return isSuccessorOf(new HashSet<>(), step);
    }

    private boolean isSuccessorOf(Set<BuildStep> visited, BuildStep step) {
        if (this == step) {
            return true;
        } else if (visited.add(this)) {
            return this.predecessors.stream().anyMatch(n -> n.isSuccessorOf(visited, step));
        } else {
            return false;
        }
    }

    public void skip() {

    }

    public void analyzePom(Model model) {
        totalPoms++;
        Set<Object> visited = new HashSet<>();
        processModelNode(model, "/project", "project", visited);
    }

    private void processModelNode(Object node, String currentPath, String elementName, Set<Object> visited) {
        if (node == null || !visited.add(node)) {
            return;
        }

        Class<?> clazz = node.getClass();

     *
     * @param sessionId The session ID.
     */
    void saveSession(String sessionId);

    /**
     * Checks if a URL has been visited.
     *
     * @param urlQueue The URL queue.
     * @return true if the URL has been visited, otherwise false.
     */
    boolean visited(QUEUE urlQueue);

    /**
     * Generates URL queues.
     *
     * @param previousSessionId The previous session ID.

import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

class Graph {
    private enum DfsState {
        VISITING,
        VISITED
    }

    final Map<String, Vertex> vertices = new LinkedHashMap<>();

    public Vertex getVertex(String id) {
        return vertices.get(id);
    }

    public Collection<Vertex> getVertices() {

import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

class Graph {
    private enum DfsState {
        VISITING,
        VISITED
    }

    final Map<String, Vertex> vertices = new LinkedHashMap<>();

    public Vertex getVertex(String id) {
        return vertices.get(id);
    }

    public Collection<Vertex> getVertices() {

    limiter.acquire(Integer.MAX_VALUE / 4);
    limiter.acquire(Integer.MAX_VALUE / 2);
    limiter.acquire(Integer.MAX_VALUE);
    assertEvents("R0.00", "R0.00", "R0.00");

    limiter.setRate(1.0);
    limiter.acquire();
    limiter.acquire();
    limiter.acquire();
    assertEvents("R0.00", "R1.00", "R1.00");

    limiter.acquire(Integer.MAX_VALUE / 4);
    limiter.acquire(Integer.MAX_VALUE / 2);
    limiter.acquire(Integer.MAX_VALUE);
    assertEvents("R0.00", "R0.00", "R0.00");

    limiter.setRate(1.0);
    limiter.acquire();
    limiter.acquire();
    limiter.acquire();
    assertEvents("R0.00", "R1.00", "R1.00");

    private void nonEmptyPredecessors(BuildStep step, Set<BuildStep> preds, Set<BuildStep> visited) {
        if (visited.add(step)) {
            step.predecessors.forEach(ch -> {
                if (ch.executions().findAny().isPresent()) {
                    preds.add(ch);
                } else {
                    nonEmptyPredecessors(ch, preds, visited);
                }
            });
        }
    }

                        "Edge between '" + from + "' and '" + to + "' introduces to cycle in the graph", cycle);
            }
        }
    }

    private enum DfsState {
        VISITING,
        VISITED
    }

    private static List<String> visitCycle(
            Map<String, Set<String>> graph,
            Collection<String> children,
            Map<String, DfsState> stateMap,

    public void saveSession(final String sessionId) {
        // NOP
    }

    /*
     * (non-Javadoc)
     *
     * @see org.codelibs.fess.crawler.service.UrlQueueService#visited(UrlQueue)
     */
    @Override
    public boolean visited(final UrlQueueImpl<Long> urlQueue) {
        final Queue<UrlQueueImpl<Long>> urlQueueList = dataHelper.getUrlQueueList(urlQueue.getSessionId());
        synchronized (urlQueueList) {