[GitHub] [kafka] ijuma commented on a change in pull request #10095: MINOR: Introduce the KIP-500 Broker lifecycle manager

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

ijuma commented on a change in pull request #10095:
URL: https://github.com/apache/kafka/pull/10095#discussion_r573839484



##########
File path: core/src/main/scala/kafka/server/BrokerLifecycleManager.scala
##########
@@ -0,0 +1,457 @@
+/**
+ * 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
+import java.util.concurrent.TimeUnit.{MILLISECONDS, NANOSECONDS}
+import java.util.concurrent.{CompletableFuture, TimeUnit}
+import kafka.utils.Logging
+import org.apache.kafka.clients.ClientResponse
+import org.apache.kafka.common.Uuid
+import org.apache.kafka.common.message.BrokerRegistrationRequestData.ListenerCollection
+import org.apache.kafka.common.message.{BrokerHeartbeatRequestData, BrokerRegistrationRequestData}
+import org.apache.kafka.common.protocol.Errors
+import org.apache.kafka.common.requests.{BrokerHeartbeatRequest, BrokerHeartbeatResponse, BrokerRegistrationRequest, BrokerRegistrationResponse}
+import org.apache.kafka.metadata.{BrokerState, VersionRange}
+import org.apache.kafka.queue.EventQueue.DeadlineFunction
+import org.apache.kafka.common.utils.{ExponentialBackoff, LogContext, Time}
+import org.apache.kafka.queue.{EventQueue, KafkaEventQueue}
+import scala.jdk.CollectionConverters._
+
+
+class BrokerLifecycleManager(val config: KafkaConfig,
+                             val time: Time,
+                             val threadNamePrefix: Option[String]) extends Logging {
+  val logContext = new LogContext(s"[BrokerLifecycleManager id=${config.nodeId}] ")
+
+  this.logIdent = logContext.logPrefix()
+
+  /**
+   * The broker id.
+   */
+  private val nodeId = config.nodeId
+
+  /**
+   * The broker rack, or null if there is no configured rack.
+   */
+  private val rack = config.rack.orNull
+
+  /**
+   * How long to wait for registration to succeed before failing the startup process.
+   */
+  private val initialTimeoutNs = NANOSECONDS.

Review comment:
       Nit: Isn't `TimeUnit.MILLISECONDS.toNanos(config.initialRegistrationTimeoutMs)` more readable?

##########
File path: core/src/main/scala/kafka/server/BrokerLifecycleManager.scala
##########
@@ -0,0 +1,457 @@
+/**
+ * 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
+import java.util.concurrent.TimeUnit.{MILLISECONDS, NANOSECONDS}
+import java.util.concurrent.{CompletableFuture, TimeUnit}
+import kafka.utils.Logging
+import org.apache.kafka.clients.ClientResponse
+import org.apache.kafka.common.Uuid
+import org.apache.kafka.common.message.BrokerRegistrationRequestData.ListenerCollection
+import org.apache.kafka.common.message.{BrokerHeartbeatRequestData, BrokerRegistrationRequestData}
+import org.apache.kafka.common.protocol.Errors
+import org.apache.kafka.common.requests.{BrokerHeartbeatRequest, BrokerHeartbeatResponse, BrokerRegistrationRequest, BrokerRegistrationResponse}
+import org.apache.kafka.metadata.{BrokerState, VersionRange}
+import org.apache.kafka.queue.EventQueue.DeadlineFunction
+import org.apache.kafka.common.utils.{ExponentialBackoff, LogContext, Time}
+import org.apache.kafka.queue.{EventQueue, KafkaEventQueue}
+import scala.jdk.CollectionConverters._
+
+
+class BrokerLifecycleManager(val config: KafkaConfig,
+                             val time: Time,
+                             val threadNamePrefix: Option[String]) extends Logging {
+  val logContext = new LogContext(s"[BrokerLifecycleManager id=${config.nodeId}] ")
+
+  this.logIdent = logContext.logPrefix()
+
+  /**
+   * The broker id.
+   */
+  private val nodeId = config.nodeId
+
+  /**
+   * The broker rack, or null if there is no configured rack.
+   */
+  private val rack = config.rack.orNull
+
+  /**
+   * How long to wait for registration to succeed before failing the startup process.
+   */
+  private val initialTimeoutNs = NANOSECONDS.
+    convert(config.initialRegistrationTimeoutMs.longValue(), TimeUnit.MILLISECONDS)
+
+  /**
+   * The exponential backoff to use for resending communication.
+   */
+  private val resendExponentialBackoff =
+    new ExponentialBackoff(100, 2, config.brokerSessionTimeoutMs.toLong, 0.1)

Review comment:
       We seem to use `0.2` as jitter elsewhere. Any reason to deviate? Maybe we should have an `ExponentialBackoff` static factory method that only takes the initial interval and the max interval. It seems that the other two parameters can be the same most of the time.

