#122 Seek direction backend support (#562)

kafka-ui-api/src/main/java/com/provectus/kafka/ui/controller/MessagesController.java

@@ -2,6 +2,7 @@ package com.provectus.kafka.ui.controller;
 
 import com.provectus.kafka.ui.api.MessagesApi;
 import com.provectus.kafka.ui.model.ConsumerPosition;
+import com.provectus.kafka.ui.model.SeekDirection;
 import com.provectus.kafka.ui.model.SeekType;
 import com.provectus.kafka.ui.model.TopicMessage;
 import com.provectus.kafka.ui.service.ClusterService;
@@ -40,13 +41,15 @@ public class MessagesController implements MessagesApi {
   @Override
   public Mono<ResponseEntity<Flux<TopicMessage>>> getTopicMessages(
       String clusterName, String topicName, @Valid SeekType seekType, @Valid List<String> seekTo,
-      @Valid Integer limit, @Valid String q, ServerWebExchange exchange) {
-    return parseConsumerPosition(seekType, seekTo)
+      @Valid Integer limit, @Valid String q, @Valid SeekDirection seekDirection,
+      ServerWebExchange exchange) {
+    return parseConsumerPosition(seekType, seekTo, seekDirection)
         .map(consumerPosition -> ResponseEntity
             .ok(clusterService.getMessages(clusterName, topicName, consumerPosition, q, limit)));
   }
 
-  private Mono<ConsumerPosition> parseConsumerPosition(SeekType seekType, List<String> seekTo) {
+  private Mono<ConsumerPosition> parseConsumerPosition(
+      SeekType seekType, List<String> seekTo,  SeekDirection seekDirection) {
     return Mono.justOrEmpty(seekTo)
         .defaultIfEmpty(Collections.emptyList())
         .flatMapIterable(Function.identity())
@@ -61,7 +64,7 @@ public class MessagesController implements MessagesApi {
         })
         .collectMap(Pair::getKey, Pair::getValue)
         .map(positions -> new ConsumerPosition(seekType != null ? seekType : SeekType.BEGINNING,
-            positions));
+            positions, seekDirection));
   }
 
 }

kafka-ui-api/src/main/java/com/provectus/kafka/ui/model/ConsumerPosition.java

@@ -8,5 +8,5 @@ public class ConsumerPosition {
 
   private SeekType seekType;
   private Map<Integer, Long> seekTo;
-
+  private SeekDirection seekDirection;
 }

kafka-ui-api/src/main/java/com/provectus/kafka/ui/service/ConsumingService.java

@@ -6,12 +6,14 @@ import com.provectus.kafka.ui.deserialization.DeserializationService;
 import com.provectus.kafka.ui.deserialization.RecordDeserializer;
 import com.provectus.kafka.ui.model.ConsumerPosition;
 import com.provectus.kafka.ui.model.KafkaCluster;
-import com.provectus.kafka.ui.model.SeekType;
+import com.provectus.kafka.ui.model.SeekDirection;
 import com.provectus.kafka.ui.model.TopicMessage;
 import com.provectus.kafka.ui.util.ClusterUtil;
+import com.provectus.kafka.ui.util.OffsetsSeek;
+import com.provectus.kafka.ui.util.OffsetsSeekBackward;
+import com.provectus.kafka.ui.util.OffsetsSeekForward;
 import java.time.Duration;
 import java.util.Collection;
-import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
@@ -53,7 +55,10 @@ public class ConsumingService {
         .orElse(DEFAULT_RECORD_LIMIT);
     RecordEmitter emitter = new RecordEmitter(
         () -> kafkaService.createConsumer(cluster),
-        new OffsetsSeek(topic, consumerPosition));
+        consumerPosition.getSeekDirection().equals(SeekDirection.FORWARD)
+            ? new OffsetsSeekForward(topic, consumerPosition)
+            : new OffsetsSeekBackward(topic, consumerPosition, recordsLimit)
+    );
     RecordDeserializer recordDeserializer =
         deserializationService.getRecordDeserializerForCluster(cluster);
     return Flux.create(emitter)
@@ -79,7 +84,7 @@ public class ConsumingService {
    * returns end offsets for partitions where start offset != end offsets.
    * This is useful when we need to verify that partition is not empty.
    */
-  private static Map<TopicPartition, Long> significantOffsets(Consumer<?, ?> consumer,
+  public static Map<TopicPartition, Long> significantOffsets(Consumer<?, ?> consumer,
                                                               String topicName,
                                                               Collection<Integer>
                                                                   partitionsToInclude) {
@@ -159,98 +164,4 @@ public class ConsumingService {
     }
   }
 
