104 lines
3.2 KiB
Python
104 lines
3.2 KiB
Python
#!/usr/bin/env python3
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"""
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短作业优先调度算法 (SJF)
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Shortest Job First / Shortest Remaining Time First (SRTF)
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"""
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from typing import List, Dict
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from base import (
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Process,
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ProcessScheduler,
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generate_random_processes,
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print_processes
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)
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class SJFScheduler(ProcessScheduler):
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"""短作业优先调度 (Shortest Job First)"""
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def __init__(self, processes: List[Process], preemptive: bool = False):
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super().__init__(processes)
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self.preemptive = preemptive
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def schedule(self) -> Dict:
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"""SJF 调度算法"""
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if self.preemptive:
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return self.schedule_preemptive()
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return self.schedule_non_preemptive()
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def schedule_non_preemptive(self) -> Dict:
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"""非抢占式 SJF"""
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processes = sorted(self.processes, key=lambda p: p.arrival_time)
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ready_queue: List[Process] = []
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current_time = 0
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completed = 0
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while completed < len(processes):
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for p in processes:
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if p.arrival_time <= current_time and p not in ready_queue and p not in self.results:
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ready_queue.append(p)
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if ready_queue:
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ready_queue.sort(key=lambda p: p.burst_time)
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p = ready_queue.pop(0)
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p.start_time = current_time
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current_time += p.burst_time
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self.calculate_metrics(p, current_time)
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self.results.append(p)
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completed += 1
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else:
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current_time += 1
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return self.print_results("SJF (短作业优先 - 非抢占)")
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def schedule_preemptive(self) -> Dict:
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"""抢占式 SJF (SRTF)"""
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processes = sorted(self.processes, key=lambda p: p.arrival_time)
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ready_queue: List[Process] = []
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current_time = 0
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completed = 0
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while completed < len(processes):
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for p in processes:
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if p.arrival_time <= current_time and p not in ready_queue and p not in self.results:
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ready_queue.append(p)
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if ready_queue:
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ready_queue.sort(key=lambda p: p.remaining_time)
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p = ready_queue[0]
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if p.start_time == -1:
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p.start_time = current_time
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p.remaining_time -= 1
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current_time += 1
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if p.remaining_time == 0:
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self.calculate_metrics(p, current_time)
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self.results.append(p)
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ready_queue.remove(p)
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completed += 1
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else:
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current_time += 1
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return self.print_results("SRTF (最短剩余时间优先 - 抢占)")
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if __name__ == "__main__":
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processes = generate_random_processes(n=5, seed=42)
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print_processes(processes, "测试数据")
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print("\n" + "="*60)
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print("非抢占式 SJF")
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print("="*60)
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scheduler1 = SJFScheduler(processes, preemptive=False)
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scheduler1.schedule()
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print("\n" + "="*60)
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print("抢占式 SJF (SRTF)")
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print("="*60)
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scheduler2 = SJFScheduler(processes, preemptive=True)
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scheduler2.schedule()
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