Github user hmcl commented on a diff in the pull request:
https://github.com/apache/storm/pull/1687#discussion_r85643212
--- Diff:
external/storm-kafka-client/src/main/java/org/apache/storm/kafka/spout/trident/KafkaTridentSpoutEmitter.java
---
@@ -0,0 +1,187 @@
+/*
+ * 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.storm.kafka.spout.trident;
+
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.clients.consumer.OffsetAndMetadata;
+import org.apache.kafka.common.TopicPartition;
+import org.apache.storm.kafka.spout.KafkaSpoutConfig;
+import org.apache.storm.kafka.spout.KafkaSpoutTuplesBuilder;
+import org.apache.storm.trident.operation.TridentCollector;
+import org.apache.storm.trident.spout.IOpaquePartitionedTridentSpout;
+import org.apache.storm.trident.topology.TransactionAttempt;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import static
org.apache.storm.kafka.spout.KafkaSpoutConfig.FirstPollOffsetStrategy.EARLIEST;
+import static
org.apache.storm.kafka.spout.KafkaSpoutConfig.FirstPollOffsetStrategy.LATEST;
+import static
org.apache.storm.kafka.spout.KafkaSpoutConfig.FirstPollOffsetStrategy.UNCOMMITTED_EARLIEST;
+import static
org.apache.storm.kafka.spout.KafkaSpoutConfig.FirstPollOffsetStrategy.UNCOMMITTED_LATEST;
+
+public class KafkaTridentSpoutEmitter<K,V> implements
IOpaquePartitionedTridentSpout.Emitter<List<TopicPartition>,
KafkaTridentSpoutTopicPartition, KafkaTridentSpoutBatchMetadata<K,V>>,
Serializable {
+ private static final Logger LOG =
LoggerFactory.getLogger(KafkaTridentSpoutEmitter.class);
+
+ // Kafka
+ private final KafkaConsumer<K, V> kafkaConsumer;
+
+ // Bookkeeping
+ private final KafkaTridentSpoutManager<K, V> kafkaManager;
+ // Declare some KafkaTridentSpoutManager references for convenience
+ private final KafkaSpoutTuplesBuilder<K, V> tuplesBuilder;
+ private final long pollTimeoutMs;
+ private final KafkaSpoutConfig.FirstPollOffsetStrategy
firstPollOffsetStrategy;
+
+ public KafkaTridentSpoutEmitter(KafkaTridentSpoutManager<K,V>
kafkaManager) {
+ this.kafkaManager = kafkaManager;
+ this.kafkaManager.subscribeKafkaConsumer();
+
+ //must subscribeKafkaConsumer before this line
+ kafkaConsumer = kafkaManager.getKafkaConsumer();
+
+ tuplesBuilder = kafkaManager.getTuplesBuilder();
+ final KafkaSpoutConfig<K, V> kafkaSpoutConfig =
kafkaManager.getKafkaSpoutConfig();
+ pollTimeoutMs = kafkaSpoutConfig.getPollTimeoutMs();
+ firstPollOffsetStrategy =
kafkaSpoutConfig.getFirstPollOffsetStrategy();
+ LOG.debug("Created {}", this);
+ }
+
+ @Override
+ public KafkaTridentSpoutBatchMetadata<K, V>
emitPartitionBatch(TransactionAttempt tx, TridentCollector collector,
+ KafkaTridentSpoutTopicPartition partitionTs,
KafkaTridentSpoutBatchMetadata<K, V> lastBatch) {
+ LOG.debug("Emitting batch: [transaction = {}], [partition = {}],
[collector = {}], [lastBatchMetadata = {}]",
+ tx, partitionTs, collector, lastBatch);
+
+ final TopicPartition topicPartition =
partitionTs.getTopicPartition();
+ KafkaTridentSpoutBatchMetadata<K, V> currentBatch = lastBatch;
+ Collection<TopicPartition> pausedTopicPartitions =
Collections.EMPTY_SET;
+
+ try {
+ // pause other topic partitions to only poll from current
topic partition
+ pausedTopicPartitions = pauseTopicPartitions(topicPartition);
+
+ seek(topicPartition, lastBatch);
+
+ // poll
+ final ConsumerRecords<K, V> records =
kafkaConsumer.poll(pollTimeoutMs);
+ LOG.debug("Polled [{}] records from Kafka.", records.count());
+
+ if (!records.isEmpty()) {
+ emitTuples(collector, records);
+ // build new metadata
+ currentBatch = new
KafkaTridentSpoutBatchMetadata<>(topicPartition, records, lastBatch);
