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