-  @RequiredArgsConstructor
-  static class OffsetsSeek {
-
-    private final String topic;
-    private final ConsumerPosition consumerPosition;
-
-    public WaitingOffsets assignAndSeek(Consumer<Bytes, Bytes> consumer) {
-      SeekType seekType = consumerPosition.getSeekType();
-      log.info("Positioning consumer for topic {} with {}", topic, consumerPosition);
-      switch (seekType) {
-        case OFFSET:
-          assignAndSeekForOffset(consumer);
-          break;
-        case TIMESTAMP:
-          assignAndSeekForTimestamp(consumer);
-          break;
-        case BEGINNING:
-          assignAndSeekFromBeginning(consumer);
-          break;
-        default:
-          throw new IllegalArgumentException("Unknown seekType: " + seekType);
-      }
-      log.info("Assignment: {}", consumer.assignment());
-      return new WaitingOffsets(topic, consumer);
-    }
-
-    private List<TopicPartition> getRequestedPartitions(Consumer<Bytes, Bytes> consumer) {
-      Map<Integer, Long> partitionPositions = consumerPosition.getSeekTo();
-      return consumer.partitionsFor(topic).stream()
-          .filter(
-              p -> partitionPositions.isEmpty() || partitionPositions.containsKey(p.partition()))
-          .map(p -> new TopicPartition(p.topic(), p.partition()))
-          .collect(Collectors.toList());
-    }
-
-    private void assignAndSeekForOffset(Consumer<Bytes, Bytes> consumer) {
-      List<TopicPartition> partitions = getRequestedPartitions(consumer);
-      consumer.assign(partitions);
-      consumerPosition.getSeekTo().forEach((partition, offset) -> {
-        TopicPartition topicPartition = new TopicPartition(topic, partition);
-        consumer.seek(topicPartition, offset);
-      });
-    }
-
-    private void assignAndSeekForTimestamp(Consumer<Bytes, Bytes> consumer) {
-      Map<TopicPartition, Long> timestampsToSearch =
-          consumerPosition.getSeekTo().entrySet().stream()
-              .collect(Collectors.toMap(
-                  partitionPosition -> new TopicPartition(topic, partitionPosition.getKey()),
-                  Map.Entry::getValue
-              ));
-      Map<TopicPartition, Long> offsetsForTimestamps = consumer.offsetsForTimes(timestampsToSearch)
-          .entrySet().stream()
-          .filter(e -> e.getValue() != null)
-          .collect(Collectors.toMap(Map.Entry::getKey, e -> e.getValue().offset()));
-
-      if (offsetsForTimestamps.isEmpty()) {
-        throw new IllegalArgumentException("No offsets were found for requested timestamps");
-      }
-
-      consumer.assign(offsetsForTimestamps.keySet());
-      offsetsForTimestamps.forEach(consumer::seek);
-    }
-
-    private void assignAndSeekFromBeginning(Consumer<Bytes, Bytes> consumer) {
-      List<TopicPartition> partitions = getRequestedPartitions(consumer);
-      consumer.assign(partitions);
-      consumer.seekToBeginning(partitions);
-    }
-
-    static class WaitingOffsets {
-      final Map<Integer, Long> offsets = new HashMap<>(); // partition number -> offset
-
-      WaitingOffsets(String topic, Consumer<?, ?> consumer) {
-        var partitions = consumer.assignment().stream()
-            .map(TopicPartition::partition)
-            .collect(Collectors.toList());
-        significantOffsets(consumer, topic, partitions)
-            .forEach((tp, offset) -> offsets.put(tp.partition(), offset - 1));
-      }
-
-      void markPolled(ConsumerRecord<?, ?> rec) {
-        Long waiting = offsets.get(rec.partition());
-        if (waiting != null && waiting <= rec.offset()) {
-          offsets.remove(rec.partition());
-        }
-      }
-
-      boolean endReached() {
-        return offsets.isEmpty();
-      }
-    }
-
-  }
 }