##########
File path: core/src/main/scala/kafka/server/BrokerLifecycleManager.scala
##########
@@ -0,0 +1,457 @@
+/**
+ * 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
+import java.util.concurrent.TimeUnit.{MILLISECONDS, NANOSECONDS}
+import java.util.concurrent.{CompletableFuture, TimeUnit}
+import kafka.utils.Logging
+import org.apache.kafka.clients.ClientResponse
+import org.apache.kafka.common.Uuid
+import org.apache.kafka.common.message.BrokerRegistrationRequestData.ListenerCollection
+import org.apache.kafka.common.message.{BrokerHeartbeatRequestData, BrokerRegistrationRequestData}
+import org.apache.kafka.common.protocol.Errors
+import org.apache.kafka.common.requests.{BrokerHeartbeatRequest, BrokerHeartbeatResponse, BrokerRegistrationRequest, BrokerRegistrationResponse}
+import org.apache.kafka.metadata.{BrokerState, VersionRange}
+import org.apache.kafka.queue.EventQueue.DeadlineFunction
+import org.apache.kafka.common.utils.{ExponentialBackoff, LogContext, Time}
+import org.apache.kafka.queue.{EventQueue, KafkaEventQueue}
+import scala.jdk.CollectionConverters._
+
+
+class BrokerLifecycleManager(val config: KafkaConfig,
+                             val time: Time,
+                             val threadNamePrefix: Option[String]) extends Logging {
+  val logContext = new LogContext(s"[BrokerLifecycleManager id=${config.nodeId}] ")
+
+  this.logIdent = logContext.logPrefix()
+
+  /**
+   * The broker id.
+   */
+  private val nodeId = config.nodeId
+
+  /**
+   * The broker rack, or null if there is no configured rack.
+   */
+  private val rack = config.rack.orNull
+
+  /**
+   * How long to wait for registration to succeed before failing the startup process.
+   */
+  private val initialTimeoutNs = NANOSECONDS.
+    convert(config.initialRegistrationTimeoutMs.longValue(), TimeUnit.MILLISECONDS)
+
+  /**
+   * The exponential backoff to use for resending communication.
+   */
+  private val resendExponentialBackoff =
+    new ExponentialBackoff(100, 2, config.brokerSessionTimeoutMs.toLong, 0.1)
+
+  /**
+   * The number of tries we've tried to communicate.
+   */
+  private var failedAttempts = 0L
+
+  /**
+   * The broker incarnation ID.  This ID uniquely identifies each time we start the broker
+   */
+  val incarnationId = Uuid.randomUuid()
+
+  /**
+   * A future which is completed just as soon as the broker has caught up with the latest
+   * metadata offset for the first time.
+   */
+  val initialCatchUpFuture = new CompletableFuture[Void]()
+
+  /**
+   * A future which is completed when controlled shutdown is done.
+   */
+  val controlledShutdownFuture = new CompletableFuture[Void]()
+
+  /**
+   * The broker epoch, or -1 if the broker has not yet registered.
+   * This variable can only be written from the event queue thread.
+   */
+  @volatile private var _brokerEpoch = -1L
+
+  /**
+   * The current broker state.
+   * This variable can only be written from the event queue thread.
+   */
+  @volatile private var _state = BrokerState.NOT_RUNNING
+
+  /**
+   * A callback function which gives this manager the current highest metadata offset.
+   * This function must be thread-safe.
+   */
+  private var _highestMetadataOffsetProvider: () => Long = null
+
+  /**
+   * True only if we are ready to unfence the broker.
+   * This variable can only be accessed from the event queue thread.
+   */
+  private var readyToUnfence = false
+
+  /**
+   * True if we sent a heartbeat to the active controller requesting controlled
+   * shutdown.
+   */
+  private var gotControlledShutdownResponse = false
+
+  /**
+   * Whether or not we this broker is registered with the controller quorum.
+   * This variable can only be accessed from the event queue thread.
+   */
+  private var registered = false
+
+  /**
+   * True if the initial registration succeeded.
+   * This variable can only be accessed from the event queue thread.
+   */
+  private var initialRegistrationSucceeded = false
+
+  /**
+   * The cluster ID, or null if this manager has not been started yet.
+   * This variable can only be accessed from the event queue thread.
+   */
+  private var _clusterId: Uuid = null
+
+  /**
+   * The listeners which this broker advertises.
+   */
+  private var _advertisedListeners: ListenerCollection = null
+
+  /**
+   * The features supported by this broker.
+   */
+  private var _supportedFeatures: util.Map[String, VersionRange] = null
+
+  /**
+   * The channel manager, or null if this manager has not been started yet.
+   * This variable can only be accessed from the event queue thread.
+   */
+  var _channelManager: BrokerToControllerChannelManager = null
+
+  /**
+   * The event queue.
+   */
+  val eventQueue = new KafkaEventQueue(time, logContext, threadNamePrefix.getOrElse(""))
+
+  /**
+   * Start the BrokerLifecycleManager.
+   *
+   * @param highestMetadataOffsetProvider Provides the current highest metadata offset.
+   * @param channelManager                The brokerToControllerChannelManager to use.
+   * @param clusterId                     The cluster ID.
+   */
+  def start(highestMetadataOffsetProvider: () => Long,
+            channelManager: BrokerToControllerChannelManager,
+            clusterId: Uuid,
+            advertisedListeners: ListenerCollection,
+            supportedFeatures: util.Map[String, VersionRange]): Unit = {

