juplo.de Git - demos/kafka/chat/blob - src/main/java/de/juplo/kafka/chat/backend/implementation/kafka/DataChannel.java

   1 package de.juplo.kafka.chat.backend.implementation.kafka;
   2
   3 import de.juplo.kafka.chat.backend.domain.ChatRoomData;
   4 import de.juplo.kafka.chat.backend.domain.ChatRoomInfo;
   5 import de.juplo.kafka.chat.backend.domain.Message;
   6 import de.juplo.kafka.chat.backend.domain.ShardingPublisherStrategy;
   7 import de.juplo.kafka.chat.backend.domain.exceptions.ShardNotOwnedException;
   8 import de.juplo.kafka.chat.backend.implementation.kafka.messages.AbstractMessageTo;
   9 import de.juplo.kafka.chat.backend.implementation.kafka.messages.data.EventChatMessageReceivedTo;
  10 import lombok.Getter;
  11 import lombok.ToString;
  12 import lombok.extern.slf4j.Slf4j;
  13 import org.apache.kafka.clients.consumer.*;
  14 import org.apache.kafka.clients.producer.Producer;
  15 import org.apache.kafka.clients.producer.ProducerRecord;
  16 import org.apache.kafka.common.TopicPartition;
  17 import org.apache.kafka.common.errors.WakeupException;
  18 import reactor.core.publisher.Mono;
  19
  20 import java.time.*;
  21 import java.util.Collection;
  22 import java.util.HashMap;
  23 import java.util.Map;
  24 import java.util.UUID;
  25 import java.util.stream.IntStream;
  26
  27
  28 @ToString(of = { "topic", "instanceId" })
  29 @Slf4j
  30 public class DataChannel implements Channel, ConsumerRebalanceListener
  31 {
  32   private final String instanceId;
  33   private final String topic;
  34   private final Producer<String, AbstractMessageTo> producer;
  35   private final Consumer<String, AbstractMessageTo> consumer;
  36   private final ZoneId zoneId;
  37   private final int numShards;
  38   private final Duration pollingInterval;
  39   private final int historyLimit;
  40   private final Clock clock;
  41   private final boolean[] isShardOwned;
  42   private final long[] currentOffset;
  43   private final long[] nextOffset;
  44   private final Map<UUID, ChatRoomData>[] chatRoomData;
  45   private final ChannelMediator channelMediator;
  46   private final ShardingPublisherStrategy shardingPublisherStrategy;
  47
  48   private boolean running;
  49   @Getter
  50   private volatile ChannelState channelState = ChannelState.STARTING;
  51
  52
  53   public DataChannel(
  54     String instanceId,
  55     String topic,
  56     Producer<String, AbstractMessageTo> producer,
  57     Consumer<String, AbstractMessageTo> dataChannelConsumer,
  58     ZoneId zoneId,
  59     int numShards,
  60     Duration pollingInterval,
  61     int historyLimit,
  62     Clock clock,
  63     ChannelMediator channelMediator,
  64     ShardingPublisherStrategy shardingPublisherStrategy)
  65   {
  66     log.debug(
  67         "{}: Creating DataChannel for topic {} with {} partitions",
  68         instanceId,
  69         topic,
  70         numShards);
  71     this.instanceId = instanceId;
  72     this.topic = topic;
  73     this.consumer = dataChannelConsumer;
  74     this.producer = producer;
  75     this.zoneId = zoneId;
  76     this.numShards = numShards;
  77     this.pollingInterval = pollingInterval;
  78     this.historyLimit = historyLimit;
  79     this.clock = clock;
  80     this.isShardOwned = new boolean[numShards];
  81     this.currentOffset = new long[numShards];
  82     this.nextOffset = new long[numShards];
  83     this.chatRoomData = new Map[numShards];
  84     IntStream
  85         .range(0, numShards)
  86         .forEach(shard -> this.chatRoomData[shard] = new HashMap<>());
  87     this.channelMediator = channelMediator;
  88     this.shardingPublisherStrategy = shardingPublisherStrategy;
  89   }
  90
  91
  92
  93   Mono<Message> sendChatMessage(
  94       UUID chatRoomId,
  95       Message.MessageKey key,
  96       LocalDateTime timestamp,
  97       String text)
  98   {
  99     ZonedDateTime zdt = ZonedDateTime.of(timestamp, zoneId);
 100     return Mono.create(sink ->
 101     {
 102       ProducerRecord<String, AbstractMessageTo> record =
 103           new ProducerRecord<>(
 104               topic,
 105               null,
 106               zdt.toEpochSecond(),
 107               chatRoomId.toString(),
 108               EventChatMessageReceivedTo.of(key.getUsername(), key.getMessageId(), text));
 109
 110       producer.send(record, ((metadata, exception) ->
 111       {
 112         if (exception == null)
 113         {
 114           // On successful send
