Limit the number of shortcuts per app that can be retained by system

This is a second attempt at fixing the issue, the previous CL
ag/20642213 was reverted because it simply throws an exception when the
limit is reached, which causes apps to crash since chat apps tends to be
sending large amount of conversation shortcuts and they have no way to
know how many of these shortcuts are still cached by the system.

Instead of throwing an exception, this CL simply removes excessive
shortcuts to avoid crashes. Currently there is a limit on the number
of shortcuts an app can publish in respect to each launcher activity.
This CL further implements a global maximum of total number of shortcuts
that can be retained for an app to mitigate from any potential system
health issue.

When the global maximum is reached, ShortcutService will proactively
removes shortcuts from system memory. Cached shortcuts are removed
first, followed by dynamic shortcuts, using last updated time as
tie-breaker.

This CL additionally addresses an unexpected flow where re-publishing
previously removed shortcuts that are still retained by the system could
cause the total number of shortcuts to exceed previously set limit.

Bug: 250576066 233155034
Test: manual
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:a6e7958ab84edbd9e5f4653d4d1f56a7438cd7dc)
Merged-In: I001c7a87b62aefa9487bf8efaf3cd02d7cb21521
Change-Id: I001c7a87b62aefa9487bf8efaf3cd02d7cb21521

2 files changed, 112 insertions, 12 deletions

diff --git a/services/core/java/com/android/server/pm/ShortcutPackage.java b/services/core/java/com/android/server/pm/ShortcutPackage.java
index 890c89152a7c..8507ad028a19 100644
--- a/services/core/java/com/android/server/pm/ShortcutPackage.java
+++ b/services/core/java/com/android/server/pm/ShortcutPackage.java
@@ -430,6 +430,7 @@ class ShortcutPackage extends ShortcutPackageItem {
             @NonNull List<ShortcutInfo> changedShortcuts) {
         Preconditions.checkArgument(newShortcut.isEnabled(),
                 "pushDynamicShortcuts() cannot publish disabled shortcuts");
+        ensureShortcutCountBeforePush();
 
         newShortcut.addFlags(ShortcutInfo.FLAG_DYNAMIC);
 
@@ -437,7 +438,7 @@ class ShortcutPackage extends ShortcutPackageItem {
         final ShortcutInfo oldShortcut = findShortcutById(newShortcut.getId());
         boolean deleted = false;
 
-        if (oldShortcut == null) {
+        if (oldShortcut == null || !oldShortcut.isDynamic()) {
             final ShortcutService service = mShortcutUser.mService;
             final int maxShortcuts = service.getMaxActivityShortcuts();
 
@@ -446,18 +447,12 @@ class ShortcutPackage extends ShortcutPackageItem {
             final ArrayList<ShortcutInfo> activityShortcuts = all.get(newShortcut.getActivity());
 
             if (activityShortcuts != null && activityShortcuts.size() > maxShortcuts) {
-                Slog.e(TAG, "Error pushing shortcut. There are already "
-                        + activityShortcuts.size() + " shortcuts, exceeding the " + maxShortcuts
-                        + " shortcuts limit when pushing the new shortcut " + newShortcut
-                        + ". Id of shortcuts currently available in system memory are "
-                        + activityShortcuts.stream().map(ShortcutInfo::getId)
-                        .collect(Collectors.joining(",", "[", "]")));
-                // TODO: This should not have happened. If it does, identify the root cause where
-                //  possible, otherwise bail-out early to prevent memory issue.
+                // Root cause was discovered in b/233155034, so this should not be happening.
+                service.wtf("Error pushing shortcut. There are already "
+                        + activityShortcuts.size() + " shortcuts.");
             }
             if (activityShortcuts != null && activityShortcuts.size() == maxShortcuts) {
                 // Max has reached. Delete the shortcut with lowest rank.
-
                 // Sort by isManifestShortcut() and getRank().
                 Collections.sort(activityShortcuts, mShortcutTypeAndRankComparator);
 
