From f354c67bd8c32439c6392228722ff00d8b5d74b8 Mon Sep 17 00:00:00 2001
From: Dave Mankoff <mankoff@google.com>
Date: Fri, 1 May 2020 10:21:26 -0400
Subject: [PATCH] Prevent NPE in ProximitySensor.

There was a pseudo-race in ProximitySensor where, if a listener
tried to cancel its proximity sensor, the sensor would then add
a delayed runnable _after_ being canceled, causing it to NPE the
next time it ran. This only occured on phones using a dual-sensor
approach to proximity. It happened particularly regularly with the
ProxCheck utility class.

Fixes: 155183913
Test: atest SystemUITests && manual.
Change-Id: Id399c6d577e3c43f91a3d3a2e3b49fd4fa1918e4
---
 .../util/sensors/ProximitySensor.java         |  4 +--
 .../util/sensors/ProximitySensorDualTest.java | 31 +++++++++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/packages/SystemUI/src/com/android/systemui/util/sensors/ProximitySensor.java b/packages/SystemUI/src/com/android/systemui/util/sensors/ProximitySensor.java
index 9be42f3fc5f48..a59d101c9f11b 100644
--- a/packages/SystemUI/src/com/android/systemui/util/sensors/ProximitySensor.java
+++ b/packages/SystemUI/src/com/android/systemui/util/sensors/ProximitySensor.java
@@ -92,11 +92,11 @@ public class ProximitySensor implements ThresholdSensor {
             }
             logDebug("Secondary sensor event: " + event.getBelow() + ".");
 
-            onSensorEvent(event);
-
             // Check this sensor again in a moment.
             mCancelSecondaryRunnable = mDelayableExecutor.executeDelayed(
                     mSecondaryThresholdSensor::resume, SECONDARY_PING_INTERVAL_MS);
+
+            onSensorEvent(event);
         }
     };
 
diff --git a/packages/SystemUI/tests/src/com/android/systemui/util/sensors/ProximitySensorDualTest.java b/packages/SystemUI/tests/src/com/android/systemui/util/sensors/ProximitySensorDualTest.java
index a39c201695183..81a57478f6efb 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/util/sensors/ProximitySensorDualTest.java
+++ b/packages/SystemUI/tests/src/com/android/systemui/util/sensors/ProximitySensorDualTest.java
@@ -262,6 +262,37 @@ public class ProximitySensorDualTest extends SysuiTestCase {
         mProximitySensor.unregister(listener);
     }
 
+    @Test
+    public void testSecondaryCancelsSecondary() {
+        TestableListener listener = new TestableListener();
+        ThresholdSensor.Listener cancelingListener = new ThresholdSensor.Listener() {
+            @Override
+            public void onThresholdCrossed(ThresholdSensor.ThresholdSensorEvent event) {
+                mProximitySensor.pause();
+            }
+        };
+
+        mProximitySensor.register(listener);
+        mProximitySensor.register(cancelingListener);
+        assertNull(listener.mLastEvent);
+        assertEquals(0, listener.mCallCount);
+
+        mThresholdSensorPrimary.triggerEvent(true, 0);
+        assertNull(listener.mLastEvent);
+        assertEquals(0, listener.mCallCount);
+        mThresholdSensorSecondary.triggerEvent(true, 0);
+        assertTrue(listener.mLastEvent.getBelow());
+        assertEquals(1, listener.mCallCount);
+
+        // The proximity sensor should now be canceled. Advancing the clock should do nothing.
+        assertEquals(0, mFakeExecutor.numPending());
+        mThresholdSensorSecondary.triggerEvent(false, 1);
+        assertTrue(listener.mLastEvent.getBelow());
+        assertEquals(1, listener.mCallCount);
+
+        mProximitySensor.unregister(listener);
+    }
+
     private static class TestableListener implements ThresholdSensor.Listener {
         ThresholdSensor.ThresholdSensorEvent mLastEvent;
         int mCallCount = 0;