1 package de.juplo.kafka.chat.backend.implementation.kafka;
3 import de.juplo.kafka.chat.backend.domain.*;
4 import de.juplo.kafka.chat.backend.domain.exceptions.LoadInProgressException;
5 import de.juplo.kafka.chat.backend.domain.exceptions.ShardNotOwnedException;
6 import de.juplo.kafka.chat.backend.implementation.kafka.messages.AbstractMessageTo;
7 import de.juplo.kafka.chat.backend.implementation.kafka.messages.data.EventChatMessageReceivedTo;
9 import lombok.extern.slf4j.Slf4j;
10 import org.apache.kafka.clients.consumer.*;
11 import org.apache.kafka.clients.producer.Producer;
12 import org.apache.kafka.clients.producer.ProducerRecord;
13 import org.apache.kafka.common.TopicPartition;
14 import org.apache.kafka.common.errors.WakeupException;
15 import reactor.core.publisher.Mono;
19 import java.util.stream.IntStream;
23 public class DataChannel implements Runnable, ConsumerRebalanceListener
25 private final String instanceId;
26 private final String topic;
27 private final Producer<String, AbstractMessageTo> producer;
28 private final Consumer<String, AbstractMessageTo> consumer;
29 private final ZoneId zoneId;
30 private final int numShards;
31 private final int bufferSize;
32 private final Clock clock;
33 private final boolean[] isShardOwned;
34 private final long[] currentOffset;
35 private final long[] nextOffset;
36 private final Map<UUID, ChatRoomData>[] chatRoomData;
37 private final InfoChannel infoChannel;
38 private final ShardingPublisherStrategy shardingPublisherStrategy;
40 private boolean running;
42 private volatile boolean loadInProgress;
48 Producer<String, AbstractMessageTo> producer,
49 Consumer<String, AbstractMessageTo> dataChannelConsumer,
54 InfoChannel infoChannel,
55 ShardingPublisherStrategy shardingPublisherStrategy)
58 "{}: Creating DataChannel for topic {} with {} partitions",
62 this.instanceId = instanceId;
64 this.consumer = dataChannelConsumer;
65 this.producer = producer;
67 this.numShards = numShards;
68 this.bufferSize = bufferSize;
70 this.isShardOwned = new boolean[numShards];
71 this.currentOffset = new long[numShards];
72 this.nextOffset = new long[numShards];
73 this.chatRoomData = new Map[numShards];
76 .forEach(shard -> this.chatRoomData[shard] = new HashMap<>());
77 this.infoChannel = infoChannel;
78 this.shardingPublisherStrategy = shardingPublisherStrategy;
83 Mono<Message> sendChatMessage(
85 Message.MessageKey key,
86 LocalDateTime timestamp,
89 ZonedDateTime zdt = ZonedDateTime.of(timestamp, zoneId);
90 return Mono.create(sink ->
92 ProducerRecord<String, AbstractMessageTo> record =
97 chatRoomId.toString(),
98 EventChatMessageReceivedTo.of(key.getUsername(), key.getMessageId(), text));
100 producer.send(record, ((metadata, exception) ->
102 if (exception == null)
104 // On successful send
105 Message message = new Message(key, metadata.offset(), timestamp, text);
106 log.info("Successfully send message {}", message);
107 sink.success(message);
113 "Could not send message for chat-room={}, key={}, timestamp={}, text={}: {}",
119 sink.error(exception);
126 public void onPartitionsAssigned(Collection<TopicPartition> partitions)
128 log.info("Newly assigned partitions! Pausing normal operations...");
129 loadInProgress = true;
131 consumer.endOffsets(partitions).forEach((topicPartition, currentOffset) ->
133 int partition = topicPartition.partition();
134 isShardOwned[partition] = true;
135 this.currentOffset[partition] = currentOffset;
138 "Partition assigned: {} - loading messages: next={} -> current={}",
140 nextOffset[partition],
143 consumer.seek(topicPartition, nextOffset[partition]);
144 infoChannel.sendShardAssignedEvent(partition);
145 shardingPublisherStrategy
146 .publishOwnership(partition)
147 .doOnSuccess(instanceId -> log.info(
148 "Successfully published instance {} as owner of shard {}",
151 .doOnError(throwable -> log.error(
152 "Could not publish instance {} as owner of shard {}: {}",
159 consumer.resume(partitions);
163 public void onPartitionsRevoked(Collection<TopicPartition> partitions)
165 partitions.forEach(topicPartition ->
167 int partition = topicPartition.partition();
168 isShardOwned[partition] = false;
169 nextOffset[partition] = consumer.position(topicPartition);
170 log.info("Partition revoked: {} - next={}", partition, nextOffset[partition]);
171 infoChannel.sendShardRevokedEvent(partition);
176 public void onPartitionsLost(Collection<TopicPartition> partitions)
178 log.warn("Lost partitions: {}, partitions");
179 // TODO: Muss auf den Verlust anders reagiert werden?
