Example usage for com.google.common.collect MinMaxPriorityQueue iterator

Introduction

In this page you can find the example usage for com.google.common.collect MinMaxPriorityQueue iterator.

Prototype

@Override
public Iterator<E> iterator() 

Source Link

Document

Returns an iterator over the elements contained in this collection, in no particular order.

Usage

From source file:com.linkedin.pinot.tools.StarTreeIndexViewer.java

private int build(StarTreeIndexNodeInterf indexNode, StarTreeJsonNode json) {
    Iterator<? extends StarTreeIndexNodeInterf> childrenIterator = indexNode.getChildrenIterator();
    if (!childrenIterator.hasNext()) {
        return 0;
    }//from   w  ww .j  ava  2 s.c om
    int childDimensionId = indexNode.getChildDimensionName();
    String childDimensionName = dimensionNameToIndexMap.inverse().get(childDimensionId);
    Dictionary dictionary = dictionaries.get(childDimensionName);
    int totalChildNodes = indexNode.getNumChildren();

    Comparator<Pair<String, Integer>> comparator = new Comparator<Pair<String, Integer>>() {

        @Override
        public int compare(Pair<String, Integer> o1, Pair<String, Integer> o2) {
            return -1 * Integer.compare(o1.getRight(), o2.getRight());
        }
    };
    MinMaxPriorityQueue<Pair<String, Integer>> queue = MinMaxPriorityQueue.orderedBy(comparator)
            .maximumSize(MAX_CHILDREN).create();
    StarTreeJsonNode allNode = null;

    while (childrenIterator.hasNext()) {
        StarTreeIndexNodeInterf childIndexNode = childrenIterator.next();
        int childDimensionValueId = childIndexNode.getDimensionValue();
        String childDimensionValue = "ALL";
        if (childDimensionValueId != StarTreeIndexNodeInterf.ALL) {
            childDimensionValue = dictionary.get(childDimensionValueId).toString();
        }
        StarTreeJsonNode childJson = new StarTreeJsonNode(childDimensionValue);
        totalChildNodes += build(childIndexNode, childJson);
        if (childDimensionValueId != StarTreeIndexNodeInterf.ALL) {
            json.addChild(childJson);
            queue.add(ImmutablePair.of(childDimensionValue, totalChildNodes));
        } else {
            allNode = childJson;
        }
    }
    //put ALL node at the end
    if (allNode != null) {
        json.addChild(allNode);
    }
    if (totalChildNodes > MAX_CHILDREN) {
        Iterator<Pair<String, Integer>> qIterator = queue.iterator();
        Set<String> topKDimensions = new HashSet<>();
        topKDimensions.add("ALL");
        while (qIterator.hasNext()) {
            topKDimensions.add(qIterator.next().getKey());
        }
        Iterator<StarTreeJsonNode> iterator = json.getChildren().iterator();
        while (iterator.hasNext()) {
            StarTreeJsonNode next = iterator.next();
            if (!topKDimensions.contains(next.getName())) {
                iterator.remove();
            }
        }
    }
    return totalChildNodes;
}

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