org.apache.storm.kafka.spout.internal

## Class OffsetManager

- java.lang.Object
- - org.apache.storm.kafka.spout.internal.OffsetManager

-     public class OffsetManager
      extends Object

  Manages acked and committed offsets for a TopicPartition. This class is not thread safe

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `OffsetManager(org.apache.kafka.common.TopicPartition tp, long initialFetchOffset)` Creates a new OffsetManager.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `addToAckMsgs(KafkaSpoutMessageId msgId)`
    `void` | `addToEmitMsgs(long offset)`
    `long` | `commit(org.apache.kafka.clients.consumer.OffsetAndMetadata committedOffsetAndMeta)` Marks an offset as committed.
    `boolean` | `contains(KafkaSpoutMessageId msgId)`
    `org.apache.kafka.clients.consumer.OffsetAndMetadata` | `findNextCommitOffset(String commitMetadata)` An offset can only be committed when all emitted records with lower offset have been acked.
    `long` | `getCommittedOffset()`
    `long` | `getLatestEmittedOffset()`
    `long` | `getNthUncommittedOffsetAfterCommittedOffset(int index)` Gets the offset of the nth emitted message after the committed offset.
    `int` | `getNumUncommittedOffsets()`
    `boolean` | `hasCommitted()` Checks if this OffsetManager has committed to Kafka.
    `String` | `toString()`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### OffsetManager

          public OffsetManager(org.apache.kafka.common.TopicPartition tp,
                               long initialFetchOffset)

      Creates a new OffsetManager.

      Parameters:
        `tp` - The TopicPartition
        `initialFetchOffset` - The initial fetch offset for the given TopicPartition

  - ### Method Detail

    - #### addToAckMsgs

          public void addToAckMsgs(KafkaSpoutMessageId msgId)

    - #### addToEmitMsgs

          public void addToEmitMsgs(long offset)

    - #### getNumUncommittedOffsets

          public int getNumUncommittedOffsets()

    - #### getNthUncommittedOffsetAfterCommittedOffset

          public long getNthUncommittedOffsetAfterCommittedOffset(int index)

      Gets the offset of the nth emitted message after the committed offset. Example: If the committed offset is 0 and offsets 1, 2, 8, 10 have been emitted, getNthUncommittedOffsetAfterCommittedOffset(3) returns 8.

      Parameters:
        `index` - The index of the message to get the offset for
      Returns:
        The offset
      Throws:
        `NoSuchElementException` - if the index is out of range

    - #### findNextCommitOffset

          public org.apache.kafka.clients.consumer.OffsetAndMetadata findNextCommitOffset(String commitMetadata)

      An offset can only be committed when all emitted records with lower offset have been acked. This guarantees that all offsets smaller than the committedOffset have been delivered, or that those offsets no longer exist in Kafka.

      The returned offset points to the earliest uncommitted offset, and matches the semantics of the KafkaConsumer.commitSync API.
      Parameters:
        `commitMetadata` - Metadata information to commit to Kafka. It is constant per KafkaSpout instance per topology
      Returns:
        the next OffsetAndMetadata to commit, or null if no offset is ready to commit.

    - #### commit

          public long commit(org.apache.kafka.clients.consumer.OffsetAndMetadata committedOffsetAndMeta)

      Marks an offset as committed. This method has side effects - it sets the internal state in such a way that future calls to `findNextCommitOffset(String)` will return offsets greater than or equal to the offset specified, if any.

      Parameters:
        `committedOffsetAndMeta` - The committed offset. All lower offsets are expected to have been committed.
      Returns:
        Number of offsets committed in this commit

    - #### hasCommitted

          public boolean hasCommitted()

      Checks if this OffsetManager has committed to Kafka.

      Returns:
        true if this OffsetManager has made at least one commit to Kafka, false otherwise

    - #### contains

          public boolean contains(KafkaSpoutMessageId msgId)

    - #### getLatestEmittedOffset

          public long getLatestEmittedOffset()

    - #### getCommittedOffset

          public long getCommittedOffset()

    - #### toString

          public final String toString()

      Overrides:
        `toString` in class `Object`

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