fileRetrofitSerializer<T> function

Future<T> fileRetrofitSerializer<T>(AtKeysIo keysIo, String atSign, Future<T> action())

Serialises a retrofit against other processes holding the same .atKeys file, by taking a lock beside it.

Assign to retrofitSerializer in a process whose keys live on disk:

retrofitSerializer = fileRetrofitSerializer;

A store that is not a FileAtKeysIo runs unserialised — it is process-local by construction, so there is no second writer to exclude. The lock is held across the whole read-decide-write sequence, which is wider than the flush FileAtKeysIo.update guards on its own: the decision of what to write is made from what the read returned, so a second process must not be reading while this one is still deciding.

Implementation

Future<T> fileRetrofitSerializer<T>(
    AtKeysIo keysIo, String atSign, Future<T> Function() action) {
  if (keysIo is FileAtKeysIo) {
    return AtKeysFileLock('${keysIo.filePath!(atSign)}.retrofit',
            timeout: const Duration(seconds: 30),
            staleAfter: const Duration(minutes: 2))
        .synchronized(action);
  }
  return action();
}