 		if err != nil {
@@ -1070,6 +1076,15 @@ func (api *API) calculateUsage() {
 // time that is spent recalculating this cache. It is specified relatively, rather than by a set interval, because
 // scans can take an unpredictably long time.
 func (api *API) RefreshUsageCache(dutyCycle float64) {
+
+	if dutyCycle == 0 {
+		api.server.logger.Warnf("usage-duty-cycle set to 0, usage cache and /ui/usage endpoint are disabled")
+		api.usageCache = &usageCache{
+			disable: true,
+		}
+		return
+	}
+
 	trigger := make(chan bool)
 	defer close(trigger)
 

ctl/server.go

@@ -113,7 +113,7 @@ func BuildServerFlags(cmd *cobra.Command, srv *server.Command) {
 	flags.Uint16Var(&srv.Config.Postgres.ConnectionLimit, "postgres.connection-limit", srv.Config.Postgres.ConnectionLimit, "Maximum number of simultaneous postgres connections to allow. (set 0 to disable)")
 
 	// Disk and Memory usage cache for ui/usage endpoint
-	flags.Float64Var(&srv.Config.UsageDutyCycle, "usage-duty-cycle", srv.Config.UsageDutyCycle, "Sets the percentage of time that is spent recalculating the disk and memory usage cache. 100.0 for always-running, must be > 0.")
+	flags.Float64Var(&srv.Config.UsageDutyCycle, "usage-duty-cycle", srv.Config.UsageDutyCycle, "Sets the percentage of time that is spent recalculating the disk and memory usage cache. 100.0 for always-running, 0 disables the cache and the /ui/usage endpoint.")
 
 	// Future flags.
 	flags.BoolVar(&srv.Config.Future.Rename, "future.rename", false, "Present application name as FeatureBase. Defaults to false, will default to true in an upcoming release.")

server/server.go

@@ -277,9 +277,7 @@ func (m *Command) Start() (err error) {
 		}
 	}
 
-	if m.Config.UsageDutyCycle > 0 {
-		go m.API.RefreshUsageCache(m.Config.UsageDutyCycle)
-	}
+	go m.API.RefreshUsageCache(m.Config.UsageDutyCycle)
 
 	_ = testhook.Opened(pilosa.NewAuditor(), m, nil)
 	close(m.Started)