Change logic for determining minimum polling frequency.

Since polling is tied to housekeeping, minimum supported polling
frequency is 1s.

Users can specify polling frequency higher than 1s. The polling loop
will be called at the minimum frequency specified in config as long as
its higher than the minimum supported frequency.

collector/generic_collector.go

@@ -65,18 +65,15 @@ func NewCollector(collectorName string, configfile string) (*GenericCollector, e
 		return nil, fmt.Errorf("No metrics provided in config")
 	}
 
-	minPollFrequency := configInJSON.MetricsConfig[0].PollingFrequency
-
-	//set minPollFrequency to housekeepingInterval if config returns minpollFrequency=0
-	if minPollFrequency == 0 {
-		minPollFrequency = 1 * time.Second
-	}
-
+	minPollFrequency := time.Duration(0)
 	regexprs := make([]*regexp.Regexp, len(configInJSON.MetricsConfig))
 
 	for ind, metricConfig := range configInJSON.MetricsConfig {
-		if metricConfig.PollingFrequency < minPollFrequency && metricConfig.PollingFrequency != 0 {
-			minPollFrequency = metricConfig.PollingFrequency
+		// Find the minimum specified polling frequency in metric config.
+		if metricConfig.PollingFrequency != 0 {
+			if minPollFrequency == 0 || metricConfig.PollingFrequency < minPollFrequency {
+				minPollFrequency = metricConfig.PollingFrequency
+			}
 		}
 
 		regexprs[ind], err = regexp.Compile(metricConfig.Regex)
@@ -85,6 +82,12 @@ func NewCollector(collectorName string, configfile string) (*GenericCollector, e
 		}
 	}
 
+	// Minimum supported polling frequency is 1s.
+	minSupportedFrequency := 1 * time.Second
+	if minPollFrequency < minSupportedFrequency {
+		minPollFrequency = minSupportedFrequency
+	}
+
 	return &GenericCollector{
 		name:       collectorName,
 		configFile: configInJSON,