RelayEnvironment.js

const DISK_CACHE_ENABLED = true;
const ONE_DAY = 24 * 60 * 60 * 1000;
const MAX_STORE_SIZE = 1 * 1024 * 1024; // 1mb, TODO: figure out how big this can be.
const RELAY_STORE_KEY = 'relay_store';
const RELAY_STORE_META_KEY = 'relay_store_meta';
const DEFAULT_META = {
  lastGC: Date.now(),
  environment: getConfig().environment,
  appVersion: Device.version(),
};

let _relayEnvironment;
let _relayStoreMeta = DEFAULT_META;

export async function initialize() {
  try {
    if (!DISK_CACHE_ENABLED) {
      _relayEnvironment = createRelayEnvironment();
      return;
    }
    // For now we will be conservative with the offline cache and purge it after
    // one day.
    const storeMetaJSON = await AsyncStorage.getItem(RELAY_STORE_META_KEY);
    _relayStoreMeta = storeMetaJSON ? JSON.parse(storeMetaJSON) : DEFAULT_META;
    if (
      Date.now() - _relayStoreMeta.lastGC > ONE_DAY ||
      _relayStoreMeta.appVersion !== Device.version() ||
      _relayStoreMeta.environment !== getConfig().environment
    ) {
      doStoreGC();
      _relayEnvironment = createRelayEnvironment();
    } else {
      const serializedData = await AsyncStorage.getItem(RELAY_STORE_KEY);
      _relayEnvironment = createRelayEnvironment(
        serializedData ? JSON.parse(serializedData) : null,
      );
    }
  } catch (err) {
    Log.error(err);
    _relayEnvironment = createRelayEnvironment();
  }
}

async function saveStore() {
  if (!_relayEnvironment || !DISK_CACHE_ENABLED) {
    return;
  }
  const seralizedData = JSON.stringify(
    _relayEnvironment.getStore().getSource(),
  );
  if (seralizedData.length > MAX_STORE_SIZE) {
    doStoreGC();
  } else {
    AsyncStorage.setItem(RELAY_STORE_KEY, seralizedData);
    updateStoreMeta({
      environment: getConfig().environment,
      appVersion: Device.version(),
    });
  }
}

function updateStoreMeta(data) {
  _relayStoreMeta = {
    ..._relayStoreMeta,
    ...data,
  };
  AsyncStorage.setItem(RELAY_STORE_META_KEY, JSON.stringify(_relayStoreMeta));
}

function doStoreGC() {
  if (_relayEnvironment) {
    _relayEnvironment.getStore()._scheduleGC();
  }
  if (DISK_CACHE_ENABLED) {
    AsyncStorage.removeItem(RELAY_STORE_KEY);
    updateStoreMeta({ lastGC: Date.now() });
  }
}