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 Detail

      • 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.