 115           Message message = new Message(key, metadata.offset(), timestamp, text);
 116           log.info("Successfully send message {}", message);
 117           sink.success(message);
 118         }
 119         else
 120         {
 121           // On send-failure
 122           log.error(
 123               "Could not send message for chat-room={}, key={}, timestamp={}, text={}: {}",
 124               chatRoomId,
 125               key,
 126               timestamp,
 127               text,
 128               exception);
 129           sink.error(exception);
 130         }
 131       }));
 132     });
 133   }
 134
 135   @Override
 136   public void onPartitionsAssigned(Collection<TopicPartition> partitions)
 137   {
 138     log.info("Newly assigned partitions! Pausing normal operations...");
 139     channelState = ChannelState.LOAD_IN_PROGRESS;
 140
 141     consumer.endOffsets(partitions).forEach((topicPartition, currentOffset) ->
 142     {
 143       int partition = topicPartition.partition();
 144       isShardOwned[partition] =  true;
 145       this.currentOffset[partition] = currentOffset;
 146
 147       chatRoomData[partition]
 148           .values()
 149           .forEach(chatRoomData -> chatRoomData.activate());
 150
 151       log.info(
 152           "Partition assigned: {} - loading messages: next={} -> current={}",
 153           partition,
 154           nextOffset[partition],
 155           currentOffset);
 156
 157       consumer.seek(topicPartition, nextOffset[partition]);
 158       channelMediator.shardAssigned(partition);
 159       shardingPublisherStrategy
 160           .publishOwnership(partition)
 161           .doOnSuccess(instanceId -> log.info(
 162               "Successfully published instance {} as owner of shard {}",
 163               instanceId,
 164               partition))
 165           .doOnError(throwable -> log.error(
 166               "Could not publish instance {} as owner of shard {}: {}",
 167               instanceId,
 168               partition,
 169               throwable.toString()))
 170           .onErrorComplete()
 171           .block();
 172     });
 173
 174     consumer.resume(partitions);
 175   }
 176
 177   @Override
 178   public void onPartitionsRevoked(Collection<TopicPartition> partitions)
 179   {
 180     partitions.forEach(topicPartition ->
 181     {
 182       int partition = topicPartition.partition();
 183       isShardOwned[partition] = false;
 184       nextOffset[partition] = consumer.position(topicPartition);
 185
 186       log.info("Partition revoked: {} - next={}", partition, nextOffset[partition]);
 187
 188       chatRoomData[partition]
 189           .values()
 190           .forEach(chatRoomData -> chatRoomData.deactivate());
 191
 192       channelMediator.shardRevoked(partition);
 193     });
 194   }
 195
 196   @Override
 197   public void onPartitionsLost(Collection<TopicPartition> partitions)
 198   {
 199     log.warn("Lost partitions: {}, partitions");
 200     // TODO: Muss auf den Verlust anders reagiert werden?
 201     onPartitionsRevoked(partitions);
 202   }
 203
 204   @Override
 205   public void run()
 206   {
 207     running = true;
 208
 209     while (running)
 210     {
 211       try
 212       {
 213         ConsumerRecords<String, AbstractMessageTo> records = consumer.poll(pollingInterval);
 214         log.info("Fetched {} messages", records.count());
 215
 216         switch (channelState)
 217         {
 218           case LOAD_IN_PROGRESS ->
 219           {
 220             loadChatRoomData(records);
 221
 222             if (isLoadingCompleted())
 223             {
 224               log.info("Loading of messages completed! Pausing all owned partitions...");
 225               pauseAllOwnedPartions();
 226               log.info("Resuming normal operations...");
 227               channelState = ChannelState.READY;
 228             }
 229           }
 230           case SHUTTING_DOWN -> log.info("Shutdown in progress: ignoring {} fetched messages.", records.count());
 231           default ->
 232           {
 233             if (!records.isEmpty())
 234             {
 235               throw new IllegalStateException("All owned partitions should be paused, when in state " + channelState);
 236             }
 237           }
 238         }
 239       }
 240       catch (WakeupException e)
 241       {
 242         log.info("Received WakeupException, exiting!");
 243         channelState = ChannelState.SHUTTING_DOWN;
 244         running = false;
 245       }
 246     }
