refactor: Call Close() on collector

Doesn't do anything at present, but will be used later.

Change the signature on BillingEmitter.Close() to match. Note we didn't use the error returned.

app/collector.go

@@ -58,6 +58,7 @@ type Adder interface {
 type Collector interface {
 	Reporter
 	Adder
+	Close()
 }
 
 // Collector receives published reports from multiple producers. It yields a
@@ -112,6 +113,9 @@ func NewCollector(window time.Duration) Collector {
 	}
 }
 
+// Close is a no-op for the regular collector
+func (c *collector) Close() {}
+
 // Add adds a report to the collector's internal state. It implements Adder.
 func (c *collector) Add(_ context.Context, rpt report.Report, _ []byte) error {
 	c.mtx.Lock()
@@ -243,6 +247,9 @@ func (c StaticCollector) Report(context.Context, time.Time) (report.Report, erro
 	return report.Report(c), nil
 }
 
+// Close is a no-op for the static collector
+func (c StaticCollector) Close() {}
+
 // HasReports indicates whether the collector contains reports between
 // timestamp-app.window and timestamp.
 func (c StaticCollector) HasReports(context.Context, time.Time) (bool, error) {

app/multitenant/aws_collector.go

@@ -182,6 +182,10 @@ func NewAWSCollector(config AWSCollectorConfig) (AWSCollector, error) {
 	}, nil
 }
 
+// Close is a no-op for awsCollector
+func (c *awsCollector) Close() {
+}
+
 // CreateTables creates the required tables in dynamodb
 func (c *awsCollector) CreateTables() error {
 	// see if tableName exists

app/multitenant/billing_emitter.go

@@ -166,6 +166,7 @@ func hasWeaveNet(r report.Report) bool {
 }
 
 // Close shuts down the billing emitter and billing client flushing events.
-func (e *BillingEmitter) Close() error {
-	return e.billing.Close()
+func (e *BillingEmitter) Close() {
+	e.Collector.Close()
+	_ = e.billing.Close()
 }

prog/app.go

@@ -259,9 +259,9 @@ func appMain(flags appFlags) {
 			log.Fatalf("Error creating emitter: %v", err)
 			return
 		}
-		defer billingEmitter.Close()
 		collector = billingEmitter
 	}
+	defer collector.Close()
 
 	controlRouter, err := controlRouterFactory(userIDer, flags.controlRouterURL, flags.controlRPCTimeout)
 	if err != nil {