英文:
Adding a values to Mutex in tokio is causing moving error
问题
在我的代码中，我创建了一个类型为 use tokio::sync::Mutex; 的共享向量 shared_vec，如下所示：
let shared_vec: Arc<Mutex<Vec<user::User>>> = Arc::new(Mutex::new(Vec::new()));
我试图在 tokio::spawn 内部获取锁并向列表中添加值，这应该是异步的，但我遇到了以下错误：
value moved here, in previous iteration of loop
here 在 tokio::spawn(async move {... 的末尾。
有人可以告诉我如何解决这个问题吗？以下是我的代码：
use tokio::{io::{AsyncBufReadExt, AsyncWriteExt, BufReader},net::TcpListener,sync::broadcast,};use serde_json::json;use serde_json::Value;use tokio::sync::Mutex;use std::sync::Arc;mod user;#[tokio::main]async fn main() {let listener = TcpListener::bind("localhost:8080").await.unwrap();let (tx, _rx) = broadcast::channel(10);let shared_vec: Arc<Mutex<Vec<user::User>>> = Arc::new(Mutex::new(Vec::new()));loop {let (mut socket, addr) = listener.accept().await.unwrap();let tx = tx.clone();let mut rx = tx.subscribe();tokio::spawn(async move {let (reader, mut writer) = socket.split();let mut reader = BufReader::new(reader);let mut line = String::new();loop {tokio::select! {result = reader.read_line(&mut line) => {if result.unwrap() == 0 {break;}tx.send((line.clone(), addr)).unwrap();line.clear();}result = rx.recv() => {let (msg, other_addr) = result.unwrap();let json_msg: Value = json!(msg);let mut vec = shared_vec.lock().await;let mut indices_to_update = Vec::new();for (index, usr) in vec.iter().enumerate() {if usr.get_ip() != &addr {indices_to_update.push(index);}}for _index in indices_to_update {let user = user::User::new(json_msg["username"].to_string(), addr);vec.push(user);}if addr == other_addr {writer.write_all(msg.as_bytes()).await.unwrap();}}}}});}}
英文:
In my code I'm creating
let shared_vec: Arc<Mutex<Vec<user::User>>> = Arc::new(Mutex::new(Vec::new()));
which is type use tokio::sync::Mutex;.
I'm trying to acquire lock and add values to the list inside of tokio::spawn, which should work async, but I'm getting an error
value moved here, in previous iteration of loop
here is at the end of tokio::spawn(async move {...
Could someone tell me workaround for this?
Here is my code
use tokio::{io::{AsyncBufReadExt, AsyncWriteExt, BufReader},net::TcpListener,sync::broadcast,};use serde_json::json;use serde_json::Value;use tokio::sync::Mutex;use std::sync::Arc;mod user;#[tokio::main]async fn main() {let listener = TcpListener::bind("localhost:8080").await.unwrap();let (tx, _rx) = broadcast::channel(10);let shared_vec: Arc<Mutex<Vec<user::User>>> = Arc::new(Mutex::new(Vec::new()));loop {let (mut socket, addr) = listener.accept().await.unwrap();let tx = tx.clone();let mut rx = tx.subscribe();tokio::spawn(async move {let (reader, mut writer) = socket.split();let mut reader = BufReader::new(reader);let mut line = String::new();loop {tokio::select! {result = reader.read_line(&mut line) => {if result.unwrap() == 0 {break;}tx.send((line.clone(), addr)).unwrap();line.clear();}result = rx.recv() => {let (msg, other_addr) = result.unwrap();let json_msg: Value = json!(msg);let mut vec = shared_vec.lock().await;let mut indices_to_update = Vec::new();for (index, usr) in vec.iter().enumerate() {if usr.get_ip() != &addr {indices_to_update.push(index);}}for _index in indices_to_update {let user = user::User::new(json_msg["username"].to_string(), addr);vec.push(user);}if addr == other_addr {writer.write_all(msg.as_bytes()).await.unwrap();}}}}});}}
答案1
得分: 3
你必须使用 Arc::clone(&shared_vec) 来克隆 Arc，然后将克隆的对象传递给 move block，以便在循环块中使用。如果不克隆，共享的引用将传递给其他线程/块，并且不能再使用。
英文:
You have to clone the Arc to be passed to the async move block using Arc::clone(&shared_vec) in the loop block. You can then pass the new clone to the move block.
Without the clone the shared referenced is passed to the other thread / block and is not allowed to be used anymore.
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