mjsax commented on code in PR #20730:
URL: https://github.com/apache/kafka/pull/20730#discussion_r2492703023
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/streams/CurrentAssignmentBuilder.java:
##########
@@ -304,6 +304,101 @@ private static boolean
computeAssignmentDifferenceForOneSubtopology(final String
return hasUnreleasedTasks;
}
+ /**
+ * Takes the current currentAssignment and the targetAssignment, and
generates three
+ * collections:
+ *
+ * - the resultAssignedTasks: the tasks that are assigned in both the
current and target
+ * assignments.
+ * - the resultTasksPendingRevocation: the tasks that are assigned in the
current
+ * assignment but not in the target assignment.
+ * - the resultTasksPendingAssignment: the tasks that are assigned in the
target assignment but
+ * not in the current assignment, and can be assigned currently (i.e.,
they are not owned by
+ * another member, as defined by the `isUnreleasedTask` predicate).
+ *
+ * Epoch Handling:
+ * - For tasks in resultAssignedTasks and resultTasksPendingRevocation,
the epoch from currentAssignment is preserved.
+ * - For tasks in resultTasksPendingAssignment, the targetAssignmentEpoch
is used.
+ */
+ private boolean computeAssignmentDifferenceWithEpoch(Map<String,
Map<Integer, Integer>> currentAssignment,
+ Map<String,
Set<Integer>> targetAssignment,
+ int
targetAssignmentEpoch,
+ Map<String,
Map<Integer, Integer>> resultAssignedTasks,
+ Map<String,
Map<Integer, Integer>> resultTasksPendingRevocation,
+ Map<String,
Map<Integer, Integer>> resultTasksPendingAssignment,
+ BiPredicate<String,
Integer> isUnreleasedTask) {
+ boolean hasUnreleasedTasks = false;
+
+ Set<String> allSubtopologyIds = new
HashSet<>(targetAssignment.keySet());
+ allSubtopologyIds.addAll(currentAssignment.keySet());
+
+ for (String subtopologyId : allSubtopologyIds) {
+ hasUnreleasedTasks |=
computeAssignmentDifferenceForOneSubtopologyWithEpoch(
+ subtopologyId,
+ currentAssignment.getOrDefault(subtopologyId, Map.of()),
+ targetAssignment.getOrDefault(subtopologyId, Set.of()),
+ targetAssignmentEpoch,
+ resultAssignedTasks,
+ resultTasksPendingRevocation,
+ resultTasksPendingAssignment,
+ isUnreleasedTask
+ );
+ }
+ return hasUnreleasedTasks;
+ }
+
+ private static boolean
computeAssignmentDifferenceForOneSubtopologyWithEpoch(final String
subtopologyId,
+
final Map<Integer, Integer> currentTasksForThisSubtopology,
+
final Set<Integer> targetTasksForThisSubtopology,
+
final int targetAssignmentEpoch,
+
final Map<String, Map<Integer, Integer>> resultAssignedTasks,
+
final Map<String, Map<Integer, Integer>> resultTasksPendingRevocation,
+
final Map<String, Map<Integer, Integer>> resultTasksPendingAssignment,
+
final BiPredicate<String, Integer> isUnreleasedTask) {
+ // Result Assigned Tasks = Current Tasks ∩ Target Tasks
+ // i.e. we remove all tasks from the current assignment that are not
in the target
+ // assignment
+ Map<Integer, Integer> resultAssignedTasksForThisSubtopology = new
HashMap<>();
+ for (Map.Entry<Integer, Integer> entry :
currentTasksForThisSubtopology.entrySet()) {
+ if (targetTasksForThisSubtopology.contains(entry.getKey())) {
+ resultAssignedTasksForThisSubtopology.put(entry.getKey(),
entry.getValue());
+ }
+ }
+
+ // Result Tasks Pending Revocation = Current Tasks - Result Assigned
Tasks
+ // i.e. we will ask the member to revoke all tasks in its current
assignment that
+ // are not in the target assignment
+ Map<Integer, Integer> resultTasksPendingRevocationForThisSubtopology =
new HashMap<>(currentTasksForThisSubtopology);
+
resultTasksPendingRevocationForThisSubtopology.keySet().removeAll(resultAssignedTasksForThisSubtopology.keySet());
+
+ // Result Tasks Pending Assignment = Target Tasks - Result Assigned
Tasks - Unreleased Tasks
+ // i.e. we will ask the member to assign all tasks in its target
assignment,
+ // except those that are already assigned, and those that are
unreleased
+ Map<Integer, Integer> resultTasksPendingAssignmentForThisSubtopology =
new HashMap<>();
+ for (Integer taskId : targetTasksForThisSubtopology) {
+ if (!resultAssignedTasksForThisSubtopology.containsKey(taskId)) {
+ resultTasksPendingAssignmentForThisSubtopology.put(taskId,
targetAssignmentEpoch);
+ }
+ }
+ boolean hasUnreleasedTasks =
resultTasksPendingAssignmentForThisSubtopology.keySet().removeIf(taskId ->
+ isUnreleasedTask.test(subtopologyId, taskId)
Review Comment:
For my own education. Why are not all tasks, form
`resultTasksPendingAssignmentForThisSubtopology` unreleased? Or to rephrase:
how can `resultTasksPendingAssignmentForThisSubtopology` contain tasks which
are already released?
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