Comunication between threads

[sarambur]

I am developing a program that is loaded at windows startup. At the beggining of my program, i create a thread, that has to wait for a library to be loaded. That library is loaded by windows, and I dont know when exactly is loaded.
So, in the thread, i wait for 30000 milliseconds.
After that, I assume that the library has been loaded by windows, and the thread starts its execution.

I would like to know, how can I pause (from the main program) the thread and how can I resume the execution from the main program too.

I want to know this just in the case, I am able to know when the library I need to be loaded IS loaded by windows.

Thanks in advance,
sarambur

[kuphryn]

Are you referring to a worker threader?

[sarambur]

HANDLE  hThread;

BOOL
WINAPI
DllMain(
    HINSTANCE       hInstance,
    DWORD           dwReason,
    LPVOID          lpReserved)
{

dwThrdParam = 1;
switch (dwReason)
{
case DLL_PROCESS_ATTACH: 
  DisableThreadLibraryCalls ( hInstance );
  
  hThread = CreateThread( 
	NULL,                        // no security attributes 
	0,                           // use default stack size  
	ThreadEscuchaTarjetaUAX,     // thread function 
	&dwThrdParam,				 
	0,                           // use default creation flags 
	&dwThreadId);                // returns the thread identifier 

  // Check the return value for success. 
  if (hThreadTUAX == NULL) 
  {
     MessageBox(NULL,L"CreateThread failed.",L"ERROR",MB_OK);
     return(FALSE);
  }
  break;

case DLL_PROCESS_DETACH: 
  CloseHandle( hThread );
  break;

default:
  return(TRUE);

}//Switch

return (TRUE);
}//DllMain

I dont know what is a worker threader, so, please, have a look at the code, and see for yourself.

After the hThread is launched, I want it to pause its execution until some other events happened.

In fact, the ideal execution is:

-The tread starts its execution and waits for a signal/event/notification/ThreadNotification, whatever.
-The main program does what it has to do and tells the thread to continue the execution via a signal/event/notification/ThreadNotification, whatever again.
-The thread receives the signal/event/notification/ThreadNotification and continues the execution.

I mean something like Wait / Notify, but for windows.


Thanks in advance,
Sarambur

[Valen]

SuspendThread(hThread);
ResumeThread(hThread);

These functions allow for remote manupulation of a thread.

Hope this is what you're looking for!

[NigelQ]

You should also look at WaitForSingleObject which describes almost exactly what you want to do.

Hope this helps,

- Nigel

[sarambur]

Hi NigelQ,

I have read the documentation for the WaitForSingleObject, and I dont know what do I have to put as a parameter in that function.

Do you have an example?

I also dont know what are kind of Objects that the WaitForSingleObject procedure can wait for.

Any example?

[kuphryn]

You pass WaifForSingleObject() a handle to your worker thread and a time in millisecond to which you want to wait. For example:

-----
// m_pWorkerThread is a pointer to CWinThread
//
// ThreadFunc is a function you want to call to perform a job
// ptp is a data structure you use to pass data from main thread
// to worker thread. Usually you will want to pass in data.
//

m_pWorkerThread = AfxBeginThread(ThreadFunc, ptp, THREAD_PRIORITY_NORMAL, 0, CREATE_SUSPENDED);

// Disable auto delete after worker thread ends

m_pWorkerThread->m_bAutoDelete = FALSE;

// Get a handle to the worker thread
// You will need this handle later when you want to delete
// the thread.

m_hWorkerThread = m_pWorkerThread->m_hThread;
m_pWorkerThread->ResumeThread();
-----

// Here is one example of the use of WaitForSingleObject
// Here you use it to wait until the worker thread finishes so
// you can delete it
//

-----
ASSERT(m_pWorkerThread != NULL && m_hWorkerThread != NULL);

// Here you pass WaitForSingleObject() a handle to the worker
// thread and a time indicating how long you want to waint.
// INFINITE means you want to wait infinitely
// If you pass in 25, that means you want to wait 25 milliseconds

::WaitForSingleObject(m_hWorkerThread, INFINITE);
delete m_pWorkerThread;
m_pWorkerThread = NULL;
m_hWorkerThread = NULL;
-----

Kuphryn