csudharsanan commented on code in PR #3043:
URL: https://github.com/apache/helix/pull/3043#discussion_r2155593565
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helix-core/src/main/java/org/apache/helix/controller/stages/MessageGenerationPhase.java:
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@@ -290,7 +327,110 @@ 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> trueSecondaryTopStates =
getTrueSecondaryTopStates(stateModelDef);
+ return (int) currentStateMap.values().stream()
+ .filter(state -> stateModelDef.getTopState().contains(state) // Top
states (MASTER, ONLINE,
+ // LEADER)
+ || trueSecondaryTopStates.contains(state) // True secondary states
(SLAVE, STANDBY,
+ // BOOTSTRAP)
+ || HelixDefinedState.ERROR.name().equals(state) // ERROR states
(still considered
+ // active)
+ // DROPPED and OFFLINE are automatically excluded by
getTrueSecondaryTopStates()
+ ).count();
+ }
+
+ /**
+ * Get true secondary top states - states that:
+ * 1. Are not the top state itself (avoid double-counting)
+ * 2. Are not non-serving states like OFFLINE and DROPPED.
+ * Reasons for elimination:
+ * - getSecondTopStates() can include the top state itself in some state
models.
+ * Example - OnlineOfflineWithBootstrap:
+ * topState="ONLINE", getSecondTopStates()=["ONLINE", "BOOTSTRAP"]
+ * After filtering: trueSecondaryTopStates=["BOOTSTRAP"] (removes "ONLINE"
as it is top state.)
+ * - getSecondTopStates() can also include OFFLINE as a secondary top state
in some state models.
+ * Example - OnlineOffline:
+ * getSecondTopStates() = ["OFFLINE"] as it transitions to ONLINE.
+ * After filtering: trueSecondaryTopStates=[] (removes "OFFLINE" as it's not
a serving state).
+ * @param stateModelDef State model definition containing state hierarchy
information
+ */
+ private List<String> getTrueSecondaryTopStates(StateModelDefinition
stateModelDef) {
+ return stateModelDef.getSecondTopStates().stream()
+ // Remove top-state duplicates
+ .filter(state -> !stateModelDef.getTopState().equals(state))
+ // Remove non-serving states
+ .filter(state -> !OFFLINE.equals(state) &&
!HelixDefinedState.DROPPED.name().equals(state))
+ .collect(Collectors.toList());
+ }
+
+ /**
+ * Determines if the given current state is considered active based on the
state model type.
+ * For single-top state models, top, true secondary top, and ERROR states
are active.
+ * For multi-top state models, top and ERROR states are active.
+ * ERROR state replicas are considered active in HELIX as they do not affect
availability.
+ * @param currentState The current state to check
+ * @param stateModelDef State model definition containing state hierarchy
information
+ * @param isSingleTopState Whether this is a single-top state model
+ * @return true if the current state is considered active, false otherwise
+ */
+ private boolean isCurrentlyActive(String currentState, StateModelDefinition
stateModelDef,
+ boolean isSingleTopState) {
+ // ERROR state is always considered active regardless of state model type
+ if (HelixDefinedState.ERROR.name().equals(currentState)) {
+ return true;
+ }
+ if (isSingleTopState) {
+ return stateModelDef.getTopState().contains(currentState)
+ || getTrueSecondaryTopStates(stateModelDef).contains(currentState);
+ } else {
+ return stateModelDef.getTopState().contains(currentState);
+ }
+ }
+
+ /**
+ * Determines if the given target state is considered active based on the
state model type.
+ * For single-top state models, both top,true secondary top and ERROR states
are active.
+ * For multi-top state models, top and ERROR states are active.
+ * @param targetState The target state to check
+ * @param stateModelDef State model definition containing state hierarchy
information
+ * @param isSingleTopState Whether this is a single-top state model
+ * @return true if the target state is considered active, false otherwise
+ */
+ private boolean isTargetActive(String targetState, StateModelDefinition
stateModelDef,
Review Comment:
yes
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