kafka-ui-api/src/main/java/com/provectus/kafka/ui/util/OffsetsSeek.java

@@ -0,0 +1,84 @@
+package com.provectus.kafka.ui.util;
+
+import com.provectus.kafka.ui.model.ConsumerPosition;
+import com.provectus.kafka.ui.model.SeekType;
+import com.provectus.kafka.ui.service.ConsumingService;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+import lombok.extern.log4j.Log4j2;
+import org.apache.kafka.clients.consumer.Consumer;
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.utils.Bytes;
+
+@Log4j2
+public abstract class OffsetsSeek {
+  protected final String topic;
+  protected final ConsumerPosition consumerPosition;
+
+  public OffsetsSeek(String topic, ConsumerPosition consumerPosition) {
+    this.topic = topic;
+    this.consumerPosition = consumerPosition;
+  }
+
+  public WaitingOffsets assignAndSeek(Consumer<Bytes, Bytes> consumer) {
+    SeekType seekType = consumerPosition.getSeekType();
+    log.info("Positioning consumer for topic {} with {}", topic, consumerPosition);
+    switch (seekType) {
+      case OFFSET:
+        assignAndSeekForOffset(consumer);
+        break;
+      case TIMESTAMP:
+        assignAndSeekForTimestamp(consumer);
+        break;
+      case BEGINNING:
+        assignAndSeekFromBeginning(consumer);
+        break;
+      default:
+        throw new IllegalArgumentException("Unknown seekType: " + seekType);
+    }
+    log.info("Assignment: {}", consumer.assignment());
+    return new WaitingOffsets(topic, consumer);
+  }
+
+  protected List<TopicPartition> getRequestedPartitions(Consumer<Bytes, Bytes> consumer) {
+    Map<Integer, Long> partitionPositions = consumerPosition.getSeekTo();
+    return consumer.partitionsFor(topic).stream()
+        .filter(
+            p -> partitionPositions.isEmpty() || partitionPositions.containsKey(p.partition()))
+        .map(p -> new TopicPartition(p.topic(), p.partition()))
+        .collect(Collectors.toList());
+  }
+
+
+  protected abstract void assignAndSeekFromBeginning(Consumer<Bytes, Bytes> consumer);
+
+  protected abstract void assignAndSeekForTimestamp(Consumer<Bytes, Bytes> consumer);
+
+  protected abstract void assignAndSeekForOffset(Consumer<Bytes, Bytes> consumer);
+
+  public static class WaitingOffsets {
+    final Map<Integer, Long> offsets = new HashMap<>(); // partition number -> offset
+
+    public WaitingOffsets(String topic, Consumer<?, ?> consumer) {
+      var partitions = consumer.assignment().stream()
+          .map(TopicPartition::partition)
+          .collect(Collectors.toList());
+      ConsumingService.significantOffsets(consumer, topic, partitions)
+          .forEach((tp, offset) -> offsets.put(tp.partition(), offset - 1));
+    }
+
+    public void markPolled(ConsumerRecord<?, ?> rec) {
+      Long waiting = offsets.get(rec.partition());
+      if (waiting != null && waiting <= rec.offset()) {
+        offsets.remove(rec.partition());
+      }
+    }
+
+    public boolean endReached() {
+      return offsets.isEmpty();
+    }
+  }
+}

