Instana tracer implementation

vendor/github.com/instana/go-sensor/sensor.go

@@ -0,0 +1,76 @@
+package instana
+
+import (
+	"os"
+	"path/filepath"
+)
+
+const (
+	DefaultMaxBufferedSpans = 1000
+	DefaultForceSpanSendAt  = 500
+)
+
+type sensorS struct {
+	meter       *meterS
+	agent       *agentS
+	options     *Options
+	serviceName string
+}
+
+var sensor *sensorS
+
+func (r *sensorS) init(options *Options) {
+	//sensor can be initialized explicit or implicit through OpenTracing global init
+	if r.meter == nil {
+		r.setOptions(options)
+		r.configureServiceName()
+		r.agent = r.initAgent()
+		r.meter = r.initMeter()
+	}
+}
+
+func (r *sensorS) setOptions(options *Options) {
+	r.options = options
+	if r.options == nil {
+		r.options = &Options{}
+	}
+
+	if r.options.MaxBufferedSpans == 0 {
+		r.options.MaxBufferedSpans = DefaultMaxBufferedSpans
+	}
+
+	if r.options.ForceTransmissionStartingAt == 0 {
+		r.options.ForceTransmissionStartingAt = DefaultForceSpanSendAt
+	}
+}
+
+func (r *sensorS) getOptions() *Options {
+	return r.options
+}
+
+func (r *sensorS) configureServiceName() {
+	if r.options != nil {
+		r.serviceName = r.options.Service
+	}
+
+	if r.serviceName == "" {
+		r.serviceName = filepath.Base(os.Args[0])
+	}
+}
+
+// InitSensor Intializes the sensor (without tracing) to begin collecting
+// and reporting metrics.
+func InitSensor(options *Options) {
+	if sensor == nil {
+		sensor = new(sensorS)
+		// If this environment variable is set, then override log level
+		_, ok := os.LookupEnv("INSTANA_DEV")
+		if ok {
+			options.LogLevel = Debug
+		}
+
+		sensor.initLog()
+		sensor.init(options)
+		log.debug("initialized sensor")
+	}
+}