180 onPartitionsRevoked(partitions);
192 ConsumerRecords<String, AbstractMessageTo> records = consumer.poll(Duration.ofMinutes(1));
193 log.info("Fetched {} messages", records.count());
197 loadChatRoomData(records);
199 if (isLoadingCompleted())
201 log.info("Loading of messages completed! Pausing all owned partitions...");
202 pauseAllOwnedPartions();
203 log.info("Resuming normal operations...");
204 loadInProgress = false;
209 if (!records.isEmpty())
211 throw new IllegalStateException("All owned partitions should be paused, when no load is in progress!");
215 catch (WakeupException e)
217 log.info("Received WakeupException, exiting!");
222 log.info("Exiting normally");
225 private void loadChatRoomData(ConsumerRecords<String, AbstractMessageTo> records)
227 for (ConsumerRecord<String, AbstractMessageTo> record : records)
229 UUID chatRoomId = UUID.fromString(record.key());
231 switch (record.value().getType())
233 case EVENT_CHATMESSAGE_RECEIVED:
234 Instant instant = Instant.ofEpochSecond(record.timestamp());
235 LocalDateTime timestamp = LocalDateTime.ofInstant(instant, zoneId);
240 (EventChatMessageReceivedTo) record.value(),
246 "Ignoring message for chat-room {} with offset {}: {}",
252 nextOffset[record.partition()] = record.offset() + 1;
256 private void loadChatMessage(
258 LocalDateTime timestamp,
260 EventChatMessageReceivedTo chatMessageTo,
263 Message.MessageKey key = Message.MessageKey.of(chatMessageTo.getUser(), chatMessageTo.getId());
264 Message message = new Message(key, offset, timestamp, chatMessageTo.getText());
266 ChatRoomData chatRoomData = this
267 .chatRoomData[partition]
268 .computeIfAbsent(chatRoomId, this::computeChatRoomData);
269 KafkaChatMessageService kafkaChatRoomService =
270 (KafkaChatMessageService) chatRoomData.getChatRoomService();
273 "Loaded message from partition={} at offset={}: {}",
277 kafkaChatRoomService.persistMessage(message);
280 private boolean isLoadingCompleted()
284 .filter(shard -> isShardOwned[shard])
287 TopicPartition partition = new TopicPartition(topic, shard);
288 long position = consumer.position(partition);
289 return position >= currentOffset[shard];
293 private void pauseAllOwnedPartions()
295 consumer.pause(IntStream
297 .filter(shard -> isShardOwned[shard])
298 .mapToObj(shard -> new TopicPartition(topic, shard))
303 int[] getOwnedShards()
307 .filter(shard -> isShardOwned[shard])
311 Mono<ChatRoomData> getChatRoomData(int shard, UUID id)
315 return Mono.error(new LoadInProgressException());
318 if (!isShardOwned[shard])
320 return Mono.error(new ShardNotOwnedException(instanceId, shard));
326 chatRoomData[shard].computeIfAbsent(id, this::computeChatRoomData));
329 private ChatRoomData computeChatRoomData(UUID chatRoomId)
331 log.info("Creating ChatRoom {} with buffer-size {}", chatRoomId, bufferSize);
332 KafkaChatMessageService service = new KafkaChatMessageService(this, chatRoomId);
333 return new ChatRoomData(clock, service, bufferSize);
336 ConsumerGroupMetadata getConsumerGroupMetadata()
338 return consumer.groupMetadata();