kafka-ui-api/src/main/java/com/provectus/kafka/ui/util/OffsetsSeekBackward.java

@@ -0,0 +1,121 @@
+package com.provectus.kafka.ui.util;
+
+import com.provectus.kafka.ui.model.ConsumerPosition;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+import lombok.extern.log4j.Log4j2;
+import org.apache.kafka.clients.consumer.Consumer;
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.utils.Bytes;
+import reactor.util.function.Tuple2;
+import reactor.util.function.Tuples;
+
+@Log4j2
+public class OffsetsSeekBackward extends OffsetsSeek {
+
+  private final int maxMessages;
+
+  public OffsetsSeekBackward(String topic,
+                             ConsumerPosition consumerPosition, int maxMessages) {
+    super(topic, consumerPosition);
+    this.maxMessages = maxMessages;
+  }
+
+
+  protected void assignAndSeekForOffset(Consumer<Bytes, Bytes> consumer) {
+    List<TopicPartition> partitions = getRequestedPartitions(consumer);
+    consumer.assign(partitions);
+    final Map<TopicPartition, Long> offsets =
+        findOffsetsInt(consumer, consumerPosition.getSeekTo());
+    offsets.forEach(consumer::seek);
+  }
+
+  protected void assignAndSeekFromBeginning(Consumer<Bytes, Bytes> consumer) {
+    List<TopicPartition> partitions = getRequestedPartitions(consumer);
+    consumer.assign(partitions);
+    final Map<TopicPartition, Long> offsets = findOffsets(consumer, Map.of());
+    offsets.forEach(consumer::seek);
+  }
+
+  protected void assignAndSeekForTimestamp(Consumer<Bytes, Bytes> consumer) {
+    Map<TopicPartition, Long> timestampsToSearch =
+        consumerPosition.getSeekTo().entrySet().stream()
+            .collect(Collectors.toMap(
+                partitionPosition -> new TopicPartition(topic, partitionPosition.getKey()),
+                e -> e.getValue() + 1
+            ));
+    Map<TopicPartition, Long> offsetsForTimestamps = consumer.offsetsForTimes(timestampsToSearch)
+        .entrySet().stream()
+        .filter(e -> e.getValue() != null)
+        .map(v -> Tuples.of(v.getKey(), v.getValue().offset() - 1))
+        .collect(Collectors.toMap(Tuple2::getT1, Tuple2::getT2));
+
+    if (offsetsForTimestamps.isEmpty()) {
+      throw new IllegalArgumentException("No offsets were found for requested timestamps");
+    }
+
+    consumer.assign(offsetsForTimestamps.keySet());
+    final Map<TopicPartition, Long> offsets = findOffsets(consumer, offsetsForTimestamps);
+    offsets.forEach(consumer::seek);
+  }
+
+  protected Map<TopicPartition, Long> findOffsetsInt(
+      Consumer<Bytes, Bytes> consumer, Map<Integer, Long> seekTo) {
+
+    final Map<TopicPartition, Long> seekMap = seekTo.entrySet()
+        .stream().map(p ->
+            Tuples.of(
+                new TopicPartition(topic, p.getKey()),
+                p.getValue()
+            )
+        ).collect(Collectors.toMap(Tuple2::getT1, Tuple2::getT2));
+
+    return findOffsets(consumer, seekMap);
+  }
+
+  protected Map<TopicPartition, Long> findOffsets(
+      Consumer<Bytes, Bytes> consumer, Map<TopicPartition, Long> seekTo) {
+
+    List<TopicPartition> partitions = getRequestedPartitions(consumer);
+    final Map<TopicPartition, Long> beginningOffsets = consumer.beginningOffsets(partitions);
+    final Map<TopicPartition, Long> endOffsets = consumer.endOffsets(partitions);
+
+    final Map<TopicPartition, Long> seekMap = new HashMap<>(seekTo);
+    int awaitingMessages = maxMessages;
+
+    Set<TopicPartition> waiting = new HashSet<>(partitions);
+
+    while (awaitingMessages > 0 && !waiting.isEmpty()) {
+      final int msgsPerPartition = (int) Math.ceil((double) awaitingMessages / partitions.size());
+      for (TopicPartition partition : partitions) {
+        final Long offset = Optional.ofNullable(seekMap.get(partition))
+            .orElseGet(() -> endOffsets.get(partition));
+        final Long beginning = beginningOffsets.get(partition);
+
+        if (offset - beginning > msgsPerPartition) {
+          seekMap.put(partition, offset - msgsPerPartition);
+          awaitingMessages -= msgsPerPartition;
+        } else {
+          final long num = offset - beginning;
+          if (num > 0) {
+            seekMap.put(partition, offset - num);
+            awaitingMessages -= num;
+          } else {
+            waiting.remove(partition);
+          }
+        }
+
+        if (awaitingMessages <= 0) {
+          break;
+        }
+      }
+    }
+
+    return seekMap;
+  }
+}

