csudharsanan commented on code in PR #3043:
URL: https://github.com/apache/helix/pull/3043#discussion_r2162510152
##########
helix-core/src/main/java/org/apache/helix/controller/stages/MessageGenerationPhase.java:
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@@ -290,7 +325,82 @@ private void generateMessage(final Resource resource,
final BaseControllerDataPr
} // end of for-each-partition
}
- private boolean shouldCreateSTCancellation(Message pendingMessage, String
desiredState,
+ /**
+ * Calculate the current active replica count based on state model type.
+ * The count includes replicas in top states, secondary top states (where
applicable),
+ * and ERROR states since helix considers them active.
+ * State model handling:
+ * - Single-top state models: Differentiates between patterns with and
without secondary top
+ * states
+ * - ONLINE-OFFLINE: Counts ONLINE + ERROR states only
+ * - MASTER-SLAVE-OFFLINE: Counts MASTER + SLAVE + ERROR states
+ * - ONLINE-STANDBY-OFFLINE: Counts ONLINE + STANDBY + ERROR states
+ * - Multi-top state models: Counts only top states + ERROR states
+ * @param currentStateMap Map of instance name to current state for this
partition, representing
+ * the actual state of each replica before any pending transitions
+ * @param stateModelDef State model definition containing the state
hierarchy and transition rules
+ * used to determine which states are considered active
+ * @return The number of replicas currently in active states, used to
determine the
+ * currentActiveReplicaNumber for the partition.
+ */
+ private int calculateCurrentActiveReplicaCount(Map<String, String>
currentStateMap,
+ StateModelDefinition stateModelDef) {
+ List<String> activeSecondaryTopStates =
getActiveSecondaryTopStates(stateModelDef);
+ return (int) currentStateMap.values().stream()
+ .filter(state -> stateModelDef.getTopState().contains(state) // Top
states (MASTER, ONLINE,
+ // LEADER)
+ || activeSecondaryTopStates.contains(state) // Active secondary
states (SLAVE, STANDBY,
+ // BOOTSTRAP)
+ || HelixDefinedState.ERROR.name().equals(state) // ERROR states
(still considered
+ // active)
+ // DROPPED and OFFLINE are automatically excluded by
getActiveSecondaryTopStates()
+ ).count();
+ }
+
+ /**
+ * Get active secondary top states - states that are not non-serving states
like OFFLINE and DROPPED.
+ * Reasons for elimination:
+ * - getSecondTopStates() can include OFFLINE as a secondary top state in
some state models.
+ * Example - OnlineOffline:
+ * getSecondTopStates() = ["OFFLINE"] as it transitions to ONLINE.
+ * After filtering: activeSecondaryTopStates=[] (removes "OFFLINE" as it's
not a serving state).
+ * @param stateModelDef State model definition containing state hierarchy
information
+ */
+ private List<String> getActiveSecondaryTopStates(StateModelDefinition
stateModelDef) {
+ return stateModelDef.getSecondTopStates().stream()
+ // Remove non-serving states
+ .filter(state -> !OFFLINE.equals(state) &&
!HelixDefinedState.DROPPED.name().equals(state))
+ .collect(Collectors.toList());
+ }
+
+ /**
+ * Determines if the given state is considered active based on the state
model type.
+ * Active states are defined as:
+ * - For single-top state models: top states, active secondary top states,
and ERROR states
+ * - For multi-top state models: top states and ERROR states
+ * ERROR state replicas are always considered active in HELIX as they do not
affect
+ * availability.
+ * @param state The state to check (can be current state or target state)
+ * @param stateModelDef State model definition containing state hierarchy
information
+ * @return true if the state is considered active, false otherwise
+ */
+ private boolean isStateActive(String state, StateModelDefinition
stateModelDef) {
+ // ERROR state is always considered active regardless of state model type
+ if (HelixDefinedState.ERROR.name().equals(state)) {
+ return true;
+ }
+
+ if (stateModelDef.isSingleTopStateModel()) {
+ // For single-top models, both primary top states and active secondary
states are considered active
+ return stateModelDef.getTopState().contains(state)
+ || getActiveSecondaryTopStates(stateModelDef).contains(state);
+ } else {
+ // For multi-top models, only top states are considered active
+ return stateModelDef.getTopState().contains(state);
Review Comment:
spoke offline, consolidated logic for single top state and multi top state.
we have some state model Defs that have multiple top states with secondary top
state (For eg. onlineConsumingOffline).
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