Debounce calendar changes to avoid excessive view refreshes.

Fixes: 166410455
Test: atest CarCalendarUnitTests CarCalendarUiTests
Change-Id: I504c624be90d85b8c61ac9461bbb73b62014b9f8

3 files changed, 90 insertions, 12 deletions

diff --git a/src/com/android/car/calendar/common/Dialer.java b/src/com/android/car/calendar/common/Dialer.java
index 889a3c8..df843aa 100644
--- a/src/com/android/car/calendar/common/Dialer.java
+++ b/src/com/android/car/calendar/common/Dialer.java
@@ -26,6 +26,8 @@ import android.util.Log;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Strings;
 
+import java.util.Objects;
+
 import javax.annotation.Nullable;
 
 /** Calls the default dialer with an optional access code. */
@@ -94,5 +96,18 @@ public class Dialer {
                     .add("mAccess", mAccess)
                     .toString();
         }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            NumberAndAccess that = (NumberAndAccess) o;
+            return mNumber.equals(that.mNumber) && Objects.equals(mAccess, that.mAccess);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(mNumber, mAccess);
+        }
     }
 }
diff --git a/src/com/android/car/calendar/common/Event.java b/src/com/android/car/calendar/common/Event.java
index 4395d33..6f88717 100644
--- a/src/com/android/car/calendar/common/Event.java
+++ b/src/com/android/car/calendar/common/Event.java
@@ -20,6 +20,9 @@ import com.android.car.calendar.common.Dialer.NumberAndAccess;
 
 import java.time.Duration;
 import java.time.Instant;
+import java.util.Objects;
+
+import javax.annotation.Nullable;
 
 /**
  * An immutable value representing a calendar event. Should contain only details that are relevant
@@ -34,9 +37,7 @@ public final class Event {
         NONE,
     }
 
-    /**
-     * The details required for display of the calendar indicator.
-     */
+    /** The details required for display of the calendar indicator. */
     public static class CalendarDetails {
         private final String mName;
         private final int mColor;
@@ -53,6 +54,19 @@ public final class Event {
         public String getName() {
             return mName;
         }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            CalendarDetails that = (CalendarDetails) o;
+            return mColor == that.mColor && mName.equals(that.mName);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(mName, mColor);
+        }
     }
 
     private final boolean mAllDay;
@@ -62,8 +76,8 @@ public final class Event {
     private final Instant mDayEndInstant;
     private final String mTitle;
     private final Status mStatus;
-    private final String mLocation;
-    private final NumberAndAccess mNumberAndAccess;
+    @Nullable private final String mLocation;
+    @Nullable private final NumberAndAccess mNumberAndAccess;
     private final CalendarDetails mCalendarDetails;
 
     Event(
@@ -74,8 +88,8 @@ public final class Event {
             Instant dayEndInstant,
             String title,
             Status status,
-            String location,
-            NumberAndAccess numberAndAccess,
+            @Nullable String location,
+            @Nullable NumberAndAccess numberAndAccess,
             CalendarDetails calendarDetails) {
         mAllDay = allDay;
         mStartInstant = startInstant;
@@ -109,6 +123,7 @@ public final class Event {
         return mTitle;
     }
 
+    @Nullable
     public NumberAndAccess getNumberAndAccess() {
         return mNumberAndAccess;
     }
@@ -117,6 +132,7 @@ public final class Event {
         return mCalendarDetails;
     }
 