kafka-ui-api/src/main/java/com/provectus/kafka/ui/util/OffsetsSeekForward.java

@@ -0,0 +1,59 @@
+package com.provectus.kafka.ui.util;
+
+import com.provectus.kafka.ui.model.ConsumerPosition;
+import com.provectus.kafka.ui.model.SeekType;
+import com.provectus.kafka.ui.service.ConsumingService;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.log4j.Log4j2;
+import org.apache.kafka.clients.consumer.Consumer;
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.utils.Bytes;
+
+@Log4j2
+public class OffsetsSeekForward extends OffsetsSeek {
+
+  public OffsetsSeekForward(String topic, ConsumerPosition consumerPosition) {
+    super(topic, consumerPosition);
+  }
+
+  protected void assignAndSeekForOffset(Consumer<Bytes, Bytes> consumer) {
+    List<TopicPartition> partitions = getRequestedPartitions(consumer);
+    consumer.assign(partitions);
+    consumerPosition.getSeekTo().forEach((partition, offset) -> {
+      TopicPartition topicPartition = new TopicPartition(topic, partition);
+      consumer.seek(topicPartition, offset);
+    });
+  }
+
+  protected void assignAndSeekForTimestamp(Consumer<Bytes, Bytes> consumer) {
+    Map<TopicPartition, Long> timestampsToSearch =
+        consumerPosition.getSeekTo().entrySet().stream()
+            .collect(Collectors.toMap(
+                partitionPosition -> new TopicPartition(topic, partitionPosition.getKey()),
+                Map.Entry::getValue
+            ));
+    Map<TopicPartition, Long> offsetsForTimestamps = consumer.offsetsForTimes(timestampsToSearch)
+        .entrySet().stream()
+        .filter(e -> e.getValue() != null)
+        .collect(Collectors.toMap(Map.Entry::getKey, e -> e.getValue().offset()));
+
+    if (offsetsForTimestamps.isEmpty()) {
+      throw new IllegalArgumentException("No offsets were found for requested timestamps");
+    }
+
+    consumer.assign(offsetsForTimestamps.keySet());
+    offsetsForTimestamps.forEach(consumer::seek);
+  }
+
+  protected void assignAndSeekFromBeginning(Consumer<Bytes, Bytes> consumer) {
+    List<TopicPartition> partitions = getRequestedPartitions(consumer);
+    consumer.assign(partitions);
+    consumer.seekToBeginning(partitions);
+  }
+
+}

kafka-ui-api/src/test/java/com/provectus/kafka/ui/service/RecordEmitterTest.java

@@ -1,13 +1,14 @@
 package com.provectus.kafka.ui.service;
 
-import static com.provectus.kafka.ui.service.ConsumingService.OffsetsSeek;
 import static com.provectus.kafka.ui.service.ConsumingService.RecordEmitter;
 import static org.assertj.core.api.Assertions.assertThat;
 
 import com.provectus.kafka.ui.AbstractBaseTest;
 import com.provectus.kafka.ui.model.ConsumerPosition;
+import com.provectus.kafka.ui.model.SeekDirection;
 import com.provectus.kafka.ui.model.SeekType;
 import com.provectus.kafka.ui.producer.KafkaTestProducer;
+import com.provectus.kafka.ui.util.OffsetsSeekForward;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
@@ -65,7 +66,10 @@ class RecordEmitterTest extends AbstractBaseTest {
   void pollNothingOnEmptyTopic() {
     var emitter = new RecordEmitter(
         this::createConsumer,
-        new OffsetsSeek(EMPTY_TOPIC, new ConsumerPosition(SeekType.BEGINNING, Map.of())));
+        new OffsetsSeekForward(EMPTY_TOPIC,
+            new ConsumerPosition(SeekType.BEGINNING, Map.of(), SeekDirection.FORWARD)
+        )
+    );
 
