使用 RefCell 和 Rc 处理循环图中的内存泄漏

Question

我按照https://ricardomartins.cc/2016/06/08/interior-mutability 中提到的方法使用Rc 和RefCell 在Rust 中创建图形。

type NodeRef<i32> = Rc<RefCell<_Node<i32>>>;

#[derive(Clone)]
// The private representation of a node.
struct _Node<i32> {
    inner_value: i32,
    adjacent: Vec<NodeRef<i32>>,
}
#[derive(Clone)]
// The public representation of a node, with some syntactic sugar.
struct Node<i32>(NodeRef<i32>);

impl<i32> Node<i32> {
    // Creates a new node with no edges.
    fn new(inner: i32) -> Node<i32> {
        let node = _Node { inner_value: inner, adjacent: vec![] };
        Node(Rc::new(RefCell::new(node)))
    }

    // Adds a directed edge from this node to other node.
    fn add_adjacent(&self, other: &Node<i32>) {
        (self.0.borrow_mut()).adjacent.push(other.0.clone());
    }
}
#[derive(Clone)]
struct Graph<i32> {
    nodes: Vec<Node<i32>>,
}

impl<i32> Graph<i32> {
    fn with_nodes(nodes: Vec<Node<i32>>) -> Self {
        Graph { nodes: nodes }
    }

}

我认为这种方法在循环图的情况下会导致内存泄漏。我该如何解决？

Answer 1

您无需阅读博文即可找到答案，只需read the documentation：

Rc 指针之间的循环永远不会被释放。出于这个原因，Weak 用于中断循环。例如，一棵树可能具有从父节点到子节点的强 Rc 指针，以及从子节点返回父节点的 Weak 指针。

另见：

• Is there a way to build a structure with cyclic links without runtime overhead?
• Implement graph-like datastructure in Rust
• Recursive Data Structures in Rust