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