Extract Start() function from Collector

Makes it easier to test.

cmd/respond-collector/main.go

@@ -50,7 +50,8 @@ func main() {
 
 	if config.Respondd.Enable {
 		collectInterval := time.Second * time.Duration(config.Respondd.CollectInterval)
-		collector = respond.NewCollector(db, nodes, collectInterval, config.Respondd.Interface)
+		collector = respond.NewCollector(db, nodes, config.Respondd.Interface)
+		collector.Start(collectInterval)
 		defer collector.Close()
 	}
 

respond/collector.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"compress/flate"
 	"encoding/json"
+	"io/ioutil"
 	"log"
 	"net"
 	"reflect"
@@ -29,7 +30,7 @@ type Collector struct {
 }
 
 // Creates a Collector struct
-func NewCollector(db *database.DB, nodes *models.Nodes, interval time.Duration, iface string) *Collector {
+func NewCollector(db *database.DB, nodes *models.Nodes, iface string) *Collector {
 	// Parse address
 	addr, err := net.ResolveUDPAddr("udp", "[::]:0")
 	if err != nil {
@@ -49,7 +50,6 @@ func NewCollector(db *database.DB, nodes *models.Nodes, interval time.Duration,
 		nodes:         nodes,
 		multicastAddr: net.JoinHostPort(multiCastGroup+"%"+iface, port),
 		queue:         make(chan *Response, 400),
-		ticker:        time.NewTicker(interval),
 		stop:          make(chan interface{}, 1),
 	}
 
@@ -60,30 +60,40 @@ func NewCollector(db *database.DB, nodes *models.Nodes, interval time.Duration,
 		go collector.globalStatsWorker()
 	}
 
-	// Run senders
-	go func() {
-		collector.sendOnce() // immediately
-		collector.sender()   // periodically
-	}()
-
 	return collector
 }
 
+// Start Collector
+func (coll *Collector) Start(interval time.Duration) {
+	if coll.ticker != nil {
+		panic("already started")
+	}
+
+	coll.ticker = time.NewTicker(interval)
+	go func() {
+		coll.sendOnce() // immediately
+		coll.sender()   // periodically
+	}()
+}
+
 // Close Collector
 func (coll *Collector) Close() {
 	// stop ticker
+	if coll.ticker != nil {
 		coll.ticker.Stop()
 		close(coll.stop)
+	}
 
 	coll.connection.Close()
 	close(coll.queue)
 }
 
 func (coll *Collector) sendOnce() {
-	coll.sendPacket(coll.multicastAddr)
+	coll.SendPacket(coll.multicastAddr)
 }
 
-func (coll *Collector) sendPacket(address string) {
+// Sends a UDP request to the given unicast or multicast address
+func (coll *Collector) SendPacket(address string) {
 	addr, err := net.ResolveUDPAddr("udp", address)
 	if err != nil {
 		log.Panic(err)