Check condition presence before updating callbacks.

It is possible that a condition is removed on an execution loop with a
subsequent update callback for that condition queued. This changelist
checks the presence of the condition's callbacks before proceeding to
update them.

Fixes: 237362971
Test: atest ConditionMonitorTest#testUpdateRemovedCallback
Change-Id: If2e4fcc8ff82f51134d91434ad7f2043f531ae77

packages/SystemUI/src/com/android/systemui/util/condition/Monitor.java

@@ -92,7 +92,15 @@ public class Monitor {
     }
 
     private void updateConditionMetState(Condition condition) {
-        mConditions.get(condition).stream().forEach(token -> mSubscriptions.get(token).update());
+        final ArraySet<Subscription.Token> subscriptions = mConditions.get(condition);
+
+        // It's possible the condition was removed between the time the callback occurred and
+        // update was executed on the main thread.
+        if (subscriptions == null) {
+            return;
+        }
+
+        subscriptions.stream().forEach(token -> mSubscriptions.get(token).update());
     }
 
     /**

packages/SystemUI/tests/src/com/android/systemui/util/condition/ConditionMonitorTest.java

@@ -159,6 +159,24 @@ public class ConditionMonitorTest extends SysuiTestCase {
         Mockito.clearInvocations(callback);
     }
 
+    // Ensure that updating a callback that is removed doesn't result in an exception due to the
+    // absence of the condition.
+    @Test
+    public void testUpdateRemovedCallback() {
+        final Monitor.Callback callback1 =
+                mock(Monitor.Callback.class);
+        final Monitor.Subscription.Token subscription1 =
+                mConditionMonitor.addSubscription(getDefaultBuilder(callback1).build());
+        ArgumentCaptor<Condition.Callback> monitorCallback =
+                ArgumentCaptor.forClass(Condition.Callback.class);
+        mExecutor.runAllReady();
+        verify(mCondition1).addCallback(monitorCallback.capture());
+        // This will execute first before the handler for onConditionChanged.
+        mConditionMonitor.removeSubscription(subscription1);
+        monitorCallback.getValue().onConditionChanged(mCondition1);
+        mExecutor.runAllReady();
+    }
+
     @Test
     public void addCallback_addFirstCallback_addCallbackToAllConditions() {
         final Monitor.Callback callback1 =