Class SortBuffer


  • class SortBuffer
    extends java.lang.Object
    This class implements an in-memory ordered set based on the balanced binary tree algorithm from Knuth Vol. 3, Sec. 6.2.3, pp. 451-471. Nodes are always maintained in order, so that inserts and deletes can be intermixed.

    This algorithm will insert/delete N elements in O(N log(N)) time using O(N) space.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private NodeAllocator allocator
      Where to allocate nodes from.
      private DataValueDescriptor[] deletedKey
      Set, as a side effect of deleteLeftMost (only), to the key from the node that was deleted from the tree.
      private Node head
      Special head node for the tree.
      private int height
      The current height of the tree.
      static int INSERT_DUPLICATE
      Returned from insert when the row which was inserted was a duplicate.
      static int INSERT_FULL
      Returned from insert when the row was not able to be inserted because the set was full.
      static int INSERT_OK
      Returned from insert when the row was inserted without incident.
      private int lastAux
      Read by the getLastAux() method.
      private int nextAux
      Set by the setNextAux() method.
      private MergeSort sort
      The sort this set is associated with.
      private boolean subtreeShrunk
      Set, as a side effect of deleteLeftMost and rotateRight, if the subtree they're working on decreased in height.
    • Constructor Summary

      Constructors 
      Constructor Description
      SortBuffer​(MergeSort sort)
      Construct doesn't do anything, callers must call init and check its return code.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      (package private) int capacity()
      Return the number of elements this sorter can sort.
      void check()  
      private java.lang.String checkNode​(Node n)  
      (package private) void close()  
      private void debug​(java.lang.String s)  
      private Node deleteLeftmost​(Node thisNode)
      Delete the node with the lowest key from the subtree defined by 'thisNode', maintaining balance in the subtree.
      private int depth​(Node n)  
      (package private) int getLastAux()
      Retrieve the aux value from the last node deallocated from the tree.
      (package private) void grow​(int percent)
      Grow by a certain percent if we can
      (package private) boolean init()
      Initialize.
      (package private) int insert​(DataValueDescriptor[] k)
      Insert a key k into the tree.
      void print()  
      private void printRecursive​(Node n, int depth)  
      (package private) DataValueDescriptor[] removeFirst()
      Return the lowest key and delete it from the tree, preserving the balance of the tree.
      (package private) void reset()  
      private Node rotateRight​(Node thisNode)
      Perform either a single or double rotation, as appropriate, to get the subtree 'thisNode' back in balance, assuming that the right subtree of 'thisNode' is higher than the left subtree.
      (package private) void setNextAux​(int aux)
      Arrange that the next node allocated in the tree have it's aux field set to the argument.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • INSERT_OK

        public static final int INSERT_OK
        Returned from insert when the row was inserted without incident.
        See Also:
        Constant Field Values
      • INSERT_DUPLICATE

        public static final int INSERT_DUPLICATE
        Returned from insert when the row which was inserted was a duplicate. The set will have aggregated it in.
        See Also:
        Constant Field Values
      • INSERT_FULL

        public static final int INSERT_FULL
        Returned from insert when the row was not able to be inserted because the set was full.
        See Also:
        Constant Field Values
      • sort

        private MergeSort sort
        The sort this set is associated with.
      • allocator

        private NodeAllocator allocator
        Where to allocate nodes from.
      • head

        private Node head
        Special head node for the tree. Head.rightLink is the root of the tree.
      • height

        private int height
        The current height of the tree.
      • deletedKey

        private DataValueDescriptor[] deletedKey
        Set, as a side effect of deleteLeftMost (only), to the key from the node that was deleted from the tree. This field is only valid after a call to deleteLeftMost.
      • subtreeShrunk

        private boolean subtreeShrunk
        Set, as a side effect of deleteLeftMost and rotateRight, if the subtree they're working on decreased in height. This field is only valid after a call to deleteLeftMost or rotateRight.
      • nextAux

        private int nextAux
        Set by the setNextAux() method. This value is stuffed into the aux field of the next node that's allocated.
      • lastAux

        private int lastAux
        Read by the getLastAux() method. This value is read out of the last node that was deallocated from the tree.
    • Constructor Detail

      • SortBuffer

        SortBuffer​(MergeSort sort)
        Construct doesn't do anything, callers must call init and check its return code.
    • Method Detail

      • setNextAux

        void setNextAux​(int aux)
        Arrange that the next node allocated in the tree have it's aux field set to the argument.
      • getLastAux

        int getLastAux()
        Retrieve the aux value from the last node deallocated from the tree.
      • init

        boolean init()
        Initialize. Returns false if the allocator couldn't be initialized.
      • reset

        void reset()
      • close

        void close()
      • grow

        void grow​(int percent)
        Grow by a certain percent if we can
      • capacity

        int capacity()
        Return the number of elements this sorter can sort. It's the capacity of the node allocator minus one because the sorter uses one node for the head.
      • insert

        int insert​(DataValueDescriptor[] k)
            throws StandardException
        Insert a key k into the tree. Returns true if the key was inserted, false if the tree is full. Silently ignores duplicate keys.

        See Knuth Vol. 3, Sec. 6.2.3, pp. 455-457 for the algorithm.

        Throws:
        StandardException
      • removeFirst

        DataValueDescriptor[] removeFirst()
        Return the lowest key and delete it from the tree, preserving the balance of the tree.
      • deleteLeftmost

        private Node deleteLeftmost​(Node thisNode)
        Delete the node with the lowest key from the subtree defined by 'thisNode', maintaining balance in the subtree. Returns the node that should be the new root of the subtree. This method sets this.subtreeShrunk if the subtree of thisNode decreased in height. Saves the key that was in the deleted node in 'deletedKey'.
      • rotateRight

        private Node rotateRight​(Node thisNode)
        Perform either a single or double rotation, as appropriate, to get the subtree 'thisNode' back in balance, assuming that the right subtree of 'thisNode' is higher than the left subtree. Returns the node that should be the new root of the subtree.

        These are the cases depicted in diagrams (1) and (2) of Knuth (p. 454), and the node names reflect these diagrams. However, in deletion, the single rotation may encounter a case where the "beta" and "gamma" subtrees are the same height (b.balance == 0), so the resulting does not always shrink.

        Note: This code will not do the "mirror image" cases. It only works when the right subtree is the higher one (this is the only case encountered when deleting leftmost nodes from the tree).

      • check

        public void check()
      • checkNode

        private java.lang.String checkNode​(Node n)
      • depth

        private int depth​(Node n)
      • print

        public void print()
      • printRecursive

        private void printRecursive​(Node n,
                                    int depth)
      • debug

        private void debug​(java.lang.String s)