Package org.apache.activemq.store.kahadb

Interface KahaDBMetaData<T>

All Known Implementing Classes:
AbstractKahaDBMetaData, JobSchedulerKahaDBMetaData
public interface KahaDBMetaData<T>
Interface for the store meta data used to hold the index value and other needed information to manage a KahaDB store instance.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    CLOSED_STATE
    Indicates that this meta data instance has been closed and is no longer active.
    static final int
    OPEN_STATE
    Indicates that this meta data instance has been opened and is active.

  • Method Summary

    Modifier and Type
    Method
    Description
    Location
    getLastUpdateLocation()
    Returns the Journal Location value that indicates that last recorded update that was successfully performed for this KahaDB store implementation.
    Page<T>
    getPage()
    Gets the Page in the store PageFile where the KahaDBMetaData instance is stored.
    int
    getState()
    Gets the state flag of this meta data instance.
    void
    initialize(Transaction tx)
    For a newly created KahaDBMetaData instance this method is called to allow the instance to create all of it's internal indices and other state data.
    void
    load(Transaction tx)
    Instructs this object to load its internal data structures from the KahaDB PageFile and prepare itself for use.
    void
    read(DataInput in)
    Reads the serialized for of this object from the KadaDB PageFile and prepares it for use.
    void
    setLastUpdateLocation(Location location)
    Updates the value of the last successful update.
    void
    setPage(Page<T> page)
    Sets the Page instance used to load and store the KahaDBMetaData instance.
    void
    setState(int value)
    Sets the current value of the state flag.
    void
    write(DataOutput out)
    Writes the object into a serialized form which can be read back in again using the read method.

  • Field Details

    • OPEN_STATE

      static final int OPEN_STATE
      Indicates that this meta data instance has been opened and is active.
      See Also:

    • CLOSED_STATE

      static final int CLOSED_STATE
      Indicates that this meta data instance has been closed and is no longer active.
      See Also:

  • Method Details

    • getPage

      Page<T> getPage()
      Gets the Page in the store PageFile where the KahaDBMetaData instance is stored.
      Returns:
      the Page to use to start access the KahaDBMetaData instance.

    • setPage

      void setPage(Page<T> page)
      Sets the Page instance used to load and store the KahaDBMetaData instance.
      Parameters:
      page - the new Page value to use.

    • getState

      int getState()
      Gets the state flag of this meta data instance.
      Returns:
      the current state value for this instance.

    • setState

      void setState(int value)
      Sets the current value of the state flag.
      Parameters:
      value - the new value to assign to the state flag.

    • getLastUpdateLocation

      Location getLastUpdateLocation()
      Returns the Journal Location value that indicates that last recorded update that was successfully performed for this KahaDB store implementation.
      Returns:
      the location of the last successful update location.

    • setLastUpdateLocation

      void setLastUpdateLocation(Location location)
      Updates the value of the last successful update.
      Parameters:
      location - the new value to assign the last update location field.

    • initialize

      void initialize(Transaction tx) throws IOException
      For a newly created KahaDBMetaData instance this method is called to allow the instance to create all of it's internal indices and other state data.
      Parameters:
      tx - the Transaction instance under which the operation is executed.
      Throws:
      IOException - if an error occurs while creating the meta data structures.

    • load

      void load(Transaction tx) throws IOException
      Instructs this object to load its internal data structures from the KahaDB PageFile and prepare itself for use.
      Parameters:
      tx - the Transaction instance under which the operation is executed.
      Throws:
      IOException - if an error occurs while creating the meta data structures.

    • read

      void read(DataInput in) throws IOException
      Reads the serialized for of this object from the KadaDB PageFile and prepares it for use. This method does not need to perform a full load of the meta data structures only read in the information necessary to load them from the PageFile on a call to the load method.
      Parameters:
      in - the DataInput instance used to read this objects serialized form.
      Throws:
      IOException - if an error occurs while reading the serialized form.

    • write

      void write(DataOutput out) throws IOException
      Writes the object into a serialized form which can be read back in again using the read method.
      Parameters:
      out - the DataOutput instance to use to write the current state to a serialized form.
      Throws:
      IOException - if an error occurs while serializing this instance.