C / C++ / MFC

learningvisualc wrote:

my problem is

//
#include "stdafx.h"

#include "iostream"
using namespace std;

HANDLE hThread1 = NULL;	//worker thread 1
HANDLE hThread2 = NULL;	//worker therad 2

HANDLE hEvt1 = NULL;


DWORD __stdcall ThreadProc_1( LPVOID lpParameter )
{
	// populating the list ...
	for(int i = 0; i<10; i++)
	{
		cout<<"populating the list -- "<<i<<endl;
	}

	// after populate the list , set event, then the worker thread 2 will stop waiting and do operation on the list...
	::SetEvent(hEvt1);

	return 0;
}

DWORD __stdcall ThreadProc_2( LPVOID lpParameter )
{
	// wait 
	while(::WaitForSingleObject(hEvt1, 5) == WAIT_TIMEOUT)
	{
		//keep waiting ...
		Sleep(5);
		continue;
	}

	// To do operation on that list...
	for(int i = 0; i<10; i++)
	{
		cout<<"doing operation on that list -- "<<i<<endl;
	}

	return 0;
}

int _tmain(int argc, _TCHAR* argv[])
{
	hEvt1 = CreateEvent(NULL, TRUE, FALSE, NULL);

	//Create the two worker threads
	hThread1 = CreateThread(NULL, 0, ThreadProc_1, NULL, 0, NULL);
	hThread2 = CreateThread(NULL, 0, ThreadProc_2, NULL, 0, NULL);

	// waiting , 
	while(::WaitForSingleObject(hThread2, 5) == WAIT_TIMEOUT)
	{
		Sleep(5);
		continue;
	}

	if(hThread1)
		::CloseHandle(hThread1);
	if(hThread2)
		::CloseHandle(hThread2);

	if(hEvt1)
		::CloseHandle(hEvt1);

	return 0;
}

1. Xie Jinghui wrote:

   while(::WaitForSingleObject(hEvt1, 5) == WAIT_TIMEOUT)
   {
       //keep waiting ...
       Sleep(5);
       continue;
   }
   

   
   
   This has the same effect than:
   
   
   C++

   ::WaitForSingleObject(hEvt1, INFINITE);

   
   
   but is more complex and less efficient as the OS every 5 seconds schedule the thread to be runt again; using a wait timeout of INFINITE is better because the OS suspend the thread and resume it only when the eventis signeled.
   
2. You don't really need to create an event: the second thread could simply wait for the first thread to terminate
   
   
   C++

   ::WaitForSingleObject(hThread1, INFINITE);