X-Git-Url: https://juplo.de/gitweb/?a=blobdiff_plain;f=src%2Fmain%2Fjava%2Fde%2Fjuplo%2Fkafka%2Fchat%2Fbackend%2Fpersistence%2Fkafka%2FKafkaChatHomeService.java;h=3ca5b7f7436f33d9476fec5be4f899a4f4244ee9;hb=ead1db4a7daa0bcf944063f3920b3974c2f62e07;hp=556a22683b0d4459c70117e638abf047538578cc;hpb=60aaf90c0288be9af3e73e024970d1f874bf2448;p=demos%2Fkafka%2Fchat

diff --git a/src/main/java/de/juplo/kafka/chat/backend/persistence/kafka/KafkaChatHomeService.java b/src/main/java/de/juplo/kafka/chat/backend/persistence/kafka/KafkaChatHomeService.java
index 556a2268..3ca5b7f7 100644
--- a/src/main/java/de/juplo/kafka/chat/backend/persistence/kafka/KafkaChatHomeService.java
+++ b/src/main/java/de/juplo/kafka/chat/backend/persistence/kafka/KafkaChatHomeService.java
@@ -3,198 +3,267 @@ package de.juplo.kafka.chat.backend.persistence.kafka;
 import de.juplo.kafka.chat.backend.domain.ChatHomeService;
 import de.juplo.kafka.chat.backend.domain.ChatRoom;
 import de.juplo.kafka.chat.backend.domain.Message;
-import lombok.RequiredArgsConstructor;
+import de.juplo.kafka.chat.backend.domain.ShardNotOwnedException;
+import de.juplo.kafka.chat.backend.persistence.KafkaLikeShardingStrategy;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.kafka.clients.consumer.Consumer;
 import org.apache.kafka.clients.consumer.ConsumerRebalanceListener;
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.clients.producer.Producer;
+import org.apache.kafka.clients.producer.ProducerRecord;
 import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.errors.RecordDeserializationException;
+import org.apache.kafka.common.errors.WakeupException;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
+import java.time.*;
 import java.util.*;
+import java.util.concurrent.ExecutorService;
+import java.util.stream.IntStream;
 
 
 @Slf4j
-public class KafkaChatHomeService implements ChatHomeService, ConsumerRebalanceListener
+public class KafkaChatHomeService implements ChatHomeService, Runnable, ConsumerRebalanceListener
 {
+  private final ExecutorService executorService;
   private final Consumer<String, MessageTo> consumer;
+  private final Producer<String, MessageTo> producer;
   private final String topic;
-  private final long[] offsets;
-  private final MessageHandler[] handlers;
-  private final Map<UUID, ChatRoom>[] chatrooms;
+  private final ZoneId zoneId;
+  private final int numShards;
+  private final boolean[] isShardOwned;
+  private final long[] currentOffset;
+  private final long[] nextOffset;
+  private final Map<UUID, ChatRoom>[] chatRoomMaps;
+  private final KafkaLikeShardingStrategy shardingStrategy;
+
+  private boolean running;
+  private volatile boolean loadInProgress;
 
 
   public KafkaChatHomeService(
+    ExecutorService executorService,
     Consumer<String, MessageTo> consumer,
+    Producer<String, MessageTo> producer,
     String topic,
+    ZoneId zoneId,
     int numShards)
   {
     log.debug("Creating KafkaChatHomeService");
+    this.executorService = executorService;
     this.consumer = consumer;
+    this.producer = producer;
     this.topic = topic;
-    this.offsets = new long[numShards];
-    this.handlers = new MessageHandler[numShards];
-    for (int i=0; i< numShards; i++)
-    {
-      this.offsets[i] = 0l;
-      this.handlers[i] = new MessageHandler(new TopicPartition(topic, i));
-    }
-    this.chatrooms = new Map[numShards];
+    this.zoneId = zoneId;
+    this.numShards = numShards;
+    this.isShardOwned = new boolean[numShards];
+    this.currentOffset = new long[numShards];
+    this.nextOffset = new long[numShards];
+    this.chatRoomMaps = new Map[numShards];
+    this.shardingStrategy = new KafkaLikeShardingStrategy(numShards);
   }
 
 
   @Override
   public void onPartitionsAssigned(Collection<TopicPartition> partitions)
   {
-    consumer.endOffsets(partitions).forEach((tp, currentOffset) ->
+    log.info("Newly assigned partitions! Pausing normal operations...");
+    loadInProgress = true;
+
+    consumer.endOffsets(partitions).forEach((topicPartition, currentOffset) ->
     {
-      if (!tp.topic().equals(topic))
-      {
-        log.warn("Ignoring partition from unwanted topic: {}", tp);
-        return;
-      }
+      int partition = topicPartition.partition();
+      isShardOwned[partition] =  true;
+      this.currentOffset[partition] = currentOffset;
 
