Banker's Algorithm

This C++ program implements the Banker's Algorithm for resource allocation. The program loads a file that contains resource allocation information for 5 processes and finds a safe sequence.

Run the program

On Linux:

Clone this repo and from the folder run the following

g++ main.cpp
./a.out

On Windows:

Beats me

Input File Format

The program reads the input from a file named "input.txt". The format of the input file is as follows:

• The first line of the file contains the available instances of resources A, B and C. These values are separated by spaces. Then it provides the max instances of A, B, and C.
• The next five lines of the file represent the current allocation of resources for each process. Each line contains the current allocation of resources A, B, and C for a particular process. These values are separated by spaces.
• The final five lines of the file represent the maximum demand of each process. Each line contains the maximum demand for resources A, B, and C for a particular process. These values are separated by spaces.

Code Explanation

The program loads the input file and stores the information in arrays. Then, it calls the bankers function, which implements the Banker's Algorithm. If a safe sequence is found, the function returns true, and the safe sequence is stored in the safeOrder vector. Otherwise, the function returns false.

The bankers function takes three arrays as input:

• work: an array of available resources.
• maxRes: a 2D array of maximum resources needed by each process.
• allocation: a 2D array of currently allocated resources for each process.

The function then initializes an array called finish, which keeps track of whether a process has found a spot yet. It also initializes an array called need, which keeps track of the resources still needed by each process.

The function then enters a loop, which runs until a safe sequence has been found. Within this loop, the function checks each process to see if its resource needs can be satisfied. If a process can be accommodated, the function updates the work array and adds the process to the safe sequence. If no process can be accommodated, the function returns false, indicating that no safe sequence exists.

Finally, if a safe sequence is found, the safeOrder vector is printed to the console.

Constants

The program defines the following constants:

• PROCESS_COUNT: the number of processes in the input file.
• RESOURCE_COUNT: the number of resource types in the input file.
• ATTRIBUTE_COUNT: the number of attributes for each resource in the input file.

Globals

The program defines a global vector called safeOrder, which stores the safe sequence of processes.

Functions

The program defines the following functions:

• bankers: the main function that implements the Banker's Algorithm.
• main: the function that loads the input file and calls the bankers function.