@@ -473,7 +468,8 @@ class ShortcutPackage extends ShortcutPackageItem {
                 deleted = deleteDynamicWithId(shortcut.getId(), /* ignoreInvisible =*/ true,
                         /*ignorePersistedShortcuts=*/ true) != null;
             }
-        } else {
+        }
+        if (oldShortcut != null) {
             // It's an update case.
             // Make sure the target is updatable. (i.e. should be mutable.)
             oldShortcut.ensureUpdatableWith(newShortcut, /*isUpdating=*/ false);
@@ -505,6 +501,32 @@ class ShortcutPackage extends ShortcutPackageItem {
         return deleted;
     }
 
+    private void ensureShortcutCountBeforePush() {
+        final ShortcutService service = mShortcutUser.mService;
+        // Ensure the total number of shortcuts doesn't exceed the hard limit per app.
+        final int maxShortcutPerApp = service.getMaxAppShortcuts();
+        synchronized (mLock) {
+            final List<ShortcutInfo> appShortcuts = mShortcuts.values().stream().filter(si ->
+                    !si.isPinned()).collect(Collectors.toList());
+            if (appShortcuts.size() >= maxShortcutPerApp) {
+                // Max has reached. Removes shortcuts until they fall within the hard cap.
+                // Sort by isManifestShortcut(), isDynamic() and getLastChangedTimestamp().
+                Collections.sort(appShortcuts, mShortcutTypeRankAndTimeComparator);
+
+                while (appShortcuts.size() >= maxShortcutPerApp) {
+                    final ShortcutInfo shortcut = appShortcuts.remove(appShortcuts.size() - 1);
+                    if (shortcut.isDeclaredInManifest()) {
+                        // All shortcuts are manifest shortcuts and cannot be removed.
+                        throw new IllegalArgumentException(getPackageName() + " has published "
+                                + appShortcuts.size() + " manifest shortcuts across different"
+                                + " activities.");
+                    }
+                    forceDeleteShortcutInner(shortcut.getId());
+                }
+            }
+        }
+    }
+
     /**
      * Remove all shortcuts that aren't pinned, cached nor dynamic.
      *
@@ -1367,6 +1389,61 @@ class ShortcutPackage extends ShortcutPackageItem {
     };
 
     /**
+     * To sort by isManifestShortcut(), isDynamic(), getRank() and
+     * getLastChangedTimestamp(). i.e. manifest shortcuts come before non-manifest shortcuts,
+     * dynamic shortcuts come before floating shortcuts, then sort by last changed timestamp.
+     *
+     * This is used to decide which shortcuts to remove when the total number of shortcuts retained
+     * for the app exceeds the limit defined in {@link ShortcutService#getMaxAppShortcuts()}.
+     *
+     * (Note the number of manifest shortcuts is always <= the max number, because if there are
+     * more, ShortcutParser would ignore the rest.)
+     */
+    final Comparator<ShortcutInfo> mShortcutTypeRankAndTimeComparator = (ShortcutInfo a,
+            ShortcutInfo b) -> {
+        if (a.isDeclaredInManifest() && !b.isDeclaredInManifest()) {
+            return -1;
+        }
+        if (!a.isDeclaredInManifest() && b.isDeclaredInManifest()) {
+            return 1;
+        }
+        if (a.isDynamic() && b.isDynamic()) {
+            return Integer.compare(a.getRank(), b.getRank());
+        }
+        if (a.isDynamic()) {
+            return -1;
+        }
+        if (b.isDynamic()) {
+            return 1;
+        }
+        if (a.isCached() && b.isCached()) {
+            // if both shortcuts are cached, prioritize shortcuts cached by people tile,
+            if (a.hasFlags(ShortcutInfo.FLAG_CACHED_PEOPLE_TILE)
+                    && !b.hasFlags(ShortcutInfo.FLAG_CACHED_PEOPLE_TILE)) {
+                return -1;
+            } else if (!a.hasFlags(ShortcutInfo.FLAG_CACHED_PEOPLE_TILE)
+                    && b.hasFlags(ShortcutInfo.FLAG_CACHED_PEOPLE_TILE)) {
+                return 1;
+            }
+            // followed by bubbles.
+            if (a.hasFlags(ShortcutInfo.FLAG_CACHED_BUBBLES)
+                    && !b.hasFlags(ShortcutInfo.FLAG_CACHED_BUBBLES)) {
+                return -1;
+            } else if (!a.hasFlags(ShortcutInfo.FLAG_CACHED_BUBBLES)
+                    && b.hasFlags(ShortcutInfo.FLAG_CACHED_BUBBLES)) {
+                return 1;
+            }
+        }
+        if (a.isCached()) {
+            return -1;
+        }
+        if (b.isCached()) {
+            return 1;
+        }
+        return Long.compare(b.getLastChangedTimestamp(), a.getLastChangedTimestamp());
+    };
+
+    /**
      * Build a list of shortcuts for each target activity and return as a map. The result won't
      * contain "floating" shortcuts because they don't belong on any activities.
      */
diff --git a/services/core/java/com/android/server/pm/ShortcutService.java b/services/core/java/com/android/server/pm/ShortcutService.java
index 0b20683185f0..f303fedde567 100644
--- a/services/core/java/com/android/server/pm/ShortcutService.java
+++ b/services/core/java/com/android/server/pm/ShortcutService.java
@@ -181,6 +181,9 @@ public class ShortcutService extends IShortcutService.Stub {
     static final int DEFAULT_MAX_SHORTCUTS_PER_ACTIVITY = 15;
 
