Examples of org.neo4j.collections.list.UnrolledLinkedList

org.neo4j.collections.list.UnrolledLinkedList
Implementation of an UnrolledLinkedList for storage of nodes. This collection is primarily for use within an {@link org.neo4j.collections.indexedrelationship.IndexedRelationship}. The benefits of the UnrolledLinkedList is that it has very good performance in cases where items are added at the head of the list, and items are generally read from the head in the order they are added.
The structure is broken into "pages" of links to nodes where the size of the page can be controlled at initial construction time. Page size is not fixed but instead can float between a lower bound, and an upper bound. The bounds are at a fixed margin from the page size of M. When a page drops below the lower bound it will be joined onto the an adjacent page, and when the page goes above the upper bound it will be split in half. IMPORTANT NOTE: the margin must be greater than a third of the page size in order to stop a page being split, then both pages being lower than the lower bound, the default margin is 1/2 page size.
The exception to the bounds is the head page which can contain less than the lower bound. A new head page is created when adding a new node to the current head would put it above the page size, and instead a new head will be created that has a single node in it.
There is a trade off between page size and number of page to page relationships need to be followed. As nodes are not stored sorted within the page they must all be read in and compared using the comparator in order to iterate over them in order. However any given node within P(X) will be in order compared to any given node within P(X+1).
A perfect example would be an inbox where content is added sorted by date and always added in increasing date order. Then the content is read out from most recent backwards in time and generally only the first page of content is retrieved.
This data structure is not as good as a sorted tree when content is added randomly against the given order, or where the items have their position within the list change based on data changes.


    @Test
    public void testIndexRelationshipAttributes()
    {
        Node indexedNode = graphDb().createNode();
        UnrolledLinkedList ull = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir = new IndexedRelationship( indexedNode, RelTypes.INDEXED_RELATIONSHIP,
            Direction.OUTGOING, ull );


        Node node1 = graphDb().createNode();
        node1.setProperty( "name", "node 1" );

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    @Test
    public void testIndexRelationshipAttributesFromDestination()
    {
        Node indexedNode = graphDb().createNode();
        UnrolledLinkedList ull1 = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir = new IndexedRelationship( indexedNode, RelTypes.INDEXED_RELATIONSHIP,
            Direction.OUTGOING, ull1 );


        Node indexedNode2 = graphDb().createNode();
        UnrolledLinkedList ull2 = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir2 = new IndexedRelationship( indexedNode2, RelTypes.INDEXED_RELATIONSHIP,
            Direction.OUTGOING, ull2 );


        Node destination = graphDb().createNode();
        destination.setProperty( "name", "node 1" );

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    @Test
    public void testIndexRelationshipBasic()
    {
        Node indexedNode = graphDb().createNode();
        UnrolledLinkedList ull = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir = new IndexedRelationship( indexedNode, RelTypes.INDEXED_RELATIONSHIP,
            Direction.OUTGOING, ull );


        Node n1 = graphDb().createNode();
        n1.setProperty( "name", "n1" );

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    @Test
    public void testIndexRelationshipIncoming()
    {
        Node indexedNode = graphDb().createNode();
        UnrolledLinkedList ull = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir = new IndexedRelationship( indexedNode, RelTypes.INDEXED_RELATIONSHIP,
            Direction.INCOMING, ull );


        Node n1 = graphDb().createNode();
        n1.setProperty( "name", "n1" );

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    @Test
    public void testTwoIndexRelationshipsOnSingleNode()
    {
        Node indexedNode = graphDb().createNode();
        UnrolledLinkedList ull1 = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir = new IndexedRelationship( indexedNode, RelTypes.INDEXED_RELATIONSHIP,
            Direction.OUTGOING, ull1 );


        UnrolledLinkedList ull2 = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir2 = new IndexedRelationship( indexedNode, RelTypes.INDEXED_RELATIONSHIP_TWO,
            Direction.OUTGOING, ull2 );


        Node n1 = graphDb().createNode();
        n1.setProperty( "name", "n1" );

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    @Test
    public void testTwoIndexRelationshipsToSingleDestination()
    {
        Node indexedNode = graphDb().createNode();
        UnrolledLinkedList ull1 = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir = new IndexedRelationship( indexedNode, RelTypes.INDEXED_RELATIONSHIP,
            Direction.OUTGOING, ull1 );


        Node indexedNode2 = graphDb().createNode();
        UnrolledLinkedList ull2 = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir2 = new IndexedRelationship( indexedNode2, RelTypes.INDEXED_RELATIONSHIP,
            Direction.OUTGOING, ull2 );


        Node destination = graphDb().createNode();
        destination.setProperty( "name", "n1" );

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    @Test
    public void testIncomingAndOutgoingIndexRelationships()
    {
        Node indexedNode = graphDb().createNode();
        UnrolledLinkedList ull1 = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir = new IndexedRelationship( indexedNode, RelTypes.INDEXED_RELATIONSHIP,
            Direction.OUTGOING, ull1 );


        Node indexedNode2 = graphDb().createNode();
        UnrolledLinkedList ull2 = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir2 = new IndexedRelationship( indexedNode2, RelTypes.INDEXED_RELATIONSHIP,
            Direction.INCOMING, ull2 );


        Node leafEnd = graphDb().createNode();
        leafEnd.setProperty( "name", "n1" );

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    @Test
    public void testIndexedRelationshipExpanderAtDestination()
    {
        Node indexedNode = graphDb().createNode();
        Node nonIndexedNode = graphDb().createNode();
        UnrolledLinkedList ull = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir = new IndexedRelationship( indexedNode, RelTypes.INDEXED_RELATIONSHIP,
            Direction.OUTGOING, ull );


        Node n1 = graphDb().createNode();
        ir.createRelationshipTo( n1 );

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    @Test
    public void testIndexedRelationshipExpanderMultiplePage()
    {
        Node indexedNode = graphDb().createNode();
        Node nonIndexedNode = graphDb().createNode();
        UnrolledLinkedList ull = new UnrolledLinkedList( graphDb(), new IdComparator(), 4 );
        IndexedRelationship ir = new IndexedRelationship( indexedNode, RelTypes.INDEXED_RELATIONSHIP,
            Direction.OUTGOING, ull );


        ArrayList<Node> nodes = createNodes( 20 );
        for ( Node node : nodes )

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org.neo4j.collections.indexedrelationship.TestUnrolledLinkedListIndexedRelationship

org.neo4j.collections.indexedrelationship.TestUnrolledLinkedListRelationshipProperties

org.neo4j.kernel.GraphDatabaseAPI

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