Package org.apache.jena.atlas.data

Class SortedDataBag<E>

  • All Implemented Interfaces:
    java.lang.Iterable<E>, DataBag<E>, org.apache.jena.atlas.lib.Closeable, org.apache.jena.atlas.lib.Sink<E>
    Direct Known Subclasses:
    DistinctDataBag
    public class SortedDataBag<E>
extends AbstractDataBag<E>

    This data bag will gather items in memory until a size threshold is passed, at which point it will write out all of the items to disk using the supplied serializer.

    After adding is finished, call iterator() to set up the data bag for reading back items and iterating over them. The iterator will retrieve the items in sorted order using the supplied comparator.

    IMPORTANT: You may not add any more items after this call. You may subsequently call iterator() multiple times which will give you a new iterator for each invocation. If you do not consume the entire iterator, you should call Iter.close(Iterator) to close any FileInputStreams associated with the iterator.

    Additionally, make sure to call close() when you are finished to free any system resources (preferably in a finally block).

    Implementation Notes: Data is stored in an ArrayList as it comes in. When it is time to spill, that data is sorted and written to disk. An iterator will read in each file and perform a merge-sort as the results are returned.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void add​(E item)
      Add a tuple to the bag.
      void cancel()
      cancel arranges that further comparisons using the supplied comparator will abandon the sort in progress.
      void close()  
      void flush()  
      boolean isCancelled()
      isCancelled is true iff cancel has been called on this bags comparator.
      boolean isClosed()
      isClosed returns true iff this bag has been closed.
      boolean isDistinct()
      Find out if the bag is distinct.
      boolean isSorted()
      Find out if the bag is sorted.
      java.util.Iterator<E> iterator()
      Returns an iterator over a set of elements of type E.

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

      • Methods inherited from interface java.lang.Iterable

        forEach, spliterator

    • Method Detail

      • cancel

        public void cancel()
        cancel arranges that further comparisons using the supplied comparator will abandon the sort in progress.

      • isCancelled

        public boolean isCancelled()
        isCancelled is true iff cancel has been called on this bags comparator. (Used in testing.)

      • isClosed

        public boolean isClosed()
        isClosed returns true iff this bag has been closed. (Used in testing.)

      • isSorted

        public boolean isSorted()
        Description copied from interface: DataBag
        Find out if the bag is sorted.
        Returns:
        true if this is a sorted data bag, false otherwise.

      • isDistinct

        public boolean isDistinct()
        Description copied from interface: DataBag
        Find out if the bag is distinct.
        Returns:
        true if the bag is a distinct bag, false otherwise.

      • add

        public void add​(E item)
        Description copied from interface: DataBag
        Add a tuple to the bag.
        Parameters:
        item - tuple to add.

      • flush

        public void flush()

      • iterator

        public java.util.Iterator<E> iterator()
        Returns an iterator over a set of elements of type E. If you do not exhaust the iterator, you should call Iter.close(Iterator) to be sure any open file handles are closed.
        Returns:
        an Iterator

      • close

        public void close()