private Configuration oldConfFromMeta(final SnapshotMeta meta) {
        final Configuration oldConf = new Configuration();
        for (int i = 0; i < meta.getOldPeersCount(); i++) {
            final PeerId peer = new PeerId();
            peer.parse(meta.getOldPeers(i));
            oldConf.addPeer(peer);
        }
        for (int i = 0; i < meta.getOldLearnersCount(); i++) {
            final PeerId peer = new PeerId();
            peer.parse(meta.getOldLearners(i));
            oldConf.addLearner(peer);
        }
        return oldConf;
    }
Adds event to disk queue, NEVER call it in lock.
@param done
@param type
jraft-core/src/main/java/com/alipay/sofa/jraft/storage/impl/LogManagerImpl.java