+ }
+ } finally {
+ kafkaConsumer.resume(pausedTopicPartitions);
+ LOG.trace("Resumed topic partitions [{}]",
pausedTopicPartitions);
+ }
+ LOG.debug("Current batch metadata {}", currentBatch);
+ return currentBatch;
+ }
+
+ private void emitTuples(TridentCollector collector, ConsumerRecords<K,
V> records) {
+ for (ConsumerRecord<K, V> record : records) {
+ final List<Object> tuple = tuplesBuilder.buildTuple(record);
+ collector.emit(tuple);
+ LOG.debug("Emitted tuple [{}] for record: [{}]", tuple,
record);
+ }
+ }
+
+ private long seek(TopicPartition tp, KafkaTridentSpoutBatchMetadata<K,
V> lastBatchMeta) {
+ if (lastBatchMeta != null) {
+ kafkaConsumer.seek(tp, lastBatchMeta.getLastOffset() + 1); //
seek next offset after last offset from previous batch
+ LOG.debug("Seeking fetch offset to next offset after last
offset from previous batch");
+
+ } else {
+ LOG.debug("Seeking fetch offset from firstPollOffsetStrategy
and last commit to Kafka");
+ final OffsetAndMetadata committedOffset =
kafkaConsumer.committed(tp);
+ if (committedOffset != null) { // offset was
committed for this TopicPartition
+ if (firstPollOffsetStrategy.equals(EARLIEST)) {
+ kafkaConsumer.seekToBeginning(toArrayList(tp));
+ } else if (firstPollOffsetStrategy.equals(LATEST)) {
+ kafkaConsumer.seekToEnd(toArrayList(tp));
+ } else {
+ // By default polling starts at the last committed
offset. +1 to point fetch to the first uncommitted offset.
+ kafkaConsumer.seek(tp, committedOffset.offset() + 1);
+ }
+ } else { // no commits have ever been done, so start at the
beginning or end depending on the strategy
+ if (firstPollOffsetStrategy.equals(EARLIEST) ||
firstPollOffsetStrategy.equals(UNCOMMITTED_EARLIEST)) {
+ kafkaConsumer.seekToBeginning(toArrayList(tp));
+ } else if (firstPollOffsetStrategy.equals(LATEST) ||
firstPollOffsetStrategy.equals(UNCOMMITTED_LATEST)) {
+ kafkaConsumer.seekToEnd(toArrayList(tp));
+ }
+ }
+ }
+ final long fetchOffset = kafkaConsumer.position(tp);
+ LOG.debug("Set [fetchOffset = {}]", fetchOffset);
+ return fetchOffset;
+ }
+
+ private Collection<TopicPartition> toArrayList(final TopicPartition
tp) {
+ return new ArrayList<TopicPartition>(1){{add(tp);}};
+ }
+
+ // returns paused topic partitions
+ private Collection<TopicPartition> pauseTopicPartitions(TopicPartition
excludedTp) {
+ final Set<TopicPartition> pausedTopicPartitions = new
HashSet<>(kafkaConsumer.assignment());
+ LOG.debug("Currently assigned topic partitions [{}]",
pausedTopicPartitions);
+ pausedTopicPartitions.remove(excludedTp);
+ kafkaConsumer.pause(pausedTopicPartitions);
+ LOG.trace("Paused topic partitions [{}]", pausedTopicPartitions);
+ return pausedTopicPartitions;
+ }
+
+ @Override
+ public void refreshPartitions(List<KafkaTridentSpoutTopicPartition>
partitionResponsibilities) {
+ LOG.debug("Refreshing topic partitions [{}]",
partitionResponsibilities);
+ }
+
+ @Override
+ public List<KafkaTridentSpoutTopicPartition>
getOrderedPartitions(List<TopicPartition> allPartitionInfo) {
+ final List<KafkaTridentSpoutTopicPartition> topicPartitionsTrident
= new ArrayList<>(allPartitionInfo == null ? 0 : allPartitionInfo.size());
+ if (allPartitionInfo != null) {
+ for (TopicPartition topicPartition : allPartitionInfo) {
+ topicPartitionsTrident.add(new
KafkaTridentSpoutTopicPartition(topicPartition));
+ }
+ }
+ LOG.debug("OrderedPartitions = {}", topicPartitionsTrident);
+ return topicPartitionsTrident;
+ }
+
+ @Override
+ public void close() {
+ LOG.debug("Closed");
--- End diff --
Done
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