[GitHub] [kafka] cadonna commented on a change in pull request #10163: KAFKA-10357: Extract setup of changelog from Streams partition assignor

[GitBox <gi...@apache.org>]

cadonna commented on a change in pull request #10163:
URL: https://github.com/apache/kafka/pull/10163#discussion_r579332437



##########
File path: streams/src/main/java/org/apache/kafka/streams/processor/internals/ChangelogTopics.java
##########
@@ -0,0 +1,132 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.streams.processor.internals;
+
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.utils.LogContext;
+import org.apache.kafka.streams.processor.TaskId;
+import org.apache.kafka.streams.processor.internals.InternalTopologyBuilder.TopicsInfo;
+import org.slf4j.Logger;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import static org.apache.kafka.streams.processor.internals.assignment.StreamsAssignmentProtocolVersions.UNKNOWN;
+
+public class ChangelogTopics {
+
+    private final InternalTopicManager internalTopicManager;
+    private final Map<Integer, TopicsInfo> topicGroups;
+    private final Map<Integer, Set<TaskId>> tasksForTopicGroup;
+    private final Map<TaskId, Set<TopicPartition>> changelogPartitionsForTask = new HashMap<>();
+    private final Map<TaskId, Set<TopicPartition>> preExistingChangelogPartitionsForTask = new HashMap<>();
+    private final Set<TopicPartition> preExistingNonSourceTopicBasedChangelogPartitions = new HashSet<>();
+    private final Set<String> sourceTopicBasedChangelogTopics = new HashSet<>();
+    private final Set<TopicPartition> sourceTopicBasedChangelogTopicPartitions = new HashSet<>();
+    private final Logger log;
+
+    public ChangelogTopics(final InternalTopicManager internalTopicManager,
+                           final Map<Integer, TopicsInfo> topicGroups,
+                           final Map<Integer, Set<TaskId>> tasksForTopicGroup,
+                           final String logPrefix) {
+        this.internalTopicManager = internalTopicManager;
+        this.topicGroups = topicGroups;
+        this.tasksForTopicGroup = tasksForTopicGroup;
+        final LogContext logContext = new LogContext(logPrefix);
+        log = logContext.logger(getClass());
+    }
+
+    public void setup() {
+        // add tasks to state change log topic subscribers
+        final Map<String, InternalTopicConfig> changelogTopicMetadata = new HashMap<>();
+        for (final Map.Entry<Integer, TopicsInfo> entry : topicGroups.entrySet()) {
+            final int topicGroupId = entry.getKey();
+            final TopicsInfo topicsInfo = entry.getValue();
+
+            final Set<TaskId> topicGroupTasks = tasksForTopicGroup.get(topicGroupId);
+            if (topicGroupTasks == null) {
+                log.debug("No tasks found for topic group {}", topicGroupId);
+                continue;
+            } else if (topicsInfo.stateChangelogTopics.isEmpty()) {
+                continue;
+            }
+
+            for (final TaskId task : topicGroupTasks) {
+                final Set<TopicPartition> changelogTopicPartitions = topicsInfo.stateChangelogTopics
+                    .keySet()
+                    .stream()
+                    .map(topic -> new TopicPartition(topic, task.partition))
+                    .collect(Collectors.toSet());
+                changelogPartitionsForTask.put(task, changelogTopicPartitions);
+            }
+
+            for (final InternalTopicConfig topicConfig : topicsInfo.nonSourceChangelogTopics()) {
+                // the expected number of partitions is the max value of TaskId.partition + 1
+                int numPartitions = UNKNOWN;
+                for (final TaskId task : topicGroupTasks) {
+                    if (numPartitions < task.partition + 1) {
+                        numPartitions = task.partition + 1;
+                    }
+                }
+                topicConfig.setNumberOfPartitions(numPartitions);
+                changelogTopicMetadata.put(topicConfig.name(), topicConfig);
+            }
+            sourceTopicBasedChangelogTopics.addAll(topicsInfo.sourceTopicChangelogs());
+        }
+
+        final Set<String> newlyCreatedChangelogTopics = internalTopicManager.makeReady(changelogTopicMetadata);
+        log.debug("Created state changelog topics {} from the parsed topology.", changelogTopicMetadata.values());
+
+        for (final Map.Entry<TaskId, Set<TopicPartition>> entry : changelogPartitionsForTask.entrySet()) {
+            final TaskId taskId = entry.getKey();
+            final Set<TopicPartition> topicPartitions = entry.getValue();
+            for (final TopicPartition topicPartition : topicPartitions) {
+                if (!newlyCreatedChangelogTopics.contains(topicPartition.topic())) {
+                    preExistingChangelogPartitionsForTask.computeIfAbsent(taskId, task -> new HashSet<>()).add(topicPartition);
+                    if (!sourceTopicBasedChangelogTopics.contains(topicPartition.topic())) {
+                        preExistingNonSourceTopicBasedChangelogPartitions.add(topicPartition);
+                    } else {
+                        sourceTopicBasedChangelogTopicPartitions.add(topicPartition);
+                    }
+                }
+            }
+        }
+    }
+
+    public Set<TopicPartition> preExistingNonSourceTopicBasedPartitions() {
+        return Collections.unmodifiableSet(preExistingNonSourceTopicBasedChangelogPartitions);
+    }
+
+    public Set<TopicPartition> preExistingPartitionsFor(final TaskId taskId) {
+        if (preExistingChangelogPartitionsForTask.containsKey(taskId)) {
+            return Collections.unmodifiableSet(preExistingChangelogPartitionsForTask.get(taskId));
+        }
+        return Collections.emptySet();
+    }
+
+    public Set<TopicPartition> sourceTopicBasedPartitions() {
+        return Collections.unmodifiableSet(sourceTopicBasedChangelogTopicPartitions);
+    }
+
+    public Set<TaskId> taskIds() {
+        return Collections.unmodifiableSet(changelogPartitionsForTask.keySet());
+    }

Review comment:
       I added some methods to simplify some code in the assignor.




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