143 lines
4.2 KiB
Python
143 lines
4.2 KiB
Python
from dataclasses import dataclass, field
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from typing import List, Dict, Set
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import threading
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from enum import Enum, auto
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class ResourceType(Enum):
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"""
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表示不同类型的系统资源
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"""
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PRINTER = auto()
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DISK = auto()
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MEMORY = auto()
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NETWORK = auto()
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@dataclass
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class Resource:
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"""
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表示系统资源
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"""
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id: int
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type: ResourceType
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is_available: bool = True
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current_owner: int = None # 当前使用该资源的进程ID
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class DeadlockAvoidanceStrategy:
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"""
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死锁预防和解决的策略
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"""
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RESOURCE_ALLOCATION_GRAPH = 'resource_allocation_graph'
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BANKER_ALGORITHM = 'banker_algorithm'
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class ResourceManager:
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"""
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管理系统资源分配和死锁预防
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"""
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def __init__(self):
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# 资源池
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self.resources: Dict[ResourceType, List[Resource]] = {
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ResourceType.PRINTER: [Resource(i, ResourceType.PRINTER) for i in range(3)],
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ResourceType.DISK: [Resource(i, ResourceType.DISK) for i in range(2)],
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ResourceType.NETWORK: [Resource(i, ResourceType.NETWORK) for i in range(1)],
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}
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# 跟踪资源请求和分配
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self.resource_requests: Dict[int, Set[Resource]] = {}
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self.resource_allocations: Dict[int, Set[Resource]] = {}
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# 死锁预防
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self.allocation_lock = threading.Lock()
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self.deadlock_strategy = DeadlockAvoidanceStrategy.BANKER_ALGORITHM
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def request_resource(
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self,
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process_id: int,
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resource_type: ResourceType
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) -> bool:
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"""
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为进程请求资源
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:param process_id: 请求资源的进程ID
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:param resource_type: 要请求的资源类型
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:return: 如果资源分配成功，返回True，否则返回False
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"""
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with self.allocation_lock:
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# 查找指定类型的可用资源
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available_resources = [
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res for res in self.resources[resource_type]
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if res.is_available
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]
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if not available_resources:
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# 没有可用资源
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return False
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# 分配第一个可用资源
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resource = available_resources[0]
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resource.is_available = False
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resource.current_owner = process_id
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# 跟踪资源分配
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if process_id not in self.resource_allocations:
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self.resource_allocations[process_id] = set()
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self.resource_allocations[process_id].add(resource)
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return True
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def release_resource(
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self,
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process_id: int,
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resource: Resource
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):
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"""
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释放先前分配给进程的资源
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:param process_id: 释放资源的进程ID
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:param resource: 要释放的资源
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"""
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with self.allocation_lock:
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# 验证进程是否拥有该资源
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if (resource.current_owner != process_id or
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resource.type not in self.resources):
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return
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# 标记资源为可用
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resource.is_available = True
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resource.current_owner = None
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# 从分配中移除
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if process_id in self.resource_allocations:
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self.resource_allocations[process_id].discard(resource)
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def detect_deadlock(self) -> bool:
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"""
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使用资源分配图检测潜在的死锁
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:return: 如果检测到死锁，返回True，否则返回False
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"""
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# 使用资源分配图进行简单的死锁检测
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for process, resources in self.resource_allocations.items():
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for resource in resources:
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# 检查资源是否循环依赖
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if resource.current_owner != process:
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return True
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return False
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def resolve_deadlock(self):
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"""
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使用资源抢占解决死锁
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"""
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if not self.detect_deadlock():
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return
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# 从进程中抢占资源
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for process, resources in list(self.resource_allocations.items()):
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for resource in list(resources):
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self.release_resource(process, resource)
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break # 一次释放一个资源 |