-      int partition = tp.partition();
-      long unseenOffset = offsets[partition];
+      log.info(
+          "Partition assigned: {} - loading messages: next={} -> current={}",
+          partition,
+          nextOffset[partition],
+          currentOffset);
 
-      log.info("Reading partition {} from {} -> {}", partition, unseenOffset, currentOffset);
-      handlers[partition] = new ChatRoomLoadingMessageHandlingStrategy(tp, currentOffset, unseenOffset);
+      consumer.seek(topicPartition, nextOffset[partition]);
     });
+
+    consumer.resume(partitions);
   }
 
   @Override
   public void onPartitionsRevoked(Collection<TopicPartition> partitions)
   {
-    partitions.forEach(tp ->
+    partitions.forEach(topicPartition ->
     {
-      if (!tp.topic().equals(topic))
-      {
-        log.warn("Ignoring partition from unwanted topic: {}", tp);
-        return;
-      }
-
-      int partition = tp.partition();
-      long unseenOffset = offsets[partition];
-
-      log.info("Reading partition {} from {} -> {}", partition, unseenOffset, currentOffset);
+      int partition = topicPartition.partition();
+      isShardOwned[partition] = false;
+      log.info("Partition revoked: {} - next={}", partition, nextOffset[partition]);
     });
-    log.info("Revoked partitions: {}", partitions);
   }
 
   @Override
   public void onPartitionsLost(Collection<TopicPartition> partitions)
   {
-    log.info("Revoked partitions: {}", partitions);
+    log.warn("Lost partitions: {}, partitions");
+    // TODO: Muss auf den Verlust anders reagiert werden?
+    onPartitionsRevoked(partitions);
   }
 
-  private void foo()
+  @Override
+  public void run()
   {
-    Set<Integer> owned = Arrays
-      .stream(ownedShards)
-      .collect(
-        () -> new HashSet<>(),
-        (set, i) -> set.add(i),
-        (a, b) -> a.addAll(b));
-    for (int shard = 0; shard < numShards; shard++)
+    consumer.subscribe(List.of(topic));
+
+    running = true;
+
+    while (running)
     {
-      chatrooms[shard] = owned.contains(shard)
-        ? new HashMap<>()
-        : null;
-    }
-    chatroomFlux
-      .filter(chatRoom ->
+      try
       {
-        if (owned.contains(chatRoom.getShard()))
+        ConsumerRecords<String, MessageTo> records = consumer.poll(Duration.ofMinutes(5));
+        log.info("Fetched {} messages", records.count());
+
+        if (loadInProgress)
         {
-          return true;
+          loadMessages(records);
+
+          if (isLoadingCompleted())
+          {
+            log.info("Loading of messages completed! Pausing all owned partitions...");
+            pauseAllOwnedPartions();
+            log.info("Resuming normal operations...");
+            loadInProgress = false;
+          }
         }
         else
         {
-          log.info("Ignoring not owned chat-room {}", chatRoom);
-          return false;
+          if (!records.isEmpty())
+          {
+            throw new IllegalStateException("All owned partitions should be paused, when no load is in progress!");
+          }
         }
-      })
-      .toStream()
-      .forEach(chatroom -> chatrooms[chatroom.getShard()].put(chatroom.getId(), chatroom));
+      }
+      catch (WakeupException e)
+      {
+      }
+      catch (RecordDeserializationException e)
+      {
+      }
+    }
   }
 
-  @Override
-  public Mono<ChatRoom> putChatRoom(ChatRoom chatRoom)
+  void loadMessages(ConsumerRecords<String, MessageTo> records)
   {
-    chatrooms[chatRoom.getShard()].put(chatRoom.getId(), chatRoom);
-    return Mono.just(chatRoom);
-  }
+    for (ConsumerRecord<String, MessageTo> record : records)
+    {
+      nextOffset[record.partition()] = record.offset() + 1;
+      UUID chatRoomId = UUID.fromString(record.key());
+      MessageTo messageTo = record.value();
 
-  @Override
-  public Mono<ChatRoom> getChatRoom(int shard, UUID id)
-  {
-    return Mono.justOrEmpty(chatrooms[shard].get(id));
-  }
+      Message.MessageKey key = Message.MessageKey.of(messageTo.getUser(), messageTo.getId());
 
