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 (metadata != 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           .doOnNext(instanceId -> log.info(
 151               "Instance {} was published as owner of shard {}",
 152               instanceId,
 153               partition))
 154           .subscribe();
 155     });
 156
 157     consumer.resume(partitions);
 158   }
 159
 160   @Override
 161   public void onPartitionsRevoked(Collection<TopicPartition> partitions)
 162   {
 163     partitions.forEach(topicPartition ->
 164     {
 165       int partition = topicPartition.partition();
 166       isShardOwned[partition] = false;
 167       nextOffset[partition] = consumer.position(topicPartition);
 168       log.info("Partition revoked: {} - next={}", partition, nextOffset[partition]);
 169       infoChannel.sendShardRevokedEvent(partition);
 170     });
 171   }
 172
 173   @Override
 174   public void onPartitionsLost(Collection<TopicPartition> partitions)
 175   {
 176     log.warn("Lost partitions: {}, partitions");
 177     // TODO: Muss auf den Verlust anders reagiert werden?
 178     onPartitionsRevoked(partitions);
 179   }
 180
 181   @Override
 182   public void run()
 183   {
 184     running = true;
 185
 186     while (running)
 187     {
 188       try
 189       {
 190         ConsumerRecords<String, AbstractMessageTo> records = consumer.poll(Duration.ofMinutes(1));
 191         log.info("Fetched {} messages", records.count());
 192
 193         if (loadInProgress)
 194         {
 195           loadChatRoomData(records);
 196
 197           if (isLoadingCompleted())
 198           {
 199             log.info("Loading of messages completed! Pausing all owned partitions...");
 200             pauseAllOwnedPartions();
 201             log.info("Resuming normal operations...");
 202             loadInProgress = false;
 203           }
 204         }
 205         else
 206         {
 207           if (!records.isEmpty())
 208           {
 209             throw new IllegalStateException("All owned partitions should be paused, when no load is in progress!");
 210           }
 211         }
 212       }
 213       catch (WakeupException e)
 214       {
 215         log.info("Received WakeupException, exiting!");
 216         running = false;
 217       }
 218     }
 219
 220     log.info("Exiting normally");
 221   }
 222
 223   private void loadChatRoomData(ConsumerRecords<String, AbstractMessageTo> records)
 224   {
 225     for (ConsumerRecord<String, AbstractMessageTo> record : records)
 226     {
 227       UUID chatRoomId = UUID.fromString(record.key());
 228
 229       switch (record.value().getType())
 230       {
 231         case EVENT_CHATMESSAGE_RECEIVED:
 232           Instant instant = Instant.ofEpochSecond(record.timestamp());
 233           LocalDateTime timestamp = LocalDateTime.ofInstant(instant, zoneId);
 234           loadChatMessage(
 235               chatRoomId,
 236               timestamp,
 237               record.offset(),
 238               (EventChatMessageReceivedTo) record.value(),
 239               record.partition());
 240           break;
 241
 242         default:
 243           log.debug(
 244               "Ignoring message for chat-room {} with offset {}: {}",
 245               chatRoomId,
 246               record.offset(),
 247               record.value());
 248       }
 249
 250       nextOffset[record.partition()] = record.offset() + 1;
 251     }
 252   }
 253
 254   private void loadChatMessage(
 255       UUID chatRoomId,
 256       LocalDateTime timestamp,
 257       long offset,
 258       EventChatMessageReceivedTo chatMessageTo,
 259       int partition)
 260   {
 261     Message.MessageKey key = Message.MessageKey.of(chatMessageTo.getUser(), chatMessageTo.getId());
 262     Message message = new Message(key, offset, timestamp, chatMessageTo.getText());
 263
 264     ChatRoomData chatRoomData = this
 265         .chatRoomData[partition]
 266         .computeIfAbsent(chatRoomId, this::computeChatRoomData);
 267     KafkaChatMessageService kafkaChatRoomService =
 268         (KafkaChatMessageService) chatRoomData.getChatRoomService();
 269
 270     log.debug(
 271         "Loaded message from partition={} at offset={}: {}",
 272         partition,
 273         offset,
 274         message);
 275     kafkaChatRoomService.persistMessage(message);
 276   }
 277
 278   private boolean isLoadingCompleted()
 279   {
 280     return IntStream
 281         .range(0, numShards)
 282         .filter(shard -> isShardOwned[shard])
 283         .allMatch(shard ->
 284         {
 285           TopicPartition partition = new TopicPartition(topic, shard);
 286           long position = consumer.position(partition);
 287           return position >= currentOffset[shard];
 288         });
 289   }
 290
 291   private void pauseAllOwnedPartions()
 292   {
 293     consumer.pause(IntStream
 294         .range(0, numShards)
 295         .filter(shard -> isShardOwned[shard])
 296         .mapToObj(shard -> new TopicPartition(topic, shard))
 297         .toList());
 298   }
 299
 300
 301   int[] getOwnedShards()
 302   {
 303     return IntStream
 304         .range(0, numShards)
 305         .filter(shard -> isShardOwned[shard])
 306         .toArray();
 307   }
 308
 309   Mono<ChatRoomData> getChatRoomData(int shard, UUID id)
 310   {
 311     if (loadInProgress)
 312     {
 313       return Mono.error(new LoadInProgressException());
 314     }
 315
 316     if (!isShardOwned[shard])
 317     {
 318       return Mono.error(new ShardNotOwnedException(instanceId, shard));
 319     }
 320
 321     return infoChannel
 322         .getChatRoomInfo(id)
 323         .map(chatRoomInfo ->
 324             chatRoomData[shard].computeIfAbsent(id, this::computeChatRoomData));
 325   }
 326
 327   private ChatRoomData computeChatRoomData(UUID chatRoomId)
 328   {
 329     log.info("Creating ChatRoom {} with buffer-size {}", chatRoomId, bufferSize);
 330     KafkaChatMessageService service = new KafkaChatMessageService(this, chatRoomId);
 331     return new ChatRoomData(clock, service, bufferSize);
 332   }
 333 }