Proper locking, start to User-Agent population

example/main.go

@@ -55,7 +55,7 @@ func ready(s *discordgo.Session, event *discordgo.Ready) {
 	log.Println("discordgo ready!")
 	s.UpdateStatus(0, "gavalink")
 
-	lavalink = gavalink.NewLavalink("1", event.User.ID)
+	lavalink = gavalink.NewLavalink(1, event.User.ID)
 
 	err := lavalink.AddNodes(gavalink.NodeConfig{
 		REST:      "http://localhost:2333",

lavalink.go

@@ -5,6 +5,7 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"runtime"
 	"sync"
 	"time"
 )
@@ -18,11 +19,13 @@ func init() {
 
 // Lavalink manages a connection to Lavalink Nodes
 type Lavalink struct {
-	shards string
+	shards int
 	userID string
 
 	nodes []*Node
+
 	players   map[string]*Player
+	playersMu sync.RWMutex
 
 	// Event handlers
 	handlersMu   sync.RWMutex
@@ -41,11 +44,10 @@ var (
 	errVolumeOutOfRange = errors.New("Volume is out of range, must be within [0, 1000]")
 	errInvalidVersion   = errors.New("This library requires Lavalink >= 3")
 	errUnknownPayload   = errors.New("Lavalink sent an unknown payload")
-	errNilHandler       = errors.New("You must provide an event handler. Use gavalink.DummyEventHandler if you wish to ignore events")
 )
 
 // NewLavalink creates a new Lavalink manager
-func NewLavalink(shards string, userID string) *Lavalink {
+func NewLavalink(shards int, userID string) *Lavalink {
 	return &Lavalink{
 		shards:  shards,
 		userID:  userID,
@@ -56,32 +58,48 @@ func NewLavalink(shards string, userID string) *Lavalink {
 }
 
 // AddNodes adds a node to the Lavalink manager
+// This function calls all of the node connect methods at once.
+// TODO perhaps add a pool/max at a time limit?
 func (l *Lavalink) AddNodes(nodeConfigs ...NodeConfig) error {
-	nodes := make([]*Node, len(nodeConfigs))
-
 	client := &http.Client{
 		Timeout: 60 * time.Second,
 	}
 
-	for i, c := range nodeConfigs {
+	wg := &sync.WaitGroup{}
+
+	errCh := make(chan error)
+
+	for _, c := range nodeConfigs {
 		n := &Node{
 			config:  c,
 			manager: l,
 			client:  client,
 		}
 
+		wg.Add(1)
+
+		go func(n *Node, wg *sync.WaitGroup, errCh chan error) {
+			defer wg.Done()
+
 			err := n.open()
 
 			if err != nil {
+				errCh <- err
+				return
+			}
+
+			l.nodes = append(l.nodes, n)
+		}(n, wg, errCh)
+	}
+
+	wg.Wait()
+
+	select {
+	case err := <-errCh:
 		return err
-		}
-
-		nodes[i] = n
-	}
-
-	l.nodes = append(l.nodes, nodes...)
-
+	default:
 		return nil
+	}
 }
 
 // RemoveNode removes a node from the manager
@@ -99,6 +117,7 @@ func (l *Lavalink) removeNode(node *Node) error {
 
 	node.stop()
 
+	l.playersMu.RLock()
 	for _, player := range l.players {
 		if player.node == node {
 			n, err := l.BestNode()
@@ -110,6 +129,7 @@ func (l *Lavalink) removeNode(node *Node) error {
 			player.ChangeNode(n)
 		}
 	}
+	l.playersMu.RUnlock()
 
 	// temp var for easier reading
 	n := l.nodes
@@ -133,6 +153,9 @@ func (l *Lavalink) BestNode() (*Node, error) {
 
