rr_scheduler.hpp

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#pragma once
 
#include <etl/list.h>
 
#include "kernel_config.hpp"
#include "kernel_log.hpp"
#include "scheduler_base.hpp"
#include "task_control_block.hpp"
 
class RoundRobinScheduler : public SchedulerBase {
 public:
  auto Enqueue(TaskControlBlock* task) -> void override {
    if (task) {
      if (ready_queue_.full()) {
        klog::Err(
            "RoundRobinScheduler::Enqueue: ready_queue full, dropping task");
        return;
      }
      // 重新分配时间片
      task->sched_info.time_slice_remaining =
          task->sched_info.time_slice_default;
      ready_queue_.push_back(task);
      stats_.total_enqueues++;
    }
  }
 
  auto Dequeue(TaskControlBlock* task) -> void override {
    if (!task) {
      return;
    }
 
    for (auto it = ready_queue_.begin(); it != ready_queue_.end(); ++it) {
      if (*it == task) {
        ready_queue_.erase(it);
        stats_.total_dequeues++;
        break;
      }
    }
  }
 
  [[nodiscard]] auto PickNext() -> TaskControlBlock* override {
    if (ready_queue_.empty()) {
      return nullptr;
    }
    auto next = ready_queue_.front();
    ready_queue_.pop_front();
    stats_.total_picks++;
    return next;
  }
 
  [[nodiscard]] auto GetQueueSize() const -> size_t override {
    return ready_queue_.size();
  }
 
  [[nodiscard]] auto IsEmpty() const -> bool override {
    return ready_queue_.empty();
  }
 
  [[nodiscard]] auto OnTimeSliceExpired(TaskControlBlock* task)
      -> bool override {
    if (task) {
      // 重新分配时间片
      task->sched_info.time_slice_remaining =
          task->sched_info.time_slice_default;
    }
    return true;
  }
 
  auto OnPreempted([[maybe_unused]] TaskControlBlock* task) -> void override {
    stats_.total_preemptions++;
  }
 
  RoundRobinScheduler() = default;
  RoundRobinScheduler(const RoundRobinScheduler&) = delete;
  RoundRobinScheduler(RoundRobinScheduler&&) = delete;
  auto operator=(const RoundRobinScheduler&) -> RoundRobinScheduler& = delete;
  auto operator=(RoundRobinScheduler&&) -> RoundRobinScheduler& = delete;
  ~RoundRobinScheduler() override = default;
 
 private:
  etl::list<TaskControlBlock*, kernel::config::kMaxReadyTasks> ready_queue_;
};