操作系統(tǒng)-銀行家算法實(shí)驗(yàn)報(bào)告(共15頁(yè))

1、精選優(yōu)質(zhì)文檔-傾情為你奉上計(jì)算機(jī)操作系統(tǒng)課程設(shè)計(jì) 題 目 銀行家算法分析 學(xué) 院 計(jì)算機(jī)與軟件學(xué)院專 業(yè) 計(jì)算機(jī)科學(xué)與技術(shù)班 級(jí) 學(xué) 號(hào) 姓 名 指導(dǎo)教師 起止時(shí)間 1、 算法綜述 銀行家算法：在進(jìn)程向系統(tǒng)提出資源分配請(qǐng)求時(shí)，算法會(huì)先對(duì)進(jìn)程提出的請(qǐng)求進(jìn)行合法性檢查，即檢查請(qǐng)求的是不大于需要的，是否不大于可利用的。若請(qǐng)求合法，則進(jìn)行試分配。最后對(duì)試分配后的狀態(tài)調(diào)用安全性檢查算法進(jìn)行安全性檢查。若安全，則分配，否則，不分配，恢復(fù)原來狀態(tài)，拒絕申請(qǐng)。2 算法分析2.1 銀行家算法中的數(shù)據(jù)結(jié)構(gòu)為資源的種類 i進(jìn)程的數(shù)量 j可利用資源向量 int Availablej 最大需求矩陣 int Maxij

2、分配矩陣 int Allocationij 需求矩陣 int needij= Maxij- Allocationij申請(qǐng)各類資源數(shù)量 int Request ij i進(jìn)程申請(qǐng)j資源的數(shù)量工作向量 int Workx int Finishy 2.2銀行家算法設(shè)Requesti是進(jìn)程Pi的請(qǐng)求向量，如果Requestij=K，表示進(jìn)程Pi需要k個(gè)Rj類型的資源，當(dāng)Pi發(fā)出資源請(qǐng)求后，系統(tǒng)按照下述步驟進(jìn)行檢查：(1)如果RequestijNeedj,便轉(zhuǎn)向步驟（2）；否則認(rèn)為出錯(cuò)，因?yàn)樗枰馁Y源數(shù)已經(jīng)超過它所宣布的最大值。(2)如果RequestijAvailablej，便轉(zhuǎn)向步驟（3）；否則，

3、表示尚無足夠資源，Pi須等待。(3)系統(tǒng)試探著將資源分配給進(jìn)程Pi，并修改下面數(shù)據(jù)結(jié)構(gòu)中的數(shù)值：Availablej:=Availablej-Requestij;Allocationi,j:=Allocationi,j+Requestij;Needi,j:=Needi,j-Requestij;(4)系統(tǒng)執(zhí)行安全性算法，檢查此次資源分配后系統(tǒng)是否處于安全狀態(tài)。若安全，才正式將資源分配給進(jìn)程Pi，以完成本次分配；否則本次的試探分配作廢，恢復(fù)原來的資源分配狀態(tài)，讓進(jìn)程Pi等待。2.3安全性檢查算法（Check_safe()函數(shù)）(1)設(shè)置兩個(gè)向量：工作向量Work，它表示系統(tǒng)可提供給進(jìn)程繼續(xù)運(yùn)行所需

4、的各類資源數(shù)目，在執(zhí)行安全性算法開始時(shí)，Work= Available。Finish，它表示系統(tǒng)是否有足夠的資源分配給進(jìn)程，使之運(yùn)行完成。開始時(shí)先做Finishi=0；當(dāng)有足夠的資源分配給進(jìn)程時(shí)，再令Finishi=1。(2)在進(jìn)程中查找符合以下條件的進(jìn)程：條件1：Finishi=0；條件2：needij<=Workj若找到，則執(zhí)行步驟(3)否則，執(zhí)行步驟(4)(3)當(dāng)進(jìn)程獲得資源后，可順利執(zhí)行，直至完成，并釋放出分配給它的資源，故應(yīng)執(zhí)行：Workj= Workj+ Allocationij；Finishi=1；goto step 2；(4) 如果所有的Finishi=1都滿足，則表示系