-  @Override
-  public Flux<ChatRoom> getChatRooms(int shard)
-  {
-    return Flux.fromStream(chatrooms[shard].values().stream());
-  }
+      Instant instant = Instant.ofEpochSecond(record.timestamp());
+      LocalDateTime timestamp = LocalDateTime.ofInstant(instant, zoneId);
 
+      Message message = new Message(key, record.offset(), timestamp, messageTo.getText());
 
-  class MessageHandler
-  {
+      ChatRoom chatRoom = chatRoomMaps[record.partition()].get(chatRoomId);
+      KafkaChatRoomService kafkaChatRoomService =
+          (KafkaChatRoomService) chatRoom.getChatRoomService();
 
+      kafkaChatRoomService.persistMessage(message);
+    }
   }
 
-  interface MessageHandlingStrategy
+  boolean isLoadingCompleted()
   {
-    MessageHandlingStrategy handleMessage(Message message);
+    return IntStream
+        .range(0, numShards)
+        .filter(shard -> isShardOwned[shard])
+        .mapToObj(shard -> nextOffset[shard] >= currentOffset[shard])
+        .collect(
+            () -> Boolean.TRUE,
+            (acc, v) -> Boolean.valueOf(acc && v),
+            (a, b) -> Boolean.valueOf(a && b));
   }
 
-
-  @RequiredArgsConstructor
-  class NoOpMessageHandlingStrategy implements MessageHandlingStrategy
+  void pauseAllOwnedPartions()
   {
-    private final TopicPartition tp;
+    consumer.pause(IntStream
+        .range(0, numShards)
+        .filter(shard -> isShardOwned[shard])
+        .mapToObj(shard -> new TopicPartition(topic, shard))
+        .toList());
+  }
 
-    @Override
-    public MessageHandlingStrategy handleMessage(Message message)
+  Mono<Message> sendMessage(
+      UUID chatRoomId,
+      Message.MessageKey key,
+      LocalDateTime timestamp,
+      String text)
+  {
+    int shard = this.shardingStrategy.selectShard(chatRoomId);
+    TopicPartition tp = new TopicPartition(topic, shard);
+    ZonedDateTime zdt = ZonedDateTime.of(timestamp, zoneId);
+    return Mono.create(sink ->
     {
-      log.warn("Not handling message {} for partition {}", message, tp);
-      return this;
-    }
+      ProducerRecord<String, MessageTo> record =
+          new ProducerRecord<>(
+              tp.topic(),
+              tp.partition(),
+              zdt.toEpochSecond(),
+              chatRoomId.toString(),
+              MessageTo.of(key.getUsername(), key.getMessageId(), text));
+
+      producer.send(record, ((metadata, exception) ->
+      {
+        if (metadata != null)
+        {
+          // On successful send
+          Message message = new Message(key, metadata.offset(), timestamp, text);
+          log.info("Successfully send message {}", message);
+          sink.success(message);
+        }
+        else
+        {
+          // On send-failure
+          log.error(
+              "Could not send message for chat-room={}, key={}, timestamp={}, text={}: {}",
+              chatRoomId,
+              key,
+              timestamp,
+              text,
+              exception);
+          sink.error(exception);
+        }
+      }));
+    });
   }
 
-  class ChatRoomLoadingMessageHandlingStrategy implements MessageHandlingStrategy
-  {
-    private final TopicPartition tp;
-    private final long currentOffset;
-    private final long unseenOffset;
 
-    ChatRoomLoadingMessageHandlingStrategy(TopicPartition tp, long currentOffset, long unseenOffset)
+  @Override
+  public Mono<ChatRoom> getChatRoom(int shard, UUID id)
+  {
+    if (loadInProgress)
     {
-      this.tp = tp;
-      this.currentOffset = currentOffset;
-      this.unseenOffset = unseenOffset;
-
-      consumer.seek(tp, unseenOffset);
+      throw new ShardNotOwnedException(shard);
     }
-
-    @Override
-    public MessageHandlingStrategy handleMessage(Message message)
+    else
     {
-      // todo
-      return this;
+      return Mono.justOrEmpty(chatRoomMaps[shard].get(id));
     }
   }
 
-  @RequiredArgsConstructor
-  class DefaultMessageHandlingStrategy implements MessageHandlingStrategy
+  @Override
+  public Flux<ChatRoom> getChatRooms(int shard)
   {
-    private final TopicPartition tp;
-
-    @Override
-    public MessageHandlingStrategy handleMessage(Message message)
+    if (loadInProgress)
+    {
+      throw new ShardNotOwnedException(shard);
+    }
+    else
     {
-      chatrooms[tp.partition()].put()
-      return this;
+      return Flux.fromStream(chatRoomMaps[shard].values().stream());
     }
   }
 }