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       log.info("Partition revoked: {} - next={}", partition, nextOffset[partition]);
 173       infoChannel.sendShardRevokedEvent(partition);
 174     });
 175   }
 176
 177   @Override
 178   public void onPartitionsLost(Collection<TopicPartition> partitions)
 179   {
 180     log.warn("Lost partitions: {}, partitions");
 181     // TODO: Muss auf den Verlust anders reagiert werden?
 182     onPartitionsRevoked(partitions);
 183   }
 184
 185   @Override
 186   public void run()
 187   {
 188     running = true;
 189
 190     while (running)
 191     {
 192       try
 193       {
 194         ConsumerRecords<String, AbstractMessageTo> records = consumer.poll(Duration.ofMinutes(1));
 195         log.info("Fetched {} messages", records.count());
 196
 197         if (loadInProgress)
 198         {
 199           loadChatRoomData(records);
 200
 201           if (isLoadingCompleted())
 202           {
 203             log.info("Loading of messages completed! Pausing all owned partitions...");
 204             pauseAllOwnedPartions();
 205             log.info("Resuming normal operations...");
 206             loadInProgress = false;
 207           }
 208         }
 209         else
 210         {
 211           if (!records.isEmpty())
 212           {
 213             throw new IllegalStateException("All owned partitions should be paused, when no load is in progress!");
 214           }
 215         }
 216       }
 217       catch (WakeupException e)
 218       {
 219         log.info("Received WakeupException, exiting!");
 220         running = false;
 221       }
 222     }
 223
 224     log.info("Exiting normally");
 225   }
 226
 227   private void loadChatRoomData(ConsumerRecords<String, AbstractMessageTo> records)
 228   {
 229     for (ConsumerRecord<String, AbstractMessageTo> record : records)
 230     {
 231       UUID chatRoomId = UUID.fromString(record.key());
 232
 233       switch (record.value().getType())
 234       {
 235         case EVENT_CHATMESSAGE_RECEIVED:
 236           Instant instant = Instant.ofEpochSecond(record.timestamp());
 237           LocalDateTime timestamp = LocalDateTime.ofInstant(instant, zoneId);
 238           loadChatMessage(
 239               chatRoomId,
 240               timestamp,
 241               record.offset(),
 242               (EventChatMessageReceivedTo) record.value(),
 243               record.partition());
 244           break;
 245
 246         default:
 247           log.debug(
 248               "Ignoring message for chat-room {} with offset {}: {}",
 249               chatRoomId,
 250               record.offset(),
 251               record.value());
 252       }
 253
 254       nextOffset[record.partition()] = record.offset() + 1;
 255     }
 256   }
 257
 258   private void loadChatMessage(
 259       UUID chatRoomId,
 260       LocalDateTime timestamp,
 261       long offset,
 262       EventChatMessageReceivedTo chatMessageTo,
 263       int partition)
 264   {
 265     Message.MessageKey key = Message.MessageKey.of(chatMessageTo.getUser(), chatMessageTo.getId());
 266     Message message = new Message(key, offset, timestamp, chatMessageTo.getText());
 267
 268     ChatRoomData chatRoomData = this
 269         .chatRoomData[partition]
 270         .computeIfAbsent(chatRoomId, this::computeChatRoomData);
 271     KafkaChatMessageService kafkaChatRoomService =
 272         (KafkaChatMessageService) chatRoomData.getChatRoomService();
 273
 274     log.debug(
 275         "Loaded message from partition={} at offset={}: {}",
 276         partition,
 277         offset,
 278         message);
 279     kafkaChatRoomService.persistMessage(message);
 280   }
 281
 282   private boolean isLoadingCompleted()
 283   {
 284     return IntStream
 285         .range(0, numShards)
 286         .filter(shard -> isShardOwned[shard])
 287         .allMatch(shard -> nextOffset[shard] >= currentOffset[shard]);
 288   }
 289
 290   private void pauseAllOwnedPartions()
 291   {
 292     consumer.pause(IntStream
 293         .range(0, numShards)
 294         .filter(shard -> isShardOwned[shard])
 295         .mapToObj(shard -> new TopicPartition(topic, shard))
 296         .toList());
 297   }
 298
 299
 300   int[] getOwnedShards()
 301   {
 302     return IntStream
 303         .range(0, numShards)
 304         .filter(shard -> isShardOwned[shard])
 305         .toArray();
 306   }
 307
 308   Mono<ChatRoomData> getChatRoomData(int shard, UUID id)
 309   {
 310     if (loadInProgress)
 311     {
 312       return Mono.error(new LoadInProgressException());
 313     }
 314
 315     if (!isShardOwned[shard])
 316     {
 317       return Mono.error(new ShardNotOwnedException(instanceId, shard));
 318     }
 319
 320     return infoChannel
 321         .getChatRoomInfo(id)
 322         .map(chatRoomInfo ->
 323             chatRoomData[shard].computeIfAbsent(id, this::computeChatRoomData));
 324   }
 325
 326   private ChatRoomData computeChatRoomData(UUID chatRoomId)
 327   {
 328     log.info("Creating ChatRoom {} with buffer-size {}", chatRoomId, bufferSize);
 329     KafkaChatMessageService service = new KafkaChatMessageService(this, chatRoomId);
 330     return new ChatRoomData(clock, service, bufferSize);
 331   }
 332 }