     @VisibleForTesting
+    static final int DEFAULT_MAX_SHORTCUTS_PER_APP = 100;
+
+    @VisibleForTesting
     static final int DEFAULT_MAX_ICON_DIMENSION_DP = 96;
 
     @VisibleForTesting
@@ -257,6 +260,11 @@ public class ShortcutService extends IShortcutService.Stub {
         String KEY_MAX_SHORTCUTS = "max_shortcuts";
 
         /**
+         * Key name for the max shortcuts can be retained in system ram per app. (int)
+         */
+        String KEY_MAX_SHORTCUTS_PER_APP = "max_shortcuts_per_app";
+
+        /**
          * Key name for icon compression quality, 0-100.
          */
         String KEY_ICON_QUALITY = "icon_quality";
@@ -329,11 +337,16 @@ public class ShortcutService extends IShortcutService.Stub {
             new SparseArray<>();
 
     /**
-     * Max number of dynamic + manifest shortcuts that each application can have at a time.
+     * Max number of dynamic + manifest shortcuts that each activity can have at a time.
      */
     private int mMaxShortcuts;
 
     /**
+     * Max number of shortcuts that can exists in system ram for each application.
+     */
+    private int mMaxShortcutsPerApp;
+
+    /**
      * Max number of updating API calls that each application can make during the interval.
      */
     int mMaxUpdatesPerInterval;
@@ -807,6 +820,9 @@ public class ShortcutService extends IShortcutService.Stub {
         mMaxShortcuts = Math.max(0, (int) parser.getLong(
                 ConfigConstants.KEY_MAX_SHORTCUTS, DEFAULT_MAX_SHORTCUTS_PER_ACTIVITY));
 
+        mMaxShortcutsPerApp = Math.max(0, (int) parser.getLong(
+                ConfigConstants.KEY_MAX_SHORTCUTS_PER_APP, DEFAULT_MAX_SHORTCUTS_PER_APP));
+
         final int iconDimensionDp = Math.max(1, injectIsLowRamDevice()
                 ? (int) parser.getLong(
                 ConfigConstants.KEY_MAX_ICON_DIMENSION_DP_LOWRAM,
@@ -1759,6 +1775,13 @@ public class ShortcutService extends IShortcutService.Stub {
     }
 
     /**
+     * Return the max number of shortcuts can be retaiend in system ram for each application.
+     */
+    int getMaxAppShortcuts() {
+        return mMaxShortcutsPerApp;
+    }
+
+    /**
      * - Sends a notification to LauncherApps
      * - Write to file
      */