通过拓扑排序检测循环依赖

检测异步任务编排中的循环依赖

拓扑排序：

/**
     * 时间复杂度O(n+k)
     * 检测是否有向无环图 true为无环，false为有环
     * 1.建立入度表Map<Task,Integer>，入度为0的入队
     * 2.队列不为空，任务出队，将该任务相邻任务入度-1
     * 3.若入度为0，则加入队列
     * 4.全部执行完后，任务count为map大小，则无循环依赖，否则有循环依赖
     */
private void isDAGraph(Map<String, Set<String>> map) {
        if (map.isEmpty()) {
            return;
        }
        Map<String, Integer> inDegree = new HashMap<>();
        map.forEach((k, v) -> inDegree.
                computeIfAbsent(k, i -> v.size()));
        Queue<String> queue = new LinkedList<>();
        for (String key : inDegree.keySet()) {
            if (inDegree.get(key).equals(0)) {
                queue.offer(key);
            }
        }

        int count = 0;

        while (!queue.isEmpty()) {
            String task = queue.poll();
            count++;
            for (String key : map.keySet()) {
                if (map.get(key).contains(task)) {
                    inDegree.put(key, inDegree.get(key) - 1);
                    if (inDegree.get(key).equals(0)) {
                        queue.offer(key);
                    }
                }
            }
        }
        if (map.size() == count) {
            return;
        }
        throw new RuntimeException(" is not DAGraph");
    }