//***************************************************************
// illustrates two processes cooperating in a producer/consumer relationship
// This code demonstrates the parent side of handle inheritance.
// The producer/consumer relationship is managed by two semaphores
// EMPTY and FULL, When EMPTY the producer can produce into empty buffer,
// when FULL the consumer can consume buffer.
// Buffers are passed through shared memory implemented as a memory mapped file
// AUTHOR: Chris Wild
// DATE: September 10, 1997
//***************************************************************

#include <windows.h>
#include <iostream.h>
#include <stdlib.h>
const int NBUFFERS = 3;	// allow 3 buffers for bounded buffer
typedef struct{
	int bufID;
	int bufValue;
} Buffer;

void main(void)
{
	HANDLE empty, full;
	HANDLE mapFileHandle;
	Buffer* commonBuffers;
	
	
	// Create the semaphores
	empty = CreateSemaphore(0,NBUFFERS,NBUFFERS, "NTcourse.semaphore.empty");
	full = CreateSemaphore(0,0,NBUFFERS, "NTcourse.semaphore.full");
	cout << "created semaphores\n";
	
	// create in-memory file for Interprocess Communications
	mapFileHandle = CreateFileMapping(
		(HANDLE) 0xFFFFFFFF, // unnamed file maps to virtual memory
		0,	// security
		PAGE_READWRITE,	// access to file
		0,	// high word of file size
		NBUFFERS*sizeof(Buffer), // size of memory mapped area
		"commonBuffer");	// name it to share with other processes
	commonBuffers = (Buffer*) MapViewOfFile(mapFileHandle,
		FILE_MAP_WRITE,
		0,	// High offset
		0,	// Low offest
		0);	// 0 for mapping entire file

    // enter a loops producing some things
	int bufN = 0;
	for(int i = 0; i < 10; i++) {
		// First wait for previous resource to be empty (consumed)
		cout << "PRODUCER: waiting for empty buffer\n";
		WaitForSingleObject(empty, INFINITE);
		commonBuffers[bufN].bufID = bufN;
		commonBuffers[bufN].bufValue = 1000*i;
		bufN = (bufN+1) % NBUFFERS;
		// Have empty resource - use it to produce		
		// put code here to produce something	
		cout << "PRODUCER: producing a new buffer\n";
		ReleaseSemaphore(full,1,0);	// signals production
	}
	
	CloseHandle(empty);
	CloseHandle(full);
	CloseHandle(mapFileHandle);
}