     Long polledValues = Flux.create(emitter)
         .limitRequest(100)
@@ -79,7 +83,10 @@ class RecordEmitterTest extends AbstractBaseTest {
   void pollFullTopicFromBeginning() {
     var emitter = new RecordEmitter(
         this::createConsumer,
-        new OffsetsSeek(TOPIC, new ConsumerPosition(SeekType.BEGINNING, Map.of())));
+        new OffsetsSeekForward(TOPIC,
+            new ConsumerPosition(SeekType.BEGINNING, Map.of(), SeekDirection.FORWARD)
+        )
+    );
 
     var polledValues = Flux.create(emitter)
         .map(this::deserialize)
@@ -101,7 +108,10 @@ class RecordEmitterTest extends AbstractBaseTest {
 
     var emitter = new RecordEmitter(
         this::createConsumer,
-        new OffsetsSeek(TOPIC, new ConsumerPosition(SeekType.OFFSET, targetOffsets)));
+        new OffsetsSeekForward(TOPIC,
+            new ConsumerPosition(SeekType.OFFSET, targetOffsets, SeekDirection.FORWARD)
+        )
+    );
 
     var polledValues = Flux.create(emitter)
         .map(this::deserialize)
@@ -127,7 +137,10 @@ class RecordEmitterTest extends AbstractBaseTest {
 
     var emitter = new RecordEmitter(
         this::createConsumer,
-        new OffsetsSeek(TOPIC, new ConsumerPosition(SeekType.TIMESTAMP, targetTimestamps)));
+        new OffsetsSeekForward(TOPIC,
+            new ConsumerPosition(SeekType.TIMESTAMP, targetTimestamps, SeekDirection.FORWARD)
+        )
+    );
 
     var polledValues = Flux.create(emitter)
         .map(this::deserialize)

kafka-ui-api/src/test/java/com/provectus/kafka/ui/service/OffsetsSeekTest.java → kafka-ui-api/src/test/java/com/provectus/kafka/ui/util/OffsetsSeekTest.java

@@ -1,8 +1,9 @@
-package com.provectus.kafka.ui.service;
+package com.provectus.kafka.ui.util;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 import com.provectus.kafka.ui.model.ConsumerPosition;
+import com.provectus.kafka.ui.model.SeekDirection;
 import com.provectus.kafka.ui.model.SeekType;
 import java.util.List;
 import java.util.Map;
@@ -51,10 +52,16 @@ class OffsetsSeekTest {
   }
 
   @Test
-  void seekToBeginningAllPartitions() {
-    var seek = new ConsumingService.OffsetsSeek(
+  void forwardSeekToBeginningAllPartitions() {
+    var seek = new OffsetsSeekForward(
         topic,
-        new ConsumerPosition(SeekType.BEGINNING, Map.of(0, 0L, 1, 0L)));
+        new ConsumerPosition(
+            SeekType.BEGINNING,
+            Map.of(0, 0L, 1, 0L),
+            SeekDirection.FORWARD
+        )
+    );
+
     seek.assignAndSeek(consumer);
     assertThat(consumer.assignment()).containsExactlyInAnyOrder(tp0, tp1);
     assertThat(consumer.position(tp0)).isZero();
@@ -62,10 +69,28 @@ class OffsetsSeekTest {
   }
 
   @Test
-  void seekToBeginningWithPartitionsList() {
-    var seek = new ConsumingService.OffsetsSeek(
+  void backwardSeekToBeginningAllPartitions() {
+    var seek = new OffsetsSeekBackward(
+        topic,
+        new ConsumerPosition(
+            SeekType.BEGINNING,
+            Map.of(2, 0L, 3, 0L),
+            SeekDirection.BACKWARD
+        ),
+        10
+    );
+
+    seek.assignAndSeek(consumer);
+    assertThat(consumer.assignment()).containsExactlyInAnyOrder(tp2, tp3);
+    assertThat(consumer.position(tp2)).isEqualTo(15L);
+    assertThat(consumer.position(tp3)).isEqualTo(25L);
+  }
+
+  @Test
+  void forwardSeekToBeginningWithPartitionsList() {
+    var seek = new OffsetsSeekForward(
         topic,
-        new ConsumerPosition(SeekType.BEGINNING, Map.of()));
+        new ConsumerPosition(SeekType.BEGINNING, Map.of(), SeekDirection.FORWARD));
     seek.assignAndSeek(consumer);
     assertThat(consumer.assignment()).containsExactlyInAnyOrder(tp0, tp1, tp2, tp3);
     assertThat(consumer.position(tp0)).isZero();
@@ -75,10 +100,31 @@ class OffsetsSeekTest {
   }
 
