option: add gRPC Compression (#42)

Added the option to pass in a gRPC Compression.

ocagent.go

@@ -66,6 +66,7 @@ type Exporter struct {
 	grpcClientConn     *grpc.ClientConn
 	reconnectionPeriod time.Duration
 	resource           *resourcepb.Resource
+	compressor         string
 
 	startOnce      sync.Once
 	stopCh         chan bool
@@ -253,6 +254,9 @@ func (ae *Exporter) dialToAgent() (*grpc.ClientConn, error) {
 	if ae.canDialInsecure {
 		dialOpts = append(dialOpts, grpc.WithInsecure())
 	}
+	if ae.compressor != "" {
+		dialOpts = append(dialOpts, grpc.WithDefaultCallOptions(grpc.UseCompressor(ae.compressor)))
+	}
 	return grpc.Dial(addr, dialOpts...)
 }
 

options.go

@@ -76,3 +76,18 @@ func (rp reconnectionPeriod) withExporter(e *Exporter) {
 func WithReconnectionPeriod(rp time.Duration) ExporterOption {
 	return reconnectionPeriod(rp)
 }
+
+type compressorSetter string
+
+func (c compressorSetter) withExporter(e *Exporter) {
+	e.compressor = string(c)
+}
+
+// UseCompressor will set the compressor for the gRPC client to use when sending requests.
+// It is the responsibility of the caller to ensure that the compressor set has been registered
+// with google.golang.org/grpc/encoding. This can be done by encoding.RegisterCompressor. Some
+// compressors auto-register on import, such as gzip, which can be registered by calling
+// `import _ "google.golang.org/grpc/encoding/gzip"`
+func UseCompressor(compressorName string) ExporterOption {
+	return compressorSetter(compressorName)
+}

viewdata_to_metrics_test.go

@@ -55,9 +55,11 @@ func TestExportMetrics_conversionFromViewData(t *testing.T) {
 	}()
 
 	reconnectionPeriod := 2 * time.Millisecond
-	ocexp, err := NewExporter(WithInsecure(),
+	ocexp, err := NewExporter(
+		WithInsecure(),
 		WithAddress(":"+agentPortStr),
-		WithReconnectionPeriod(reconnectionPeriod))
+		WithReconnectionPeriod(reconnectionPeriod),
+	)
 	if err != nil {
 		t.Fatalf("Failed to create the ocagent exporter: %v", err)
 	}