private boolean isLegalAddEdge()

in bigtop-manager-server/src/main/java/org/apache/bigtop/manager/server/stack/dag/DAG.java [377:411]

25 lines of code
9 McCabe index (conditional complexity)


    private boolean isLegalAddEdge(Node fromNode, Node toNode, boolean createNode) {
        if (fromNode.equals(toNode)) {
            log.error("edge fromNode({}) can't equals toNode({})", fromNode, toNode);
            return false;
        }

        if (!createNode) {
            if (!containsNode(fromNode) || !containsNode(toNode)) {
                log.error("edge fromNode({}) or toNode({}) is not in vertices map", fromNode, toNode);
                return false;
            }
        }

        // Whether an edge can be successfully added(fromNode -> toNode),need to determine whether the DAG has cycle!
        int verticesCount = getNodesCount();

        Queue<Node> queue = new LinkedList<>();

        queue.add(toNode);

        // if DAG doesn't find fromNode, it's not has cycle!
        while (!queue.isEmpty() && (--verticesCount > 0)) {
            Node key = queue.poll();

            for (Node subsequentNode : getSubsequentNodes(key)) {
                if (subsequentNode.equals(fromNode)) {
                    return false;
                }

                queue.add(subsequentNode);
            }
        }

        return true;
    }