desaikomal commented on code in PR #2546:
URL: https://github.com/apache/helix/pull/2546#discussion_r1244316338
##########
helix-core/src/main/java/org/apache/helix/controller/rebalancer/DelayedAutoRebalancer.java:
##########
@@ -408,4 +420,129 @@ private int getNumExtraReplicas(ClusterConfig
clusterConfig) {
}
return numExtraReplicas;
}
+
+
+ private Map<String, String>
computeBestPossibleStateForPartition(ResourceControllerDataProvider cache,
+ StateModelDefinition stateModelDef, List<String> preferenceList,
+ CurrentStateOutput currentStateOutput, Set<String>
disabledInstancesForPartition,
+ IdealState idealState, ClusterConfig clusterConfig, Partition partition,
+ MonitoredAbnormalResolver monitoredResolver) {
+
+ Optional<Map<String, String>> optionalOverwrittenStates =
+ computeStatesOverwriteForPartition(stateModelDef, preferenceList,
currentStateOutput,
+ idealState, partition, monitoredResolver);
+ if (optionalOverwrittenStates.isPresent()) {
+ return optionalOverwrittenStates.get();
+ }
+
+ Map<String, String> currentStateMap = new HashMap<>(
+ currentStateOutput.getCurrentStateMap(idealState.getResourceName(),
partition));
+ // Instances not in preference list but still have active replica, retain
to avoid zero replica during movement
+ List<String> currentInstances = new ArrayList<>(currentStateMap.keySet());
+ Collections.sort(currentInstances);
+ Map<String, String> pendingStates =
+ new
HashMap<>(currentStateOutput.getPendingStateMap(idealState.getResourceName(),
partition));
+ for (String instance : pendingStates.keySet()) {
+ if (!currentStateMap.containsKey(instance)) {
+ currentStateMap.put(instance, stateModelDef.getInitialState());
+ currentInstances.add(instance);
+ }
+ }
+
+ Set<String> instancesToDrop = new HashSet<>();
+ Iterator<String> it = currentInstances.iterator();
+ while (it.hasNext()) {
+ String instance = it.next();
+ String state = currentStateMap.get(instance);
+ if (state == null) {
+ it.remove();
+ instancesToDrop.add(instance); // These instances should be set to
DROPPED after we get bestPossibleStateMap;
+ }
+ }
+
+ // Sort the instancesToMove by their current partition state.
+ // Reason: because the states are assigned to instances in the order
appeared in preferenceList, if we have
+ // [node1:Slave, node2:Master], we want to keep it that way, instead of
assigning Master to node1.
+
+ if (preferenceList == null) {
+ preferenceList = Collections.emptyList();
+ }
+
+ boolean isPreferenceListEmpty = preferenceList.isEmpty();
+
+ int numExtraReplicas = getNumExtraReplicas(clusterConfig);
+
+ // TODO : Keep the behavior consistent with existing state count, change
back to read from idealstate
+ // replicas
+ int numReplicas = preferenceList.size();
+ List<String> instanceToAdd = new ArrayList<>(preferenceList);
+ instanceToAdd.removeAll(currentInstances);
+
+ List<String> combinedPreferenceList = new ArrayList<>();
+
+ if (currentInstances.size() <= numReplicas
+ && numReplicas + numExtraReplicas - currentInstances.size() > 0) {
+ int subListSize = numReplicas + numExtraReplicas -
currentInstances.size();
+ combinedPreferenceList.addAll(instanceToAdd
+ .subList(0, Math.min(subListSize, instanceToAdd.size())));
+ }
+
+ // Make all initial state instance not in preference list to be dropped.
+ Map<String, String> currentMapWithPreferenceList = new
HashMap<>(currentStateMap);
+ currentMapWithPreferenceList.keySet().retainAll(preferenceList);
+
+ combinedPreferenceList.addAll(currentInstances);
+ combinedPreferenceList.sort(new
PreferenceListNodeComparator(currentStateMap, stateModelDef, preferenceList));
+
+ // if preference list is not empty, and we do have new intanceToAdd, we
should check if it has capacity to hold the partition.
+ // if (!isPreferenceListEmpty && combinedPreferenceList.size() >
numReplicas && instanceToAdd.size() > 0) {
Review Comment:
Sure,
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