How get my object into RwLock<HashMap<u32, RefCell<Client>>>

My struct is defined like this :

struct MyStruct {
clients: RwLock<HashMap<u32, RefCell<Client>>>,

I would like to write a function “find_client_by_id(id)” where I could get the client object directly. This is my final goal. For now, here is what I have to do every time that I want to access a client :

let mut clients =;
if let Some(client_ref) = clients.get(&client_id)  {
    let client = RefCell::borrow_mut(&client_ref);
    client.call_my_function_on_client_object(); // Here I can call client's functions

What I would like, is something like this :

let mut client = self.find_client_by_id(client_id);
if client.is_some() {

Is it possible ? All my tries ended up with compilation error. Thanks

What is the signature of call_my_function_on_client_object? What is your intended signature of find_client_by_id?

I suspect you are running into an issue when trying to return a reference to a Client while letting go of the RwLockReadGuard. Since the HashMap is protected by the RwLock, you can’t access the data stored in the map unless you are holding the lock.

It doesn't matter. But I want my object as mutable.

fn find_client_by_id(&mut self, id: u32) -> Option<&Client> {...}

I found help about how they build what they call a "guard" to keep object alive. Trying with that, but if you have idea, let me know. Thanks

Right, as mentioned, you need to keep guard around in order to hold a reference. This is a little tricky. The namedlock crate does exactly what you want, I think.