BurritOS/src/kernel/scheduler.rs

74 lines
2.4 KiB
Rust

use std::cell::RefCell;
use std::rc::Rc;
use crate::utility::list::List;
use crate::kernel::thread::Thread;
use super::thread_manager::ThreadManager;
#[derive(PartialEq)]
pub struct Scheduler {
ready_list: List<Rc<RefCell<Thread>>>,
pub thread_manager: Option<Rc<RefCell<ThreadManager>>>
}
impl Scheduler {
/// Constructor
///
/// Initilize the list of ready thread
pub fn new() -> Self {
Self {
ready_list: List::new(),
thread_manager: Option::None
}
}
/// Mark a thread as aready, but not necessarily running yet.
///
/// Put it in the ready list, for later scheduling onto the CPU.
///
/// ## Pamameter
///
/// **thread** is the thread to be put on the read list
pub fn ready_to_run(&mut self, thread: Rc<RefCell<Thread>>) {
self.ready_list.push(thread);
}
/// Return the next thread to be scheduled onto the CPU.
/// If there are no ready threads, return Option::None
///
/// Thread is removed from the ready list.
///
/// **return** Thread thread to be scheduled
pub fn find_next_to_run(&mut self) -> Option<Rc<RefCell<Thread>>> {
self.ready_list.pop()
}
/// Dispatch the CPU to next_thread. Save the state of the old thread
/// and load the state of the new thread.
///
/// We assume the state of the previously running thread has already been changed from running to blocked or ready.
///
/// Global variable g_current_thread become next_thread
///
/// ## Parameter
///
/// **next_thread** thread to dispatch to the CPU
pub fn switch_to(&mut self, next_thread: Rc<RefCell<Thread>>) {
if let Some(tm) = &self.thread_manager {
let rc = Rc::clone(&tm);
if let Some(old_thread) = tm.borrow_mut().get_g_current_thread() {
rc.borrow_mut().thread_save_processor_state(Rc::clone(&old_thread));
// old_thread.save_simulator_state();
if old_thread != &next_thread {
rc.borrow_mut().thread_restore_processor_state(Rc::clone(&next_thread));
// next_thread.restore_simulator_state();
rc.borrow_mut().set_g_current_thread(Option::Some(next_thread));
}
}
} else {
panic!("thread manager shouldn't be none");
}
}
}