银行家算法 python

银行家算法是一种死锁避免算法，它可以确保在分配资源时不会发生死锁。下面是一个简单的Python实现：

# 定义银行家算法类
class BankerAlgorithm:
    def __init__(self, available, max, allocation):
        self.available = available  # 可用资源向量
        self.max = max  # 最大需求矩阵
        self.allocation = allocation  # 已分配矩阵
        self.need = max - allocation  # 需求矩阵
        self.safe_sequence = []  # 安全序列

    # 检查是否存在安全序列
    def is_safe(self):
        work = self.available.copy()
        finish = [False] * len(self.max)
        while False in finish:
            found = False
            for i in range(len(self.max)):
                if not finish[i] and all(self.need[i] <= work):
                    work += self.allocation[i]
                    finish[i] = True
                    self.safe_sequence.append(i)
                    found = True
            if not found:
                return False
        return True

    # 分配资源
    def allocate(self, process, request):
        if all(request <= self.need[process]) and all(request <= self.available):
            self.available -= request
            self.allocation[process] += request
            self.need[process] -= request
            if self.is_safe():
                return True
            else:
                self.available += request
                self.allocation[process] -= request
                self.need[process] += request
                return False
        else:
            return False

使用示例：

# 初始化银行家算法类
available = [3, 3, 2]
max = [[7, 5, 3], [3, 2, 2], [9, 0, 2], [2, 2, 2], [4, 3, 3]]
allocation = [[0, 1, 0], [2, 0, 0], [3, 0, 2], [2, 1, 1], [0, 0, 2]]
ba = BankerAlgorithm(available, max, allocation)

# 检查是否存在安全序列
if ba.is_safe():
    print("存在安全序列：", ba.safe_sequence)
else:
    print("不存在安全序列")

# 分配资源
if ba.allocate(1, [1, 0, 2]):
    print("分配成功")
else:
    print("分配失败")