72 lines
2.0 KiB
Rust
72 lines
2.0 KiB
Rust
use crate::utility::list::List;
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use crate::kernel::thread::Thread;
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use crate::utility::system::{g_current_thread, g_thread_to_be_destroyed};
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use std::rc::Rc;
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struct Scheduler<> {
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ready_list: List<Thread>
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}
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impl Scheduler {
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/// Constructor
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///
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/// Initilize the list of ready thread
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pub fn new() -> Self {
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Self {
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ready_list: List::new()
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}
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}
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/// Mark a thread as aready, but not necessarily running yet.
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///
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/// Put it in the ready list, for later scheduling onto the CPU.
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///
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/// ## Pamameter
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///
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/// **thread** is the thread to be put on the read list
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pub fn ready_to_run(&mut self, thread: Thread) {
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self.ready_list.push_back(thread);
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}
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/// Return the next thread to be scheduled onto the CPU.
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/// If there are no ready threads, return Option::None
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///
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/// Thread is removed from the ready list.
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///
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/// **return** Thread thread to be scheduled
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pub fn find_next_to_run(&mut self) -> Option<Thread> {
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self.ready_list.pop_back()
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}
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/// Dispatch the CPU to next_thread. Save the state of the old thread
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/// and load the state of the new thread.
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///
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/// We assume the state of the previously running thread has already been changed from running to blocked or ready.
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///
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/// Global variable g_current_thread become next_thread
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///
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/// ## Parameter
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///
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/// **next_thread** thread to dispatch to the CPU
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pub fn switch_to(&self, next_thread: Thread) {
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let old_thread = Box::clone(&g_current_thread).unwrap();
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g_current_thread.check_overflow();
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g_current_thread = Box::new(Option::Some(next_thread));
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old_thread.save_processor_state();
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old_thread.save_simulator_state();
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if(old_thread != g_current_thread) {
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next_thread.restore_processor_state();
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next_thread.restore_simulator_state();
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}
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if(g_thread_to_be_destroyed.is_some()) {
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drop(g_thread_to_be_destroyed.take());
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}
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}
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} |