Documented the stuff in receiver.go

example/example.go

@@ -9,6 +9,6 @@ func main() {
 	f := func(m statsd.Metric) {
 		log.Printf("%s", m)
 	}
-	r := statsd.MetricReceiver{":8125", f}
+	r := statsd.MetricReceiver{":8125", HanlderFunc(f)}
 	r.ListenAndReceive()
 }

statsd/receiver.go

@@ -5,15 +5,31 @@ import (
 	"net"
 )
 
+// DefaultMetricsAddr is the default address on which a MetricReceiver will listen
 const DefaultMetricsAddr = ":8125"
 
-type Handler func(Metric)
+// Objects implementing the Handler interface can be used to handle metrics for a MetricReceiver
+type Handler interface {
+	HandleMetric(m Metric)
+}
+
+// The HandlerFunc type is an adapter to allow the use of ordinary functions as metric handlers
+type HandlerFunc func(Metric)
+
+// HandleMetric calls f(m)
+func (f HandlerFunc) HandleMetric(m Metric) {
+	f(m)
+}
 
+// MetricReceiver receives data on its listening port and converts lines in to Metrics.
+// For each Metric it calls r.Handler.HandleMetric()
 type MetricReceiver struct {
 	Addr    string  // UDP address on which to listen for metrics
 	Handler Handler // handler to invoke
 }
 
+// ListenAndReceive listens on the UDP network address of srv.Addr and then calls
+// Receive to handle the incoming datagrams. If Addr is blank then DefaultMetricsAddr is used.
 func (r *MetricReceiver) ListenAndReceive() error {
 	addr := r.Addr
 	if addr == "" {
@@ -26,6 +42,8 @@ func (r *MetricReceiver) ListenAndReceive() error {
 	return r.Receive(c)
 }
 
+// Receive accepts incoming datagrams on c and calls r.Handler.HandleMetric() for each line in the
+// datagram that successfully parses in to a Metric
 func (r *MetricReceiver) Receive(c net.PacketConn) error {
 	defer c.Close()
 
@@ -42,12 +60,13 @@ func (r *MetricReceiver) Receive(c net.PacketConn) error {
 	panic("not reached")
 }
 
+// handleMessage handles the contents of a datagram and attempts to parse a Metric from each line
 func (srv *MetricReceiver) handleMessage(msg []byte) {
 	metrics, err := parseMessage(string(msg))
 	if err != nil {
 		log.Printf("Error parsing metric %s", err)
 	}
 	for _, metric := range metrics {
-		srv.Handler(metric)
+		srv.Handler.HandleMetric(metric)
 	}
 }

statsd/server.go

@@ -429,7 +429,7 @@ func ListenAndServe(metricAddr string, consoleAddr string, graphiteAddr string,
 	f := func(metric Metric) {
 		metricChan <- metric
 	}
-	s := MetricReceiver{metricAddr, f}
+	s := MetricReceiver{metricAddr, HandlerFunc(f)}
 
 	go s.ListenAndReceive()
 	go metricAggregator(graphiteAddr, metricChan, consoleChan, flushInterval)