/**
* Assigns sequential identifiers to the provided <code>clusters</code> (and their sub-clusters).
* If a cluster already has an identifier, the identifier will not be changed.
*
* @param clusters Clusters to assign identifiers to.
* @throws IllegalArgumentException if the provided clusters contain non-unique identifiers
*/
public static void assignClusterIds(Collection<Cluster> clusters) {
final ArrayList<Cluster> flattened = Lists.newArrayListWithExpectedSize(clusters.size());
flatten(flattened, clusters);
synchronized (clusters) {
final HashSet<Integer> ids = Sets.newHashSet();
// First, find the start value for the id and check uniqueness of the ids
// already provided.
int maxId = Integer.MIN_VALUE;
for (final Cluster cluster : flattened) {
if (cluster.id != null) {
if (!ids.add(cluster.id)) {
throw new IllegalArgumentException("Non-unique cluster id found: " + cluster.id);
}
maxId = Math.max(maxId, cluster.id);
}
}
// We'd rather start with 0
maxId = Math.max(maxId, -1);
// Assign missing ids
for (final Cluster c : flattened) {
if (c.id == null) {
c.id = ++maxId;
}
}
}
}
