Concurrency Runtime in Visual C++ 2010

// Copyright (C) 2010
// Ajay Vijayvargiya

// This source code was published on CodeProject.com, under CPOL license
// This code CANNOT be used for similar publication on the web or as printed material.
// This can, however, be used as educational reference in educational institutions.
// You are allowed to use the accompanying code in your programs, 
//    commercial or non commercial. 

// This source code is only intended to explicate the Concurrency Runtime in Visual C++ 2010,
// and thus may contain bugs, some logical issues etc.
// The explanation is relevant to Visual C++ 2010 (Compiler version: 16.0)

// http://www.codeproject.com/KB/cpp/parallelcpp.aspx


// For performance benchmarking, simple approach, GetTickCount is used.
// If you prefer, you may use other high performance counters.
// Ignore the importance and non-optimized code, they are just for illustration.



#include "stdafx.h"
#include "examples.h"
#include <iostream>
#include <concrt.h>

// Uncomment following line to enable Debugging in Debug build
 #define _DEBUG_RUNNABLE 1


/************************************************************************/
/* Console Application for illustrating the Concurrency RunTime         */
/* Update History of this Code (project):								*/
/* Sept 1, 2009	First version released,									*/
/*				parallel_for, parallel_for_each, parallel_invoke		*/
/*				and combinable class demonstrated.						*/
/************************************************************************/


/*  Warnings Disabled:

	4244 : parallel_for has some bug when ULONGLONG parameter is passed.
           In short: it deduces number of CPUs needed to put for execution 
  		   and says "possible loss of data" - Can there be ULONGLONG' CPUS? 

*/


using namespace std;

int _tmain()
{
#if defined(_DEBUG) && !defined(_DEBUG_RUNNABLE)
	
	wcout << "Please run this sample with Release build. Debug build will not give "
		"optimum performance for small programs. (Or #define _DEBUG_RUNNABLE 1 to enable debugging).";

	return -1;

#endif


	// --------------------- PROGRAM STARTS HERE ---------------------


	// Ensure that concurrency runtime gets activated.
	// The is NOT mandatory, and is just one of the methods.
	// When you call ANY function/method for parallel execution,
	// the CR initializes itself.

	// The following call is needed to give correct timing, otherwise
	// the first call to CR (like parallel_for), would take some time to 
	// initialize CR and thus timing may be incorrect.
	Concurrency::CurrentScheduler::Get();

	int nChoice;

	wcout << "Sample Console Application to demonstrate Concurrency Runtime." <<
		"\nPlease select one of the options:\n";

	wcout << "\n\t1. Sum of numbers in Parallel\n\t   (parallel_for, combinable).";
	wcout << "\n\t2. Find primes from vector in Parallel\n\t   (parallel_for_each, combinable).";
	wcout << "\n\t3. Find even, odd and primes \n\t   (parallel_invoke).";



	wcout << "\n\n -- Your option: ";
	wcin >> nChoice;


	switch (nChoice)
	{
	case 1:
		ParallelSum();
		break;

	case 2:
		ParallelPrimeFind();
		break;

	case 3:
		ParallelInvokeExample();
		break;

	default:

		wcout << "\n**Not valid option...\n";
	}
	
	wcout << "\n ** Done. Press Enter to exit";
		
	wcin.ignore ( 80, '\n' );		// DONT ASK ME HOW DOES THIS WORK - I found this as quick solution
	wcin.get();	
	
	return 0;
}