Review comment:
       Why are we using a Java collection?

##########
File path: core/src/main/scala/kafka/server/BrokerLifecycleManager.scala
##########
@@ -0,0 +1,457 @@
+/**
+ * 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
+import java.util.concurrent.TimeUnit.{MILLISECONDS, NANOSECONDS}
+import java.util.concurrent.{CompletableFuture, TimeUnit}
+import kafka.utils.Logging
+import org.apache.kafka.clients.ClientResponse
+import org.apache.kafka.common.Uuid
+import org.apache.kafka.common.message.BrokerRegistrationRequestData.ListenerCollection
+import org.apache.kafka.common.message.{BrokerHeartbeatRequestData, BrokerRegistrationRequestData}
+import org.apache.kafka.common.protocol.Errors
+import org.apache.kafka.common.requests.{BrokerHeartbeatRequest, BrokerHeartbeatResponse, BrokerRegistrationRequest, BrokerRegistrationResponse}
+import org.apache.kafka.metadata.{BrokerState, VersionRange}
+import org.apache.kafka.queue.EventQueue.DeadlineFunction
+import org.apache.kafka.common.utils.{ExponentialBackoff, LogContext, Time}
+import org.apache.kafka.queue.{EventQueue, KafkaEventQueue}
+import scala.jdk.CollectionConverters._
+
+
+class BrokerLifecycleManager(val config: KafkaConfig,

Review comment:
       Worth adding a comment explaining the thread safety aspects of this class and also its general purpose. I see a few volatile fields, but `failedAttempts` is not volatile (for example).

