From 92361f2abef1d25c74f8c311e125e7579ba21fcb Mon Sep 17 00:00:00 2001
From: Jan Tomljanovic <jtomljanovic@google.com>
Date: Tue, 12 Jan 2021 17:11:02 +0000
Subject: [PATCH] Collect data for blocked toasts due to rate limiting.

We're using compat change that will report that the change was accessed
only when a toast was blocked due to rate limting. We can use these
stats to observe how much of an impact this feature has and on which
apps.

Test: manually observed that the log message appears
Bug: 174840628
Change-Id: I0cc0c76f48b392cbdaf87363248a683ae3150cf3
---
 .../NotificationManagerService.java           | 30 +++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/services/core/java/com/android/server/notification/NotificationManagerService.java b/services/core/java/com/android/server/notification/NotificationManagerService.java
index 4ab827908e347..ab5238f1ddbf7 100755
--- a/services/core/java/com/android/server/notification/NotificationManagerService.java
+++ b/services/core/java/com/android/server/notification/NotificationManagerService.java
@@ -154,6 +154,7 @@ import android.app.usage.UsageStatsManagerInternal;
 import android.companion.ICompanionDeviceManager;
 import android.compat.annotation.ChangeId;
 import android.compat.annotation.EnabledAfter;
+import android.compat.annotation.LoggingOnly;
 import android.content.BroadcastReceiver;
 import android.content.ComponentName;
 import android.content.ContentProvider;
@@ -250,6 +251,7 @@ import android.widget.Toast;
 import com.android.internal.R;
 import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.compat.IPlatformCompat;
 import com.android.internal.config.sysui.SystemUiDeviceConfigFlags;
 import com.android.internal.logging.InstanceId;
 import com.android.internal.logging.InstanceIdSequence;
@@ -446,6 +448,17 @@ public class NotificationManagerService extends SystemService {
     @EnabledAfter(targetSdkVersion = Build.VERSION_CODES.R)
     private static final long NOTIFICATION_TRAMPOLINE_BLOCK = 167676448L;
 
+    /**
+     * Rate limit showing toasts, on a per package basis.
+     *
+     * It limits the number of {@link android.widget.Toast#show()} calls to prevent overburdening
+     * the user with too many toasts in a limited time. Any attempt to show more toasts than allowed
+     * in a certain time frame will result in the toast being discarded.
+     */
+    @ChangeId
+    @LoggingOnly
+    private static final long RATE_LIMIT_TOASTS = 174840628L;
+
     private IActivityManager mAm;
     private ActivityTaskManagerInternal mAtm;
     private ActivityManager mActivityManager;
@@ -466,6 +479,7 @@ public class NotificationManagerService extends SystemService {
     private UriGrantsManagerInternal mUgmInternal;
     private RoleObserver mRoleObserver;
     private UserManager mUm;
+    private IPlatformCompat mPlatformCompat;
     private ShortcutHelper mShortcutHelper;
 
     final IBinder mForegroundToken = new Binder();
@@ -1988,6 +2002,8 @@ public class NotificationManagerService extends SystemService {
         mDeviceIdleManager = getContext().getSystemService(DeviceIdleManager.class);
         mDpm = dpm;
         mUm = userManager;
+        mPlatformCompat = IPlatformCompat.Stub.asInterface(
+                ServiceManager.getService(Context.PLATFORM_COMPAT_SERVICE));
 
         mUiHandler = new Handler(UiThread.get().getLooper());
         String[] extractorNames;
@@ -7412,6 +7428,7 @@ public class NotificationManagerService extends SystemService {
     private boolean tryShowToast(ToastRecord record, boolean rateLimitingEnabled,
             boolean isWithinQuota) {
         if (rateLimitingEnabled && !isWithinQuota) {
+            reportCompatRateLimitingToastsChange(record.uid);
             Slog.w(TAG, "Package " + record.pkg + " is above allowed toast quota, the "
                     + "following toast was blocked and discarded: " + record);
             return false;
@@ -7424,6 +7441,19 @@ public class NotificationManagerService extends SystemService {
         return record.show();
     }
 
+    /** Reports rate limiting toasts compat change (used when the toast was blocked). */
+    private void reportCompatRateLimitingToastsChange(int uid) {
+        final long id = Binder.clearCallingIdentity();
+        try {
+            mPlatformCompat.reportChangeByUid(RATE_LIMIT_TOASTS, uid);
+        } catch (RemoteException e) {
+            Slog.e(TAG, "Unexpected exception while reporting toast was blocked due to rate"
+                    + " limiting", e);
+        } finally {
+            Binder.restoreCallingIdentity(id);
+        }
+    }
+
     @GuardedBy("mToastQueue")
     void cancelToastLocked(int index) {
         ToastRecord record = mToastQueue.get(index);