5、統(tǒng)處于安全狀態(tài)，否則，處于不安全狀態(tài)。3、 算法設(shè)計(jì)初始化算法流程圖：銀行家算法流程圖：(1)采用動(dòng)態(tài)輸入的方法對(duì)進(jìn)程個(gè)數(shù)Pnum，資源種類數(shù)Stype,資源總數(shù)Ssum,最大需求Max,已分配Allocation進(jìn)行初始化；(2)根據(jù)已輸入數(shù)據(jù)計(jì)算出需求矩陣Need,可用資源數(shù)Available;(3)利用Check_safe()函數(shù)對(duì)此刻系統(tǒng)的安全性進(jìn)行檢測(cè)，如果安全，給出安全序列；(4)進(jìn)程i提出資源請(qǐng)求，利用Ask_Distribution()函數(shù)檢測(cè)請(qǐng)求是否合理；合理則滿足請(qǐng)求，并給出安全序列；不合理則給出錯(cuò)誤提示；(5)做出開始界面、選擇界面、退出界面，使程序美觀、易操作；4、 編

6、碼實(shí)現(xiàn)（實(shí)驗(yàn)的java代碼）import java.util.Scanner;public class YinHang Scanner in = new Scanner(System.in);int Pnum; / 進(jìn)程個(gè)數(shù)int Stype; / 資源種類數(shù)int Ssum;/ 各類資源總數(shù)int Max;/ 最大需求矩陣int Allocation;/ 已分配矩陣int Need;/ 需求矩陣int Available; / 可用資源數(shù)int Work;/ Available的試分配向量boolean Finish = new boolean50;/ 試分配結(jié)果標(biāo)識(shí)向量public Yin

7、Hang() start();public void start() System.out.println("*");System.out.println(" 歡迎使用銀行家算法");System.out.println(" 羅巾英 ");System.out.println("*");System.out.println("請(qǐng)選擇操作：nt1.開始使用nt2.退出");int a;a = in.nextInt();if (a = 1) input(); else quit();public v

8、oid input() System.out.println("請(qǐng)輸入T0時(shí)刻進(jìn)程個(gè)數(shù)Pnum：");this.Pnum = in.nextInt();System.out.println("請(qǐng)輸入資源種類數(shù)Stype:");this.Stype = in.nextInt();this.Ssum = getSsum();this.Max = getMax();this.Allocation = getAllocation();this.Need = getNeed();this.Available = getAvailable(Pnum, Stype);

9、System.out.println("該時(shí)刻的資源分配表：");output();this.Check_Safe(Available);this.Ask_Distribution(false);public int getSsum() Ssum = new intStype;System.out.println("請(qǐng)輸入各類資源總數(shù)Ssum:");for (int i = 0; i < Stype; i+) Ssumi = in.nextInt();return Ssum;public int getMax() Max = new intPnum

10、Stype;System.out.println("請(qǐng)輸入最大需求矩陣Max:");for (int i = 0; i < Pnum; i+) for (int j = 0; j < Stype; j+) Maxij = in.nextInt();return Max;public int getAllocation() Allocation = new intPnumStype;System.out.println("請(qǐng)輸入已分配資源情況矩陣Allocation");for (int i = 0; i < Pnum; i+) for

11、(int j = 0; j < Stype; j+) Allocationij = in.nextInt();return Allocation;public int getNeed() Need = new intPnumStype;for (int i = 0; i < Pnum; i+) for (int j = 0; j < Stype; j+) Needij = Maxij - Allocationij;return Need;public int getAvailable(int x, int y) Available = new intStype;Availab

12、le = Ssum;System.out.println("進(jìn)程的可用資源Available為：");for (int j = 0; j < Stype; j+) for (int i = 0; i < Pnum; i+) Availablej = Availablej - Allocationij;System.out.print(Availablej + " ");System.out.println("");return Available;public void setFinish(int x) for (int