##########
File path: core/src/main/scala/kafka/server/BrokerLifecycleManager.scala
##########
@@ -0,0 +1,457 @@
+/**
+ * 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
+import java.util.concurrent.TimeUnit.{MILLISECONDS, NANOSECONDS}
+import java.util.concurrent.{CompletableFuture, TimeUnit}
+import kafka.utils.Logging
+import org.apache.kafka.clients.ClientResponse
+import org.apache.kafka.common.Uuid
+import org.apache.kafka.common.message.BrokerRegistrationRequestData.ListenerCollection
+import org.apache.kafka.common.message.{BrokerHeartbeatRequestData, BrokerRegistrationRequestData}
+import org.apache.kafka.common.protocol.Errors
+import org.apache.kafka.common.requests.{BrokerHeartbeatRequest, BrokerHeartbeatResponse, BrokerRegistrationRequest, BrokerRegistrationResponse}
+import org.apache.kafka.metadata.{BrokerState, VersionRange}
+import org.apache.kafka.queue.EventQueue.DeadlineFunction
+import org.apache.kafka.common.utils.{ExponentialBackoff, LogContext, Time}
+import org.apache.kafka.queue.{EventQueue, KafkaEventQueue}
+import scala.jdk.CollectionConverters._
+
+
+class BrokerLifecycleManager(val config: KafkaConfig,
+                             val time: Time,
+                             val threadNamePrefix: Option[String]) extends Logging {
+  val logContext = new LogContext(s"[BrokerLifecycleManager id=${config.nodeId}] ")
+
+  this.logIdent = logContext.logPrefix()
+
+  /**
+   * The broker id.
+   */
+  private val nodeId = config.nodeId
+
+  /**
+   * The broker rack, or null if there is no configured rack.
+   */
+  private val rack = config.rack.orNull
+
+  /**
+   * How long to wait for registration to succeed before failing the startup process.
+   */
+  private val initialTimeoutNs = NANOSECONDS.
+    convert(config.initialRegistrationTimeoutMs.longValue(), TimeUnit.MILLISECONDS)
+
+  /**
+   * The exponential backoff to use for resending communication.
+   */
+  private val resendExponentialBackoff =
+    new ExponentialBackoff(100, 2, config.brokerSessionTimeoutMs.toLong, 0.1)
+
+  /**
+   * The number of tries we've tried to communicate.
+   */
+  private var failedAttempts = 0L
+
+  /**
+   * The broker incarnation ID.  This ID uniquely identifies each time we start the broker
+   */
+  val incarnationId = Uuid.randomUuid()
+
+  /**
+   * A future which is completed just as soon as the broker has caught up with the latest
+   * metadata offset for the first time.
+   */
+  val initialCatchUpFuture = new CompletableFuture[Void]()
+
+  /**
+   * A future which is completed when controlled shutdown is done.
+   */
+  val controlledShutdownFuture = new CompletableFuture[Void]()
+
+  /**
+   * The broker epoch, or -1 if the broker has not yet registered.
+   * This variable can only be written from the event queue thread.
+   */
+  @volatile private var _brokerEpoch = -1L
+
+  /**
+   * The current broker state.
+   * This variable can only be written from the event queue thread.
+   */
+  @volatile private var _state = BrokerState.NOT_RUNNING
+
+  /**
+   * A callback function which gives this manager the current highest metadata offset.
+   * This function must be thread-safe.
+   */
+  private var _highestMetadataOffsetProvider: () => Long = null
+
+  /**
+   * True only if we are ready to unfence the broker.
+   * This variable can only be accessed from the event queue thread.
+   */
+  private var readyToUnfence = false
+
+  /**
+   * True if we sent a heartbeat to the active controller requesting controlled
+   * shutdown.
+   */
+  private var gotControlledShutdownResponse = false
+
+  /**
+   * Whether or not we this broker is registered with the controller quorum.
+   * This variable can only be accessed from the event queue thread.
+   */
+  private var registered = false
+
+  /**
+   * True if the initial registration succeeded.
+   * This variable can only be accessed from the event queue thread.
+   */
+  private var initialRegistrationSucceeded = false
+
+  /**
+   * The cluster ID, or null if this manager has not been started yet.
+   * This variable can only be accessed from the event queue thread.
+   */
+  private var _clusterId: Uuid = null
+
+  /**
+   * The listeners which this broker advertises.
+   */
+  private var _advertisedListeners: ListenerCollection = null
+
+  /**
+   * The features supported by this broker.
+   */
+  private var _supportedFeatures: util.Map[String, VersionRange] = null
+
+  /**
+   * The channel manager, or null if this manager has not been started yet.
+   * This variable can only be accessed from the event queue thread.
+   */
+  var _channelManager: BrokerToControllerChannelManager = null
+
+  /**
+   * The event queue.
+   */
+  val eventQueue = new KafkaEventQueue(time, logContext, threadNamePrefix.getOrElse(""))
+
+  /**
+   * Start the BrokerLifecycleManager.
+   *
+   * @param highestMetadataOffsetProvider Provides the current highest metadata offset.
+   * @param channelManager                The brokerToControllerChannelManager to use.
+   * @param clusterId                     The cluster ID.
+   */
+  def start(highestMetadataOffsetProvider: () => Long,
+            channelManager: BrokerToControllerChannelManager,
+            clusterId: Uuid,
+            advertisedListeners: ListenerCollection,
+            supportedFeatures: util.Map[String, VersionRange]): Unit = {
+    eventQueue.append(new StartupEvent(highestMetadataOffsetProvider,
+      channelManager, clusterId, advertisedListeners, supportedFeatures))
+  }
+
+  def setReadyToUnfence(): Unit = {
+    eventQueue.append(new SetReadyToUnfenceEvent())
+  }
+
+  def brokerEpoch(): Long = _brokerEpoch
+
+  def state(): BrokerState = _state
+
+  class BeginControlledShutdownEvent extends EventQueue.Event {

Review comment:
       Are these events meant to be public?




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