python写银行家算法 python银行家算法代码

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mob64ca14116c53 2023-11-30 22:44:45

文章标签 python写银行家算法 python 操作系统银行家算法编程实现 文章分类 Python 后端开发

银行家算法

实验要求
编程实现银行家算法。
流程图

python写银行家算法 python银行家算法代码_python

代码

import threading
import time
import datetime
import numpy as np
from copy import deepcopy
class Process:
    def __init__(self, id:int,allocation:np.ndarray,need:np.ndarray):
        self.id = id
        self.allocation = allocation
        self.need = need
        self.isfinish = False
    def request(self,request:np.ndarray):
        global available
        if self.isfinish:
            raise Exception('Error! Process {} has finished!'.format(hex(self.id)))
        elif (self.need<request).any():
            raise Exception('Error! Request is larger than the process need')
        elif (available<request).any():
            print('Error! Request is larger than the available')
            return False
        else:
            self.allocation += request
            self.need -= request
            available -= request
            if checksafe(print=True):
                print("If accept it the system will be Safe.")
                if (self.need==0).all():
                    self.isfinish = True
                return True
            else:
                print("If accept it the system will be Dangerous.")
                self.allocation -= request
                self.need += request
                available += request
                return False

def checksafe(print=False):
    global available
    global processes
    available_bak = deepcopy(available)
    processes_bak = deepcopy(processes)
    p_list = []
    for _ in range(len(processes_bak)):
        all_finish = True
        for process in processes_bak:
            if process.isfinish:
                continue
            elif (process.need<=available_bak).all():
                available_bak += process.allocation
                process.need -= process.need
                process.allocation -= process.allocation
                process.isfinish = True
                p_list.append(hex(process.id))
                break
            else:
                all_finish = False
    if print:
        printtable(available=available_bak,processes=processes_bak)
    if all_finish:
        printtable(available=available,processes=processes)
        return True
    else:
        return False

def banker():
    if checksafe():
        print('The initial system is safe')
        while (ans:=input('Do you want continue?(Yy/Nn)')) and ans in 'Yy':
            while True:
                try:
                    pid = int(input('Please input the process id:'),16)
                    try:
                        process = processes[pid2index[pid]]
                    except:
                        print('Error! The process id is not exist')
                        raise Exception()
                    break
                except:
                    print('Please input a correct number!')
            while True:
                try:
                    request = np.array(input('Please input the request:'\
                        ).split(' '),dtype=int)
                    break
                except:
                    print('Please input a number!')
            try:
                if not process.request(request):
                    break
            except Exception as e:
                print(e)
                continue
    else:
        print('The initial system is not safe')

def printtable(available,processes):
    print('\n')
    print('Available:',available)
    print('\n')
    for process in processes:
        print('Process',hex(process.id),'allocation:',\
            process.allocation,'need:',process.need)

num_processes = np.random.randint(5,20)
available = np.random.randint(num_processes-5,num_processes+5,size=3)
processes = []
pid2index = {}
for i in range(num_processes):
    processes.append(Process(id=np.random.randint(0,1e9),\
        allocation=np.random.randint(1,10,size=3),\
            need=np.random.randint(1,10,size=3)))
    pid2index[processes[i].id] = i
banker()