1 package de.juplo.kafka.chat.backend.persistence.kafka;
3 import de.juplo.kafka.chat.backend.domain.ChatRoom;
4 import de.juplo.kafka.chat.backend.domain.Message;
5 import de.juplo.kafka.chat.backend.persistence.KafkaLikeShardingStrategy;
7 import lombok.extern.slf4j.Slf4j;
8 import org.apache.kafka.clients.consumer.Consumer;
9 import org.apache.kafka.clients.consumer.ConsumerRebalanceListener;
10 import org.apache.kafka.clients.consumer.ConsumerRecord;
11 import org.apache.kafka.clients.consumer.ConsumerRecords;
12 import org.apache.kafka.clients.producer.Producer;
13 import org.apache.kafka.clients.producer.ProducerRecord;
14 import org.apache.kafka.common.TopicPartition;
15 import org.apache.kafka.common.errors.WakeupException;
16 import reactor.core.publisher.Flux;
17 import reactor.core.publisher.Mono;
20 import java.util.Collection;
21 import java.util.List;
23 import java.util.UUID;
24 import java.util.stream.IntStream;
28 public class ChatMessageChannel implements Runnable, ConsumerRebalanceListener
30 private final String topic;
31 private final Producer<String, MessageTo> producer;
32 private final Consumer<String, MessageTo> consumer;
33 private final ZoneId zoneId;
34 private final int numShards;
35 private final boolean[] isShardOwned;
36 private final long[] currentOffset;
37 private final long[] nextOffset;
38 private final Map<UUID, ChatRoom>[] chatrooms;
39 private final KafkaLikeShardingStrategy shardingStrategy;
41 private boolean running;
43 private volatile boolean loadInProgress;
46 public ChatMessageChannel(
48 Producer<String, MessageTo> producer,
49 Consumer<String, MessageTo> consumer,
54 "Creating ChatMessageChannel for topic {} with {} partitions",
58 this.consumer = consumer;
59 this.producer = producer;
61 this.numShards = numShards;
62 this.isShardOwned = new boolean[numShards];
63 this.currentOffset = new long[numShards];
64 this.nextOffset = new long[numShards];
65 this.chatrooms = new Map[numShards];
66 this.shardingStrategy = new KafkaLikeShardingStrategy(numShards);
70 Mono<Message> sendMessage(
72 Message.MessageKey key,
73 LocalDateTime timestamp,
76 int shard = this.shardingStrategy.selectShard(chatRoomId);
77 TopicPartition tp = new TopicPartition(topic, shard);
78 ZonedDateTime zdt = ZonedDateTime.of(timestamp, zoneId);
79 return Mono.create(sink ->
81 ProducerRecord<String, MessageTo> record =
86 chatRoomId.toString(),
87 MessageTo.of(key.getUsername(), key.getMessageId(), text));
89 producer.send(record, ((metadata, exception) ->
94 Message message = new Message(key, metadata.offset(), timestamp, text);
95 log.info("Successfully send message {}", message);
96 sink.success(message);
102 "Could not send message for chat-room={}, key={}, timestamp={}, text={}: {}",
108 sink.error(exception);
115 public void onPartitionsAssigned(Collection<TopicPartition> partitions)
117 log.info("Newly assigned partitions! Pausing normal operations...");
118 loadInProgress = true;
120 consumer.endOffsets(partitions).forEach((topicPartition, currentOffset) ->
122 int partition = topicPartition.partition();
123 isShardOwned[partition] = true;
124 this.currentOffset[partition] = currentOffset;
127 "Partition assigned: {} - loading messages: next={} -> current={}",
129 nextOffset[partition],
132 consumer.seek(topicPartition, nextOffset[partition]);
135 consumer.resume(partitions);
139 public void onPartitionsRevoked(Collection<TopicPartition> partitions)
141 partitions.forEach(topicPartition ->
143 int partition = topicPartition.partition();
144 isShardOwned[partition] = false;
145 log.info("Partition revoked: {} - next={}", partition, nextOffset[partition]);
150 public void onPartitionsLost(Collection<TopicPartition> partitions)
152 log.warn("Lost partitions: {}, partitions");
153 // TODO: Muss auf den Verlust anders reagiert werden?
154 onPartitionsRevoked(partitions);
160 consumer.subscribe(List.of(topic));
168 ConsumerRecords<String, MessageTo> records = consumer.poll(Duration.ofMinutes(5));
169 log.info("Fetched {} messages", records.count());
173 loadMessages(records);
175 if (isLoadingCompleted())
177 log.info("Loading of messages completed! Pausing all owned partitions...");
178 pauseAllOwnedPartions();
179 log.info("Resuming normal operations...");
180 loadInProgress = false;
185 if (!records.isEmpty())
187 throw new IllegalStateException("All owned partitions should be paused, when no load is in progress!");
191 catch (WakeupException e)
193 log.info("Received WakeupException, exiting!");
199 void loadMessages(ConsumerRecords<String, MessageTo> records)
201 for (ConsumerRecord<String, MessageTo> record : records)
203 nextOffset[record.partition()] = record.offset() + 1;
204 UUID chatRoomId = UUID.fromString(record.key());
205 MessageTo messageTo = record.value();
207 Message.MessageKey key = Message.MessageKey.of(messageTo.getUser(), messageTo.getId());
209 Instant instant = Instant.ofEpochSecond(record.timestamp());
210 LocalDateTime timestamp = LocalDateTime.ofInstant(instant, zoneId);
212 Message message = new Message(key, record.offset(), timestamp, messageTo.getText());
214 ChatRoom chatRoom = chatrooms[record.partition()].get(chatRoomId);
215 if (chatRoom == null)
217 // Alles pausieren und erst von putChatRoom wieder resumen lassen!
219 KafkaChatRoomService kafkaChatRoomService =
220 (KafkaChatRoomService) chatRoom.getChatRoomService();
222 kafkaChatRoomService.persistMessage(message);
226 boolean isLoadingCompleted()
230 .filter(shard -> isShardOwned[shard])
231 .mapToObj(shard -> nextOffset[shard] >= currentOffset[shard])
233 () -> Boolean.TRUE, // TODO: Boolean is immutable
234 (acc, v) -> Boolean.valueOf(acc && v), // TODO: Boolean is immutable
235 (a, b) -> Boolean.valueOf(a && b)); // TODO: Boolean is immutable
238 void pauseAllOwnedPartions()
240 consumer.pause(IntStream
242 .filter(shard -> isShardOwned[shard])
243 .mapToObj(shard -> new TopicPartition(topic, shard))
248 void putChatRoom(ChatRoom chatRoom)
250 Integer partition = chatRoom.getShard();
251 UUID chatRoomId = chatRoom.getId();
252 if (chatrooms[partition].containsKey(chatRoomId))
254 log.warn("Ignoring existing chat-room: " + chatRoom);
259 "Adding new chat-room to partition {}: {}",
263 chatrooms[partition].put(chatRoomId, chatRoom);
267 Mono<ChatRoom> getChatRoom(int shard, UUID id)
269 return Mono.justOrEmpty(chatrooms[shard].get(id));
272 Flux<ChatRoom> getChatRooms()
274 return Flux.fromStream(IntStream
276 .filter(shard -> isShardOwned[shard])
277 .mapToObj(shard -> Integer.valueOf(shard))
278 .flatMap(shard -> chatrooms[shard].values().stream()));