13、i = 0; i < Pnum; i+) Finishi = false;public boolean Check_Safe(int avail) boolean boo = false;int k = new intPnum;int a = 0;Work = new intStype;for (int i = 0; i < avail.length; i+) Worki = availi;setFinish(Pnum);for (int s = 0; s < Pnum; s+) for (int i = 0; i < Pnum; i+) if (Finishi = f

14、alse) for (int j = 0; j < Stype; j+) if (Needij <= Workj) if (j + 1 = Stype) Finishi = true;ka = i;a+;for (int m = 0; m < Stype; m+) Workm = Workm + Allocationim; else continue; else break; else continue;if (a = Pnum) System.out.println("此刻系統(tǒng)處于安全狀態(tài)，存在安全序列為：");for (int i = 0; i <

15、; Pnum; i+) System.out.print("P" + ki + "t");System.out.println("");boo = true; else System.out.println("此時(shí)系統(tǒng)處于非安全狀態(tài)");choice();boo = false;return boo;public void Ask_Distribution(boolean b) int a = 0;int a0=0;int a1 = 0;boolean bo = false;for (int i = 0; i &l

16、t; Stype; i+) Worki = Availablei;System.out.println("請(qǐng)輸入請(qǐng)求分配的進(jìn)程編號(hào)：");int m = in.nextInt();System.out.println("請(qǐng)輸入請(qǐng)求的各資源數(shù)");int dis = new intStype;for (int i = 0; i < Stype; i+) disi = in.nextInt();for (int i = 0; i < Stype; i+) if (disi <= Needmi) a+;continue; else Syste

17、m.out.println("出錯(cuò)！請(qǐng)求資源數(shù)大于需求資源數(shù)!");choice();break;if (a = Stype) for (int i = 0; i < Stype; i+) if (disi <= Worki) a0=a0+1;if(a0=Stype)for (int j = 0; j < dis.length; j+) Workj = Workj - disj;Allocationmj = Allocationmj + disj;Needmj = Needmj - disj;bo = Check_Safe(Work);continue;

18、else System.out.println("出錯(cuò)！請(qǐng)求資源數(shù)大于可用資源數(shù)!");choice();break;if (bo) for (int i = 0; i < Stype; i+) Availablei = Availablei-disi;if (Allocationmi = Maxmi) a1 = a1 + 1;while (a1 = Stype) System.out.println("(進(jìn)程P"+m+"對(duì)資源的最大需求已滿足，對(duì)其占有資源進(jìn)行回收)");for (int j = 0; j <Stype;

19、 j+) Availablej = Availablej + Allocationmj;break;System.out.println("因此可以滿足" + m + "進(jìn)程的請(qǐng)求，分配后的各種變量值更新為:");output();choice();elsefor (int i = 0; i < dis.length; i+) Worki = Worki + disi;Allocationmi = Allocationmi - disi;Needmi = Needmi + disi;public void output() System.out.p

20、rintln(" 進(jìn)程 maxttallocationt needttavailable");System.out.print("P0 ");for (int i = 0; i < Stype; i+) System.out.print(Max0i + " ");System.out.print(" ");for (int i = 0; i < Stype; i+) System.out.print(Allocation0i + " ");System.out.print("

21、; ");for (int i = 0; i < Stype; i+) System.out.print(Need0i + " ");System.out.print(" ");for (int i = 0; i < Stype; i+) System.out.print(Availablei + " ");System.out.println();for (int i = 1; i < Pnum; i+) System.out.print("P" + i + " "

22、);for (int j = 0; j < Stype; j+) System.out.print(Maxij + " ");System.out.print(" ");for (int j = 0; j < Stype; j+) System.out.print(Allocationij + " ");System.out.print(" ");for (int j = 0; j < Stype; j+) System.out.print(Needij + " ");System.out.println();public void choice() System.out.println("*");System.out.println("“Y”選擇再次輸入n“N”返回銀行家算法初始位置");System.out.println("*");String str = in.next();if (str.equals("y") Ask_Distribution(false); else new YinHang();public void qui