Fix a number of potential and actual race conditions

Fixes #4

client.go

@@ -165,10 +165,11 @@ func (c *Client) removeDeviceByID(id uint64) error {
 // GetLocations returns a slice of all locations known to the client, or
 // common.ErrNotFound if no locations are currently known.
 func (c *Client) GetLocations() (locations []common.Location, err error) {
+	c.RLock()
 	if len(c.locations) == 0 {
+		c.RUnlock()
 		return locations, common.ErrNotFound
 	}
-	c.RLock()
 	for _, location := range c.locations {
 		locations = append(locations, location)
 	}
@@ -258,10 +259,11 @@ func (c *Client) GetLocationByLabel(label string) (common.Location, error) {
 // GetGroups returns a slice of all groups known to the client, or
 // common.ErrNotFound if no groups are currently known.
 func (c *Client) GetGroups() (groups []common.Group, err error) {
+	c.RLock()
 	if len(c.groups) == 0 {
+		c.RUnlock()
 		return groups, common.ErrNotFound
 	}
-	c.RLock()
 	for _, group := range c.groups {
 		groups = append(groups, group)
 	}
@@ -351,10 +353,11 @@ func (c *Client) GetGroupByLabel(label string) (common.Group, error) {
 // GetDevices returns a slice of all devices known to the client, or
 // common.ErrNotFound if no devices are currently known.
 func (c *Client) GetDevices() (devices []common.Device, err error) {
+	c.RLock()
 	if len(c.devices) == 0 {
+		c.RUnlock()
 		return devices, common.ErrNotFound
 	}
-	c.RLock()
 	for _, device := range c.devices {
 		devices = append(devices, device)
 	}

protocol/v2.go

@@ -93,17 +93,17 @@ func (p *V2) init() error {
 	if err != nil {
 		return err
 	}
-	p.broadcast = &device.Light{Device: *broadcastDev}
+	p.broadcast = &device.Light{Device: broadcastDev}
 	broadcastSub, err := p.broadcast.NewSubscription()
 	if err != nil {
 		return err
 	}
-	go p.broadcastLimiter(broadcastSub.Events())
 	p.devices = make(map[uint64]device.GenericDevice)
 	p.locations = make(map[string]*device.Location)
 	p.groups = make(map[string]*device.Group)
 	p.subscriptions = make(map[string]*common.Subscription)
 	p.quitChan = make(chan struct{})
+	go p.broadcastLimiter(broadcastSub.Events())
 	go p.dispatcher()
 	p.initialized = true
 
@@ -570,13 +570,13 @@ func (p *V2) lightOrDev(dev device.GenericDevice) device.GenericDevice {
 		switch product {
 		case device.ProductLifxOriginal1000, device.ProductLifxColor650, device.ProductLifxWhite800LowVoltage, device.ProductLifxWhite800HighVoltage, device.ProductLifxWhite900BR30, device.ProductLifxColor1000BR30, device.ProductLifxColor1000:
 			p.Lock()
-			// Need to figure if there's a way to do this without being racey on the
-			// lock inside the dev
 			d := dev.(*device.Device)
-			l := &device.Light{Device: *d}
+			d.Lock()
+			l := &device.Light{Device: d}
 			common.Log.Debugf("Device is a light: %v\n", l.ID())
 			// Replace the known dev with our constructed light
 			p.devices[l.ID()] = l
+			d.Unlock()
 			p.Unlock()
 			if err := l.Get(); err != nil {
 				common.Log.Debugf("Failed getting light state: %v\n", err)