+    @Nullable
     public String getLocation() {
         return mLocation;
     }
@@ -132,4 +148,36 @@ public final class Event {
     public Duration getDuration() {
         return Duration.between(getStartInstant(), getEndInstant());
     }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Event event = (Event) o;
+        return mAllDay == event.mAllDay
+                && mStartInstant.equals(event.mStartInstant)
+                && mDayStartInstant.equals(event.mDayStartInstant)
+                && mEndInstant.equals(event.mEndInstant)
+                && mDayEndInstant.equals(event.mDayEndInstant)
+                && mTitle.equals(event.mTitle)
+                && mStatus == event.mStatus
+                && Objects.equals(mLocation, event.mLocation)
+                && Objects.equals(mNumberAndAccess, event.mNumberAndAccess)
+                && mCalendarDetails.equals(event.mCalendarDetails);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(
+                mAllDay,
+                mStartInstant,
+                mDayStartInstant,
+                mEndInstant,
+                mDayEndInstant,
+                mTitle,
+                mStatus,
+                mLocation,
+                mNumberAndAccess,
+                mCalendarDetails);
+    }
 }
diff --git a/src/com/android/car/calendar/common/EventsLiveData.java b/src/com/android/car/calendar/common/EventsLiveData.java
index 12c91e7..f2df3fe 100644
--- a/src/com/android/car/calendar/common/EventsLiveData.java
+++ b/src/com/android/car/calendar/common/EventsLiveData.java
@@ -44,6 +44,7 @@ import java.time.temporal.ChronoUnit;
 import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.List;
+import java.util.Objects;
 
 import javax.annotation.Nullable;
 
@@ -59,6 +60,9 @@ public class EventsLiveData extends LiveData<ImmutableList<Event>> {
     private static final String TAG = "CarCalendarEventsLiveData";
     private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
 
+    // The duration to delay before updating the value to reduce the frequency of changes.
+    private static final int UPDATE_DELAY_MILLIS = 1000;
+
     // Sort events by start date and title.
     private static final Comparator<Event> EVENT_COMPARATOR =
             Comparator.comparing(Event::getDayStartInstant).thenComparing(Event::getTitle);
@@ -68,6 +72,7 @@ public class EventsLiveData extends LiveData<ImmutableList<Event>> {
     private final ContentResolver mContentResolver;
     private final EventDescriptions mEventDescriptions;
     private final EventLocations mLocations;
+    private final Runnable mUpdateRunnable = this::updateIfChanged;
 
     /** The event instances cursor is a field to allow observers to be managed. */
     @Nullable private Cursor mEventsCursor;
@@ -89,8 +94,12 @@ public class EventsLiveData extends LiveData<ImmutableList<Event>> {
     }
 
     /** Refreshes the event instances and sets the new value which notifies observers. */
-    private void update() {
-        postValue(getEventsUntilTomorrow());
+    private void updateIfChanged() {
+        ImmutableList<Event> latest = getEventsUntilTomorrow();
+        ImmutableList<Event> current = getValue();
+        if (!Objects.equals(latest, current)) {
+            postValue(latest);
+        }
     }
 
     /** Queries the content provider for event instances. */
@@ -167,7 +176,7 @@ public class EventsLiveData extends LiveData<ImmutableList<Event>> {
                     @Override
                     public void onChange(boolean selfChange) {
                         if (DEBUG) Log.d(TAG, "Events changed");
-                        update();
+                        updateWithDelay();
                     }
                 };
         cursor.setNotificationUri(mContentResolver, eventInstanceUri);
@@ -176,6 +185,12 @@ public class EventsLiveData extends LiveData<ImmutableList<Event>> {
         return cursor;
     }
 
+    private void updateWithDelay() {
+        // Do not update the events until there have been no changes for a given duration.
+        mBackgroundHandler.removeCallbacks(mUpdateRunnable);
+        mBackgroundHandler.postDelayed(mUpdateRunnable, UPDATE_DELAY_MILLIS);
+    }
+
     /** Can return multiple events for a single cursor row when an event spans multiple days. */
     private List<Event> createEventsForRow(
             Cursor eventInstancesCursor, EventDescriptions eventDescriptions) {
@@ -264,11 +279,11 @@ public class EventsLiveData extends LiveData<ImmutableList<Event>> {
         mBackgroundHandler.post(this::tearDownCursor);
     }
 
-    /** Calls {@link #update()} every minute to keep the displayed time range correct. */
+    /** Calls {@link #updateIfChanged()} every minute to keep the displayed time range correct. */
     private void updateAndScheduleNext() {
         if (DEBUG) Log.d(TAG, "Update and schedule");
         if (hasActiveObservers()) {
-            update();
+            updateIfChanged();
             ZonedDateTime now = ZonedDateTime.now(mClock);
             ZonedDateTime truncatedNowTime = now.truncatedTo(MINUTES);
             ZonedDateTime updateTime = truncatedNowTime.plus(1, MINUTES);