[GitHub] [kafka] dajac commented on a change in pull request #9579: KAFKA-9751: Forward CreateTopicsRequest for FindCoordinator/Metadata when topic creation is needed

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

dajac commented on a change in pull request #9579:
URL: https://github.com/apache/kafka/pull/9579#discussion_r571004759



##########
File path: core/src/main/scala/kafka/server/AutoTopicCreationManager.scala
##########
@@ -0,0 +1,139 @@
+/*
+ * 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 kafka.server
+
+import java.util.concurrent.ConcurrentHashMap
+
+import kafka.controller.KafkaController
+import kafka.utils.Logging
+import org.apache.kafka.clients.ClientResponse
+import org.apache.kafka.common.message.CreateTopicsRequestData
+import org.apache.kafka.common.message.CreateTopicsRequestData.CreatableTopic
+import org.apache.kafka.common.metrics.Metrics
+import org.apache.kafka.common.requests.CreateTopicsRequest
+import org.apache.kafka.common.utils.Time
+
+import scala.collection.Map
+
+trait AutoTopicCreationManager {
+
+  def createTopics(
+    topicNames: Set[CreatableTopic],
+    controllerMutationQuota: ControllerMutationQuota
+  ): Unit
+
+  def start(): Unit = {}
+
+  def shutdown(): Unit = {}
+}
+
+object AutoTopicCreationManager {
+
+  def apply(
+    config: KafkaConfig,
+    metadataCache: MetadataCache,
+    time: Time,
+    metrics: Metrics,
+    threadNamePrefix: Option[String],
+    adminManager: ZkAdminManager,
+    controller: KafkaController,
+    enableForwarding: Boolean
+  ): AutoTopicCreationManager = {
+
+    val channelManager =
+      if (enableForwarding)
+        Some(new BrokerToControllerChannelManager(
+          controllerNodeProvider = MetadataCacheControllerNodeProvider(
+            config, metadataCache),
+          time = time,
+          metrics = metrics,
+          config = config,
+          channelName = "autoTopicCreationChannel",
+          threadNamePrefix = threadNamePrefix,
+          retryTimeoutMs = config.requestTimeoutMs.longValue
+        ))
+      else
+        None
+    new AutoTopicCreationManagerImpl(channelManager, adminManager, controller, config.requestTimeoutMs)
+  }
+}
+
+class AutoTopicCreationManagerImpl(
+  channelManager: Option[BrokerToControllerChannelManager],
+  adminManager: ZkAdminManager,
+  controller: KafkaController,
+  requestTimeout: Int
+) extends AutoTopicCreationManager with Logging {
+
+  private val inflightTopics = new ConcurrentHashMap[String, CreatableTopic]
+
+  override def start(): Unit = {
+    channelManager.foreach(_.start())
+  }
+
+  override def shutdown(): Unit = {
+    channelManager.foreach(_.shutdown())
+  }
+
+  override def createTopics(topics: Set[CreatableTopic],
+                            controllerMutationQuota: ControllerMutationQuota): Unit = {

Review comment:
       @hachikuji Sorry for my late reply. I've missed the notification. We have to enforce the quota on the controller exclusively. It is a global quota and we can't really distribute it fairly in the cluster. In this case, it would be great if we could propagate the principal and clientId to the controller to enforce the quota. However, I wonder how we could propagate the error and the delay to the client if the topic creation is throttled. Perhaps, we could reply with `UNKNOW_TOPIC_OR_PARTITION` until the topic can be created.  




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