/** Move nodes from unwanted groups to wanted groups to avoid lingering groups consisting of retired nodes */ private void moveToActiveGroup(List<Node> surplusNodes, int wantedGroups, Optional<ClusterSpec.Group> targetGroup) { for (ListIterator<Node> i = surplusNodes.listIterator(); i.hasNext(); ) { Node node = i.next(); ClusterMembership membership = node.allocation().get().membership(); ClusterSpec cluster = membership.cluster(); if (cluster.group().get().index() >= wantedGroups) { ClusterSpec.Group newGroup = targetGroup.orElse(ClusterSpec.Group.from(0)); ClusterMembership newGroupMembership = membership.with(cluster.with(Optional.of(newGroup))); i.set(node.with(node.allocation().get().with(newGroupMembership))); } } }
/** * Ensure sufficient nodes are reserved or active for the given application and cluster * * @return the list of nodes this cluster will have allocated if activated */ // Note: This operation may make persisted changes to the set of reserved and inactive nodes, // but it may not change the set of active nodes, as the active nodes must stay in sync with the // active config model which is changed on activate public List<Node> prepare(ApplicationId application, ClusterSpec cluster, NodeSpec requestedNodes, int wantedGroups) { List<Node> surplusNodes = findNodesInRemovableGroups(application, cluster, wantedGroups); MutableInteger highestIndex = new MutableInteger(findHighestIndex(application, cluster)); List<Node> acceptedNodes = new ArrayList<>(); for (int groupIndex = 0; groupIndex < wantedGroups; groupIndex++) { ClusterSpec clusterGroup = cluster.with(Optional.of(ClusterSpec.Group.from(groupIndex))); List<Node> accepted = groupPreparer.prepare(application, clusterGroup, requestedNodes.fraction(wantedGroups), surplusNodes, highestIndex, spareCount); replace(acceptedNodes, accepted); } moveToActiveGroup(surplusNodes, wantedGroups, cluster.group()); replace(acceptedNodes, retire(surplusNodes)); return acceptedNodes; }