Idea for weakening shared state tasks

gistfile1.rs

fn shared_state_task(..., other_ch: comm::chan<()>) {
    while ... {
        ... 
        match msg {
            ... 
            deref {
                ... 
                if new_refcount == 0 { break; }
            }   
        }   
    }   
    comm::send(other_ch, ());
}

fn shared_state_supervisor_task(...) {
    let other_po = comm::port();
    let other_ch = comm::chan(other_po);
    do task::spawn {
        shared_state_task(..., other_ch);
    }
    // FIXME: Once weaken_task is implemented with pipes, these can be merged into one task
    do weaken_task |weak_po| {
        if comm::select2(weak_po, other_po).is_left() {
            fail ~"destroying shared state cell"; // kill actual state task
        } // otherwise the state task signalled us
    }   
}

fn shared_state(...) {
    do task::spawn_unlinked {
        shared_state_supervisor_task(...);
    }   
}