From 59594bee0eaf34b0737c5110bda4ccfc2db63959 Mon Sep 17 00:00:00 2001
From: Darrell Shi <darrellshi@google.com>
Date: Fri, 11 Feb 2022 01:50:23 +0000
Subject: [PATCH] Monitor add callback uniqueness.

Only allow the same instance of callback registered once in the
conditions monitor.

Test: atest ConditionMonitorTest#addCallback_withMultipleInstancesOfTheSameCallback_registerOnlyOne
Fix: 218921598
Change-Id: Ibbce271446e4039759e27bf889c4c672ac026c16
---
 .../android/systemui/util/condition/Monitor.java  |  4 ++++
 .../util/condition/ConditionMonitorTest.java      | 15 +++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/packages/SystemUI/src/com/android/systemui/util/condition/Monitor.java b/packages/SystemUI/src/com/android/systemui/util/condition/Monitor.java
index 7f3d54dcfee50..d3c6e9aa0da93 100644
--- a/packages/SystemUI/src/com/android/systemui/util/condition/Monitor.java
+++ b/packages/SystemUI/src/com/android/systemui/util/condition/Monitor.java
@@ -145,6 +145,10 @@ public class Monitor implements CallbackController<Monitor.Callback> {
     }
 
     private void addCallbackLocked(@NotNull Callback callback) {
+        if (mCallbacks.contains(callback)) {
+            return;
+        }
+
         if (shouldLog()) Log.d(mTag, "adding callback");
         mCallbacks.add(callback);
 
diff --git a/packages/SystemUI/tests/src/com/android/systemui/util/condition/ConditionMonitorTest.java b/packages/SystemUI/tests/src/com/android/systemui/util/condition/ConditionMonitorTest.java
index dff77f389faf7..5118637ea710e 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/util/condition/ConditionMonitorTest.java
+++ b/packages/SystemUI/tests/src/com/android/systemui/util/condition/ConditionMonitorTest.java
@@ -194,6 +194,21 @@ public class ConditionMonitorTest extends SysuiTestCase {
         verify(callback).onConditionsChanged(true);
     }
 
+    @Test
+    public void addCallback_withMultipleInstancesOfTheSameCallback_registerOnlyOne() {
+        final Monitor monitor = new Monitor(mExecutor, new HashSet<>(), null /*callbacks*/);
+        final Monitor.Callback callback = mock(Monitor.Callback.class);
+
+        // Adds the same instance multiple times.
+        monitor.addCallback(callback);
+        monitor.addCallback(callback);
+        monitor.addCallback(callback);
+        mExecutor.runAllReady();
+
+        // Callback should only be triggered once.
+        verify(callback, times(1)).onConditionsChanged(true);
+    }
+
     @Test
     public void removeCallback_shouldNoLongerReceiveUpdate() {
         final Condition condition = mock(Condition.class);