Moves callback into Run method arg

client/mdm/ticker.go

@@ -22,35 +22,33 @@ const DefaultReloadInterval = 1 * time.Minute
 var policyLoader = LoadPolicy
 
 // Ticker periodically re-reads the OS-native MDM policy via LoadPolicy and
-// invokes onChange whenever the observed Policy diverges from the last
-// observation (added / removed / changed keys). Launch with Run from a
-// goroutine; cancel the supplied context to stop.
+// invokes the onChange callback (supplied to Run) whenever the observed
+// Policy diverges from the last observation (added / removed / changed
+// keys). Launch with Run from a goroutine; cancel the supplied context
+// to stop.
 type Ticker struct {
 	interval time.Duration
-	onChange func(prev, curr *Policy) error
 	prev     *Policy
 }
 
-// NewTicker constructs a Ticker that re-reads the OS-native policy
-// every reloadInterval and invokes onChange on any diff.
-// onChange may be nil for a log-only ticker.
+// NewTicker constructs a Ticker that will re-read the OS-native policy
+// every reloadInterval once Run is called.
 // The initial snapshot is populated by calling policyLoader at
 // construction time so the first tick only fires
 // onChange when the policy actually changed since boot — without
 // this baseline the first tick would report every currently-managed
 // key as "added" and trigger a spurious engine restart.
-func NewTicker(reloadInterval time.Duration, onChange func(prev, curr *Policy) error) *Ticker {
+func NewTicker(reloadInterval time.Duration) *Ticker {
 	return &Ticker{
 		interval: reloadInterval,
-		onChange: onChange,
 		prev:     policyLoader(),
 	}
 }
 
 // Run blocks until ctx is cancelled, polling the OS-native policy store at
 // the configured cadence and emitting log lines + onChange callback on
-// every observed diff.
-func (t *Ticker) Run(ctx context.Context) {
+// every observed diff. onChange must be non-nil.
+func (t *Ticker) Run(ctx context.Context, onChange func(prev, curr *Policy) error) {
 	tk := time.NewTicker(t.interval)
 	defer tk.Stop()
 	log.Infof("MDM policy reload ticker started (interval=%s)", t.interval)
@@ -68,14 +66,11 @@ func (t *Ticker) Run(ctx context.Context) {
 			log.Infof("MDM policy changed: added=%v removed=%v changed=%v",
 				added, removed, changed)
 			prev := t.prev
-
-			if t.onChange != nil {
-				if err := t.onChange(prev, curr); err != nil {
-					log.Errorf("MDM policy change handler failed (retrying in 1 minute): %v", err)
-					continue
-				}
-				t.prev = curr
+			if err := onChange(prev, curr); err != nil {
+				log.Errorf("MDM policy change handler failed (retrying in 1 minute): %v", err)
+				continue
 			}
+			t.prev = curr
 		}
 	}
 }

client/mdm/ticker_test.go

@@ -34,18 +34,21 @@ func TestTicker_FiresOnChangeWithDelta(t *testing.T) {
 
 	type change struct{ prev, curr *Policy }
 	changes := make(chan change, 1)
-	tk := NewTicker(testReloadInterval, func(prev, curr *Policy) error {
-		select {
-		case changes <- change{prev, curr}:
-		default:
-		}
-		return nil
-	})
+	tk := NewTicker(testReloadInterval)
 	require.Equal(t, testReloadInterval, tk.interval)
 
 	ctx, cancel := context.WithCancel(context.Background())
 	done := make(chan struct{})
-	go func() { tk.Run(ctx); close(done) }()
+	go func() {
+		tk.Run(ctx, func(prev, curr *Policy) error {
+			select {
+			case changes <- change{prev, curr}:
+			default:
+			}
+			return nil
+		})
+		close(done)
+	}()
 	// Stop Run and wait for it to exit before returning, so the policyLoader
 	// restore in t.Cleanup can't race the ticker goroutine still reading it.
 	defer func() { cancel(); <-done }()
@@ -71,17 +74,20 @@ func TestTicker_NoCallbackWhenPolicyUnchanged(t *testing.T) {
 	})
 
 	fired := make(chan struct{}, 1)
-	tk := NewTicker(testReloadInterval, func(_, _ *Policy) error {
-		select {
-		case fired <- struct{}{}:
-		default:
-		}
-		return nil
-	})
+	tk := NewTicker(testReloadInterval)
 
 	ctx, cancel := context.WithCancel(context.Background())
 	done := make(chan struct{})
-	go func() { tk.Run(ctx); close(done) }()
+	go func() {
+		tk.Run(ctx, func(_, _ *Policy) error {
+			select {
+			case fired <- struct{}{}:
+			default:
+			}
+			return nil
+		})
+		close(done)
+	}()
 	defer func() { cancel(); <-done }()
 
 	// Over ~2 ticks at the 1s test cadence the policy never changes, so the

client/server/server.go

@@ -174,8 +174,8 @@ func (s *Server) Start() error {
 	// applies the freshly-read MDM policy as the last layer) and brings
 	// the engine back with the new values.
 	if s.mdmTicker == nil {
-		s.mdmTicker = mdm.NewTicker(mdm.DefaultReloadInterval, s.onMDMPolicyChange)
-		go s.mdmTicker.Run(s.rootCtx)
+		s.mdmTicker = mdm.NewTicker(mdm.DefaultReloadInterval)
+		go s.mdmTicker.Run(s.rootCtx, s.onMDMPolicyChange)
 	}
 
 	// if current state contains any error, return it