Package org.apache.jackrabbit.oak.segment

Interface Revisions

All Known Implementing Classes:
MemoryStoreRevisions, ReadOnlyRevisions, TarRevisions
public interface Revisions
Revisions instances provide read and write access to the current head state. Implementations are thread safe and all setters act atomically.

This is a low level API and it is the callers and implementors responsibility to ensure all record id passed to or returned from methods of this interface are the ids of node states.

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Interface
    Description
    static interface 
    Revisions.Option
    Implementation specific options for the setHead methods.

  • Method Summary

    Modifier and Type
    Method
    Description
    @NotNull RecordId
    getHead()
    Returns the record id of the head state.
    @NotNull RecordId
    getPersistedHead()
    Returns the persisted to disk record id of the head state.
    RecordId
    setHead(@NotNull Function<RecordId,RecordId> newHead, @NotNull Revisions.Option... options)
    Atomically set the record id of the current head state to the value returned from the newHead function when called with the record id of the current head.
    boolean
    setHead(@NotNull RecordId expected, @NotNull RecordId head, @NotNull Revisions.Option... options)
    Atomically set the record id of the current head state to the given head state if the current head state matches the expected value.

  • Method Details

    • getHead

      @NotNull @NotNull RecordId getHead()
      Returns the record id of the head state. The returned id is a valid id for a SegmentNodeState.
      Returns:
      id of the head state

    • getPersistedHead

      @NotNull @NotNull RecordId getPersistedHead()
      Returns the persisted to disk record id of the head state. The returned id is a valid id for a SegmentNodeState.
      Returns:
      id of the head state

    • setHead

      boolean setHead(@NotNull @NotNull RecordId expected, @NotNull @NotNull RecordId head, @NotNull @NotNull Revisions.Option... options)
      Atomically set the record id of the current head state to the given head state if the current head state matches the expected value.

      All record ids must be valid ids for SegmentNodeStates.

      The locking behaviour of this method regarding implementation specific.

      Parameters:
      expected - the expected head for the update to take place
      head - the new head to update to
      options - implementation specific options
      Returns:
      true if the current head was successfully updated, false otherwise.

    • setHead

      RecordId setHead(@NotNull @NotNull Function<RecordId,RecordId> newHead, @NotNull @NotNull Revisions.Option... options) throws InterruptedException
      Atomically set the record id of the current head state to the value returned from the newHead function when called with the record id of the current head.

      All record ids must be valid ids for SegmentNodeStates.

      The behaviour of this method regarding locking and handling null values returned by newHead is implementation specific.

      Parameters:
      newHead - function mapping an record id to the record id to which the current head id should be set.
      options - implementation specific options
      Returns:
      the record id of the root node if the current head was successfully updated, null otherwise.
      Throws:
      InterruptedException - Blocking implementations may throw this exception whe interrupted.