Package org.apache.kafka.streams.state

Interface SessionStore<K,AGG>

Type Parameters:
K - type of the record keys
AGG - type of the aggregated values
All Superinterfaces:
ReadOnlySessionStore<K,AGG>, StateStore
public interface SessionStore<K,AGG> extends StateStore, ReadOnlySessionStore<K,AGG>
Interface for storing the aggregated values of sessions.

The key is internally represented as Windowed<K> that comprises the plain key and the Window that represents window start- and end-timestamp.

If two sessions are merged, a new session with new start- and end-timestamp must be inserted into the store while the two old sessions must be deleted.

  • Method Details

    • findSessions

      default KeyValueIterator<Windowed<K>,AGG> findSessions(K key, Instant earliestSessionEndTime, Instant latestSessionStartTime)
      Description copied from interface: ReadOnlySessionStore
      Fetch any sessions with the matching key and the sessions end is ≥ earliestSessionEndTime and the sessions start is ≤ latestSessionStartTime iterating from earliest to latest.

      This iterator must be closed after use.

      Specified by:
      findSessions in interface ReadOnlySessionStore<K,AGG>
      Parameters:
      key - the key to return sessions for
      earliestSessionEndTime - the end timestamp of the earliest session to search for, where iteration starts.
      latestSessionStartTime - the end timestamp of the latest session to search for, where iteration ends.
      Returns:
      iterator of sessions with the matching key and aggregated values, from earliest to latest session time.

    • backwardFindSessions

      default KeyValueIterator<Windowed<K>,AGG> backwardFindSessions(K key, Instant earliestSessionEndTime, Instant latestSessionStartTime)
      Description copied from interface: ReadOnlySessionStore
      Fetch any sessions with the matching key and the sessions end is ≥ earliestSessionEndTime and the sessions start is ≤ latestSessionStartTime iterating from latest to earliest.

      This iterator must be closed after use.

      Specified by:
      backwardFindSessions in interface ReadOnlySessionStore<K,AGG>
      Parameters:
      key - the key to return sessions for
      earliestSessionEndTime - the end timestamp of the earliest session to search for, where iteration ends.
      latestSessionStartTime - the end timestamp of the latest session to search for, where iteration starts.
      Returns:
      backward iterator of sessions with the matching key and aggregated values, from latest to earliest session time.

    • findSessions

      default KeyValueIterator<Windowed<K>,AGG> findSessions(K keyFrom, K keyTo, Instant earliestSessionEndTime, Instant latestSessionStartTime)
      Description copied from interface: ReadOnlySessionStore
      Fetch any sessions in the given range of keys and the sessions end is ≥ earliestSessionEndTime and the sessions start is ≤ latestSessionStartTime iterating from earliest to latest.

      This iterator must be closed after use.

      Specified by:
      findSessions in interface ReadOnlySessionStore<K,AGG>
      Parameters:
      keyFrom - The first key that could be in the range A null value indicates a starting position from the first element in the store.
      keyTo - The last key that could be in the range A null value indicates that the range ends with the last element in the store.
      earliestSessionEndTime - the end timestamp of the earliest session to search for, where iteration starts.
      latestSessionStartTime - the end timestamp of the latest session to search for, where iteration ends.
      Returns:
      iterator of sessions with the matching keys and aggregated values, from earliest to latest session time.

    • backwardFindSessions

      default KeyValueIterator<Windowed<K>,AGG> backwardFindSessions(K keyFrom, K keyTo, Instant earliestSessionEndTime, Instant latestSessionStartTime)
      Description copied from interface: ReadOnlySessionStore
      Fetch any sessions in the given range of keys and the sessions end is ≥ earliestSessionEndTime and the sessions start is ≤ latestSessionStartTime iterating from latest to earliest.

      This iterator must be closed after use.

      Specified by:
      backwardFindSessions in interface ReadOnlySessionStore<K,AGG>
      Parameters:
      keyFrom - The first key that could be in the range A null value indicates a starting position from the first element in the store.
      keyTo - The last key that could be in the range A null value indicates that the range ends with the last element in the store.
      earliestSessionEndTime - the end timestamp of the earliest session to search for, where iteration ends.
      latestSessionStartTime - the end timestamp of the latest session to search for, where iteration starts.
      Returns:
      backward iterator of sessions with the matching keys and aggregated values, from latest to earliest session time.

    • fetchSession

      default AGG fetchSession(K key, Instant earliestSessionEndTime, Instant latestSessionStartTime)
      Description copied from interface: ReadOnlySessionStore
      Get the value of key from a single session.
      Specified by:
      fetchSession in interface ReadOnlySessionStore<K,AGG>
      Parameters:
      key - the key to fetch
      earliestSessionEndTime - start timestamp of the session
      latestSessionStartTime - end timestamp of the session
      Returns:
      The value or null if no session associated with the key can be found

    • remove

      void remove(Windowed<K> sessionKey)
      Remove the session aggregated with provided Windowed key from the store
      Parameters:
      sessionKey - key of the session to remove
      Throws:
      NullPointerException - If null is used for sessionKey.

    • put

      void put(Windowed<K> sessionKey, AGG aggregate)
      Write the aggregated value for the provided key to the store
      Parameters:
      sessionKey - key of the session to write
      aggregate - the aggregated value for the session, it can be null; if the serialized bytes are also null it is interpreted as deletes
      Throws:
      NullPointerException - If null is used for sessionKey.