Graphql-flutter: Add a cache package using Hive - graphql_cache_hive

[mainawycliffe]

I would like to add a cache package using hive, a key-value database compatible with flutter for web and written in pure dart. For now, it will be a package that will be installed independently.

[smkhalsa]

@mainawycliffe have you made any progress on this?

[mainawycliffe]

@smkhalsa I am just getting started

[kmcgill88]

@mainawycliffe how is this coming along? I am interested in this feature too. Need any help?

[mainawycliffe]

@kmcgill88 I have been busy over the last few weeks and haven't made as much progress as I would like. I have done the basics, but I will do my best and see if I can wrap up this over the next two weeks.

[kmcgill88]

@mainawycliffe Do you have any plans to have Duration based cache? My use case needs a query cached for a Duration, say 30 minutes, before marking the data as expired and re-query. I'd be happy to brainstorm and contribute to the feature.

[mainawycliffe]

Yes, that can be a useful feature - passing a timeout would be quite useful. I think all cache packages and types should be able to do this.

[jensvrai]

@mainawycliffe any update on this. We are struggling with the limitations of the current cache. See #423

[mainawycliffe]

Sorry been busy at work, will get back to it over the weekend.

[jensvrai]

For now we just extended the OptimisticCache and changed the _writeToStorage and _readFromStorage so that in stead of writing it to a file manually, we put it in a hive box. So you can call save at any time without blocking the UI. We also toggle between 2 boxes to prevent interruptions while persisting the cache.

Future<dynamic> _writeToStorage() async {
    if (_writingToStorage) {
      return;
    }
    _writingToStorage = true;

    try {
      final cacheKeyBox = await Hive.openBox('cacheKeyBox');

      String currentKey = await cacheKeyBox.get('currentKey') ?? 'cache1';
      String newKey = currentKey == 'cache1' ? 'cache2' : 'cache1';
      final cache = await Hive.openBox(newKey);

      await cache.clear();
      var promises = <Future>[];
      data.forEach((String key, dynamic value) {
        promises.add(cache.add(([key, value])));
      });

      await Future.wait(promises);
      await cache.close();

      cacheKeyBox.put('currentKey', newKey);
      _writingToStorage = false;
    } catch (err) {
      _writingToStorage = false;

      rethrow;
    }
    return;
  }

Future<HashMap<String, dynamic>> _readFromStorage() async {
    // return in-memory data when there is data, data can be a new HashMap
    if (data != null && data.isNotEmpty) {
      return data;
    }
    try {
      final cacheKeyBox = await Hive.openBox('cacheKeyBox');

      String currentKey = cacheKeyBox.get('currentKey') ?? 'cache1';

      final cache = await Hive.openBox(currentKey);
      final values = cache.values;

      final HashMap<String, dynamic> storedHashMap = HashMap<String, dynamic>();
      values.forEach((keyAndValue) {
        storedHashMap[keyAndValue[0] as String] = jsonDecode(jsonEncode(keyAndValue[1]));
      });

      return storedHashMap;
    } catch (error) {
      // TODO: handle error
      print(error);

      return HashMap<String, dynamic>();
    }
  }

[vasilich6107]

@mainawycliffe do you have any WIP repo so we can help with contribution?

[mainawycliffe]

Should be in my folk, but there are also lots of uncommitted changes.

[vasilich6107]

If you will get to some kind of MVP post the link here)

[smkhalsa]

@mainawycliffe I'm not sure how far you've gotten with this, but feel free to take anything you find useful from my hive_store implementation in gql_client.

[awaik]

If I understood correct, guys made something here https://pub.dev/packages/ferry
I'll try to use it in my app and let know how it works.

[awaik]

@jensvrai Can you please share full code. Can't understand how you overrode _writingToStorage
Thank you!

[micimize]

essentially closed via HiveStore in 4.0.0-beta.1 (#648)