pss: outbox refactor minor changes

Author: aperonam

pss/outbox/outbox.go

@@ -10,16 +10,18 @@ const (
 	defaultOutboxCapacity = 100000
 )
 
+var ErrOutboxfull = errors.New("outbox full")
+
 type Outbox interface {
-	Enqueue(outboxmsg *outboxMsg) error
+	Enqueue(*outboxMsg) error
 	ProcessOutbox()
-	SetForwardFunction(forwardFunc func(msg interface{}) error) //Eventually this will not be needed, when pss has a newMock that creates a mock outbox, this is used just for a test outside of outbox package
+	SetForwardFunction(forwardFunc) //Eventually this will not be needed, when pss has a newMock that creates a mock outbox, this is used just for a test outside of outbox package
 }
 
 type Config struct {
 	NumberSlots int
 	QuitC       chan struct{}
-	Forward     func(msg interface{}) error
+	Forward     forwardFunc
 }
 
 type outbox struct {
@@ -28,6 +30,7 @@ type outbox struct {
 	slots   chan int
 	process chan int
 }
+type forwardFunc func(msg interface{}) error
 
 func NewOutbox(config *Config) *outbox {
 	outbox := outbox{
@@ -59,7 +62,7 @@ func (o *outbox) Enqueue(outboxmsg *outboxMsg) error {
 		return nil
 	default:
 		metrics.GetOrRegisterCounter("pss.enqueue.outbox.full", nil).Inc(1)
-		return errors.New("outbox full")
+		return ErrOutboxfull
 	}
 }
 
@@ -84,8 +87,8 @@ func (o *outbox) ProcessOutbox() {
 	}
 }
 
-func (o *outbox) SetForwardFunction(forwardFunc func(msg interface{}) error) {
-	o.Forward = forwardFunc
+func (o *outbox) SetForwardFunction(f forwardFunc) {
+	o.Forward = f
 }
 
 func (o *outbox) msg(slot int) *outboxMsg {