@Override
  public synchronized boolean addReplica(ReplicaId replicaId) {
    validateIfPzManagerIsRunningOrThrowException(replicaId);
    diskToReplicaMap.putIfAbsent(replicaId.getDiskId(), new LinkedList<>());
    diskToReplicaMap.get(replicaId.getDiskId()).add(replicaId);
    logger.info("Added partition {} to prioritization Manager For Disk {}", replicaId.getReplicaPath(),
        replicaId.getDiskId().getMountPath());
    return true;
  }
The FCFSPrioritizationManager is a First-Come-First-Serve implementation of the PrioritizationManager.
ambry-prioritization/src/main/java/com/github/ambry/replica/prioritization/FCFSPrioritizationManager.java