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Banker's algorithm

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Submitted on: 8/5/2011 8:20:37 AM
By: Puneet Jindal 
Level: Advanced
User Rating: Unrated
Compatibility: UNIX C++
Views: 8996
 
     Illustrate banker's algorithm
 
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//**************************************
// Name: Banker's algorithm
// Description:Illustrate banker's algorithm
// By: Puneet Jindal
//
//This code is copyrighted and has// limited warranties.Please see http://www.Planet-Source-Code.com/vb/scripts/ShowCode.asp?txtCodeId=13616&lngWId=3//for details.//**************************************

#include<iostream>
using namespace std;
//	Tells whether a given sequence is safe or not
class Banker
{
	int total_processes;
	int remaining_processes;
	int A_avail,B_avail,C_avail;
	int A,B,C;
	
	class Process
	{
		private:
			int allocated[3];
			int max_needed[3];
			
		
		public:
			Process()
			{
				allocated[0] = allocated[1] = allocated[2] = max_needed[0] = max_needed[1] = max_needed[2] = 0;
				
				cout<<"Enter the allocated resources of types A,B and C"<<endl;
				cin>>allocated[0]>>allocated[1]>>allocated[2];
				
				cout<<"Enter the maximum number of resources needed for each of types A,B and C"<<endl;
				cin>>max_needed[0]>>max_needed[1]>>max_needed[2];
			}
			
			int Allocated(int temp)
			{
				return allocated[temp];
			}
			
			int Need(int temp)
			{
				return max_needed[temp] - allocated[temp];
			}
			
			int Max(int temp)
			{
				return max_needed[temp];
			}
	};
	
	Process *process;
	int *sequence;
	
	public:
	
	Banker()
	{
		A_avail = B_avail = C_avail = 0 ;
		A = B = C = 0 ;
		process = NULL;
		sequence = NULL;
		total_processes = remaining_processes = 0;
		int a,b,c;
		a = b = c = 0;
		
		cout<<"Available resources of type A,B and C"<<endl;
		cin>>A_avail>>B_avail>>C_avail;
		
		cout<<"Enter the total number of processes"<<endl;
		cin>>total_processes;
		remaining_processes = total_processes;
		sequence = new int[total_processes];
				
		cout<<"Please enter the required information of indivisual processes"<<endl;
		process = new Process[total_processes];
		
		cout<<"Enter the sequence(0,1,2 ... so on[in this format])"<<endl;
		for(int i = 0 ; i < total_processes ; ++i)
		{
			cin>>sequence[i];
			a += process[i].Allocated(0);
			b += process[i].Allocated(1);
			c += process[i].Allocated(2);
		}
		
		//	Calculating total number of resources of each type
		A = A_avail + a;
		B = B_avail + b;
		C = C_avail + c;
		bool safe = true;
		
		for(int i = 0 ; i < total_processes ; ++i)	//	Check fesibility of each process
		{
			if( process[sequence[i]].Need(0) <= A_avail && process[sequence[i]].Need(1) <= B_avail && process[sequence[i]].Need(2) <= C_avail )
			{
				//	i'th process can be executed safely
				A_avail += process[sequence[i]].Allocated(0);
				B_avail += process[sequence[i]].Allocated(1);
				C_avail += process[sequence[i]].Allocated(2);
			}
			else
			{
				safe = false;
				cout<<"Unsafe condition encountered after "<<i<<" process"<<endl;
				return;
			}
		}
		
		if(safe == true)
		{
			cout<<"Sequence is safe"<<endl;
			if(! (A_avail == A && B_avail == B && C_avail == C) )
				cout<<"Error encountered in the procedure.Not all resources deallocated."<<endl;
				
		}
		
	}
	
	~Banker()
	{
		delete []process;
		delete []sequence;
	}
};
int main()
{
	Banker b;
	return 0;
}


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