 // GetPlayer gets a player for a guild
 func (l *Lavalink) GetPlayer(guild string) (*Player, error) {
+	l.playersMu.RLock()
+	defer l.playersMu.RUnlock()
+
 	p, ok := l.players[guild]
 
 	if !ok {
@@ -150,3 +173,7 @@ func (l *Lavalink) AddCapability(key string, i interface{}) {
 
 	l.capabilities[key] = i
 }
+
+func gavalinkUserAgent() string {
+	return "Gavalink (v1.0, " + runtime.Version() + ")"
+}

node.go

@@ -67,11 +67,13 @@ type FrameStats struct {
 	Deficit int `json:"deficit"`
 }
 
+// Opens the connection to the Lavalink server
 func (node *Node) open() error {
 	header := http.Header{}
 
+	header.Set("User-Agent", gavalinkUserAgent())
 	header.Set("Authorization", node.config.Password)
-	header.Set("Num-Shards", node.manager.shards)
+	header.Set("Num-Shards", strconv.Itoa(node.manager.shards))
 	header.Set("User-Id", node.manager.userID)
 
 	if node.manager.capabilities != nil {
@@ -160,6 +162,7 @@ func (node *Node) listen() {
 	}
 }
 
+// Handle an event from the node
 func (node *Node) onEvent(v *fastjson.Value, msg []byte) error {
 	op := jsonStringValue(v, "op")
 
@@ -193,13 +196,13 @@ func (node *Node) onEvent(v *fastjson.Value, msg []byte) error {
 		case eventTrackStart:
 			player.track = track
 
-			player.handle(eventTrackStart, &TrackStart{
+			node.manager.handle(player, eventTrackStart, &TrackStart{
 				Track: track,
 			})
 		case eventTrackEnd:
 			player.track = ""
 
-			player.handle(eventTrackEnd, &TrackEnd{
+			node.manager.handle(player, eventTrackEnd, &TrackEnd{
 				Track:  track,
 				Reason: jsonStringValue(v, "reason"),
 			})
@@ -215,9 +218,9 @@ func (node *Node) onEvent(v *fastjson.Value, msg []byte) error {
 				ex.Exception = exception
 			}
 
-			player.handle(eventTrackException, ex)
+			node.manager.handle(player, eventTrackException, ex)
 		case eventTrackStuck:
-			player.handle(eventTrackStuck, &TrackStuck{
+			node.manager.handle(player, eventTrackStuck, &TrackStuck{
 				Track:     track,
 				Threshold: time.Duration(v.GetInt("thresholdMs")) * time.Millisecond,
 			})
@@ -229,7 +232,7 @@ func (node *Node) onEvent(v *fastjson.Value, msg []byte) error {
 				File:   track,
 			}
 
-			player.handle(eventVoiceProcessed, &VoiceProcessed{
+			node.manager.handle(player, eventVoiceProcessed, &VoiceProcessed{
 				Data:     data,
 				Hotword:  v.GetBool("hotword"),
 				Override: v.GetBool("override"),
@@ -268,6 +271,8 @@ func (node *Node) CreatePlayer(guildID string, sessionID string, event VoiceServ
 		lastVoiceServerUpdate: event,
 	}
 
+	node.manager.playersMu.Lock()
+	defer node.manager.playersMu.Unlock()
 	node.manager.players[guildID] = player
 
 	return player, nil
@@ -291,6 +296,7 @@ func (node *Node) LoadTracks(query string) (*Tracks, error) {
 		return nil, err
 	}
 
+	req.Header.Set("User-Agent", gavalinkUserAgent())
 	req.Header.Set("Authorization", node.config.Password)
 
 	resp, err := node.client.Do(req)
@@ -308,6 +314,7 @@ func (node *Node) LoadTracks(query string) (*Tracks, error) {
 	return tracks, nil
 }
 
+// Write a JSON message via the node's websocket connection
 func (node *Node) writeMessage(v interface{}) error {
 	return node.wsConn.WriteJSON(v)
 }

player.go

@@ -2,7 +2,6 @@ package gavalink
 
 import (
 	"strconv"
-	"sync"
 )
 
 // Player is a Lavalink player
@@ -203,6 +202,8 @@ func (player *Player) Destroy() error {
 		return err
 	}
 
+	player.manager.playersMu.Lock()
+	defer player.manager.playersMu.Unlock()
 	delete(player.manager.players, player.guildID)
 	return nil
 }