Create dedicated delta package, add tests, and rename distribution -> histogram

Signed-off-by: Kyle Eckhart <[email protected]>

Author: kgeckhart

collectors/delta_counter.go

@@ -23,13 +23,13 @@ const (
 	prime64  = 1099511628211
 )
 
-// hashNew initializies a new fnv64a hash value.
-func hashNew() uint64 {
+// HashNew initializies a new fnv64a hash value.
+func HashNew() uint64 {
 	return offset64
 }
 
-// hashAdd adds a string to a fnv64a hash value, returning the updated hash.
-func hashAdd(h uint64, s string) uint64 {
+// HashAdd adds a string to a fnv64a hash value, returning the updated hash.
+func HashAdd(h uint64, s string) uint64 {
 	for i := 0; i < len(s); i++ {
 		h ^= uint64(s[i])
 		h *= prime64

collectors/delta_distribution.go

@@ -54,8 +54,8 @@ type MonitoringCollector struct {
 	collectorFillMissingLabels      bool
 	monitoringDropDelegatedProjects bool
 	logger                          log.Logger
-	deltaCounterStore               DeltaCounterStore
-	deltaDistributionStore          DeltaDistributionStore
+	counterStore                    DeltaCounterStore
+	histogramStore                  DeltaHistogramStore
 	aggregateDeltas                 bool
 }
 
@@ -82,7 +82,17 @@ type MonitoringCollectorOptions struct {
 	AggregateDeltas bool
 }
 
-func NewMonitoringCollector(projectID string, monitoringService *monitoring.Service, opts MonitoringCollectorOptions, logger log.Logger, counterStore DeltaCounterStore, distributionStore DeltaDistributionStore) (*MonitoringCollector, error) {
+type DeltaCounterStore interface {
+	Increment(metricDescriptor *monitoring.MetricDescriptor, currentValue *ConstMetric)
+	ListMetrics(metricDescriptorName string) []*ConstMetric
+}
+
+type DeltaHistogramStore interface {
+	Increment(metricDescriptor *monitoring.MetricDescriptor, currentValue *HistogramMetric)
+	ListMetrics(metricDescriptorName string) []*HistogramMetric
+}
+
+func NewMonitoringCollector(projectID string, monitoringService *monitoring.Service, opts MonitoringCollectorOptions, logger log.Logger, counterStore DeltaCounterStore, histogramStore DeltaHistogramStore) (*MonitoringCollector, error) {
 	const subsystem = "monitoring"
 
 	apiCallsTotalMetric := prometheus.NewCounter(
@@ -162,8 +172,8 @@ func NewMonitoringCollector(projectID string, monitoringService *monitoring.Serv
 		collectorFillMissingLabels:      opts.FillMissingLabels,
 		monitoringDropDelegatedProjects: opts.DropDelegatedProjects,
 		logger:                          logger,
-		deltaCounterStore:               counterStore,
-		deltaDistributionStore:          distributionStore,
+		counterStore:                    counterStore,
+		histogramStore:                  histogramStore,
 		aggregateDeltas:                 opts.AggregateDeltas,
 	}
 
@@ -346,8 +356,8 @@ func (c *MonitoringCollector) reportTimeSeriesMetrics(
 	timeSeriesMetrics, err := NewTimeSeriesMetrics(metricDescriptor,
 		ch,
 		c.collectorFillMissingLabels,
-		c.deltaCounterStore,
-		c.deltaDistributionStore,
+		c.counterStore,
+		c.histogramStore,
 		c.aggregateDeltas,
 	)
 	if err != nil {