Github user koeninger commented on a diff in the pull request: https://github.com/apache/spark/pull/15102#discussion_r80614899 --- Diff: external/kafka-0-10-sql/src/main/scala/org/apache/spark/sql/kafka010/KafkaSourceProvider.scala --- @@ -0,0 +1,263 @@ +/* + * 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.spark.sql.kafka010 + +import java.{util => ju} +import java.util.UUID + +import scala.collection.JavaConverters._ + +import org.apache.kafka.clients.consumer.ConsumerConfig +import org.apache.kafka.common.serialization.ByteArrayDeserializer + +import org.apache.spark.internal.Logging +import org.apache.spark.sql.SQLContext +import org.apache.spark.sql.execution.streaming.Source +import org.apache.spark.sql.kafka010.KafkaSource._ +import org.apache.spark.sql.sources.{DataSourceRegister, StreamSourceProvider} +import org.apache.spark.sql.types.StructType + +/** + * The provider class for the [[KafkaSource]]. This provider is designed such that it throws + * IllegalArgumentException when the Kafka Dataset is created, so that it can catch + * missing options even before the query is started. + */ +private[kafka010] class KafkaSourceProvider extends StreamSourceProvider + with DataSourceRegister with Logging { + import KafkaSourceProvider._ + + /** + * Returns the name and schema of the source. In addition, it also verifies whether the options + * are correct and sufficient to create the [[KafkaSource]] when the query is started. + */ + override def sourceSchema( + sqlContext: SQLContext, + schema: Option[StructType], + providerName: String, + parameters: Map[String, String]): (String, StructType) = { + validateOptions(parameters) + ("kafka", KafkaSource.kafkaSchema) + } + + override def createSource( + sqlContext: SQLContext, + metadataPath: String, + schema: Option[StructType], + providerName: String, + parameters: Map[String, String]): Source = { + validateOptions(parameters) + val caseInsensitiveParams = parameters.map { case (k, v) => (k.toLowerCase, v) } + val specifiedKafkaParams = + parameters + .keySet + .filter(_.toLowerCase.startsWith("kafka.")) + .map { k => k.drop(6).toString -> parameters(k) } + .toMap + + val deserClassName = classOf[ByteArrayDeserializer].getName + val uniqueGroupId = s"spark-kafka-source-${UUID.randomUUID}-${metadataPath.hashCode}" + + val autoOffsetResetValue = caseInsensitiveParams.get(STARTING_OFFSET_OPTION_KEY) match { + case Some(value) => value.trim() // same values as those supported by auto.offset.reset + case None => "latest" + } + + val kafkaParamsForStrategy = + ConfigUpdater("source", specifiedKafkaParams) + .set(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, deserClassName) + .set(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, deserClassName) + + // So that consumers in Kafka source do not mess with any existing group id + .set(ConsumerConfig.GROUP_ID_CONFIG, s"$uniqueGroupId-driver") + + // So that consumers can start from earliest or latest + .set(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, autoOffsetResetValue) + + // So that consumers in the driver does not commit offsets unnecessaribly + .set(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "false") + + // So that the driver does not pull too much data + .set(ConsumerConfig.MAX_POLL_RECORDS_CONFIG, new java.lang.Integer(1)) + + // If buffer config is not set, set it to reasonable value to work around + // buffer issues (see KAFKA-3135) + .setIfUnset(ConsumerConfig.RECEIVE_BUFFER_CONFIG, 65536: java.lang.Integer) + .build() + + val kafkaParamsForExecutors = + ConfigUpdater("executor", specifiedKafkaParams) + .set(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, deserClassName) + .set(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, deserClassName) + + // So that consumers in executors never throw NoOffsetForPartitionException --- End diff -- This comment is backwards. The idea is for executors to do only what the driver tells them, i.e. _throw_ an exception if given an offset that they can't fulfill.
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