   @Test
-  void seekToOffset() {
-    var seek = new ConsumingService.OffsetsSeek(
+  void backwardSeekToBeginningWithPartitionsList() {
+    var seek = new OffsetsSeekBackward(
         topic,
-        new ConsumerPosition(SeekType.OFFSET, Map.of(0, 0L, 1, 1L, 2, 2L)));
+        new ConsumerPosition(SeekType.BEGINNING, Map.of(), SeekDirection.BACKWARD),
+        10
+    );
+    seek.assignAndSeek(consumer);
+    assertThat(consumer.assignment()).containsExactlyInAnyOrder(tp0, tp1, tp2, tp3);
+    assertThat(consumer.position(tp0)).isZero();
+    assertThat(consumer.position(tp1)).isEqualTo(10L);
+    assertThat(consumer.position(tp2)).isEqualTo(15L);
+    assertThat(consumer.position(tp3)).isEqualTo(25L);
+  }
+
+
+  @Test
+  void forwardSeekToOffset() {
+    var seek = new OffsetsSeekForward(
+        topic,
+        new ConsumerPosition(
+            SeekType.OFFSET,
+            Map.of(0, 0L, 1, 1L, 2, 2L),
+            SeekDirection.FORWARD
+        )
+    );
     seek.assignAndSeek(consumer);
     assertThat(consumer.assignment()).containsExactlyInAnyOrder(tp0, tp1, tp2);
     assertThat(consumer.position(tp0)).isZero();
@@ -86,15 +132,34 @@ class OffsetsSeekTest {
     assertThat(consumer.position(tp2)).isEqualTo(2L);
   }
 
+  @Test
+  void backwardSeekToOffset() {
+    var seek = new OffsetsSeekBackward(
+        topic,
+        new ConsumerPosition(
+            SeekType.OFFSET,
+            Map.of(0, 0L, 1, 1L, 2, 2L),
+            SeekDirection.FORWARD
+        ),
+        2
+    );
+    seek.assignAndSeek(consumer);
+    assertThat(consumer.assignment()).containsExactlyInAnyOrder(tp0, tp1, tp2);
+    assertThat(consumer.position(tp0)).isZero();
+    assertThat(consumer.position(tp1)).isEqualTo(1L);
+    assertThat(consumer.position(tp2)).isEqualTo(0L);
+  }
+
+
   @Nested
   class WaitingOffsetsTest {
 
-    ConsumingService.OffsetsSeek.WaitingOffsets offsets;
+    OffsetsSeekForward.WaitingOffsets offsets;
 
     @BeforeEach
     void assignAndCreateOffsets() {
       consumer.assign(List.of(tp0, tp1, tp2, tp3));
-      offsets = new ConsumingService.OffsetsSeek.WaitingOffsets(topic, consumer);
+      offsets = new OffsetsSeek.WaitingOffsets(topic, consumer);
     }
 
     @Test

kafka-ui-contract/src/main/resources/swagger/kafka-ui-api.yaml

@@ -323,6 +323,10 @@ paths:
           in: query
           schema:
             type: string
+        - name: seekDirection
+          in: query
+          schema:
+            $ref: "#/components/schemas/SeekDirection"
       responses:
         200:
           description: OK
@@ -1448,6 +1452,13 @@ components:
         - OFFSET
         - TIMESTAMP
 
+    SeekDirection:
+      type: string
+      enum:
+        - FORWARD
+        - BACKWARD
+      default: FORWARD
+
     Partition:
       type: object
       properties: