writeAll Atomic Transaction

[jamesstidard]

Hi,

I have a use case where I am wanting to perform data migrations on data stored in the FlutterSecureStorage, but want to be able to do that in a single transaction, to reduce (or ideally eliminate), the possibility of the migration being interrupted and left in a bad state.

This would be something like a Future<void> writeAll(Map<String, String> data).

ideal:

log("Running migrations from ${previous.version} to ${current.version}");
var data = await storage.readAll();
    
for (final m in migrations) {
  log("Running ${m.version}");
  data = await m.migrate(data);
}
    
await storage.writeAll(data);
log("Migration complete!");

current:

log("Running migrations from ${previous.version} to ${current.version}");
var data = await storage.readAll();

for (final m in migrations) {
  log("Running ${m.version}");
  data = await m.migrate(data);
}

for (final e in data.entries) {
  await storage.write(key: e.key, value: e.value);
  // <--- possible interruption leaving partially updated application state
}
log("Migration complete!");

Thanks for the library and your work.