Struct scheduler::RRScheduler

pub struct RRScheduler<T, const MAX_TIME_SLICE: usize> { /* private fields */ }

A simple Round-Robin (RR) preemptive scheduler.

It’s very similar to the FifoScheduler, but every task has a time slice counter that is decremented each time a timer tick occurs. When the current task’s time slice counter reaches zero, the task is preempted and needs to be rescheduled.

Unlike FifoScheduler, it uses VecDeque as the ready queue. So it may take O(n) time to remove a task from the ready queue.

Implementations

impl<T, const S: usize> RRScheduler<T, S>

pub const fn new() -> Self

Creates a new empty RRScheduler.

pub fn scheduler_name() -> &'static str

get the name of scheduler

Trait Implementations

impl<T, const S: usize> BaseScheduler for RRScheduler<T, S>

type SchedItem = Arc<RRTask<T, S>>

Type of scheduled entities. Often a task struct.

fn init(&mut self)

Initializes the scheduler.

fn add_task(&mut self, task: Self::SchedItem)

Adds a task to the scheduler.

fn remove_task(&mut self, task: &Self::SchedItem) -> Option<Self::SchedItem>

Removes a task by its reference from the scheduler. Returns the owned removed task with ownership if it exists.

fn pick_next_task(&mut self) -> Option<Self::SchedItem>

Picks the next task to run, it will be removed from the scheduler. Returns None if there is not runnable task.

fn put_prev_task(&mut self, prev: Self::SchedItem, preempt: bool)

Puts the previous task back to the scheduler. The previous task is usually placed at the end of the ready queue, making it less likely to be re-scheduled.

fn task_tick(&mut self, current: &Self::SchedItem) -> bool

Advances the scheduler state at each timer tick. Returns true if re-scheduling is required.

fn set_priority(&mut self, _task: &Self::SchedItem, _prio: isize) -> bool

set priority for a task