lucasbru commented on code in PR #20730:
URL: https://github.com/apache/kafka/pull/20730#discussion_r2494215919
##########
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:
Pending assignment here means "ready to be assigned". They will actually be
assigned to the member once the current assignment is built. To compute it, we
take all tasks that are assigned to us in the target assignment, minus the
tasks that are already assigned to us. The resulting set can contain released
tasks - for examples, tasks that were never assigned to a different member
before, or tasks that were already revoked by a different member. The resulting
set can also contain unreleased tasks - if another member did not revoke it
yet. The remaining tasks are "ready to be assigned".
Maybe "ready to be assigned" would be a better name but this is consistent
with consumer groups.
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