bool ReplicationCoordinatorImpl::canAcceptWritesForDatabase(StringData dbName) {
    // _canAcceptNonLocalWrites is always true for standalone nodes, always false for nodes
    // started with --slave, and adjusted based on primary+drain state in replica sets.
    //
    // That is, stand-alone nodes, non-slave nodes and drained replica set primaries can always
    // accept writes.  Similarly, writes are always permitted to the "local" database.  Finally,
    // in the event that a node is started with --slave and --master, we allow writes unless the
    // master/slave system has set the replAllDead flag.
    if (_canAcceptNonLocalWrites) {
        return true;
    }
    if (dbName == kLocalDB) {
        return true;
    }
    return !replAllDead && _settings.isMaster();
}