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use crate::callback::AppId;
use crate::common::list::{List, ListLink, ListNode};
use crate::hil::time;
use crate::hil::time::Ticks;
use crate::platform::Chip;
use crate::process::ProcessType;
use crate::sched::{Kernel, Scheduler, SchedulingDecision, StoppedExecutingReason};
use core::cell::Cell;
#[derive(Default)]
struct MfProcState {
us_used_this_queue: Cell<u32>,
}
pub struct MLFQProcessNode<'a> {
proc: &'static Option<&'static dyn ProcessType>,
state: MfProcState,
next: ListLink<'a, MLFQProcessNode<'a>>,
}
impl<'a> MLFQProcessNode<'a> {
pub fn new(proc: &'static Option<&'static dyn ProcessType>) -> MLFQProcessNode<'a> {
MLFQProcessNode {
proc,
state: MfProcState::default(),
next: ListLink::empty(),
}
}
}
impl<'a> ListNode<'a, MLFQProcessNode<'a>> for MLFQProcessNode<'a> {
fn next(&'a self) -> &'static ListLink<'a, MLFQProcessNode<'a>> {
&self.next
}
}
pub struct MLFQSched<'a, A: 'static + time::Alarm<'static>> {
alarm: &'static A,
pub processes: [List<'a, MLFQProcessNode<'a>>; 3],
next_reset: Cell<A::Ticks>,
last_reset_check: Cell<A::Ticks>,
last_timeslice: Cell<u32>,
last_queue_idx: Cell<usize>,
}
impl<'a, A: 'static + time::Alarm<'static>> MLFQSched<'a, A> {
pub const PRIORITY_REFRESH_PERIOD_MS: u32 = 5000;
pub const NUM_QUEUES: usize = 3;
pub fn new(alarm: &'static A) -> Self {
Self {
alarm,
processes: [List::new(), List::new(), List::new()],
next_reset: Cell::new(A::Ticks::from(0)),
last_reset_check: Cell::new(A::Ticks::from(0)),
last_timeslice: Cell::new(0),
last_queue_idx: Cell::new(0),
}
}
fn get_timeslice_us(&self, queue_idx: usize) -> u32 {
match queue_idx {
0 => 10000,
1 => 20000,
2 => 50000,
_ => panic!("invalid queue idx"),
}
}
fn redeem_all_procs(&self) {
let mut first = true;
for queue in self.processes.iter() {
if first {
continue;
}
first = false;
match queue.pop_head() {
Some(proc) => self.processes[0].push_tail(proc),
None => continue,
}
}
}
fn get_next_ready_process_node(&self) -> (Option<&MLFQProcessNode<'a>>, usize) {
for (idx, queue) in self.processes.iter().enumerate() {
let next = queue
.iter()
.find(|node_ref| node_ref.proc.map_or(false, |proc| proc.ready()));
if next.is_some() {
loop {
let cur = queue.pop_head();
match cur {
Some(node) => {
if node as *const _ == next.unwrap() as *const _ {
queue.push_head(node);
return (next, idx);
} else {
queue.push_tail(node);
}
}
None => {}
}
}
}
}
(None, 0)
}
}
impl<'a, A: 'static + time::Alarm<'static>, C: Chip> Scheduler<C> for MLFQSched<'a, A> {
fn next(&self, kernel: &Kernel) -> SchedulingDecision {
if kernel.processes_blocked() {
SchedulingDecision::TrySleep
} else {
let now = self.alarm.now();
let next_reset = self.next_reset.get();
let last_reset_check = self.last_reset_check.get();
if !now.within_range(last_reset_check, next_reset) {
self.next_reset
.set(now.wrapping_add(A::ticks_from_ms(Self::PRIORITY_REFRESH_PERIOD_MS)));
self.redeem_all_procs();
}
self.last_reset_check.set(now);
let (node_ref_opt, queue_idx) = self.get_next_ready_process_node();
let node_ref = node_ref_opt.unwrap();
let timeslice =
self.get_timeslice_us(queue_idx) - node_ref.state.us_used_this_queue.get();
let next = node_ref.proc.unwrap().appid();
self.last_queue_idx.set(queue_idx);
self.last_timeslice.set(timeslice);
SchedulingDecision::RunProcess((next, Some(timeslice)))
}
}
fn result(&self, result: StoppedExecutingReason, execution_time_us: Option<u32>) {
let execution_time_us = execution_time_us.unwrap();
let queue_idx = self.last_queue_idx.get();
let node_ref = self.processes[queue_idx].head().unwrap();
node_ref
.state
.us_used_this_queue
.set(self.last_timeslice.get() - execution_time_us);
let punish = result == StoppedExecutingReason::TimesliceExpired;
if punish {
node_ref.state.us_used_this_queue.set(0);
let next_queue = if queue_idx == Self::NUM_QUEUES - 1 {
queue_idx
} else {
queue_idx + 1
};
self.processes[next_queue].push_tail(self.processes[queue_idx].pop_head().unwrap());
} else {
self.processes[queue_idx].push_tail(self.processes[queue_idx].pop_head().unwrap());
}
}
unsafe fn continue_process(&self, _: AppId, _: &C) -> bool {
true
}
}