Operating system: Banker algorithm (avoid deadlock)

Algorithm Introduction:

Program implementation:

/***************************************************** Program: Banker algorithm Implementation Small single time: November 5, 2013 ******************************* /#include <iostream> #include <string>using namespace std; #define MAXPROCESS 50//  Maximum number of processes to execute # # Maxresource 50//Resource Max//banker algorithm data structure int Available[maxresource];   Available resources vector int Max[maxprocess][maxresource];  Maximum demand matrix int allocation[maxprocess][maxresource];   Allocation matrix int Need[maxprocess][maxresource];  Demand matrix int Request[maxprocess][maxresource];    Data structure in Request vector//security algorithm int Work[maxresource];    Working vector bool Finish[maxprocess];  Indicates whether there are sufficient resources allocated to the process int safeseries[maxprocess];  Safe sequence////////////////////////////////////////////////////int N;   Number of processes in the current system int m; Number of resources in the current system////////////////////////////////////////////////////////////algorithm initialize void Initalgorithm () {cout << " Please enter the total number of processes to be run by the system: "; Cin >> n;cout <<" Enter the number of resources allocated in the system: "; Cin >> M;int i,j;//The initialization of the available resource vectors cout <<" Please enter the current number of available resources for the "<< m <<" class resource: "for (i = 0; I < m; ++i) {cin >> available[i];}  Initialization of the maximum demand matrix cout << "Please enter the maximum demand matrix for each resource in each process (press" << n << "*" << m << "matrix format Input):" << endl;for (i = 0; I < n; ++i) {for (j = 0; j < m; ++j) {cin >> max[i][j];}} Initialization of the allocation matrix cout << "Please enter the allocation matrix (press" << n << "*" << m << "matrix format Input):" << endl;for (i = 0; I < n; ++i) {for (j = 0; j < m; ++j) {cin >> allocation[i][j];}} Initialization of the requirements matrix cout << "Please enter the requirements matrix at this moment (press" << n << "*" << m << "matrix format Input):" << endl;for (i = 0; I < n; ++i) {for (j = 0; j < m; ++j) {cin >> need[i][j];}}} Output resource allocation void Printsrcalloc () {int i,j;for (i = 0; i < n; ++i) {cout << "process P" << I << "Overall allocation:" < < Endl;cout << "\tmax:"; for (j = 0; J < M; ++J) {cout << max[i][j] << "";} cout << endl;cout << "\tallocation:"; for (j = 0; j < m; ++j) {cout << allocation[i][j] << "";} cout << endl;cout << "\tneed:"; for(j = 0; j < m; ++j) {cout << need[i][j] << "";} cout << endl;cout << Endl;} cout << "available resources:"; for (i = 0; i < m; ++i) {cout << available[i] << "";} cout << endl;cout << Endl;} The output at this time process iprocess exploits the analysis of the security algorithm void printsafeseries (int iprocess) {int j;cout << "process P" << iprocess << "Ann Full analysis: "<< endl;cout <<" \twork: "; for (j = 0; J < M; ++J) {cout << work[j] << "";} cout << endl;cout << "\tneed:"; for (j = 0; j < m; ++j) {cout << need[iprocess][j] << "";} cout << endl;cout << "\tallocation:"; for (j = 0; j < m; ++j) {cout << allocation[iprocess][j] <&lt ; " ";} cout << endl;cout << "\twork + Allocation:"; for (j = 0; j < m; ++j) {cout << work[j] + ALLOCATION[IPR OCESS][J] << "";} cout << endl;cout << "finish[" << iprocess << "] =" << finish[iprocess] << endl;cout << Endl;} //Determine if there is a safe sequence bool Issafe () {int i;for (i = 0; i < n; ++i) {if (!  Finish[i]) return false; There is no security sequence}return true;//exists security sequence}//interface void menu () {cout << \t\t =========================================== <                                           < Endl;cout << "\t\t|         | "<< endl;cout <<" \t\t|         Program: Simulation implementation of Banker's algorithm | "<< endl;cout <<" \t\t|         Small single | "<< endl;cout <<" \t\t|                                           Time: 2013.11.5 | "<< endl;cout <<" \t\t| | "<< endl;cout <<" \t\t =========================================== "<< Endl;} Select the process that satisfies the condition//function returns the process number//returns FALSE if no condition exists, otherwise returns Truebool selectprocess (int &iprocnum) {iprocnum = -1;int I, j;for (i = 0; I < n; ++i) {if (Finish[i])//finish[i]! = false{continue;} for (j = 0, J < m; ++j) {if (Need[i][j] > Work[j]) {break;}}  if (j = = m)//satisfies the condition {iprocnum = I;return true; }}return false;} //Security algorithm bool Safealgorithm () {int i,j;//initializes the Finish vector for (i = 0; i < n; ++i) {finish[i] = false;} Initialize work vector for (j = 0; j < m; ++j) {work[j] = available[j];} int iprocnum;//Select the process that satisfies the condition i = 0;while (selectprocess (iprocnum)) {Finish[iprocnum] = true;  Printsafeseries (Iprocnum); The output takes advantage of the analysis of the security algorithm at this time int k;for (k = 0; k < m; ++k) {work[k] + allocation[iprocnum][k];}  safeseries[i++] = Iprocnum;  The process number is added to the safe Sequence Array}if (Issafe ()) {return true;  There is a safe sequence}return false; There is no security sequence}//banker algorithm void Bankalgorithm () {int i,j;cout << "Please enter the process number of the request assignment (0-" << n-1 << "):"; Cin >> I;cout << "Please enter process P" << i << "request allocation for" << m << "class resource:"; for (j = 0; J < M; ++J) {cin >> request[i][j];} Step one for (j = 0; j < m; ++j) {if (Request[i][j] > Need[i][j]) {cout << "requested resource exceeded maximum declared value for resource, request resource failed!" << E Ndl;return;}} Step two for (j = 0; j < m; ++j) {if (Request[i][j] > Available[j]) {cout << "insufficient resources to request resource failed!!" << Endl;retu RN;}} Step three//system to test the investmentThe source is assigned to the process pi and modifies the corresponding value for (j = 0; j < m; ++j) {available[j]-= request[i][j]; ALLOCATION[I][J] + = request[i][j]; NEED[I][J]-= Request[i][j];} Step four//System execution Security algorithm if (! Safealgorithm ())//Detect unsafe, restore the original state {for (j = 0; j < m; ++j) {Available[j] + request[i][j]; ALLOCATION[I][J]-= request[i][j]; NEED[I][J] + = Request[i][j];}} int main () {Menu (); Initalgorithm ();  Printsrcalloc (); Print Current resource status system ("pause"); Safealgorithm (); while (1) {string flag;if (Issafe ()) {//existence of safe sequence cout << "Congratulations!! Resource allocation is successful!! "<< endl;int i;cout <<" A safe sequence exists at this time: "; for (i = 0; i < n-1; ++i) {cout <<" P "<< S Afeseries[i] << "--";} cout << "P" << safeseries[i] << endl;cout << "Do you want to continue?" [y/n]: "; CIN >> Flag;} Else{cout << "Resource allocation failed!" << endl;cout << "Do you want to continue?" [y/n]: "; CIN >> Flag;} if (flag = = "Y" | | flag = = "Y") {;} Else{break;} Bankalgorithm (); Executive banker algorithm}return 0;}

The program test results are as follows:

Operating system: Banker algorithm (avoid deadlock)