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如何在hashmap字段中保存对处理程序的引用

mio borrow-checker rust

Sergey · 技术社区 · 8 年前

我正在学习Rust并尝试编写一个websocket服务器。逻辑如下:WSConnectionFactory创建WSHandler,用于处理传入消息并根据任意规则将其发送给其他客户端。问题是我不知道如何实现这种行为。

限制:我无法更改Factory和Handler特性的签名,因为它们由 ws-rs 图书馆

问题:如何使用RefCell/Cell实现这一点?

extern crate rand;
extern crate rustc_serialize;
extern crate ws;
#[macro_use]
extern crate log;
#[macro_use]
extern crate env_logger;

use std::cell::RefCell;
use std::collections::HashMap;
use rand::random;
use ws::{Factory, Sender, Handler, Handshake, Message, CloseCode, WebSocket};
use ws::Result as WSResult;
use ws::util::Token;

struct WSConnectionFactory<'p> {
    handlers: HashMap<&'p u32, RefCell<&'p WSHandler<'p>>>,
}

#[derive(Debug)]
struct WSHandler<'h> {
    uid: &'h u32,
    ws: RefCell<&'h Sender>,
}

impl<'p> Factory for WSConnectionFactory<'p> {
    type Handler = WSHandler<'p>;

    fn connection_made(&mut self, ws: Sender) -> Self::Handler {
        println!("factory.connection_made token={:?}", &ws.token());
        let uid = &random::<u32>();
        let handler = WSHandler {
            uid: uid,
            ws: RefCell::new(&ws),
        };
        self.handlers.insert(uid, RefCell::new(&handler));
        handler
    }
}

impl<'h> Handler for WSHandler<'h> {
    fn on_open(&mut self, _handshake: Handshake) -> WSResult<()> {
        println!("handler.on_open");
        Ok(())
    }
    fn on_message(&mut self, msg: Message) -> WSResult<()> {
        println!("handler.on_message {:?}", msg);
        Ok(())
    }
    fn on_timeout(&mut self, _token: Token) -> WSResult<()> {
        println!("handler.on_timeout {:?}", _token);
        Ok(())
    }
    fn on_close(&mut self, code: CloseCode, reason: &str) {
        println!("handler.on_close code={:?}, reason={:?}", code, reason);
    }
}

fn main() {
    let factory = WSConnectionFactory { handlers: HashMap::new() };
    let ws_socket = WebSocket::new(factory).expect("Can't create WebSocket");
    ws_socket.listen("127.0.0.1:8080").expect("Can't bind to socket");
}

1 回复 | 直到 8 年前

Francis Gagné 8 年前

您正在尝试返回 WSHandler 从…起 connection_made 同时还存储对 WS处理程序 在 WSConnectionFactory 结构。这是不可能的(使用借用的指针),因为通过返回 WS处理程序 ,您无法控制它将发生什么(它可能被移动或删除,这将使指针无效)。当您应该直接存储值时,您也在存储借用的指针。

WSConnectionFactory(WS连接工厂) 创建 WS处理程序 它处理传入消息并根据任意规则将其发送给其他客户端。

如果您想向其他客户端发送消息,实际上需要 Sender ,不是 WS处理程序 谢天谢地 发件人 机具 Clone ,通过快速查看代码,克隆 发件人 应该为同一端点提供第二个“句柄”。因此,您应该将 发件人 在您的 HashMap ,不是 WS处理程序 .

extern crate rand;
extern crate rustc_serialize;
extern crate ws;
#[macro_use]
extern crate log;
#[macro_use]
extern crate env_logger;

use std::collections::HashMap;
use rand::random;
use ws::{Factory, Sender, Handler, Handshake, Message, CloseCode, WebSocket};
use ws::Result as WSResult;
use ws::util::Token;

struct WSConnectionFactory {
    handlers: HashMap<u32, Sender>,
}

#[derive(Debug)]
struct WSHandler {
    uid: u32,
    ws: Sender,
}

impl Factory for WSConnectionFactory {
    type Handler = WSHandler;

    fn connection_made(&mut self, ws: Sender) -> Self::Handler {
        println!("factory.connection_made token={:?}", &ws.token());
        let uid = random::<u32>();
        let handler = WSHandler {
            uid: uid,
            ws: ws.clone(),
        };
        self.handlers.insert(uid, ws);
        handler
    }
}

impl Handler for WSHandler {
    fn on_open(&mut self, _handshake: Handshake) -> WSResult<()> {
        println!("handler.on_open");
        Ok(())
    }
    fn on_message(&mut self, msg: Message) -> WSResult<()> {
        println!("handler.on_message {:?}", msg);
        Ok(())
    }
    fn on_timeout(&mut self, _token: Token) -> WSResult<()> {
        println!("handler.on_timeout {:?}", _token);
        Ok(())
    }
    fn on_close(&mut self, code: CloseCode, reason: &str) {
        println!("handler.on_close code={:?}, reason={:?}", code, reason);
    }
}

fn main() {
    let factory = WSConnectionFactory { handlers: HashMap::new() };
    let ws_socket = WebSocket::new(factory).expect("Can't create WebSocket");
    ws_socket.listen("127.0.0.1:8080").expect("Can't bind to socket");
}