 247
 248     log.info("Exiting normally");
 249   }
 250
 251   private void loadChatRoomData(ConsumerRecords<String, AbstractMessageTo> records)
 252   {
 253     for (ConsumerRecord<String, AbstractMessageTo> record : records)
 254     {
 255       UUID chatRoomId = UUID.fromString(record.key());
 256
 257       switch (record.value().getType())
 258       {
 259         case EVENT_CHATMESSAGE_RECEIVED:
 260           Instant instant = Instant.ofEpochSecond(record.timestamp());
 261           LocalDateTime timestamp = LocalDateTime.ofInstant(instant, zoneId);
 262           loadChatMessage(
 263               chatRoomId,
 264               timestamp,
 265               record.offset(),
 266               (EventChatMessageReceivedTo) record.value(),
 267               record.partition());
 268           break;
 269
 270         default:
 271           log.debug(
 272               "Ignoring message for chat-room {} with offset {}: {}",
 273               chatRoomId,
 274               record.offset(),
 275               record.value());
 276       }
 277
 278       nextOffset[record.partition()] = record.offset() + 1;
 279     }
 280   }
 281
 282   private void loadChatMessage(
 283       UUID chatRoomId,
 284       LocalDateTime timestamp,
 285       long offset,
 286       EventChatMessageReceivedTo chatMessageTo,
 287       int partition)
 288   {
 289     Message.MessageKey key = Message.MessageKey.of(chatMessageTo.getUser(), chatMessageTo.getId());
 290     Message message = new Message(key, offset, timestamp, chatMessageTo.getText());
 291
 292     ChatRoomData chatRoomData = computeChatRoomData(chatRoomId, partition);
 293     KafkaChatMessageService kafkaChatRoomService =
 294         (KafkaChatMessageService) chatRoomData.getChatRoomService();
 295
 296     log.debug(
 297         "Loaded message from partition={} at offset={}: {}",
 298         partition,
 299         offset,
 300         message);
 301     kafkaChatRoomService.persistMessage(message);
 302   }
 303
 304   private boolean isLoadingCompleted()
 305   {
 306     return IntStream
 307         .range(0, numShards)
 308         .filter(shard -> isShardOwned[shard])
 309         .allMatch(shard ->
 310         {
 311           TopicPartition partition = new TopicPartition(topic, shard);
 312           long position = consumer.position(partition);
 313           return position >= currentOffset[shard];
 314         });
 315   }
 316
 317   private void pauseAllOwnedPartions()
 318   {
 319     consumer.pause(IntStream
 320         .range(0, numShards)
 321         .filter(shard -> isShardOwned[shard])
 322         .mapToObj(shard -> new TopicPartition(topic, shard))
 323         .toList());
 324   }
 325
 326
 327   int[] getOwnedShards()
 328   {
 329     return IntStream
 330         .range(0, numShards)
 331         .filter(shard -> isShardOwned[shard])
 332         .toArray();
 333   }
 334
 335   void createChatRoomData(ChatRoomInfo chatRoomInfo)
 336   {
 337     ChatRoomData chatRoomData = computeChatRoomData(
 338         chatRoomInfo.getId(),
 339         chatRoomInfo.getShard());
 340     chatRoomData.activate();
 341   }
 342
 343   Mono<ChatRoomData> getChatRoomData(int shard, UUID id)
 344   {
 345     ChannelState capturedState = channelState;
 346     if (capturedState != ChannelState.READY)
 347     {
 348       return Mono.error(new ChannelNotReadyException(capturedState));
 349     }
 350
 351     if (!isShardOwned[shard])
 352     {
 353       return Mono.error(new ShardNotOwnedException(instanceId, shard));
 354     }
 355
 356     return Mono.justOrEmpty(chatRoomData[shard].get(id));
 357   }
 358
 359   private ChatRoomData computeChatRoomData(UUID chatRoomId, int shard)
 360   {
 361     ChatRoomData chatRoomData = this.chatRoomData[shard].get(chatRoomId);
 362
 363     if (chatRoomData != null)
 364     {
 365       log.info(
 366           "Ignoring request to create already existing ChatRoomData for {}",
 367           chatRoomId);
 368     }
 369     else
 370     {
 371       log.info("Creating ChatRoomData {} with history-limit {}", chatRoomId, historyLimit);
 372       KafkaChatMessageService service = new KafkaChatMessageService(this, chatRoomId);
 373       chatRoomData = new ChatRoomData(clock, service, historyLimit);
 374       this.chatRoomData[shard].put(chatRoomId, chatRoomData);
 375     }
 376
 377     return chatRoomData;
 378   }
 379
 380   ConsumerGroupMetadata getConsumerGroupMetadata()
 381   {
 382     return consumer.groupMetadata();
 383   }
 384 }