Github user jinossy commented on a diff in the pull request:
https://github.com/apache/tajo/pull/1041#discussion_r75106709
--- Diff:
tajo-storage/tajo-storage-kafka/src/main/java/org/apache/tajo/storage/kafka/SimpleConsumerManager.java
---
@@ -0,0 +1,184 @@
+/**
+ * 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.tajo.storage.kafka;
+
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.PartitionInfo;
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.serialization.ByteArrayDeserializer;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.net.URI;
+import java.util.Collections;
+import java.util.List;
+import java.util.Properties;
+import java.util.Random;
+
+/**
+ * SimpleConsumerManager is kafka client for KafkaScanner.
+ * It's one per partition. Each partition instantiate this class.
+ */
+public class SimpleConsumerManager implements Closeable {
+ private KafkaConsumer<byte[], byte[]> consumer = null;
+ private TopicPartition partition;
+
+ /**
+ * Create SimpleConsumer instance.
+ *
+ * @param uri Kafka Tablespace URI. ex)
kafka://localhost:9092,localhost:9091
+ * @param topic topic name
+ * @param partitionId partition id
+ */
+ public SimpleConsumerManager(URI uri, String topic, int partitionId) {
+ this(uri, topic, partitionId, Integer.MAX_VALUE);
+ }
+
+ /**
+ * Create SimpleConsumer instance.
+ *
+ * @param uri Kafka Tablespace URI. ex)
kafka://localhost:9092,localhost:9091
+ * @param topic topic name
+ * @param partitionId partition id
+ * @param fragmentSize max polling size of kafka
+ */
+ public SimpleConsumerManager(URI uri, String topic, int partitionId, int
fragmentSize) {
+ String clientId = SimpleConsumerManager.getIdentifier("TCons");
+ Properties props = getDefaultProperties(uri, clientId, fragmentSize);
+
+ partition = new TopicPartition(topic, partitionId);
+ consumer = new KafkaConsumer<>(props);
+ consumer.assign(Collections.singletonList(partition));
+ }
+
+ /**
+ * Close consumer.
+ */
+ @Override
+ public void close() {
+ if (consumer != null) {
+ consumer.close();
+ }
+ consumer = null;
+ }
+
+ /**
+ * Get the earliest offset.
+ *
+ * @return the earliest offset
+ */
+ public long getEarliestOffset() {
+ long currentPosition = consumer.position(partition);
+ consumer.seekToBeginning(Collections.singletonList(partition));
+ long earliestPosition = consumer.position(partition);
+ consumer.seek(partition, currentPosition);
+ return earliestPosition;
+ }
+
+ /**
+ * Get the latest offset.
+ *
+ * @return the latest offset
+ */
+ public long getLatestOffset() {
+ long currentPosition = consumer.position(partition);
+ consumer.seekToEnd(Collections.singletonList(partition));
+ long latestPosition = consumer.position(partition);
+ consumer.seek(partition, currentPosition);
+ return latestPosition;
+ }
+
+ /**
+ * Poll data from kafka.
+ *
+ * @param offset position of partition to seek.
+ * @param timeout polling timeout.
+ * @return records of topic.
+ */
+ public ConsumerRecords<byte[], byte[]> poll(long offset, long timeout) {
+ consumer.seek(partition, offset);
+
+ return consumer.poll(timeout);
+ }
+
+ /**
+ * Return partition information list of specific topic.
+ *
+ * @param uri Kafka Tablespace URI
+ * @param topic
+ * @return
+ * @throws IOException
+ */
+ static List<PartitionInfo> getPartitions(URI uri, String topic) throws
IOException {
+ String clientId = SimpleConsumerManager.getIdentifier("TPart");
+ Properties props = getDefaultProperties(uri, clientId,
Integer.MAX_VALUE);
+ try (KafkaConsumer<String, String> consumer = new
KafkaConsumer<String, String>(props)) {
+ return consumer.partitionsFor(topic);
+ }
+ }
+
+ /**
+ * It extracts broker addresses from a kafka Tablespace URI.
+ * For example, consider an example URI
'kafka://host1:9092,host2:9092,host3:9092'.
+ * <code>extractBroker</code> will extract only
'host1:9092,host2:9092,host3:9092'.
+ *
+ * @param uri Kafka Tablespace URI
+ * @return Broker addresses
+ */
+ static String extractBroker(URI uri) {
+ String uriStr = uri.toString();
+ int start = uriStr.indexOf("/") + 2;
+
+ return uriStr.substring(start);
+ }
+
+ /**
+ * Gets the default properties.
+ *
+ * @param uri kafka broker URIs
+ * @param clientId
+ * @param fragmentSize
+ * @return the default properties
+ */
+ private static Properties getDefaultProperties(URI uri, String clientId,
int fragmentSize) {
+ Properties props = new Properties();
+ props.put(ConsumerConfig.CLIENT_ID_CONFIG, clientId);
+ props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, extractBroker(uri));
+ props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "false");
+ props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+ props.put(ConsumerConfig.MAX_POLL_RECORDS_CONFIG, fragmentSize);
+ props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG,
ByteArrayDeserializer.class.getName());
+ props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,
ByteArrayDeserializer.class.getName());
+ return props;
+ }
+
+ /**
+ * Create identifier for SimpleConsumer.
+ * The SimpleConsumer connects at kafka using this identifier.
+ *
+ * @param prefix
+ * @return
+ */
+ private static String getIdentifier(String prefix) {
--- End diff --
Change to 'createIdentifier'
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