Bug 1822119 - Store new UUID in shared prefs and send in metrics ping (#1541)

app/metrics.yaml

@@ -2291,6 +2291,26 @@ metrics:
     metadata:
       tags:
         - Notifications
+  shared_prefs_uuid:
+    type: uuid
+    lifetime: ping
+    description: |
+      A UUID stored in Shared Preferences used to analyze technical differences
+      between storage mechanisms in Android, specifically the Glean DB and
+      Shared Preferences.
+    send_in_pings:
+      - metrics
+    notification_emails:
+      - android-probes@mozilla.com
+      - raphael@mozilla.com
+      - fbertsch@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1822119
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1822119
+    data_sensitivity:
+      - technical
+    expires: 116
 
 customize_home:
   most_visited_sites:

app/src/main/java/org/mozilla/fenix/FenixApplication.kt

@@ -726,6 +726,12 @@ open class FenixApplication : LocaleAwareApplication(), Provider {
 
             searchWidgetInstalled.set(settings.searchWidgetInstalled)
 
+            if (settings.sharedPrefsUUID.isEmpty()) {
+                settings.sharedPrefsUUID = sharedPrefsUuid.generateAndSet().toString()
+            } else {
+                sharedPrefsUuid.set(UUID.fromString(settings.sharedPrefsUUID))
+            }
+
             val openTabsCount = settings.openTabsCount
             hasOpenTabs.set(openTabsCount > 0)
             if (openTabsCount > 0) {

app/src/main/java/org/mozilla/fenix/settings/DataChoicesFragment.kt

@@ -32,6 +32,11 @@ class DataChoicesFragment : PreferenceFragmentCompat() {
                     context.components.analytics.metrics.start(MetricServiceType.Data)
                 } else {
                     context.components.analytics.metrics.stop(MetricServiceType.Data)
+
+                    // Reset the Shared Prefs UUID on opt-out since we're investigating cases of
+                    // unexpected client ID regeneration. Telemetry data collection opt-out is
+                    // expected to reset the client ID.
+                    context.settings().sharedPrefsUUID = ""
                 }
                 // Reset experiment identifiers on both opt-in and opt-out; it's likely
                 // that in future we will need to pass in the new telemetry client_id

app/src/main/java/org/mozilla/fenix/utils/Settings.kt

@@ -191,6 +191,16 @@ class Settings(private val appContext: Context) : PreferencesHolder {
         default = "",
     )
 
+    /**
+     * A UUID stored in Shared Preferences used to analyze technical differences
+     * between storage mechanisms in Android, specifically the Glean DB and
+     * Shared Preferences.
+     */
+    var sharedPrefsUUID by stringPreference(
+        appContext.getPreferenceKey(R.string.pref_key_shared_prefs_uuid),
+        default = "",
+    )
+
     var currentWallpaperName by stringPreference(
         appContext.getPreferenceKey(R.string.pref_key_current_wallpaper),
         default = Wallpaper.Default.name,

app/src/main/res/values/preference_keys.xml

@@ -328,6 +328,7 @@
     <string name="pref_key_custom_sponsored_stories_site_id" translatable="false">pref_key_custom_sponsored_stories_site_id</string>
     <string name="pref_key_custom_sponsored_stories_country" translatable="false">pref_key_custom_sponsored_stories_country</string>
     <string name="pref_key_custom_sponsored_stories_city" translatable="false">pref_key_custom_sponsored_stories_city</string>
+    <string name="pref_key_shared_prefs_uuid" translatable="false">pref_key_shared_prefs_uuid</string>
 
     <!-- Growth Data -->
     <string name="pref_key_growth_set_as_default" translatable="false">pref_key_growth_set_as_default</string>

app/src/test/java/org/mozilla/fenix/FenixApplicationTest.kt

@@ -148,6 +148,9 @@ class FenixApplicationTest {
         assertTrue(settings.contileContextId.isEmpty())
         assertNull(TopSites.contextId.testGetValue())
 
+        assertTrue(settings.sharedPrefsUUID.isEmpty())
+        assertNull(Metrics.sharedPrefsUuid.testGetValue())
+
         application.setStartupMetrics(browserStore, settings, browsersCache, mozillaProductDetector)
 
         // Verify that browser defaults metrics are set.
@@ -192,6 +195,14 @@ class FenixApplicationTest {
         assertNotNull(TopSites.contextId.testGetValue())
         assertEquals(contextId, settings.contileContextId)
 
+        // Verify that setStartupMetrics() creates `the Metrics.sharedPrefsUuid`
+        // Glean metric and that it stores the value in shared preferences at
+        // settings.sharedPrefsUUID. Subsequent calls load the UUID value from
+        // shared preferences rather than generating a new one.
+        val sharedPrefsUUIDMetricValue = Metrics.sharedPrefsUuid.testGetValue()!!.toString()
+        assertNotNull(Metrics.sharedPrefsUuid.testGetValue())
+        assertEquals(sharedPrefsUUIDMetricValue, settings.sharedPrefsUUID)
+
         // Verify that search engine defaults are NOT set. This test does
         // not mock most of the objects telemetry is collected from.
         assertNull(SearchDefaultEngine.code.testGetValue())
@@ -202,6 +213,9 @@ class FenixApplicationTest {
 
         assertEquals(contextId, TopSites.contextId.testGetValue()!!.toString())
         assertEquals(contextId, settings.contileContextId)
+
+        assertEquals(sharedPrefsUUIDMetricValue, Metrics.sharedPrefsUuid.testGetValue()!!.toString())
+        assertEquals(sharedPrefsUUIDMetricValue, settings.sharedPrefsUUID)
     }
 
     @Test