nomad: remove unused NotifyGroup struct

I don't think it's been used for a long time.

nomad/state/notify.go

@@ -1,62 +0,0 @@
-package state
-
-import (
-	"sync"
-)
-
-// NotifyGroup is used to allow a simple notification mechanism.
-// Channels can be marked as waiting, and when notify is invoked,
-// all the waiting channels get a message and are cleared from the
-// notify list.
-type NotifyGroup struct {
-	l      sync.Mutex
-	notify map[chan struct{}]struct{}
-}
-
-// Notify will do a non-blocking send to all waiting channels, and
-// clear the notify list
-func (n *NotifyGroup) Notify() {
-	n.l.Lock()
-	defer n.l.Unlock()
-	for ch := range n.notify {
-		select {
-		case ch <- struct{}{}:
-		default:
-		}
-	}
-	n.notify = nil
-}
-
-// Wait adds a channel to the notify group
-func (n *NotifyGroup) Wait(ch chan struct{}) {
-	n.l.Lock()
-	defer n.l.Unlock()
-	if n.notify == nil {
-		n.notify = make(map[chan struct{}]struct{})
-	}
-	n.notify[ch] = struct{}{}
-}
-
-// Clear removes a channel from the notify group
-func (n *NotifyGroup) Clear(ch chan struct{}) {
-	n.l.Lock()
-	defer n.l.Unlock()
-	if n.notify == nil {
-		return
-	}
-	delete(n.notify, ch)
-}
-
-// WaitCh allocates a channel that is subscribed to notifications
-func (n *NotifyGroup) WaitCh() chan struct{} {
-	ch := make(chan struct{}, 1)
-	n.Wait(ch)
-	return ch
-}
-
-// Empty checks if there are no channels to notify
-func (n *NotifyGroup) Empty() bool {
-	n.l.Lock()
-	defer n.l.Unlock()
-	return len(n.notify) == 0
-}

nomad/state/notify_test.go

@@ -1,72 +0,0 @@
-package state
-
-import (
-	"testing"
-)
-
-func TestNotifyGroup(t *testing.T) {
-	grp := &NotifyGroup{}
-
-	ch1 := grp.WaitCh()
-	ch2 := grp.WaitCh()
-
-	select {
-	case <-ch1:
-		t.Fatalf("should block")
-	default:
-	}
-	select {
-	case <-ch2:
-		t.Fatalf("should block")
-	default:
-	}
-
-	grp.Notify()
-
-	select {
-	case <-ch1:
-	default:
-		t.Fatalf("should not block")
-	}
-	select {
-	case <-ch2:
-	default:
-		t.Fatalf("should not block")
-	}
-
-	// Should be unregistered
-	ch3 := grp.WaitCh()
-	grp.Notify()
-
-	select {
-	case <-ch1:
-		t.Fatalf("should block")
-	default:
-	}
-	select {
-	case <-ch2:
-		t.Fatalf("should block")
-	default:
-	}
-	select {
-	case <-ch3:
-	default:
-		t.Fatalf("should not block")
-	}
-}
-
-func TestNotifyGroup_Clear(t *testing.T) {
-	grp := &NotifyGroup{}
-
-	ch1 := grp.WaitCh()
-	grp.Clear(ch1)
-
-	grp.Notify()
-
-	// Should not get anything
-	select {
-	case <-ch1:
-		t.Fatalf("should not get message")
-	default:
-	}
-}