[shared_preferences] Fix initialization race (#4159)

During the NNBD transition, the structure of the completer logic in the initialization flow was incorrectly changed to set the field after an `await` instead of immediately. Also updates the error handling to handle `Error` the same way it currently handles `Exception`, which this change surfaced. Fixes flutter/flutter#42407
flutter · Jun 8, 2023 · d935cb0 · d935cb0
1 parent 010ba50
commit d935cb0
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Showing 4 changed files with 193 additions and 175 deletions.
diff --git a/packages/shared_preferences/shared_preferences/CHANGELOG.md b/packages/shared_preferences/shared_preferences/CHANGELOG.md
@@ -1,5 +1,7 @@
-## NEXT
+## 2.1.2
 
+* Fixes singleton initialization race condition introduced during NNBD
+  transition.
 * Updates minimum supported macOS version to 10.14.
 * Updates minimum supported SDK version to Flutter 3.3/Dart 2.18.
 

diff --git a/packages/shared_preferences/shared_preferences/lib/shared_preferences.dart b/packages/shared_preferences/shared_preferences/lib/shared_preferences.dart
@@ -62,19 +62,19 @@ class SharedPreferences {
     if (_completer == null) {
       final Completer<SharedPreferences> completer =
           Completer<SharedPreferences>();
+      _completer = completer;
       try {
         final Map<String, Object> preferencesMap =
             await _getSharedPreferencesMap();
         completer.complete(SharedPreferences._(preferencesMap));
-      } on Exception catch (e) {
+      } catch (e) {
         // If there's an error, explicitly return the future with an error.
         // then set the completer to null so we can retry.
         completer.completeError(e);
         final Future<SharedPreferences> sharedPrefsFuture = completer.future;
         _completer = null;
         return sharedPrefsFuture;
       }
-      _completer = completer;
     }
     return _completer!.future;
   }

diff --git a/packages/shared_preferences/shared_preferences/pubspec.yaml b/packages/shared_preferences/shared_preferences/pubspec.yaml
@@ -3,7 +3,7 @@ description: Flutter plugin for reading and writing simple key-value pairs.
   Wraps NSUserDefaults on iOS and SharedPreferences on Android.
 repository: https://github.com/flutter/packages/tree/main/packages/shared_preferences/shared_preferences
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+shared_preferences%22
-version: 2.1.1
+version: 2.1.2
 
 environment:
   sdk: ">=2.18.0 <4.0.0"